sae ata lat ale WN Yaad was oyy a rae’ havola ge yo oy ou » sd te Vee ; he OO ara a) tale While ' " ee tae Lt ae PL Ae erry ‘f sha eo Dah Weg eh a eres ies Tae ae LAE he © tae Be re tea) A \ yataly Thain tg VP EMA PA adi ate beg NEES iy CSE Mee aN Py cata eye Wee r + ' aly Lule tee a See Pep Wa a ay He tek Ss he Peewee nies > Sor PiT od aris Ye Sar day riipetee aly ' , » rut Dn aes ee ane te ar oy 5 s SAU at | , . } eae aas ye 4 RNS te oa ve f Viv ? Pata AVA 4 voacn ali MAY ae ; ha Re HtT aw we) weds 4 4 et t " 7 . » 4 sais He Polo o> iy 9 > wi hy a Fue, Rit matt A Win Wi vt 57 A fi UE ahed Bat hip dag mew 4 ‘ esha ea eae CH ee i i Te tat Sys btipeg des usaspui ys A , “df 19 9S) } ETC ahs Cites Uk dau ND sey Ure, Tee Mt ee She i { 5 stn i CNC te cant ama mi a UT ene eae AFH eG) eid - K ni he ae ht EH oe Atala ost a) ast pet eee i) Sih da eo i " Pa ei 7 P held PD WKN ee irk) f EU ae Tt oa nae Divehi be > WA a 7 i FAA} yi i 4 A ADEE, Fees 8, De { { 4 ete Hew SA pele ih, Dat WOE TOV NOUN SEH SH WMD R Ti eMC uate oe A ut 3 Mtr = teva be “ AN eae 5 SO. A ‘ |} ph 4 pi One Te ACat | De YESS A ee ea TR 0d , : itty ® ‘i Ute ’ Le ee | aT Be ee ek ae ‘ Mo bho fol DOA Hy | 4 TE RADY. ae P58) USAR GWE PPG COEF yuh bay ” Hh ‘ 4 ve “irr : (a Ciuaitt #4 py sine oa ee Ghee etch Go asreietoebaie ii H Mehviehed Biter rhe > D Walpe Ge ie hey a i) {Hi Ke A eis ee 3 Voy nea iPr achi dae On AnD Veni ua FURIUT A TRUER LAR Pi NG i bo) hb $2 id ae yi * nuded ae Beak By sa scaritst YD WAT is tine: oy VDE Pe he autre does X y se i PU i ay VF dah hte FAA rt Mehta tf Wx sey he » + f f yw UA i, % ie j ci 5 f oe fy Hira eye; PIN agit syakege im Aw i) a8 : ; 3) OM ied tM “ith rh'bag aE UCR Re Hau ite pina nathan an enaes ist tite Boe He sate any A Ss Ler oh 446 iio it rig tor ibe os ry MEd ain 4s H . 9 han i » p if ‘4 “ i yeas me aM aaah) ; i * dara 1 Aare ; Oth ¥ wana) oy) a = a _ an — = _- eS By Se = z rr g uf Cc e feed | cost { 1 oe oc = * s jo = : oA ad 5 eel) pr S44 40m. - AN INSTITUTION NOILNLILSNI _NVINOSHLINS S3I¥VudiT LIBRARIES SMITHSONIAN _INSTIT iN a ae z is = * = = a o — ow — wo a | : » 5 Be = x A > - > Ke > = . > “2 = 2 i 2 = 2 er 7) 2) ae 29) o Zz o ie D Z o | NS SAINVUGIT_ LIBRARIES SMITHSONIAN INSTITUTION NOILALILSNI_ NWINOSHLIWS S31u\ wn ; ri n a ” = 27) . = < <= < < < = 4 a 4 a UM 4 = 4 \, MSs te. = ro) NS Se Bae a cr] 1 Ww on ” ; NS pe (eR sy Ly wn } O Fa : fe) zr WAN oO = fe) Zz es 2 E Nv 2 E zZ 3 ee Pee 5 : AN INSTITUTION 1p POILALIESNI _NVINOSHIINS S33 byvVudit LIBRARI ES SMITHSONIAN _INSTIT "bar a ea na = ow es an = > : = te = WY) iP ee ” 4 ” 5 ” Ws saluvagiy_ (SMITHSONIAN _ INSTITUTION | NOILOLILSNI_NVINOSHLINS S31¥ uJ = tu : ee ee) = Nl ul = 4 wat Foy ey 4 = : aGPip = < =I < oc “« YY a 3 oc 00 = m (ji = ja) - fan) a = a _ Cc = Aros ide Fe = < - z= Ser J : IAN" INSTITUTION | NOILOLILSNINVINOSHLINS (S31YVYGIT LIBRARIES SMITHSONIAN, INSTI ~ Oo See fe) — ra 4 = | w — ow S _— — wo Yn a Be) \ = a 5 =e) VE. > = > Ok > E i> oe E 2 WY E 2 : ‘2 INS SAIYVUGIT LIBRARIES SMITHSONIAN INSTITUTION NOILOLILSNI NVINOSHLINS S3IU w ay te ” ike ” z 2) =| &, : 5 5 = a SIA. <= Y fii 2 OLY. 5 x 5 N \ NE 4 4 8 zy 8 Pt; ® g 2 «wits WG ? 8G s ia 2 E W224 e 2 A E B 5 iam ee 3 s IAN INSTITUTION NOILOLILSNI_NVINOSHLINS S31NVUGIT LIBRARIES SMITHSONIAN _INSTI ie 2 A a | 3 | PGRN y= z + YQ = = - Uy % fate < Cy SSS = = Wipe c ae - A NEN zi aah fer os 3 = See S a 3 a ear a 4 2 af FA IWS S2IMNYNS@IT LIBRARIES SMITHSONIAN INSTITUTION WOILGHLILSNI NVINOSHLINS S3I% [2 a = a _ ao = { < a << a < G | ee = jong er ~ 4 f = fe 3 = 3 = S) par =z —t zZ re | Fs SNI NVINOSHLINS S3IYVYSIT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI oS Be fas ia = y = = o ee o , = lg w = \ 2 E ° © GY > z - = > e y * i | 2 pas a hee YP fl) ae - | om ‘SS 2 m m = | wm : — op) = w = ' ARI ES SMITHSONIAN INSTITUTION NOILNLILSNI _ NVINOSRIIWS |S fuvudly _t! BRARI ES s z 4 ae a Zz , & 8 & AB zs 2 Z = 2 E Z. E 2 a 2 a 2 rs Saluvy G!7 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI - - a 3 A b u! fe us : u! - a = o be = fea | oes te: = kK > — is > ad : b 2° ; : a) = w = w = 3RARIES SMITHSONIAN INSTITUTION NOILALILSNI NVINOSHLINS S3SI1YVYUEIT ~ ” rd * 22) FL +2) =< ; =r = oN = J z= =I 2 \N MEM ys. oO XX G 2 WS 5 Uf Zi 9 ® 2 WE E ANE Oe E : : “yrs =a ee = 5 = e ” ve Zz “” ILALILSNI_ NVINOSHLINS SSIYVYUGIT LIBRARIES INSTITUTION | = nt < 2 uw po a 7) 7) 5 = oc pa ow hee cx a or « == Dekayia Ambonychia praecursa Orthorhynchula /schyrodonta truncata Modiolopsis modiolaris Rafinesquina ‘a/ternata™ BY Lu <= & ° <= ta = ao ‘o) a 5 Pit Ne aay We © ao ~— (e) A ae ela a/ternata Sowerbyella(Sowerbye//a) sericea Sowerbyel/a(Sowerbyel/a) sericea Palit multisecta LE Sowerbyella (Sowerbye//a) sericea —oa-—- Onniella multisecta Ww ua alee Zygospira modesta a> an = (a) Ss Ww Ww or Be FIG. 15. A composite columnar section from the upper and middle(?) Reedsville in south- central Pennsylvania showing the stratigraphic-faunal separation of brachiopod provinces I and II. See Figure 14 for geographic extent of this overlap. stratigraphic succession of the faunas follows a pattern whereby the linguloids overlie the rhynchonellids (Fig. 15). Brachiopod province III, dominated by orthids and spiriferids, broadly overlaps province II in southwestern Virginia, but there is no marked stratigraphic separation of the faunas. In the southern part of the mixed zone the linguloids of province II disappear suddenly, but Orthorhynchula linneyt is gradu- ally outnumbered by Hebertella sinuata. The two dominant species of brachiopod ORDOVICIAN APPALACHIAN ECOLOGY 31 province III, Hebertella sinuata and Zygospira recurvirostra, only occasionally occur together; they do not occur in any characteristic stratigraphic order as did the species in brachiopod provinces I and II. Gastropoda The distributional pattern of the gastropods is presented in Figure 16. Each of the three gastropod faunal provinces is dominated by species of only one superfamily GASTROPOD ZOOGEOGRAPHY Fic. 16. A generalized outline of the distribution of the most common gastropod species in the central Appalachian Upper Ordovician. The three major gastropod faunal provinces are: I. Pleurotomariid Loxoplocus (Lophospira) spp. Ruedemannia? lirata Sinuopea? II. Bellerophontid Plectonotus? sp. Bucania sp. III. Murchisoniid Murchisonia? Note that in this instance mixing of the faunas in gastropod provinces I and II occurs where overlap takes place. 32 PEABODY MUSEUM BULLETIN 34 (Table 6). Gastropod zoogeography shows strikingly consistent pattern in the central Appalachians throughout the Late Ordovician. Three gastropod provinces have been TABLE 6. Gastropod faunal provinces. See also Fig. 16. Location Abundant Fauna I Central Pennsylvania to central Pleurotomariacea Virginia Loxoplocus (Lophospira) abbreviata L. (L.) perangulata Ruedemannia? lirata Sinuopea? II South-central Pennsylvania to Bellerophontacea eastern West Virginia Plectonotus? sp. Bucania sp. III Northern Tennessee Murchisoniacea Murchisonia? delimited and are again designated I, II, and III. The pleurotomariacean gastropods, whose presence delineates gastropod province I, clearly dominate the easternmost exposures of the upper Reedsville and Martinsburg Formations from central Penn- sylvania to central Virginia, but are also considerably mixed with the bellerophonta- cean gastropods of province II in southern Pennsylvania and south-central Virginia. Where this overlap of province I and II faunas takes place there is no noticeable strati- graphic separation of the faunas, but the stratigraphic range of the faunas of province I, the pleurotomariaceans, is much greater than that of the bellerophontaceans of province II which appear to be more confined to the uppermost portions of the upper Reedsville. The bellerophontaceans are also normally limited to the western- most exposures of the upper Reedsville Formation along this same part of the strike belt. The murchisoniacean gastropods, which constitute gastropod province III, are geographically distinct and not mixed with the dominant northern faunas but appear to occur at the same stratigraphic horizon as the bellerophontaceans of province II, hence occupying the uppermost portions of the upper Reedsville. Bivalvia The north-south zoogeographic pattern outlined by the Upper Ordovician Bivalvia in the central Appalachians is quite similar to that of the Brachiopoda (Fig. 17, cf. Fig. 14). The bivalve faunas are, however, often restricted to the westernmost expo- sures of the upper Reedsville Formation. As in other instances, three bivalve provinces have been delimited, and each of these is characteristically dominated by two or three abundant species (Table 7). Bivalve province I occupies much of central Pennsylvania, with only locally abundant nuculoid and actinodontoid bivalve molluscs. The overlap with province II, a diverse assemblage of mussel-like bivalves, in south-central Pennsylvania shows a marked stratigraphic separation of the two faunas (Fig. 18). The species of bivalve province I are found from 100 to 150 feet lower in the section than those of province II. The fauna of bivalve province II shows the greatest number and diversity of the Bivalvia in the central Appalachians. The four dominant bivalve species in province ORDOVICIAN APPALACHIAN ECOLOGY 33 II are not randomly mixed; rather, they occur in a characteristic stratigraphic order with Tancrediopsis and Ischyrodonta overlying Ambonychia and Modiolopsis (Fig. 18). In addition Modiolopsis modiolaris dominates bivalve province II in the more easterly exposures in central Virginia; Tancrediopsis cuneata and Ambonychia prae- cursa are dominant in south-central Pennsylvania and eastern West Virginia. Tancre- diopsis cuneata and Ischyrodonta truncata are only occasionally found on the same BIVALVE ZOOGEOGRAPHY NORTH Zs + HRY y x + 4 FIG. 17. A generalized outline of the distribution of the most common bivalve mollusc species in the central Appalachian Upper Ordovician. The three major bivalve faunal provinces are: I. Lyrodesma poststriatum Ambonychia radiata Ctenodonta? pulchella Praenucula levata Il. Tancrediopsis cuneata Ambonychia praecursa Modiolopsis modiolaris Ischyrodonta truncata III. Pterinea (Caritodens) demissa Note as was the case with the brachiopod faunal provinces overlay may not indicate faunal mixing since the faunas are separated stratigraphically, see Fig. 18. 34 PEABODY MUSEUM BULLETIN 34 BIVALVE-STRATIGRAPHIC RELATIONSHIPS < Tancrediopsis cuneata /schyrodonta ftruncatra Ambonychia praecursa Modiolopsis mod/o/aris orrhorhynchula Zone UPPER REED SVINEIee FEW BIVALVES =. 250 feet BRACHIOPOD DOMINATED (See fig. 15) | ? | REEDS Vise Lyrodesma poststriatum Praenucu/la /evata aE Crenodonta? pulchella ‘MIDDLE FIG. 18. A composite columnar section from the upper and middle(?) Reedsville in south-central Pennsylvania showing a pronounced stratigraphic-faunal separation of bivalve provinces I and II. See Figure 17 for geographic extent of this overlap. bedding plane, in contrast to the much stronger association between Ambonychia praecursa and Modiolopsis modiolaris. There is a slight mixing of faunas of provinces II and III in southwestern Virginia, where there is no stratigraphic separation like that between I and II in the north. Bivalve province III is as restricted geographically as province I and shows no greater diversity, but. the specimens are more numerous in a series of closely spaced localities. The two dominant species in province III, Pterinea (Caritodens) demissa and Ambonychia cultrata, exhibit no consistent stratigraphic separation, ORDOVICIAN APPALACHIAN ECOLOGY 35 TABLE 7. Bivalve faunal provinces. See also Fig. 17. Location Abundant Fauna I Central Pennsylvania Lyrodesma poststriatum Praenucula levata Ctenodonta? pulchella II South-central Pennsylvania to Tancrediopsis cuneata south-central Virginia Ambonychia praecursa Modiolopsis modiolaris Ischyrodonta? truncata III Southwestern Virginia and northern Pterinea (Caritodens) demissa Tennessee Ambonychia cultrata PALEOAUTECOLOGY Each of the twelve systematically segregated faunal provinces discussed in the pre- ceding chapter was shown to be composed of normally less than four abundant genera and/or species. The important point is, however, that particular faunas do outline discernible zoogeographic patterns, and thus provide a basis for the interpre- tations of the life habits of each of the major taxonomic groups. Furthermore, under- standing why these zoogeographic patterns exist in view of the autecology of the component species will provide for the recognition of probable environmental set- tings. Then by combining the ideas of zoogeography, autecology and the environ- mental setting, further interpretations of the structure of the Upper Ordovician faunal communities can be made. The discussion of the Upper Ordovician invertebrate com- munities will be reserved for the succeeding chapter. BRYOZOA The most important Bryozoa in the central Appalachian clastic facies are trepostomes, although there are rare fragments of cyclostomes and cryptostomes. Morphologically, the trepostomes are commonly ramose; the branches are either subcylindrical or lobate, flattened plates. The diameter of the lobations is not known to exceed 20 mm, and the cylindrical stems may be as thin as 1 mm. Irregular to hemispherical encrusting growth forms occur in a few localities but are never very numerous. Size differences in the diameters of the branches often may be of secondary taxonomic value at any one locality, but extrapolation of these data to nearby exposures was shown to be unreliable. Comparison of the growth forms of the trepostomatous bryozoans with those of Recent bryozoans aids in reconstructing a probable environmental setting for these Upper Ordovician specimens. The most common Upper Ordovician clastic-facies forms are most like the Recent adeoniform and vinculariiform zoarial types (Stach, 1936; Lagaaij and Gautier, 1965)*. Lagaaij and Gautier (1965) have recognized these zoarial types off the Rhone delta and have found them widely distributed in 30 to 140 meters of water with mixtures of the two types in 50 to 80 meters of water, an area which can be generally classified as near the boundary between the inner and outer sublittoral — a quiet-water environment. Lagaaij and Gautier (1965, p. 45) consider the correlation between depth and external morphological type primarily as a reflection of the sensitivity of the bryozoans *Lagaaij and Gautier (1965, p. 51, text-fig. 24) : Adeoniform — zoarium erect, rigid, lobate, firmly attached to firm substratum. Vincu- lariiform — zoarium, erect, rigid, subcylindrical branches, attached to firm substratum. 36 t ORDOVICIAN APPALACHIAN ECOLOGY 37 to sedimentation rate. Maps of species numbers and diversity indicate that most Re- cent bryozoans are able to tolerate only very moderate to low rates of deposition, and therefore they are abundant only in quiet-water environments away from the delta fronts and inaccessible to sediment-laden currents. The common surface of attachment is a very slightly mobile sand-silt (Lagaaij and Gautier, 1965, p. 52). There is no reason to expect the Upper Ordovician forms to have been more tolerant of high sedimentation rates than modern forms. Recent bryozoans adopt an encrusting form when turbulence increases and the substratum becomes more mobile. Similarly, the Ordovician encrusting bryozoans are found in a coarser, better sorted sandstone. In some stratigraphic sections, increase in the silt/mud ratio is accompanied by a change from the ramose to the encrusting habit within the same genus (Fig. 30). Generic diversity as related to sediment influx along the central Appalachian Late Ordovician shoreline is shown in Figure 19. Bryozoans are generally lacking in south- central Pennsylvania, Maryland and northern Virginia, the most probable source of BRYOZOAN DIVERSITY 100 Fic. 19. A generalized outline of trepostomatous bryozoan diversity (genera) in the central Appalachian Upper Ordovician. Of particular note is that the low generic diversity in Pennsyl- vania, northern Virginia and eastern West Virginia may be directly related to the main source of terrigenous clastic influx during the Late Ordovician. Numerals refer to number of genera identified at each locality where abundance of the indi- vidual genus was greater than 2 on the relative abundance scale. 38 PEABODY MUSEUM BULLETIN 34 a major Late Ordovician influx of terrigenous clastics. Immediately to the north and south of this source area, bryozoans are locally common and of the same genus in each locality. In southwestern Virginia and northern Tennessee, well away from the main terrigenous source, many localities have as many as five common genera. The obvious change in sediment type from sands and silts in the north to silty muds and muds in the south and the accompanying increase in bryozoan diversity probably indi- cate less turbulence and a lower rate of sedimentation in the south. Figure 20* is a reconstruction of the probable environmental setting of the bryo- zoans during the Late Ordovician in the central Appalachians. Dekayia dominates the nearshore environments in the muddy silts and sands just off the main source area. Hallopora is abundant in many environments further offshore. With the increased diversity away from the area of clastic influx, there is a mixing of more bryozoan species, and the faunal composition of particular bryozoan populations is very un- predictable. A substratum of muddy silts or muds instead of coarser clastics is much preferred by the Upper Ordovician trepostomes; the diversity gradient may reflect a general gradient in the rates of sedimentation. BRACHIOPODA The interpretation of the life habits of the Upper Ordovician brachiopods is hin- dered by our lack of knowledge of the anatomy and ecology of modern brachiopods. Furthermore, there are no living representatives of the orthids, spiriferids and stro- phomenids, with the possible exception of the Recent genus Lacazella (see Elliott, 1965, p. H857). Some ecological speculations are possible, however, from both living brachiopods and from bivalve molluscs which show morphological and ecological convergence with the brachiopods. *Figures 20-23 are reconstructions of the probable onshore to offshore Late Ordovician environmental settings within each of the four major taxonomic groups based on the stratigraphic relationships (Figs. 15, 18), present zoogeographic distributions (Figs. 13, 14, 16, 17) and the Late Ordovician sedimentological framework of a prograding depositional regime (Fig. 12). Provincial boundaries as depicted in these figures are entirely interpretational and are not plots of collected distributional data. FIG. 20. Reconstruction of the Late Ordovician bryozoan environmental setting in the central Appalachians. [See Fig. 13 which is an outline of bryozoan distribution (zoogeography) compiled directly from locality data without environmental interpretations.] This reconstruction, however, combines stratigraphic, sedimentological and ecological interpretations to form a general pattern of onshore to offshore environments occupied by abundant bryozoans. Genera abundant in these three bryozoan faunas: I. Hallopora II. Dekayia III. Monticulipora Amplexopora Dekayia Heterotrypa Batostomella Peronopora? Hallopora The scale refers to distance along the shore; onshore to offshore exaggeration is approxi- mately <4. a9 ORDOVICIAN APPALACHIAN ECOLOGY gassauual DIvlbslf hte Re niarey eae So JYHOHSNO JFHOHSIIO ie ONILLAS IWLNAWNOYIANS NVOZOAYS auojsowily] a)DYS Seas auo}ss!S went teeets® i g@uo|spuods oe tee 8 Mee ote ete tee teases weet set ee tees GQN3941 40 PEABODY MUSEUM BULLETIN 34 The study of the distribution of marine animals involves salinity, temperature, feeding type and substratum composition. All modern articulate brachiopods are limited to waters of normal marine salinity, and no fossil articulates are known from undoubted brackish-water deposits (Hyman, 1959, p. 520; Rudwick, 1965, p. H211); this indicates that all the central Appalachian Upper Ordovician species, except the linguloid species, were probably restricted to waters of normal marine salinity. By analogy with Recent linguloids, the occurrence of only numerous Lingula? probably reflects brackish-water conditions (Craig, 1952, p. 114). Its occasional mixture with Orthorhynchula linneyi probably indicates, however, other nearshore normally saline environments. Lingula? in the central Appalachians has not been found associated with any articulate brachiopod other than Orthorhynchula linneyt. The sparse information concerning Ordovician paleotemperatures is of question- able significance. Spjeldnaes (1960), Opdyke (1962), Irving (1964) and Whitting- ton (1966) have presented lithologic, paleomagnetic and faunal data in the recon- struction of the climatic zones and geography of the Ordovician. The paleomagnetic data presented by Irving (1964, p. 202), the evaporite-lithologic data of Opdyke (1962, p. 57, fig. 10) and the faunal data of Spjeldnaes (1960, p. 66, fig. 5A) and Whittington (1966, p. 730, fig. 16) are all consistent with a paleoequator that de- scribes an arc bisecting the United States from Wisconsin to Texas. These data indi- cate a subtropical or warm temperate environment for eastern North America during the Late Ordovician. Whittington (1966, p. 731), working primarily with Ordovician trilobites, explains the extremely diverse Upper Ordovician faunas as reflecting the warmest of all Ordovician climates, probably responding to the direction and inten- sities of ocean currents much more than to substratum, | Recent brachiopods, with the exception of Lingula, appear to prefer cooler or deeper waters (Hyman, 1959, p. 594-599), but this may be a consequence of the general reduction in numbers, diversity, and bathymetric distribution of the phylum. The existence of local current patterns (McBride 1960, 1962) during deposition of the Martinsburg and Reedsville Formations must also be considered. Upwelling of colder, deeper basinal waters onto the Ordovician shelf and possible longshore cur- rents could drastically influence the mean annual surface temperature patterns. Bayer (1967, p. 421), working with similar Mid-Continent Upper Ordovician orthid and strophomenid brachiopod faunas (cf. brachiopod faunal province I), considered the large number of individuals of relatively few species characteristic of cooler waters. We have little knowledge of the actual temperature and current controls that may have influenced the distribution of these central Appalachian Upper Ordovician bra- chiopods, although the central Appalachian shelf phosphates suggest a deep-water up- welling as the source of this phosphate. Brachiopods are lophophorate suspension feeders. They do not filter in the same way as some of the filter-feeding bivalve molluscs, which sieve particles through their gill filaments. They feed by producing ciliary currents which bring a constant stream of water over the lophophore (Atkins, 1960; Atkins and Rudwick, 1962). Recent brachiopods are able to adjust the velocity of the feeding current by altering ciliary beat. Food gathering in brachiopods is more nearly equivalent to the filtering mecha- nism used by bryozoans, polychaetes, or crinoids. Food particles are perhaps removed from the water by trapping by a mucous layer on the lophophore (Chuang, 1956), but the mechanism of retention of food particles is not well understood (Jorgensen, ORDOVICIAN APPALACHIAN ECOLOGY 41 1966). There is apparently no sorting of the particles either according to shape or size (Jorgensen, 1966; for evidence of a different kind of sorting mechanism in fossil bra- chiopods see Ager, 1963, p. 58-59), or according to value as food (Rudwick, 1962; Hyman, 1959, p. 589-590). To secure the optimum quantities of suspended organic matter, the mechanism of suspension feeding in the brachiopods may have required less current activity than necessary for the bivalves; therefore, differences in feeding methods may have resulted in the adaptation of brachiopods to life in areas where most epifaunal bivalve mul- luscs had been excluded. However, the rhynchonellid brachiopod Orthorhynchula linneyi is most abundant in an area where there are numerous mussel-like Ambony- chia praecursa, Modiolopsis modiolaris and Ischyrodonta truncata nearby. The orthid Hebertella sinuata and the spiriferid Zygospira recurvirostra are also occasionally found with abundant Pterinea (Caritodens) demissa and locally abundant species of Ambonychia and Modiolopsis. Only the northern brachiopod fauna (faunal province I), dominated by the strophomenids Rafinesquina “alternata” and Sowerbyella (Sowerbyella) sericea and the dalmanellid Onniella multisecta, lacks an extensive epifaunal bivalve molluscan element. Here it is possible that the actual mechanisms of feeding, or a more efficient metabolism, of these brachiopod species could give them a selective advantage over the bivalves, but this is speculative. The substratum, the only major environmental parameter for which we have any direct evidence in the central Appalachian Upper Ordovician, is particularly significant because of the sessile benthonic habit of the brachiopods. It appears that the nature of the substratum may have direct control over the pattern of brachiopod distribution, and also may determine the localization of species within the broader pat- tern of regional distribution. The rhynchonellids are most abundant in the coarse silts and sands. The strophomenids, dominant in the north, are more common in muddy silts, whereas the orthids, both in the north and in the south, appear in silty muds, muds and lime muds. The spiriferids show a preference for extremely fine sediments and are most abundant in the lime muds. Each of these brachiopods may also at times be found in other types of substratum. In addition, it appears that sedi- mentation rates and turbulence, as well as the substratum, play a major role in geo- graphic distribution. Rudwick (1965, p. H212) suggested that while brachiopods may tolerate moder- ate turbulence, they are less tolerant of actual sediment influx. Living brachiopods can interrupt the feeding process, adjust and reverse their ciliary beat to reject too large quantities of suspended particles and if necessary close their valves for several hours. Unlike some bivalve molluscs, they neither can maintain this complete shutdown for long periods nor (with the exception of linguoids) can they change their position if sedimentation becomes too rapid. According to Hyman (1959, p. 588) brachiopod powers of adjusting the feeding currents were a direct adaptation to life on “muddy” substratum where high turbidity occurs intermittently. The segregation of the brachiopod faunas in the central Appalachian Upper Ordovician appears to be the result of the location and rate of the terrigenous clastic influx. The environmental setting of the brachiopods would begin at an early stage in the development of the source areas east of southern Pennsylvania and northern Virginia, when the clastic influx was low and the sedimentation rate low enough to permit the development of a major brachiopod shelf fauna, faunal provinces I 42 PEABODY MUSEUM BULLETIN 34 and III. With increased influx the shoreline prograded westward and distinct near- shore and offshore brachiopod components developed. Lingula? and Orthorhynchula linneyt, faunal province II, were more able to cope with the nearshore increase in terrigenous influx, but never thrived to the south in a presumably less turbid near- shore environment. The dominance of the nearshore faunas of province II reflects a dynamic change in the environmental conditions along the shoreline. Figure 21 is a representation of the environmental setting of the Late Ordovician brachiopod faunas during the development of the Oswego bar and barrier deposits in south- central Pennsylvania and eastern West Virginia. The central Appalachian strophomenids, orthids and spiriferids probably lived in an environment where the average sedimentation rate was low, but where the sporadic occurrence of a high sedimentation rate probably took the form of sudden local turbi- dite flows. The brachiopods may have been able to adapt, to some extent, to these periodic sediment influxes, but localized populations may have been eliminated with subsequent repopulation from some other source. Recurrent orthid-strophomenid faunas in the Mid-Continent Upper Ordovician have been recently described by Bayer (1967). The orthid-strophomenid populations, decimated by increased rates of sedimentation, re-established themselves when sedimentation rates decreased. Since the central Appalachian linguloids and rhynchonellids existed in areas of high sedi- mentation, the possible vertical mobility of the linguloids was apparently an effective adaptation of Lingula?, but the morphological adaptations of Orthorhynchula linney are obscure. A long, stout pedicle and globose, sulcate form may have provided the necessary protection against complete annihilation of large segments of the popula- tion during periods of rapid sediment influx. Again the stratigraphic-sedimentological record seems to support an irregular rate of sedimentation. The transport of near- shore sands along the coast may have been sufficiently sporadic to permit the estab- lishment of large rhynchonellid populations. The morphological adaptations of indi- vidual species are considered in more detail in the systematic discussion of each taxon. Hyman (1959, p. 591) stated that no combination of species of Recent brachio- pods has been shown to recur in a predictable way in Recent level-bottom associa- tions, although as sessile animals the brachiopods would be expected to have some common associations with other sessile, sedentary animals. Like most modern brachio- FIG. 21. Reconstruction of the Late Ordovician brachiopod environmental setting in the central Appalachians. [See Fig. 14 which is an outline of brachiopod distribution (zoogeography) com- piled directly from locality data without environmental interpretations.] This reconstruction, however, combines stratigraphic, sedimentological and ecological interpretations to form a general pattern of onshore to offshore environments occupied by abundant brachiopods. Species abundant in these three brachiopod faunas: I. Rafinesquina “alternata”’ Sowerbyella (Sowerbyella) sericea Onniella multisecta Zygospira modesta II. Orthorhynchula linneyi Lingula? III. Zygospira recurvirostra Hebertella sinuata The scale refers to distance along the shore; onshore to offshore exaggeration is approxi- mately <4. 43 ORDOVICIAN APPALACHIAN ECOLOGY - gasSsaUuUuaT] DIVIBIIA DIUDA/ASUU ag JFJYOHSNO nnenasseagame lt JFYHOHSIAIO — ee = Be ONILLAS IWLNAWNOYIANS CGOdO!IHOVYSs SaSeSe auojsawi 7 a}D0US See UO ING SMESHEA euoispups QN3941 44 PEABODY MUSEUM BULLETIN 34 pods, the central Appalachian Upper Ordovician forms appear to have been gregari- ous (see Mattox, 1955, for a Recent example). Recent brachiopods have a pelagic larval stage that lasts only a few hours. Although it appears that the powers of larval dispersal are limited (Hyman, 1959, p. 590; Rudwick, 1965), I doubt that the vagaries of larval settling alone could account for the absence of a species from an apparently suitable substratum. GASTROPODA An interpretation of the life habits and environmental setting of the Upper Ordovi- cian bellerophontacean and pleurotomariacean gastropods can be made by inference from the Recent Pleurotomariacea; there are no living Bellerophontacea. Batten (1958, p. 169) and Yochelson (1960, p. 215) reviewed the sparse ecologic data, de- rived mainly from the work of Yonge (1947), dealing with pleurotomariaceans. Ar- chaeogastropods require a firm substratum and low turbidity. Their bipectinate, as- pidobranch gills are easily fouled because their ciliary action is not capable of freeing quantities of mud from the gill filaments. Batten (1958) also noted that the majority of recent Pleurotomariacea live at depths between 50 and 200 fathoms and seem better adapted to colder, possibly deeper waters with some, however, tolerating brackish-water conditions. All are presumably macrophagous herbivores, browsing on algal fronds or collecting algal material from the substratum surface (Graham, 19555595149). The Upper Ordovician pleurotomariacean gastropods, faunal province I, are most abundant in fine sandstones and siltstones. The stratigraphic and sedimentologi- cal evidence indicates that they existed farther from shore than the bellophontaceans of faunal province II. The characteristic local patchiness of province I species may reflect the irregular distribution of detrital plant material by gentle currents moving over the substratum. Since the influence of water temperature is difficult to ascertain, I find it difficult to attribute the distribution of Loxoplocus (Lophospira) solely to current patterns. The most abundant bellerophontid gastropod, Plectonotus? sp. of faunal province II, is found in the area where the upper Reedsville silts and sands are transitional upward into the cross-bedded sands and organic-rich muds of the lower Oswego. Plectonotus? sp. is not commonly associated with the pleurotomariaceans, though both types of gastropods inhabit silts of the same general texture. Seemingly this com- bination of Reedsville-Oswego lithologies could be a major influence on the distribu- tion of abundant plectonotid species. The organic-rich black muds of the lagoons may be protected areas of Ordovician algal stands; the browsing of the bellerophontid on the algal fronds would probably place it above any sporadic turbid currents which would tend to clog its delicate ctenidia. The low pH of the organic-rich muds prob- ably prevented the preservation of the calcareous shells of this species, if indeed they did inhabit this region; but shells were preserved farther off-shore, clumped to- gether and often surrounded by a sediment with more organic matter than the surrounding rock. Plectonotus? sp. could have been rafted out into the deeper marine waters on algal fronds during periods of high water, or even have been maintained on a firm substratum if there had been an adequate supply of plant ORDOVICIAN APPALACHIAN ECOLOGY 45 detritus near the site of preservation. The patchiness or clumping of the bellerophon- tids, which is also characteristic of the pleurotomariaceans, could result from a highly localized food source, such as algal material concentrated in shallow basins or hollows between shoals. These also appear to be the areas of the highest concentration of phosphate grains, many forming as internal molds of Plectonotus? sp. In faunal province III the murchisoniid gastropods are confined exclusively to the Upper Ordovician carbonate muds of northern Tennessee, in contrast to the silty sub- stratum of the bellerophontid and pleurotomariid provinces to the north. Figure 22 reconstructs the environmental setting of the gastropod fauna along the Late Ordovi- cian central Appalachian shoreline. Cox and Knight (1960, p. 1290) describe murchi- soniid morphology. These snails have the inhalant siphon characteristic of the meso- gastropods, although they retain features characteristic of the archaeogastropods. Re- cent Pleurotomariacea can exist only in clear waters and on a firm substratum. As Lower Paleozoic pleurotomariacean populations gradually expanded onto a muddier substratum, individuals possessing a ctenidial structure from which mud particles could be more easily removed would have had a selective advantage over those individuals whose powers of removing mud particles from the ctenidia was limited. Along with the development of monopectinate ctenidia, evolutionary changes advantageous to the mud dweller would be the development of an extensible inhalant siphon and the modification of the foot to allow the ancestral mesogastropod to move through or over the soft substratum. Thus the clear separation of the northern bellerophontid and pleurotomariid gastropod faunas from the southern murchisoniid gastropods was probably influenced by substratum type. BIVALVIA The life habits and environmental setting of the central Appalachian Upper Ordovi- cian bivalves may be inferred by comparison with analogous modern bivalve families. Recent nuculoids, mussels and pterioids give some clues as to the ecology of the Upper Ordovician species, but uncertainties exist because only a few Recent studies have gathered enough data for an adequate reconstruction of ancient autecology. Also, some abundant central Appalachian Upper Ordovician bivalve genera — for example, Lyrodesma—permit few comparisons with any known Recent species. As pointed out in the discussion of the Brachiopoda, four of the most critical factors con- trolling the distribution of marine animals are salinity, temperature, feeding type and substratum. These environmental variables, singly or in combination, control the dis- tribution of fossil and Recent Bivalvia. Most Upper Ordovician bivalve species appear to have lived in waters of normal marine salinity, as they either are associated with species that are commonly accepted as being normally marine (e.g., articulate brachiopods) or have Recent morphological analogues that live in waters of normal marine salinity. One possible euryhaline species is the nuculoid Tancrediopsis cuneata, which commonly occurs with numerous speci- mens of Lingula? in the upper parts of the upper Reedsville Formation (see Figs. 7 and 29). Here the upper Reedsville muddy siltstones and sandstones are inter- bedded with the bar-barrier deposits of the Oswego-like sandstones. Tancre- diopsis cuneata may have been able to tolerate periods of fresh-water influx and 46 GASTROPOD ENVIRONMENTAL SETTING LEGEND Sandstone NORTH Siltstone Pennsylvania Shale PEABODY MUSEUM BULLETIN 34 Limestone ul Virginia Tennessee ONSHORE nh uu na | Wlitiitt Se SH Y HAH il SiUatniitt Nl vil OFFSHORE MILES 200 100 ORDOVICIAN APPALACHIAN ECOLOGY 47 accompanying changes in salinity. Parker (1960, p. 310) lists two species of Nuculana, a Recent nuculoid, as occurring in an enclosed lagoonal environment along a considerable length of the northern coast of the Gulf of Mexico. Nuculana was found on both sides of the prograding Mississippi deltaic complex and appar- ently is tolerant of changes in salinity, temperature, and substratum type. The central Appalachian Tancrediopsis cuneata could also have been adapted to a variety of environmental conditions; it is found in sediment types ranging from muds to silts and shows a considerable north-south distribution on both sides of the area of maxi- mum terrigenous influx. The only other possible exception to a normal marine exist- ence may be found in the few isolated patches of abundant Modiolopsis modiolaris along the eastern exposures of the Reedsville Formation in central Virginia. These Upper Ordovician mussel-like bivalves may have occupied an intertidal silt-mud flat situation like that inhabited by the related Modiolus rectum, a common species along the west coast of the United States. Temperature is also likely to have controlled the distribution of the central Ap- palachian Upper Ordovician Bivalvia, but evidence for temperature variations is indirect. Kinne (1963), Read (1964) and Hall (1964) have reviewed and sum- marized a great deal of information pertaining to the distribution and physiological adaptations of the modern bivalves as a function of temperature. Hutchins’ (1947) classic paper outlines the strict temperature tolerances that exist in Recent shelf in- vertebrates. Well-defined latitudinal boundaries of particular associations of Recent bivalves have proved extremely useful in ecological interpretations of Tertiary and Quaternary bivalves. Woodring, Bramlette and Kew (1946), Durham (1950) and Valentine (1961) have shown distinct isothermal control of the distribution of species through time. The north-south temperature gradient of the Upper Ordovician has been surveyed in the discussion of brachiopod life habits, and it appears that the central Appalachian Upper Ordovician shoreline was located somewhere between 10 and 20 degrees of latitude with reference to the paleoequator (see Opdyke, 1962, p. 57, fig. 10), a subtropical or warm temperate environment. Temperature control of the Upper Ordovician Bivalvia may have been effected either by local current patterns or by a broader onshore-offshore change in tempera- ture. Local current patterns have been documented from previous sedimentologi- cal studies in the Reedsville and Martinsburg Formations (McBride, 1960, 1962) and FIG. 22. Reconstruction of the Late Ordovician gastropod environmental setting in the central Appalachians. [See Fig. 16 which is an outline of gastropod distribution (zoogeography) compiled directly from locality data without environmental interpretations.] This reconstruction, however, combines stratigraphic, sedimentological and ecological interpretations to form a general pattern of onshore to offshore environments occupied by abundant gastropods. Species abundant in these three gastropod faunas: I. Loxoplocus (Lophospira) abbreviata L. (L.) perangulata L. (L.) ventricosta Ruedemannia? lirata Sinuopea? II. Plectonotus? sp. Bucania sp. III. Murchisonia? The scale refers to distance along the shore; onshore to offshore exaggeration is approximately a. 48 PEABODY MUSEUM BULLETIN 34 could result from colder upwellings along the shelf. The sharp separation of the species of faunal provinces I and II may reflect an onshore-offshore temperature gradient. The species of faunal province I appear, from stratigraphic and sedimentological evidence, to occupy an outer sublittoral environment; the characteristic patchy dis- tribution of Lyrodesma poststriatum may reflect localized colder currents on the shelf. The species in faunal provinces II and III, predominantly inner sublittoral types, may have adapted to a less localized, longshore, warmer isothermal pattern that extended almost the entire length of the central Appalachains. Figure 23 is a diagram of the bivalve species as they were probably distributed during the development of the Oswego bar and lagoonal deposits. The three main feeding types of most Recent species of Bivalvia are: infaunal deposit or detritus feeders, epifaunal suspension feeders, and infaunal, usually siphon- ate, suspension feeders. All three feeding types are represented in the central Appala- chian Upper Ordovician. Epifaunal suspension feeders dominate the Upper Ordovi- cian, whereas an infaunal suspension feeding habit, which is very common in Recent bivalves, probably existed in only one species, Lyrodesma poststriatum (Table 8). The infaunal deposit feeding habit is summarized in a paper by Yonge (1939) on the Recent protobranch bivalves. The Recent genera Nucula and Solemya corre- spond very closely to the Ordovician Tancrediopsis cuneata, Ctenodonta? pulchella TABLE 8. Upper Ordovician Bivalve Feeding Types Infaunal Epifaunal Deposit Suspension Suspension Tancrediopsis cuneata* Lyrodesma poststriatum* Ambonychia praecursa* Praenucula levata’ Modiolopsis modiolaris* Ctenodonta? pulchella’ Ischyrodonta truncata® Ambonychia cultrata® Pterinea (Caritodens) demissa* Numbers refer to bivalve faunal provinces (Fig. 17) ; 1 = offshore, 2 and 3 = onshore. This chart of Upper Ordovician bivalve feeding types emphasizes the fact that bivalve associations are domi- nated by either infaunal deposit feeders or epifaunal suspension feeders. A reconstruction of the bivalve environmental setting (Fig. 23) shows a pronounced increase in the numbers and diver- sity of infaunal species from onshore to offshore. FIG. 23..Reconstruction of the Late Ordovician bivalve environmental setting on the central Appalachians. [See Fig. 17 which is an outline of bivalve distribution (zoogeography) compiled directly from locality data without any environmental interpretations.] This reconstruction, however, combines stratigraphic, sedimentological and ecological interpretations to form a general pattern of onshore to offshore environments occupied by abundant bivalve molluscs. Species abundant in these three bivalve faunas: I. Lyrodesma poststriatum Praenucula levata Ctenodonta? pulchella Il. Ambonychia praecursa Modiolopsis modiolaris Tancrediopsis cuneata Ischyrodonta truncata III. Ambonychia cultrata Pterinea (Caritodens) demissa The scale refers to distance along the shoreline; onshore to offshore exaggeration is approxi- mately <4. BIVALVE ENVIRONMENTAL SETTING LEGEND ORDOVICIAN APPALACHIAN ECOLOGY Pennsylvania Virginia NORTH Co) 2 © 2 o US 2 + lo} ee i cS o we o © = = Cope is) Ee fo) = aS a i¢p) (op) wn — Tennessee ONSHORE OFFSHORE MILES 49 200 100 50 PEABODY MUSEUM BULLETIN 34 and Praenucula levata; all of these were presumably deposit feeding bivalves. They occupy a number of diverse environments, as do Recent nuculoid species. The few Nuculites found in the central Appalachian Upper Ordovician are also members of the infaunal deposit feeding group, but more closely resemble the Recent genus Nuculana. Epifaunal suspension feeders, dominant in the central Appalachian Upper Ordovi- clan, represent the most important type of bivalve feeding in early Paleozoic time. Though epifaunal suspension feeding bivalves are numerically somewhat less impor- tant today than infaunal ones, the feeding habits of various species of C’rassostrea, Ostrea and Mytilus have been carefully studied. Graham (1949) summarized many of the bivalve feeding types and supplemented the previously reported data with his analysis of the contents of the bivalve stomach. The effects of various types and con- centrations of micro-organisms on the feeding habits and pumping abilities of the epi- faunal suspension feeders have been the subject of a few recent investigations (Davids, 1964), but the data is incomplete and of only limited use. There are numbers of epi- faunal Bivalvia in the Lower Paleozoic living with some abundant brachiopod species and seemingly in direct competition with the Brachiopoda, which feed similarly. The possible adaptive advantages of the Bivalvia which allowed them to dominate the nearshore, more turbulent environments or, conversely, those which may explain the superiority the Brachiopoda had over the epifaunal Bivalvia in quieter sublittoral environments are not known (Figs. 21 and 23 show the offshore area limitations of the Bivalvia as compared to the Brachiopoda). Brachiopod diversity increases notice- ably in the less turbulent, presumably offshore waters, whereas the epifaunal suspen- sion feeding bivalves are much more diverse in a current-influenced, nearshore en- vironment. Mechanisms for dealing with a shifting substratum thus may have been more effective in the Bivalvia than in the Brachiopoda, something that needs further study in modern environments. The infaunal suspension feeder, a very important feeding type in many Recent environments, is rare in the Lower Paleozoic and is represented only by Lyrodesma poststriatum in the central Appalachian Upper Ordovician. The presence of the pallial sinus in the genus Lyrodesma was first figured by Ulrich (1893, pl. 47, fig. 9), and I have collected specimens from the central Appalachians that show an equally well-defined sinus. The evolutionary significance of this scattered, but locally abun- dant, infaunal siphonate bivalve is uncertain. It seems very likely, however, that Lyrodesma did not give rise to the later prolific siphonate fauna, but was rather a short-lived offshoot with no descendants. Newell (1965, p. 19) lists the Family Lyro- desmatidae as a questionable member of the trigonids, and Babin (1966, p. 304, fig. 26) shows Lyrodesma as a possible ancestor of the genus Modiolopsis. But both these interpretations appear to be unlikely with recognition of the distinct pallial sinus. The central Appalachian Late Ordovician substratum is the major environmental parameter for which direct evidence is available. Recent studies have stressed the importance of a suitable substratum for the settling of pelagic larvae of benthic in- vertebrates (Wilson, 1952; Thorson, 1957); and Purdy (1964) summarized the abundance, diversity and distribution of marine invertebrates as a function of sub- stratum type. Carey (1965), working off the coast of Oregon, Sanders (1958) in Buzzards Bay, and Craig and Jones (1966) in the Irish Sea have demonstrated the close correlation between the diversity and abundance of epifaunal and infaunal ORDOVICIAN APPALACHIAN ECOLOGY 51 invertebrates, including bivalves, as related to substratum. Generally, infaunal deposit feeders are most common in the more organically rich, finer-grained sediments. The coarser silt and sand environments are dominated by epifaunal suspension feeders. As Carey (1965, p. 100) has stressed, although there is always a complex of factors at work, particle size of sediment generally decreases with distance from shore, with an accompanying increase in the number of deposit feeding organisms. Savilov (1959), working in the northern Okhotsk Sea, found that a replacement of one feeding type by another was related to distance from shore and substratum type. In the Ordovician, the substratum differences probably account for some of the patterns of bivalve dis- tribution in certain parts of the central Appalachians. The changes in the bivalve species among the three faunal provinces interpreted in the light of these Recent distributions are as follows: The epifaunal suspension feeders dominate the silt and muddy silt nearshore environments, but there is a noticeable decrease in numbers and diversity from province II to province III, with an accompanying decrease in the particle size of the sediment. The presumably offshore faunal province I, abundant in the fine silts and muds, shows a higher percentage of infaunal detritus feeders than the other two nearshore provinces. Savilov (1959) states that in Recent environments suspension feeders predominate in shallow waters whereas infaunal detritus feeders dominate offshore muddy silts. Thus it can now be shown that the twelve systematically segregated faunal provinces each contain species that are not only ecologically compatible within the provinces themselves, but also provide evidence for the definition of distinct marine shelf environments. These environmental interpretations are consistent for those bryozoan, brachiopod, gastropod and bivalve faunal provinces that are superposed without stratigraphic separation (Figs. 20-23; refer also to Figs. 13, 14, 16 and 17). Furthermore this allows for the synthesis of this data into benthic marine communi- ties that are composed of a variety of taxonomic groups and that occupied particular environmental regimes. The following chapter considers this provincial synthesis. APPALACHIAN UPPER ORDOVICIAN FOSSIL COMMUNITIES In the preceding discussion of zoogeography and autecology of the Upper Ordovician faunas it is evident that systematically segregated bryozoan, brachiopod, gastropod and bivalve faunas are not isolated from one another, but rather are closely interre- lated geographically and stratigraphically. Consistent and recurrent associations of species among the twelve faunal provinces has led to the recognition of three main faunal associations, termed communities; these are outlined in Table 9. Two num- erically less significant taxa, the crinoids and trilobites, are also included in Table 9, though neither of these taxa has been treated in detail in this study. The three communities are composed of groups of species, all of which show a high degree of affinity and a pronounced tendency to recur together throughout the Upper Ordovician strata (Table 3; the recurrences are based on those species which show a relative taxonomic density index of 3 or more). This consistent association of certain species was the basis of Petersen’s (1914) concept of a marine bottom com- munity, a concept which is accepted by most marine ecologists today (see Jones, 1950; Thorson, 1957; Valentine, 1961; Fager, 1963; and Speden, 1966), and was employed by Johnson (1962) in his study of Mid-Continent Pennsylvanian assem- blages. Each Late Ordovician community is named for its most conspicuous and co- dominant species. The communities are as follows (the specific designation is omitted throughout the remainder of the text) : 1. Sowerbyella sericea-Onniella multisecta Community 2. Orthorhynchula linneyi-Ambonychia praecursa Community 3. Zygospira recurvirostra—Hebertella sinuata Community The communities are subdivided into seven multi-species populations, also on the basis of consistent species associations and recurrence (see again Table 3; as before, the species considered in the recurrence are those whose density index is 3 or more at any one locality). The communities and populations are similarily defined but the latter are more restricted geographically and stratigraphically; clustering of particular species takes place within the overall community structure and is believed to reflect more localized environmental conditions. Table 10 outlines the seven multi-species populations composing these three Late Ordovician communities, The populations are: 52 53 ORDOVICIAN APPALACHIAN ECOLOGY {DL0gouo1ag DgGh1j013}9 FY DLOg 010 DIDL}INI piogoxaigup eae MLONULY, DLISOMALNIAL Ue Onn cr ed AytunuIUuIOT) pssimap (suap pingsoshz pidoy aq 011914299 ared AOA ael AIaA = -072D)) Daursajg éDIUuosiyIINpy DIDNUIS DI]A}49g99 FY DLOg]NI1UO Ww —p1iigsosnh7 DIDIUNA} DIUOpOLhy IST SLLD] OLIpOU sisg 0]01p 0 Dsinzav1lg piyrhuoqup ‘ds piuvong éDpnsurT Ayrunururory DIDaUNI 1dauury piyIkuoquy ared AIZ A, ared AOA sisg o1paLoun J, ‘ds isnjouoj2a1g DnyIUcYy10Y7I40 pidvyaq —vinyrudys0yj40O DID éDIUuUuDWAapanyY DISapou ivagonurs DLligsogh7Z DIaYI]ng 04I9aS1q]NUL snyI1j07Ghsy ¢DJUOpoUal) DysoIid4juan ("T) “7T D1] a1uuoO DyDQAa} DaniLas aUuawMd IIx aL DININUaDLT Dyojnsuviag ("T) “TJ Dyakqsamos Ayunurwo0r) wnqp144S0g DIDIA9LQqD (21DULaID,, DIJa1UuUC) SUUIN]OO pIourIO $N] 9] 0ST DULSapoLsnT (oudsoygoT) sna0)GoxoT puinbsauyoy DL0G 0110 FT —pyjakquamos Sproul So}IQOTI J, SOATPAIG spodonsey spodoryovig suvozAlg seune J (¢ 214e], Os[e vag) *payst] sarseds ay} Jo Uor}eII0sse JUaIINIII & uo paseq yova “vyjaj4aqayy—vuugsosdzZ pure “piy2tuoqup—vjnyoudys0yj1C ‘vp]a1UuUuQ—vjJakquamog :sarytUuNUIWUOT) [eUNeY ULIDIAOPIC 23e'T OUT, “G6 TTAVL 54 PEABODY MUSEUM BULLETIN 34 Sowerbyella—Onniella Community Strophomenid Population Orthid-Crinoid Population Orthorhynchula~-Ambonychia Community Linguloid Population Rhynchonellid Population Modiolopsid Population Zygospira-Hebertella Community Spiriferid Population Orthid Population It is important to emphasize that the definition of communities and populations is quite distinct from that of the systematically segregated faunal provinces. The bryozoan, brachiopod, gastropod and bivalve faunal provinces occupied distinct geo- graphic areas within the central Appalachians and were strictly defined by the pres- ence or absence of a particular fauna, whereas the Late Ordovician communities are composed of numbers of recurrent species, one or more of which may be absent or rare at a given locality within the area occupied by the community. The areal distribution of the three communities throughout the Upper Ordovi- cian is shown in Figure 24. This is not a reconstruction based on the stratigraphic or sedimentological framework, but rather a plot of the collected data for each central Appalachian exposure. These data can further be viewed stratigraphically, as pre- sented in Figure 6. It cannot be overemphasized that both geographic and strati- graphic presentations are based solely on the association and recurrence of the abun- dant Upper Ordovician species. Figure 6 also details the stratigraphic distribution of the seven multi-species populations. The biofacies relationships of these populations are the basis for a reconstruction of the faunal distribution along the central Appala- chian Late Ordovician shelf. Figure 25 is a reconstruction of the onshore to offshore community distribution based on stratigraphic relationships (Fig. 6), present geographic distribution (Fig. 24), autecological interpretations of the individual faunas (Figs. 20-23) and the Late Ordovician sedimentological framework of a prograding depositional regime (Fig. 12). Figures 26 and 27 are profiles taken across this reconstructed central Ap- palachian Late Ordovician shelf, showing the inferred distribution of the abundant faunal elements (see also Figs. 10 and 11, showing Late Ordovician depositional en- vironments). These figures emphasize the pronounced nearshore to offshore change in abundant faunas, although there is considerable mixing and overlap of the individual species. In Figure 28 the diversity of the preserved Late Ordovician shelf fauna is contoured. The low diversity of nearshore and offshore environments, although documented in the Late Ordovician only by those animals preservable as fossils, is also characteristic of Recent environments. The Late, Ordovician nearshore low count (C in Fig. 28) was probably caused by salinity, temperature and desiccation stress conditions in the lagoonal and tidal flat environments of the upper Reedsville and lower Oswego strata, and by shifting substratum along the margins of the lower Oswego bars and barriers. The offshore low diversity (C’ in Fig. 28) found only in the north, represents predominantly a trilobite fauna not examined in detail, and is com- mon in the lower Reedsville gray-black muds; it appears to reflect, by analogy with ORDOVICIAN APPALACHIAN ECOLOGY 55 LATE ORDOVICIAN FAUNAL ASSOCIATIONS FIG. 24. Distribution of Late Ordovician faunal associations (Communities) in the central Ap- palachians. The data from Figures 13, 14, 16 and 17 are combined to form this distributional pattern (see Table 9 for species composition). Figure 6 outlines the stratigraphic relationships of the faunal association overlaps. The communities are: 1. Sowerbyella—Onniella Community 2. Orthorhynchula-Ambonychia Community 3. Zygospira—Hebertella Community Recent environments, an area of low primary benthonic productivity and poor cir- culation with a low level of oxidation, which is expressed in the texture and colora- tion of the sediments. The areas of high fossil diversities (A and A’ in Fig. 28) indi- cate regions of high primary productivity, normal marine bottom salinities, hence adequate circulation, and suitable substratum attachment sites for the numerous benthic, epifaunal suspension feeding trepostomatous bryozoans (A’) and the articu- late brachiopods (A and A’). Also included in the high diversity in the north (A) are high numbers of infaunal deposit-feeding protobranch bivalve molluscs, which emphasize not only an adequate food supply for the suspension feeders but sufficient organic detritus to support a major infaunal element. 56 ENVIRONMENTAL SETTING—LATE ORDOVICIAN COMMUNITIES LEGEND Sandstone ELIOT er el Sry Siltstone Pennsylvania Shale PEABODY MUSEUM BULLETIN 34 Virginia Tennessee Limestone ONSHORE OFFSHORE MILES 200 100 ORDOVICIAN APPALACHIAN ECOLOGY 57 SOWERBYELLA-ONNIELLA COMMUNITY The fauna of the Sowerbyella—Onniella Community occupies an area extending from eastern and central Pennsylvania to north-central Virginia (see also Bretsky et al., 1969). The environmental setting was presumably outer sublittoral, slightly off and to the north of the Late Ordovician deltaic complex (see Figs. 25 and 26). The pre- dominant substratum type was a silty mud and silt; the fauna appears to have been totally normal marine. Of the two populations which compose the Sowerbyella— Onniella Community, the Orthid—Crinoid Population is found most in silty muds, is dominated by Onniella multisecta and crinoids, and has an overall high faunal diver- sity (Table 10). This population grades seaward into a sparse trilobite fauna which is found in a dark lower Reedsville mud. Species in the Orthid—Crinoid Population grade shoreward into the Strophomenid Population. This latter population is com- pletely dominated by the strophomenid brachiopods Sowerbyella (Sowerbyella) sericea and Rafinesquina “‘alternata’. This Strophomenid Population is, however, only locally abundant in a medium to coarse silt and has a considerably lower faunal diversity than the Orthid—Crinoid Population (Table 10). The strophomenid bra- chiopods are gradually outnumbered by pleurotomariid gastropods in northern Vir- ginia. Although more characteristic of coarser sediment than the Orthid—Crinoid Population, the Strophomenid population ends abruptly shoreward, showing little gradation into the faunas of the Orthorhynchula~-Ambonychia Community, which occupies a similar type of bottom but closer to shore. The faunas of both these populations tend to be patchily distributed within the Sowerbyella—Onniella Community and individuals of a species are often gregarious. The common epifaunal suspension feeders (articulate brachiopods) and epifaunal and infaunal detritus feeders (pleurotomariids and nuculoids) are rarely found mixed together, but recur throughout many local stratigraphic sections. The community is rather abruptly terminated in east-central Virginia, where it ends in a sequence of well-laminated silts and muds, totally unfossiliferous and seemingly undisturbed by biogenic activity. This environmental situation finds a Recent analogue in the deeper- water basin and sill environment described off the coast of southern California by Emery and Hulsemann (1962). Bayer (1967) outlined what appears to be an iso- community or parallel community from the Mid-Continent Upper Ordovician rocks. Bayer’s Thaerodonta (= Eoplectodonta)—Onniella Community has as its major faunal components the Sowerbyella-like Thaerodonta, Onniella, Ctenodonta similis (a nuculoid, probably Palaeoconcha) and Isotelus. FIG. 25. Environmental reconstruction of the Late Ordovician Communities in the central Ap- palachians based on stratigraphic, sedimentological and faunal evidence (see Fig. 24 which out- lines the distribution of Upper Ordovician faunal associations directly from locality data with no environmental interpretations). The generalized distribution of the communities is portrayed at some time during the deposition of the Oswego barrier-lagoonal deposits along the northeastern shoreline. The communities are: I. Sowerbyella—Onniella Community II. Orthorhynchula—Ambonychia Community Ill. Zygospira—Hebertella Community f The scale refers to distance along shoreline; onshore to offshore exaggeration is approxi- mately x 4. PEABODY MUSEUM BULLETIN 34 58 *(svuney Jfoys urayynos 6/7 “BIy JO) Surjzas [eotSo[oyusuIpas oy} Jo uOTONA}suOIaL a}a[duIOD s10UI ev 10J Z] Pue [| ‘OT sean “SI 07 Jojoy ‘sonrunumuoy v7ja1uuQ—vyjadtquamog pure viyrtuoqup—vjnyrudy10y7z4¢—) ay} Ul seuNey yUepUNge ay} Jo UONNAINSIP patajut ayy, ‘gz ‘Old ALINQNWWOO ALINNWWOO VIHOANOGWNYV VIT3SINNO - VINHONAHYOHLYO ~VW1T13A8YNSMOS o4sOdo||DH D}D4I| DJ UUDWEepENnYy DIJEYoINd DsUOpOUByD DJ DAG] DINONUEeDI,g wnioisssysod pwseposky SNYPO¥dKIO euowAjoo1xe|4 —— $n} eos} splouiso pssepow psidsobAZ DJOOSI4INW DIjeluuUO pedonuis ‘dds (p4idsoydo 4) snoojdoxo7 D20148S (DjJeAqsaMOS) DI|eAquemMoS ,040U20410 DUINbseUlyoY SIJDJOIpOW sisdojOo! pow ee Dsunoenid pyyohuoquy ! DIiADyeQg ese \Aeuui] Dj NYyoUukYsOY AIO ene ae D}JDOUNIL DZ-UOPOIAYOS| = —— ‘ds piupong ee | Dg apa ‘ds snjouojoeld | EES RE DP APPA D ALARA Aan DyDeUND sisdoipei9uDdL = AAA RODD DDN pinbultq ———— Eee | SYOHSNO JYOHSIA0 SVNNV4 ST3SHS NYSHLYON 59 ORDOVICIAN APPALACHIAN ECOLOGY ‘(seuney J[ays UlsyIJOU “gz “BIq JO) Surjas [eo1Soojusurtpas ay} Jo uoTJON.AWsUOdaI a}a]d -WI0D a10U & IOJ Z] pue |] ‘OJ Sernsry 0} ajay ‘AyUNWIWIOT D7J/a74aqGaFJ—-V4Igsosh7Z ay} Ul seUNe; JULpUNQe 2Y} Jo UONNIIjsIp pasisojuI ay, /Z “Old Dsodouosed pdAksjoso}oH D||ewo,So,oG pDiuOsiyounpw & DI$SOFIAANOGI DIAIdSOBAZ piodoxeajduy DJD44|ND DIYOoOKAUOquY DSSIWEP (SUBPOJIIDD) DEUIIAatd D4Iodo||DH DIOd!Ijnoljuop DIADYeQ DJDNUIS DI |esJeqay ALINQNWWOSD VIISLYSESH- VYlIdSODAZ Ss SJYOHSNO SYOHS44I0 SVNNV4 STSHS NYSHLNOS 60 LATE ORDOVICIAN DIVERSITY LEGEND Sandstone NORTH Siltstone Pennsylvania Shale Limestone PEABODY MUSEUM BULLETIN 34 i ue Virginia Tennessee ONSHORE a ee es ee an Gas es —— 2. OFFSHORE MILES 200 100 ORDOVICIAN APPALACHIAN ECOLOGY 61 The Orthid—Crinoid Population may be compared to the Recent Yoldia hyper- borea Community of Sparck (1937). This community is common in subarctic waters of 10 to 70 meters depth, and its fauna is dominated by a variety of infaunal, detritus feeding protobranchs (Yoldia, Nucula and Leda) in a muddy substratum. The Late Or- dovician Orthid—Crinoid Population in north-central Pennsylvania consists, in part, of an abundant but patchy distribution of the infaunal photobranch genera Ctenodonta?, Praenucula and Palaeconcha, also in a muddy substratum. The analogy is made to emphasize only an apparent similarity in the feeding habits of the abundant bivalve molluscs in Recent and Late Ordovician muds. Any extrapolation of depth and tem- perature conditions is very speculative. ORTHORHYNCHULA-AMBONYCHIA COMMUNITY The fauna of the Orthorhynchula~Ambonychia Community extends from south- central Pennsylvania to south-central Virginia. The environmental setting appears to have been predominantly inner sublittoral and intertidal. The sediments preserve a record of nearshore environments, including barriers, beaches and lagoons, and these particular faunas appear to have thrived only in this sedimentological regime (Figs. 25 and 26). The substratum was highly variable, from a muddy silt and silty sand to a coarse, well-sorted sand. It appears that members of the community were able to tolerate periods of variable salinity. The nearest-shore fauna, the Linguloid Population, is dominated by large numbers of very few species (Table 10). This population is in some way related to the proxi- mity of an upper Reedsville—lower Oswego shallow marine-barrier-lagoonal environ- ment (see Fig. 8) that developed immediately south of the Late Ordovician deltaic complex in central Pennsylvania (Fig. 25). It is possible that the southward trans- port of sands by longshore currents from this deltaic complex permitted the develop- ment of the barriers. Directly seaward of the barriers in the upper Reedsville are found organically rich muddy silts and sands, highly reworked biogenically, and in- habited by a few eurytypic species able to tolerate the variable stress conditions such as changes in salinity and current reworking of the bottom sediment. Conditions of vari- able intensity of current reworking are manifested by occasional concentrated patches of phosphate grains, which accumulated in shallows during periods of low sedimenta- tion, limited circulation and high productivity. In direct contrast are the interbedded, FIG. 28. Reconstruction of Late Ordovician generic diversity in the central Appalachians based on apparent diversity as shown only by those animals preservable as fossils. It is important to note, however, that the onshore to offshore low fossil diversities are characteristic of Recent shelf environments. The stratigraphic-sedimentological framework is the one used in Figures 20-23 and Figure 25 (see esp. Fig. 25 for generalized environmental distribution of Late Ordovician com- munities). Diversity Genera A & A’ — High 15 B — Moderate 6-15 Cc & C’ — Low 1-5 The scale refers to distance along the shore; onshore to offshore exaggeration is approxi- mately x4. PEABODY MUSEUM BULLETIN 34 62 = aqqeynueprun _Dyvusayp,, vuinbsauyoy ( pruswioydo.ys ) wauuy vjnyoudysoyz4O (prfeuoyoudys) DIvNUIs Dj]3}4999 (Pryi40) DLOGUNII4UOW pikoyaqd D104 0]]0 H (sourojsoda.} ) NOILV1NdOd GIHLYO StLDJOIpOW sisgojoipow ( prydsouzorpour) iDjoipps DiyIhuoqup DIDLYINI DIYIMUoqUPp (sprryoAuoquue ) pssimap (suapojuvy)) vaur.ajig ( prorszayd ) i DIUOSIYIIN WW ( piruostyonur ) D4sysounsnzas DLIGSOTLT ( pHxaqiatds ) pLogoxajqup D4L0G0]]0 DLOGYNI4UOP {psogouoLag Dghsq01919 FY D1] 9UL0}SO]0g (sauro}sodal} ) :epodoryoeig : eozoAIg : epodoryorlg : BOZOAIG NOILV1INdOd GIasTalds re ee ee AyrunuIwi0T) 011914399 —-D411gsoshZ °¢ DIDLAYJNI vIYICUOqUp psanzavig viyIhuoqup (sprryoAuoque ) SILDJOIPOWU sisgo]o1po-w (prydzourorpout) NOILV1NdOd CISdOTOIGON > BIATRAT. Dsinzavig viysItuoqup (piryoAuoquie ) S1DjOIpOW sisgojoipop (prydzouzorpour ) wauur pjnyoudysoyj1C) (prjeuoqoudyz) pidoyaqd (sur10}soda}) DLA Leth sf : epodoryorig : BOZOAIG erred =NOLLVINdOd GITIENOHONAHY :epodoljyses) DIvIUNA] DJUOPOLAY IST ( prouos14} Jo prydiourorpout) DyDauny sisgoipasmun [, ( ptoynonu ) > VIATeATG ipiupsng ésnjouoj2ajq = epodorseyy (sppuoydosay[eq ) evnsurT (projnsur,) :epodoryoeig NOILV1INdOd CGIOTNONIT Ayrunuiuw07r) piystuoqup—vjnyrudysoyz40 “SG — s[euuinjoo prour9 snyj104G hy gUuawMd)D IIx apy $a} 0ST DIDIpDL DIYIKUOqup (piryoAuoquie ) wunjo144sjsog pDusapos'T DIDAa] DININUavsT Dyay2jng j{vjuopouar/y) (sptopnonu ) DIDI) {DIUUDWapaNY ( przewi0j01na7d ) panisas (vpjadquamog) vijadqsamog ( prusuoydol}s ) Disapou v4sigsosh7 (presttds ) D4I9S1qJINU DIJIIUUC ( pryizo ) DLOG OND FT (au10}sodaJ} ) :@aprloully : BUGOTT, : BIA[VAIG :epodoljysesy) : epodoryoeig 3 :e2ozoAIg NOLLV1INdOd GIONIYO-dIHLYO ivagonurs DjSOI1jUAaA Ca) DIDInsuvLag (qn) 96 p4012914QqD (vsrgsoygoT) $nI0]G oxo T (sprtzeui0jo1na{d ) _D}0uLIyV,, Duinbsauyoy paniuas (vpakqsamog) vpjakquamog (sprusuoydo,ys ) :epodomsesy : epodoryoeig NOLLV1NdOd GINANOHdOULS AYLUNUIUIOL) DauUuUQ—vpJatquamos *T ee OO eee ‘suolje[ndog pue sat}IUNWIWIOL) ULIDIAOPIO 93e'T ueryoreddy [enuan ‘O] aTavL 63 ORDOVICIAN APPALACHIAN ECOLOGY “(LS61 ‘uosioy ,,) syidap [es0331,qQns JQUUI 9}e19pOU 0} MOTTeYS *‘suI0}}0q PNUI 3JOs ‘soT}TUNUIUIOT) UN1Y7149/) IO DI]A}14AN [ :uolelndog prayiuidg ‘s}UUIUOIIAUD yey [epy sjqissod ‘sonseyo snoudssi119} JO xnyur pue xo[duiod o1e}[ap Ureuw Jo yyNOs £Jfeys Surdoys Aj}uss ‘peoiq & uo [e10}}1[qQns 19}no pue JaUUTI spnul su] — spnui — spnut Aj{[Is ‘uu J, uzay}Jou pue ‘eA UJo}samMy NOS 01191499 a —v411gsosh 7 ‘7X9} OY} UI peMatAad SI I[qQeI SITY} UIYIIM poyesodsooUr [eo}yeUI ayy, ‘SUOTyeWIxOIdde [e1aUas AraA ATUO Sv “IaAQMOY “PaMaIA aq 3SNUL YOIYM sonSZojeur yusoy 2[qQIssod jo ourpjNo jariq & SI papnyoUy ‘sayTUNUWIWOD UeIOIAOpIC Joddy uetyoeyeddy [esjus0 oy) jo Areumtuns YW “[] aATaVL “(LG61 “uosz0y J ) s19}@M ystued duTIeNyss pue pez9}[2Ys ‘suI0}}0q PNUI MOT -[eys ‘sorunuiui0ry viwusopudys ‘(0961 “9G6I “EG6I “stepueg) Avg sprezzng ‘punos ‘| “J — spnur Ayyis ‘spnur ‘A4qrunurw0ry vs29u1 shyigan-puixo1g pjnonny "(0961 “t947%q) FIND YWON — uoose], posopuy 6 aL :uoneindog projnsury ‘UOT}e}USUIIpas xoTduIoD dIe}[9P YIIM pozer1o0sse Aj[e1893 UT ¢ s}UsUTUOITAUS [euoose|—yovoq—so111eq SUIpNyoul ‘TeprjsojUur pur [e10771[qns J9uUUT MOTTE YS sq[Is APpnul — spurs "BA [eIqUI_ -YyNOs 0} ‘eg [e41}UI9-YyNOS piyrtuoqup—vjnyIudyLoyj1CV “(LE61 “yoredg) vpaT ‘vjnanny ‘p1ipjo X JuepuNnqe — d101eqQns — $19}9UI (Q/ 0} 0] — spnur ‘AyunUIWIOT) Dasoguagay vipjo x suoneindog proursg—prywO *xo[dUIOD OTe}[ap JO prem -¥9S 5 [V10}}1[qQns 13}n0 spnul Aq[Is — s}[Is ‘eA [e1}U90-Y}IOU 07 ‘eg [e13U99 pue Usa3sv9 DyjauuQ—vjakquamog suonetndod URIDIAOPIO 93¥'T 0} sonso[VuL JUIIII I[QISssOg sutqjas Je }UIWIUOIIAUD patiojuy ad4} winyesysqns rofeyy uo1e00] o1ydeis0a4y SoTJIUNUIUIOT) 64 PEABODY MUSEUM BULLETIN 34 well-sorted, cross-bedded sands of the bars and barriers. Figure 29 reconstructs a very general environmental setting of the Linguloid Population, showing both the domin- ance of the epifaunal and infaunal detritus feeders and the probable primary food source in the lagoonal and off-beach algal stands. The beach and tidal flat environ- ments of the lower Oswego are characterized by only a few elongate, slender, vertical worm tubes and a very few linguloids. Seaward, however, the Linguloid Population grades rapidly into the Rhynchonellid and Modiolopsid Populations. The former, dominated by Orthorhynchula linneyi and Ischyrodonta truncata, is located seaward of the bars and barriers where there is a sandy bottom, whereas the Modiolopsid Population, Ambonychia praecursa and Modtolopsis modiolaris, seems to have pre- ferred a muddier substratum. Gradations are common between these two latter populations, but where the silts become extremely muddy only the Modiolopsid Population, and Modiolopsis modiolaris in particular, is numerous. The faunas of both Rhynchonellid and the Modiolopsid Populations are composed of epifaunal suspension feeders, of moderate diversity, occasionally patchy in distribution, resem- bling Recent shallow mussel-dominated habitats. The sediment is, however, often thoroughly reworked; a major infaunal element may thus have been locally present. Whereas the Linguloid Population ends abruptly in central Virginia (see Fig. 6) with little evidence of mixing with the Zygospira—Hebertella Community, some species of the Rhynchonellid and Modiolopsid Populations grade over a fairly broad area with the dominant southern faunas. In the north there is only a very limited seaward mixing with the faunas of the Sowerbyella—Onniella Community. A review of the Recent marine literature points up three possible modern analogues to the Linguloid Population: the enclosed lagoonal assemblage along the northern coast of the Gulf of Mexico (Parker, 1960, p. 310); the Nucula proxtma—Nepthys inctsa Community in the muds of Buzzards Bay, Massachusetts, and Long Island Sound (Sanders, 1956, 1958, 1960) ; and the Syndosmya Communities in the shel- tered mud bottoms and estuaries along the coast of Denmark (Thorson, 1957, p. 510). In diversity, numbers and kinds of species, bathymetric position and substratum type, these Recent communities are quite comparable to the Late Ordovician environmen- tal setting of the Linguloid Population. ZYGOSPIRA-HEBERTELLA COMMUNITY The fauna of the Zygospira—Hebertella Community extends over much of south- western Virginia and northern Tennessee. The environmental setting appears to have included both inner and outer sublittoral regimes, with possibly an occasional lagoonal or tidal flat occurrence. The broad, gently sloping shelf that seems to have existed in the south-central Appalachians during the Late Ordovician allowed for the devel- opment of a virtual shallow epicontinental sea. This area was well south of the major terrigenous influx (Figs. 25 and 27). The predominant substratum type was a silty mud, mud and lime mud. The environment appears to have been normal marine in character with the exception of a few places where brackish water would have existed on low, gently sloping tidal flats. In the central Appalachians the Zygospira—Hebertella Community is the closest approximation to a typical, highly diversified Mid-Continental shallow sea fauna. 65 ORDOVICIAN APPALACHIAN ECOLOGY saqn} Wiom spuods job\y7 DyoouNnIY DLUOPOsAYIS/ 3 p{paUuNID i>) SiISAO/PaAsIUDL ©) ‘ds piuogng @ GS snjovo0sIa/g { 6 o/nbul7 VNNVG4 d suiloi6hb ayoyudsoud —— ajous a= aUud{S4IIS we bulppaq-ssoi9 REG auojspuos ADOTOHLID iN a4 —— 85 50010 8 eee Sete See ah anions S Qotke a =e foie d aot SSD m sept 3 m ee tees aoe a eactens = ee op) ieee Sees Se sore —G © < a3Au3aSaud py ohh ner (er a he = SNIVW34 1 bere d4y4omau ANOISIIIS 3NIN VW r IVNAW4 ON : ATHOIH Aganw MO1T1VHS m —_——— = -—— ————_ — _ pear ——S eS 2s == : sTisso4 ae onc ee ae ates kee 8 Suaiyuve foe ee oi §-SsSoud ‘3syuvoo suva ee a VLA La. 9 ee at AIO iS C'(R9 Sao SS Sage) Oo WA bot Yo SONVLS Ty9oO7V HOIY ATTVOINYOYO at = =< ea ees ae 4 Sai 171S-anw TVNOO9V7 m SS SINE ye oe UA Oi a ee eg en ee Se ao - 2/7617 M34 Sly14 ao SNLOUO{IA/d as Vv ATNO ST3NN Sa re GNYS~—J 415 VHO ONISMONS ene es sy le ee Git = DIUDA|ASUUadg DIUIBJIA 4SOM Nie S TVENEWINOSTANA NOCHARy aiiicdGds C/O7ION /7 —<————— 13514) 06 NOILOAS 43LISOdWOD 66 PEABODY MUSEUM BULLETIN 34 The community is dominated by epifaunal suspension feeders. The species are gener- ally very widespread and the individual populations tend to be much less patchy than those in the north-central Appalachians. Although both Spiriferid and Orthid Popu- lations contain numerous trepostomatous bryozoans, Zygospira recurvirostra is con- sistently characteristic of the muds and lime muds, along with a variety of epifaunal, suspension feeding ambonychiid and pterioid bivalves and the possibly epifaunal mur- chisoniid gastropods. The Orthid Population is characterized by numerous Hebertella stnuata and the trepostomes Monticulipora and Dekayia in silty muds and muddy silts. The Spiriferid and Orthid Populations intergrade over the entire area covered by the Zygospira—Hebertella Community, and both also exhibit considerable mixing with the Rynchonellid and Modiolopsid Populations of the Orthorhynchula—Ambony- chia Community to the north and northeast. There is, however, only limited mixing with the deeper-water Sowerbyella—Onniella Community to the north. There is one possible Recent analogue to the Spiriferid Population, the Turntella or Cerithium Communities that occupy soft mud bottoms at shallow to moderate inner sublittoral depths (Thorson, 1957, p. 514). The analogy is again only a rough ap- proximation of the probable Late Ordovician environmental settings. Table 11 is a brief survey of the environmental settings and probable Recent analogues of the central Appalachian Late Ordovician communities. CONCLUSIONS This study has shown that the Upper Ordovician rocks in the central Appalachians enclose a shallow marine fauna that exhibits not only a distinctive onshore to offshore distributional pattern but also a longshore one. The combined zoogeographic and autecological study also has pointed out that the nearshore environments are com- monly dominated by bellerophontid gastropods, nuculoid and modiomorphid bivalve molluscs, and linguloid and rhynchonellid brachiopods, whereas the offshore regimes are composed predominantly of orthid, strophomenid and spiriferid brachiopods, crinoids and trepostomatous bryozoans. This general distributional pattern is modified significantly by the position of the major source area in central Pennsylvania as the characteristically offshore brachiopods and bryozoans come to occupy more nearshore environments in southwestern Virginia and northern Tennessee farther away from this major deltaic complex. The effect of this deltaic complex acting as a barrier to the migration and dispersal of the Late Ordovician benthic marine invertebrates has yet to be explored in detail since this study was confined exclusively to those marine environments immediately off and to the south of the complex. The recognition of these three Late Ordovician benthic invertebrate communi- ties furthermore has emphasized the likelihood of mapping parallel benthic com- munities for any segment of the geologic past, and will not only permit more detailed explanations of the evolutionary development of selected taxonomic groups, but also presents the issue of community stability and evolution over extended periods of geologic time. Many problems of the evolution of stable community structures — what kinds of benthic communities are stable, where they are most stable and how long they remained stable — remain virtually untouched. Additional studies of Late Ordo- vician fossiliferous rocks in eastern and central North America should provide the data needed to elaborate the development of benthic community structures on these Late Ordovician shelf environments. Only a few other Paleozoic studies, however, have emphasized the community approach in studying the history of life. The most noteworthy contributions are Copper’s (1966) study of Devonian atrypid brachiopods, which is primarily autecological; and the synecological studies of Elias (1937), Johnson (1962), Zangerl and Richardson (1963), Laporte (1967), Stevens (1966) and Sutton et al. (1966). There is a great need for further detailed paleoecological investigations throughout the entire Paleozoic record in order to attempt to trace well-defined fossil communities throughout this extended period of geologic time. Although the structure of marine benthic communities is generally thought to be relatively uncomplicated, and the basic food-web pattern (producers, consumers, de- composers and transformers) was probably established by the early Paleozoic, the prospects for studying community evolution in the Paleozoic are especially promising. This is the time of initial phylogenetic radiation of many invertebrate groups. The 67 68 PEABODY MUSEUM BULLETIN 34 length of time a community maintains a constant faunal composition would seem to provide a key to the evolution of a stable community structure. By tracing the evolution of marine invertebrate community structures throughout a long period of geologic time, we can begin to document variable rates of change in the faunal composition of the community and thus recognize particular benthic environmental settings where community stability or instability exists. A synthesis of detailed Paleozoic community faunal compositions should point out major changes in the faunal composition on benthic communities at particular times and in specific places on the marine shelf. Periods of major reorganization of shelf invertebrate faunas are well known and have been the subject of numerous papers especially concerned with the causal factors in this change in faunal composition. To date one of the more serious flaws in any discussion of the paleoecology and evolution of benthic invertebrates is that the invertebrate taxa have been considered as almost exclusively separate entities or as parts of only a very general marine realm, With in- creased knowledge of these ancient communities, species and higher categories may be viewed as part of an integrated community structure subject to a variety of biotic and physio-chemical factors whose interactions determine the stability or instability of the organization of a particular community. ee SYSTEMATIC PALEONTOLOGY INTRODUCTION In this study of the central Appalachian Upper Ordovician faunas more than 95 per cent of the total fauna belonged to three phyla: Bryozoa, Brachiopoda and Mollusca (Gastropoda and Bivalvia). Specimens of Arthropoda (Trilobita) and Echinoder- mata (Crinoidea) were much more scattered and rare. Since identification of the abundant specimens was critical to the outlining of the zoogeographic distribution and faunal associations, preliminary ecological data, identifications, and descriptions of the various Bryozoa, Brachiopoda, Gastropoda and Bivalvia were submitted to spe- cialists within each field for their critical evaluation. Species-level taxonomy was normally possible within the Brachiopoda and Mollusca, given sufficiently well-pre- served materials. Within the Bryozoa, however, generic identifications were thought reasonably sound, but species-level taxonomy in this group awaits a more thorough taxonomic investigation. For the major part of this study, I examined material which I had collected from the central Appalachians. Descriptions and identifications, however, were reviewed in light of the relevant comparative literature for the Paleozoic of North America as well as some outstanding taxonomic contributions on the Lower Paleozoic faunas of Europe. I attempted to place each central Appalachian taxon into the most accept- able category. No new taxa are introduced, but my reservations concerning any par- ticular classification are placed in the discussion of each taxon. Synonymies are in- cluded where species-level identification seemed feasible in view of the data I had accumulated. Previous descriptions from strictly systematic literature could, I believe, be somewhat more critically evaluated in light of the new ecological data, i.e., an integrated morphological and distributional approach. It cannot be overstressed that features unknown to me in any of the taxa described may be found in other collec- tions. The following descriptions pertain only to those specimens collected by me from the Upper Ordovician rocks of the central Appalachians. The format used in this section normally consists of Synonymy-Description-Mate- rials-Discussion for each species, but a general discussion is substituted where species- level taxonomy was not possible. All the materials used in this study are deposited in the Peabody Museum of Yale University along with a complete card index indicating species abundance, faunal and lithologic associations for the individual taxon at each locality and/or horizon. Localities are listed by number on p. 135. 69 70 PEABODY MUSEUM BULLETIN 34 - BRYOZOA Plates 3-9 The Bryozoa constitute an important faunal element in the central Appalachian Upper Ordovician clastic facies. Although normally less abaundant than the Mollusca and Brachiopoda, Bryozoa may be co-dominant locally with spiriferid, orthid and rhynchonellid brachiopods. . A survey of the central Appalachian Ordovician literature reveals an almost com- plete lack of recent bryozoan taxonomic investigations, and as Boardman and Utgaard (1966, p. 1082) pointed out, there are few usable illustrations of the established Paleozoic taxa. Current taxonomic philosophies and concepts stress the re-evaluation of type materials through extensive microsectioning; much of the pre-1960 bryozoan literature lacks adequate treatment of microstructure and therefore is of limited use. Utgaard and Perry (1964) presented detailed descriptions of some Upper Ordovi- cian trepostomatous bryozoans and included a valuable historical review of these changing taxonomic philosophies with special reference to the Cincinnatian Mid- Continent species. Recent papers of taxonomic value used in studying the Bryozoa are those of Bassler (1953), Boardman (1960), Ross (1963) and Brown (1965). Par- ticularly useful were earlier papers by Cumings (1908) and Cumings and Galloway (1913, 1915), in which numbers of zooecial wall microstructures were examined in detail for the first time. The current taxonomic re-evaluation by those investigators mentioned above places the definition of many Paleozoic taxa in doubt. I have undertaken only a generic-level assignment of the central Appalachian bryozoan taxa. Species-level bryozoan taxonomy would not have contributed materially to this study and probably should await complete taxonomic reviews. PuyLum BRYOZOA SuBPpHYLUM ECTOPROCTA CLtass GYMNOLAEMATA OrpER TREPOSTOMATA SuBorDER AMALGAMATA Famity MONTICULIPORIDAE Genus MONTICULIPORA Plate 3, figures 1-3 Identification of the genus Monticulipora is based on the analysis of 12 microsections of specimens from localities in southwestern Virginia. The zoaria are characteristically ramose and frondescent; the median diameter of the 12 sectioned specimens is 11 mm. Zooecial walls are thin in the endozone but finely laminated zooecial linings are present in the exozone. Planar and cystose diaphragms are abundant throughout the entire zooecium. Mesopores are common and clustered on monticules; there are few acanthopores and these occur only at zooecial corners. Assignment of these specimens to the genus Monticulipora is substantiated by the recent generic redescription by Boardman and Utgaard (1966, p. 1093). Excellent plates and descriptions of certain Cincinnatian species of Monticulipora are also pre- ORDOVICIAN APPALACHIAN ECOLOGY 71 sented by Utgaard and Perry (1964, p. 42). I tried to avoid possible misidentification of these specimens with the very similar genera Prasopora or Prasoporina by using an extensive Paleozoic trepostome catalogue made available to me by Dr. Richard Board- man of the U. S. National Museum. The genus Monticulipora is abundant (see Table 3 for numbers; relative density index equal to or greater than 3) only at localities 141 and 142 in southwestern Vir- ginia, although it is present at a number of nearby localities (loc. 132, 128, 125; possibly 126 and 140; see Fig. 1). Where Monticulipora is abundant, the most com- monly associated faunal elements are a smaller ramose Dekayia, Zygospira recurvi- rostra, Ambonychia cultrata, Pterinea (Caritodens) demissa, and Modiolopsis modio- laris, all part of the Spiriferid Population of the Zygospira—Hebertella Community. Monticulipora is geographically confined to southwestern Virginia and northern Ten- nessee; its distribution is much like that of Batostomella and Amplexopora, i.e., bryo- zoan faunal province III (see Fig. 13). The associated faunal elements, including Dekayia, are more widely distributed geographically than is Monticultpora. Famity HETEROTRYPIDAE Genus DEKAYIA Plate 3, figure 4; plate 4, figures 1-6; plate 5, figures 1-4 Identification of the genus Dekayia is based on the analysis of 41 microsections of specimens from localities in West Virginia, Virginia, and Tennessee. The zoaria are commonly ramose and have a median diameter of 9 mm. Only a few encrusting forms have been identified. Zooecial walls are characteristically thin and crenulated in the endozone, but there are distally curved, finely laminated zooecial linings in the exo- zone. There are a few thin, simple diaphragms in each zooecium; they are irregularly spaced in the exozone. Mesopores are rare, but acanthopores are common and are usually exozonal, oblique to the axis of the zooecia and occur at the zooecial corners. The genera Dekayia and Dekayella were cited by various investigators as occurring in the central Appalachian Upper Ordovician clastic facies, but their figures and descriptions, for the most part, depended on hand specimens and are now of little use. It was not until Boardman and Utgaard (1966, p. 1103) emended the defini- tions of Dekayia and Dekayella that I was able to assign these Upper Ordovician specimens to the genus Dekayta. Dekayella is considered by them to be a junior sub- jective synonym of Heterotrypa. Dekayia is one of the most widespread Bryozoa in the Upper Ordovician clastic facies (bryozoan faunal provinces II and III, see Fig. 13) ; only Hallopora is more widely dispersed. Dekayia is numerous in three distinctive faunal associations, the Spiriferid and Orthid Populations of the Zygospira—Hebertella Community and the Rhynchonellid Population of the Orthorhynchula~Ambonychia Community. Table 12 outlines these associations. West Virginia locality 203 exhibits a particularly well-exposed section where there is a change in the external morphology of Dekayia specimens accompanying a change in the silt-mud ratio. Figure 30 depicts about 40 feet of this upper Reedsville section at locality 203 (North Fork Mountain, West Virginia). At least two samples (A-6301, A-6302) contain abundant fine, stem-like fragments in a silty mudstone. Fifteen to 72 PEABODY MUSEUM BULLETIN 34 , i s _ TABLE 12, The associated faunal elements of Dekayia in northern Tennessee, southwestern Virginia and eastern West Virginia. i ————— SSS eEEEeEaSanhnana98B9R98RERa9RBEpBaRBaBaRES@Q@Q@oeeeeeee—e—e—e—e——e—eeeeeeeeeeeee OOOO Cumberland Mt., Va. Big Ridge and Wallen East River Mt., Peters Mt., Va. North Fork Mt., Va. and Ridge, Tenn. Powell Mt., Va. W. Va. Locality numbers 128 1320037 141 | 186,190,202,203 Associated faunal Hallopora Monticulipora Orthorhynchula linneyi elements Hebertella sinuata Zygospira recurvirostra Ambonychia cultrata Zygospira recurvirostra Modiolopsis modiolaris Ambonychia praecursa Murchisonia? Modiolopsis modiolaris Pterinea (Caritodens) demissa Population Orthid Spiriferid Rhynchonellid Substratum mud and silty mud silty mud muddy silt and silt ‘ COLUMNAR DE KAY/A ASSOCIATED ~ SECTION MORPHOLOGY FAUNAL ELEMENTS 40' ee ee Se Se es i ee As 'f Tancrediopsis cuneata — NO Dekayia Plectonorus? sp. f Lingu/a? 35 — = — — ——_. _ — Dekay/a; encrusting on Orthorhynchu/a Or thorhynchula /inneyi lobate |O-15 mm. diameter /schyrodonta truncata branches Legend 30' lnaanl a. |A-6311 Sandstone ——— Tancrediopsis cuneata Stereos Plectonotus? sp. areas ? Shall Lingu/a: i /schyrodonta truncata Limestone === ah 20' Dekayia: \|obate |0-I5 mm. diameter ; subcylindrical 7-15 mm. Orthorhynchula linneyi ; diameter Ambonychia praecursa Modiolopsis modiolaris — 10' ad || a “a Dekay/a: subcylindrical 7-12 mm. diameter Modiolopsis modiolaris subcylindrical |-2 mm. Ambonychia praecuret diameter A-6301 bo! == FIG. 30. Variability in external morphology of the trepostome genus Dekayia at locality 203 i North Fork Mountain, West Virginia. ““A-numbers” refer to the Peabody Museum catalogued 4, collection. ORDOVICIAN APPALACHIAN ECOLOGY 73 twenty feet above the bed containing these two samples, sample A-6304 contains abundant larger cylindrical branches in addition to a few massive lobate forms in a muddy siltstone. The final appearance of numerous Dekayia specimens is in sample A-6311, where massive lobate and encrusting forms predominate in a shelly siltstone. The encrusting Dekayia are usually found on the disarticulated valves of the large rhynchonellid brachiopod O. linneyi. Dekayia is absent where the sands are fairly well sorted and there is sedimentological evidence of considerable substratum mobility, such as channeling and intraformational conglomerates. These three distinct morphological types of Bryozoa in the Upper Ordovician are similar to modern (or Recent) bryozoan shapes and may serve as indicators of environ- mental setting. The nature of the substratum and the intensity of the water move- ment appear to be the main controlling factors in bryozoan morphology off the present Rhone delta (Lagaaij and Gautier, 1965). In the Upper Ordovician, the finer sub- cylindrical forms are more common in the muddier sediments; the stout lobate and encrusting habits predominate where there is a higher percentage of sand and silt (Fig. 30). All were presumably firmly attached to the substratum. Where Dekayia is abundant, the rates of deposition were apparently low to moderate, but turbulence may have been at a maximum higher in the section where the substratum consisted of sand and rhynchonellid brachiopod shells, All of these morphological habits are com- mon in the Recent sublittoral, but the encrusting form may also occur in littoral re- gions where there is some protection from the rigors of a very turbulent environment. Famity BATOSTOMELLIDAE Genus BATOSTOMELLA Plate 6, figures 1-3 Identification of the genus Batostomella is based on the analysis of 45 microsections of specimens from southwestern Virginia and northern Tennessee. The zoaria are ramose and show a median diameter of 8 mm. The zooecial walls are thick and mural lacunae are occasionally abundant. Diaphragms are thin, planar and spaced regularly throughout the zooecium. Subangular mesopores are common but there are few acanthopores. Assignment of these common Upper Ordovician specimens to the genus Batosto- mella was aided by the use of plates and descriptions given by Utgaard and Perry (1964, p. 85) and Bassler (1953, p. G99). Dr. Richard Boardman also made avail- able an extensive catalogue of Paleozoic trepostome genera. Specimens of Batostomella are abundant at localities 125, 126 and 140 in south- western Virginia and northern Tennessee (see Table 3, Clinch Mountain), 1. bryozoan faunal province III (see Fig. 13). As with many other trepostomes, frag- ments can be found at a number of nearby localities. Specimens from locality 126 are four to five times larger in diameter than those from localities 125 and 140. These larger, ramose stems average between 12 and 15 mm in diameter and show a slight increase in the number of mesopores and an abundance of mural lacunae. Finer, more delicate branches (2 to 3 mm in diameter) occur at localities 125 and 140; the zooecial walls show few, if any, mural lacunae. Boardman (pers. comm.) emphasized the importance of mural lacunae, pointing out that they have been found previously in abundance only in species of Richmond age (upper Upper Ordovician). Thus there 74 PEABODY MUSEUM BULLETIN 34 may be not only specific differences between the Batostomella specimens at locality 126 and those at localities 125 and 140, but also a slight temporal discrepancy. There is, however, no significant change in the associated faunal elements: Hallopora, Zygo- spira recurvirostra and Modiolopsis modiolaris, which are part of the Spiriferid Population of the Zygospira—Hebertella Community. Localities 125 and 140 contain, in addition to Batostomella, about 20 fragments of Heterotrypa (Pl. 7, figs. 1-2) and a peronoporid trepostome (PI. 6, figs. 4-6). The peronoporid appears to have been an encrusting form, rather than the more common frondose, bifoliate morphological type. The characteristic grouping of trepostomatous Bryozoa (Batostomella, Hallopora, Heterotrypa and Peronopora?) in addition to Zygospira recurvirostra forms a part of the Spiriferid Population and is found only along the eastern margin (Clinch Mountain, see Fig. 7) of upper Reedsville exposures in southwestern Virginia and northern Tennes- see At locality 140, where muddy siltstones rather than calcareous mudstones begin to dominate the upper portions of the Reedsville section, numerous specimens of Batosto- mella are found about 30 to 40 feet below strata dominated by Ambonychia cultrata, Ischyrodonta truncata, Modiolopsis modtolaris, and some Dekayia and Monticulipora, also part of the Spiriferid Population. These latter trepostomes, commonly higher in the section, are larger ramose forms in a muddy silt, occasionally encrusting on one an- other, whereas Batostomella is confined to a calcareous mud, always finely ramose, never encrusting. The Richmondian age of Batostomella and the possibility of a Richmond species of Hallopora in northern Tennessee (see below p. 75), in contrast to northern faunal elements that are definitely Maysvillian, points up the possibility of a slight decrease in the age of the faunal assemblage from the north-central to the south-central Ap- palachians. This would appear to coincide with the expected variations in rate of progradation from east to west throughout Late Ordovician time. It seems that the environments in the more northerly localities throughout the Late Ordovician would be less static and hence only Maysvillian forms have been preserved. The areas in the south, experiencing a considerably diminished and diluted terrigenous influx, would remain environmentally stable for a somewhat longer period of time, perhaps into the Richmondian. SuBorDER INTEGRATA Famity AMPLEXOPORIDAE Genus AMPLEXOPORA Plate 7, figures 3-6; plate 8, figures 1-4 The identification of the genus Amplexopora is based upon analysis of seven micro- sections from southwestern Virginia. The zoaria are ramose and have a median di- ameter of 12 mm. Zooecial walls are thick and integrate in the exozone and have well- developed laminated zooecial linings. There are a few planar diaphragms regularly spaced within the exozone. Mesopores are absent and acanthopores few. Assignment of these specimens to the genus Amplexopora was aided by the plates and descriptions given by Boardman (1960, p. 16) in his revision of the genus Am- ORDOVICIAN APPALACHIAN ECOLOGY 75 plexopora. Specimens were positively identified only at localities 131 and 138, whereas at locality 141 Amplexopora could be tentatively identified only from two specimens which came from an assemblage that had fewer trepostome zoaria, i.e. bryozoan faunal province III (see Fig. 13). Amplexopora is found at sites with numerous speci- mens of Zygospira recurvirostra, Pterinea (Caritodens) demissa and Ambonychia cultrata, somewhat less common Hebertella sinuata, and fragments of a peronoporid trepostome; all part of the Spiriferid Population of the Zygospira—Hebertella Com- munity. The external morphology of Amplexopora is no different from that of the other abundant trepostomatous Bryozoa, emphasizing the existence of fairly uniform, quiet water conditions throughout much of the southwestern Virginia and northern Tennessee area during the Late Ordovician. Famity HALLOPORIDAE Genus HALLOPORA Plate 9, figures 1-6 Identification of the genus Hallopora is based on the analysis of 57 microsections of specimens from southwestern Virginia and northern Tennessee, and 11 microsections from central Pennsylvania. The zoaria are ramose and show a median diameter of 2 mm in southwestern Virginia and northern Tennessee, increasing to 10 mm in cen- tral Pennsylvania. Zooecial walls are thick and integrate in the exozone and have laminated zooecial linings. Thin, planar diaphragms are crowded near the exozone. Mesopores are abundant and clustered on monticules, whereas acanthopores are absent. Hallopora is one of the most characteristic and distinctive Upper Ordovician trepostomes. The assignment of these central Appalachian specimens to this genus was made with the aid of plates and descriptions given by Bassler (1953, p. G112) and Utgaard and Perry (1964, p. 101). Hallopora is abundant at localities in central Pennsylvania (loc. 34, 34A, 36) and southwestern Virginia-northern Tennessee (loc. 127, 137, 147, 184) and is the most widespread central Appalachian trepostome. Hallopora characterizes two quite geo- graphically distinct bryozoan faunal provinces; i.e., provinces I and III (see Fig. 13), and because of this isolation it is possible that these specimens represent two different species. This possibility is further emphasized by significant differences in the associ- ated faunal populations. In central Pennsylvania, crinoids and Onniella multisecta occur with lesser numbers of Hallopora, Rafinesquina “alternata” and Sowerbyella (Sowerbyella) sericea, which are part of the Orthid—Crinoid Population of the Sowerbyella—Onniella Community. In southwestern Virginia and northern Tennessee, more numerous specimens of Hallopora are found in both the Spiriferid and Orthid Populations of the Zygospira—Hebertella Community (see Table 13). Furthermore specimens of Hallopora from northern Tennessee localities (see Pl. 9, figs. 1 and 4) have been tentatively identified as a form resembling Lower Richmond species in Kentucky, whereas specimens from central Pennsylvania localities do not resemble these forms and may be slightly older. The significance of a slight decrease in the age of the fauna from north to south has been discussed above. 76 PEABODY MUSEUM BULLETIN 34 TABLE 13. The associated faunal elements of Hallopora in southwestern Virginia and northern Tennessee. The Hallopora faunal association in central Pennsylvania is not listed in this table but discussed in the text. Lone Mt., Big Ridge, Wallen Ridge, Tenn. Cumberland Mt., Clinch Mt., Tenn. Clinch Mt., Rich Mt., Va. Locality numbers 125. 126 127, 128, 132, 137, 147, 184 Associated faunal elements Hallopora Hallopora—Dekayia Batostomella Zygospira recurvirostra Zygospira recurvirostra Pterinea (Caritodens) demissa Modiolopsis modiolaris Hebertella sinuata Rafinesquina “‘alternata” Population Spiriferid Orthid Substratum lime mud silty mud BRACHIOPODA Plates 10-15 Brachiopods are the most numerous and widespread faunal elements in the central Appalachian Upper Ordovician rocks. The phylum is represented by five orders and eight species. There have been only a few recent comprehensive taxonomic reviews of North American Lower Paleozoic Brachiopoda useful to this study; these include Schuchert and Cooper (1932), Salmon (1942), D. Hall (1962) and Williams and Wright (1963). The generic review by Williams et al. (1965) and the studies of predominantly European species by Jones (1928), Bancroft (1928, 1945), Whitting- ton (1938) and Williams (1953, 1962) proved valuable. PHyLumM BRACHIOPODA CLiass INARTICULATA Orper LINGULIDA SUPERFAMILY LINGULACEA Famity LINGULIDAE Genus LINGULA? Plate 10, figures 1-5 A small to medium-size linguloid shell (over 150 specimens, averaging 15 mm length) is a widespread and common faunal element throughout the central Appalachian Upper Ordovician strata. Unfortunately preservation is so poor that no internal fea- tures are known, and hence the precise generic designation must remain in doubt. The linguloid fossils of the North American Ordovician have usually been referred to Lingula or Pseudolingula, and Bassler (1919, p. 232) introduced the name Lingula nicklesi for specimens in the “Orthorhynchula Bed” of south-central Pennsylvania. I have collected from this same general region but at present do not feel that these specimens can be shown to be equivalent to L. nicklesi from the Ohio Valley (Bassler, 1919, pl. 57, figs. 1-3, figures specimens only from Cincinnati, Ohio). The following list includes possible subjective synonyms. ORDOVICIAN APPALACHIAN ECOLOGY a7 Pseudolingula iowensis (Owen, 1894) P. rectilateratis (Emmons, 1842) Lingula elderi Whitfield 1880 L. quadrata Hall 1847 L. waynesboroensts Foerste 1910 L. cincinnatiensis (Hall and Whitfield, 1875) L. nicklesi Bassler 1919 Lingula? is numerous from south-central Pennsylvania to southern Virginia, bra- chiopod faunal province II (Fig. 14), and is most often found with: 1) Tancrediopsis cuneata, Plectonotus? sp. and Ischyrodonta truncata, 2) by itself, and 3) locally with Orthorhynchula linneyt. The first two occurrences characterize the Linguloid Population of the Orthorhynchula~Ambonychia Community, whereas the third con- stitutes a portion of the Rhynchonellid Population of the same community. The rock type ranges from muddy silt to a clean sand, and scattered linguloids have been found in hard orthoquartzitic Oswego sandstones. Linguloids are found higher in the upper Reedsville section than any other species, occasionally occurring alone and in signifi- cant numbers only a few feet below the contact with the Oswego Sandstone. Figure 31 outlines the general faunal-stratigraphic relationships. L/NGULA? —STRATIGRAPHIC RELATIONSHIPS ENVIRONMENTAL SETTING ABUNDANT FAUNAS Bar—Barrier Lingu/a? (rare) Intertidal Lingu/a? silt-mud Flat E Lingula? Neer ial? : 7 Plectonotus®? sp. = S Tancred/opsis cuneara ® Ce) /schyrodonta truncata iu Shallow rs ; ; w Orthorhynchula /inneyi Inner a Ischyrodonta ftruncata Sublittoral 5 Lingu/a? (rare) Legend sandstone : sss crossbeds AS siltstone Baer Sass: shale FIG. 31. Associated faunal elements of Lingula?. Stratigraphic section is a composite from ex- posures in south-central Pennsylvania and eastern West Virginia. Lithology schematically pre- sented. Lingula? is common only in the environments interpreted as intertidal and silt-mud flat. 78 PEABODY MUSEUM BULLETIN 34 The life habits of Recent linguloids, Lingula and Glottidia, are probably better known than those of any other brachiopods (see Craig, 1952; Hyman, 1959; Rudwick, 1965). Jorgensen (1966, p. 8-10) summarized the suspension feeding mechanism of linguloids. Hyman (1959, p. 589) quotes earlier investigators to the effect that lingu- loids are very general feeders, their digestive tracts containing a variety of organic and inorganic materials. Yatsu (1902) has found that Recent linguloids can burrow about a foot below the surface of the substratum and that their pedicle is attached to shell fragments or more consolidated, coarser sediments. I have found definite vertical linguloid bur- rows in the lower Oswego sandstones, though linguloid burrows need not be vertical. Rudwick (1965, p. H203) felt that this infaunal mode of life was not reflected in any distinctive feature of the shell itself and that many fossil linguloids may have been epifaunal. The Recent linguloids inhabit shoals, banks, mud-sand flats and beaches; the sub- stratum ranges through muds and coarse sands. Hatai (1940) has found Recent lingu- loids limited to depths of less than 20 meters with only rare occurrences in deeper waters. Craig (1952, p. 115) added that besides being a shallow water marine animal, the Recent linguloids could probably withstand prolonged periods of brackish water conditions; none have been reported from truly fresh water environments. Rudwick (1965, p. H212) claimed that few fossil brachiopods could be used as reliable indicators of water depth, with the possible exception of fossil linguloids found without any other associated brachiopods. The latter occurrences could be taken to reflect a possible intertidal environmental setting. I believe that a very nearshore, possibly intertidal, environment is highly likely where linguloids are the single abun- dant faunal element, and is probable where Lingula? occurs with Tancrediopsis cune- ata, Plectonotus? sp. and Ischyrodonta truncata. Association with O. linneyt probably reflects a shallow sublittoral regime as contrasted to the sheltered mud-silt flats of the other two associations. One other inarticulate brachiopod, Schizocrania, is found in the central Appala- chian Upper Ordovician rocks. It is not common, being found at only one locality in a silty mud associated with large Modiolopsis modiolaris and a few Ambonychia prae- cursa from the Rynchonellid Population of Orthorhynchula—Ambonychia Commu- nity (see Table 10). Apparently, it lived in a normal marine, quiet sublittoral en- vironment. Crass ARTICULATA OrpER ORTHIDA SuporDER ORTHIDINA SUPERFAMILY ORTHACEA Famity PLECTORTHIDAE SuBFAMILY PLECTORTHINAE Genus HEBERTELLA Hebertella sinuata (Hall, 1847) Plate 11, figures 7-8; plate 12, figures 1-2 Orthis sinuata Hall, 1847, p. 128, pl. 32B, figs. 2a-i, 2k; pl. 32C, figs. 21-s. Meek, 1873, p. 96, pl. 9, figs. 4a-g. ORDOVICIAN APPALACHIAN ECOLOGY 79 [?]Orthis subjugata Hall, 1847, p. 129, pl. 32C, figs. la-i, 1k, 1m, In. [?]Orthis occidentalis Hall, 1847, p. 127, pl. 32A, figs. 2a-i, 2h, 21, 2m; pl. 32B, figs. la-i. [not] Meek, 1873, p. 96, pl. 9, figs. 3a-h. [not] Hall, 1883, pl. 34, figs. 31-34; pl. 35, figs. 16-21. Orthis occidentalis var. sinuata (Hall). Meek, 1873, p. 98. Hebertella sinuata (Hall). Hall and Clarke, 1892, p. 222, figs. 1-8. Foerste, 1910, p. 52, pl. 2, fig. 5. Foerste, 1924, p. 110, pl. 10, fig. 11. Butts, 1941, p. 117, pl. 97, figs. 1-4. Cooper, 1944, p. 299, pl. 113, figs. 14-20. Williams and Wright, 1965, p. H324, figs. 205, 5a-e. Hebertella occidentalis var. sinuata (Hall). Cumings, 1908, p. 908, pl. 34, figs. 3, 3a-e. Schuchert and Cooper, 1932, p. 59, pl. 11, figs. 14, 17, 19, 20, 22-26. [?]Hebertella occidentalis (Hall) . {not] Hall and Clarke, 1892, p. 222, pl. 5A, figs. 11, 12. [not] Cumings, 1908, p. 906, pl. 34, fig. 4. Foerste, 1910, p. 53, pl. 2, figs. 1a, 1b, 2a, 2b. Foerste, 1924, p. 110, pl. 5, figs. 5a, b; pl. 10, figs. 10a, b. [?] Ruede- mann, !925b, p: 120; pl. 13, figs. 1, 2. [?]Hebertella subjugata (Hall). Foerste, 1910, p. 54, pl. 2, fig. 8. Foerste, 1912, p. 129, pl. 8, fig. 6. [?]Hebertella latasulcata Foerste, 1914b, p. 131, pl. 3, figs. 7a, b. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER OrbDo- victAN. Shell of moderately large size (median length of 24 specimens, 16 mm; median width of 17 specimens, 23 mm), inequivalved, biconvex, globose, outline subelliptical. Shape only slightly variable, wider than long, greatest width near hinge line, length varying between 62 and 76 per cent of width (median of 12 specimens, 74 per cent). Hinge line long, straight, wide; interarea curved, both valves more or less apsacline. Cardinal angle obtuse; extremities subround. Anterior commissure unipli- cate to sulcate; anterior margin broadly curved to flat, or slightly concave; lateral margins subparallel. Multicostellate, costae broad, rounded, numerous; spaces be- tween costae narrow, deep; costellae few, prominent, bifurcation only near valve margins of larger shells; concentric striae faint, very few, widely spaced near valve margins. Pedicle valve broadly convex, broad sulcus, umbo inflated, beak slightly incurved ; delthyrium moderately large, deltidium unknown; delthyrial chamber deep; dental plates extend as elevated ridges anterolaterally to surround ventral muscle scar. Two diductor scars, broad, subcrescentic, not enclosing adductor scar anteriorly; two dis- tinct adductor scars, impression of support on internal mold, double median ridge with shallow central grove; adjustor scars unknown. Brachial valve sharply convex, wide fold, prominent beak arched over ventral interarea, Notothyrial chamber deep; cardinalia preserved on internal mold; brachio- pores at lateral margins of notothyrium, divergent anteriorly, short, pointed. Dental sockets deep. Cardinal process, thick ridge, extends anteriorly part way toward center of valve, myophore prominent. Dorsal muscle scars obscure, two posterior adductors, subovate. Mantle canal system unknown. Shell fibrous, impunctate, possibly endopunc- tate, irregular pitting of internal surface. Materiats. The description is based on over 45 specimens from central Virginia and northern Tennessee deposited in the Peabody Museum. 80 PEABODY MUSEUM BULLETIN 34 Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Hebertella sinuata is tentative pending a complete taxonomic review of the North American species of Hebertella. H. sinuata, the type of the genus proposed by Hall and Clarke (1892, p. 198), comprises a heterogeneous assemblage of orthids. Their definition was subsequently emended by Schuchert and Cooper (1932, p. 59), who should be consulted for outstanding figures of H. occidentalis var. sinuata (Schuchert & Cooper, 1932, pl. 11, figs. 14, 17, 19, 20, 22-26). Hall (1847, p. 128), in the original description of Orthis sinuata, stated that the misidentification of this and other “similar species” could result from collections of only small amounts of material. He believed that variations related to age were very important. Schuchert and Cooper (1932, p. 60) found that young forms of Hebertella could scarcely be distinguished from mature species of Plectorthis, either internally or externally. Within the genus itself uncertainty exists as to assignment of specimens among H. occidentalis, H. sinuata and H. subjugata. These three eastern North American Upper Ordovician species show only slight differences in external morphology, are commonly listed as occurring at the same horizon (Hall, 1847, p. 130), and have very poorly defined comparative internal features. H. swbjugata has been usually distin- guished from the other two by its finer plications. H. occidentalis is supposed to show a slight sulcus near the beak of the brachial valve that distinguishes it from the non- sulcate H. subjugata and H. sinuata. All previous investigators have admitted that the distinctions are difficult to make. Complete gradations in the shell plications and brachial valve depressions have been noted by Foerste (1910, p. 53) at a number of Upper Ordovician localities in the Ohio River Valley. Earlier Foerste (1909, p. 224) had described what appears to be a specific differ- ence in the external shell morphology of Hebertella; the presence of a pronounced sulcus in the brachial valve, not just a slight depression near the beak. H. alveata (cf. H. alveata var. richmondensis) Foerste 1909 incorporated many of the dorsally sulcate forms that earlier authors had called Orthis occidentalis. One of these authors was Meek (1873, p. 98) who remarked that all gradations exist between those specimens that have a well-defined mesial sinus on the dorsal valve (i.e., H. alveata Foerste 1909 = Orthis occidentalis Meek 1873) and others in which no trace of a sinus can be found [i.e. H. sinuata (Hall, 1847)]. Thus it seems that H. sinuata must be placed in the category of nomen inquirendum pending a restudy of this material. Very well preserved internal and external molds have been found at a few Upper Ordovician localities in the central Appalachians. A slight mesial sulcus near the beak of the brachial valve has been noted in a few specimens, scattered throughout a num- ber of localities. A distinctive pattern of coarser or finer plications has not been recog- nized, and none of the extremely sulcate forms have been obtained at any of the central Appalachian localities. The highly sulcate Hebertella has been reported only from Upper Ordovician strata of the Ohio River Valley. Hebertella sinuata is abundant only along the more southeasterly exposures of the Reedsville Formation, south-central Virginia and northern Tennessee, brachiopod faunal province III (see Fig. 14). Specimens tentatively identified by me as H. sinuata have been found in the Shochary Ridge Sandstone of eastern Pennsylvania, but gener- ORDOVICIAN APPALACHIAN ECOLOGY 81 ally poor preservation prevents discrimination from Plectorthis. Table 14 lists the commonly associated abundant faunal elements, all part of the Zygospira—Hebertella Community. Not included on the table are the eastern Pennsylvania localities where questionable H. sinuata occurs with two distinctly northern species of brachiopod faunal province I, the numerous Onniella multisecta and Sowerbyella (Sowerbyella) sericea, which are part of the Sowerbyella—Onniella Community. TABLE 14. The associated faunal elements of Hebertella sinuata in northern Tennessee and sounthwestern Virginia. All brachiopods are part of the Zygospira—Hebertella Community. Powell Mt., Va. Cumberland Mt., Va. & Tenn. Clinch Mt., Wallen Ridge, Catawba Mt., Vt. Walker Mt., Va. Clinch Mt., Tenn. Locality 177,179 147, 149, 150 E30, 31,152; 133; 139 numbers Associated Rafinesquina “alternata” Zygospirarecurvirostra Zygospira recurvirostra faunal Zygospira recurvirostra Pterinea (Caritodens) Hallopora elements demissa Amplexopora Hallopora Pterinea (Caritodens) demissa Modiolopsis modiolaris Orthorhynchula linneyi Substratum — sand-silt muddy silts lime muds The life habits and environmental setting of H. stnuata can be inferred from the few studies of Recent brachiopods, even though there are no living orthids. It is as- sumed that H. sinuata thrived in waters of normal marine salinity and was rooted to the silty substratum by a fairly stout pedicle. Attachment in the normal fashion of articulate brachiopods would allow the heavy shelled form with a much more convex brachial valve to rest on or be partially buried in the substratum, the convexity raising the plane of commissure above the ctenidial-fouling, sediment-laden bottom currents. The patchiness of the distribution even in areas where the shells are abundant is com- mon in the other Upper Ordovician brachiopod species and is characteristic of the eregarious nature of Recent brachiopods. The distinctly globose, trilobate form of H. sinuata, superficially much like that of O. linneyt, may be indicative of adaptation to more turbulent conditions than that experienced by the other central Appalachian orthids, strophomenids and spiriferids. The functional significance of shape is re- viewed in the discussion of O. linneyt. The stratigraphic and geographic evidence points to a quiet, but sporadically turbulent, sublittoral habitat for H. sinuata. The overall restriction of the fauna to the south may be explained as a function of currents, rates of sedimentation or tempera- ture control. H. sinuata is most common in fine sands and silts and appears to replace O. linneyi in southwestern Virginia and northern Tennessee, brachiopod faunal province III, as the dominant inner sublittoral brachiopod species. H. stnuata, how- ever, gives way to the smaller atrypid Zygospira recurvirostra in finer silts and muds of the same geographic region, possibly indicating more sheltered nearshore regions. 82 PEABODY MUSEUM BULLETIN 34 SUPERFAMILY ENTELETACEA Famity DALMANELLIDAE Genus ONNIELLA Onniella multisecta (Meek, 1873) Plate 11, figures 1-6 Orthis multisecta James, 1871, p. 10 (nomen nudum). Miller, 1875, p. 22. Sardeson, 1897, p. 97, pl. 4, figs. 20-23. Dalmanella testudinaria var. multisecta Meek, 1873, p. 112, pl. 8, figs. 3a-d, [?]figs. la-c. Cumings, 1908, p. 901, pl. 33, figs. 4, 4a-c. Dalmanella multisecta (Meek). Bassler, 1909, pl. 14, figs. 4-6. Foerste, 1909, p. 217. Bassler, 1919, p. 244, pl. 54, figs. 5, 6. Rudemann, 1925b, p. 117, pl. 12, figs. 1-3. Secrist and Evitt, 1943, p. 367. [?]Dalmanella fultonensis var. lorrainensis Ruedemann, 1925b, p. 119, pl. 12, fig. 7. [?]Dalmanella fultonensis var. rotunda Ruedemann, 1925b, p. 120, pl. 12, figs. 4-6. [?]Dalmanella fertilis (Bassler). Butts, 1941, p. 113, pl. 96, figs. 3-6. [?|Dalmanella emacerata (Hall). Butts, 1941, p. 114, pl. 96, fig. 16. Resserella multisecta (Meek). Cooper, 1944, p. 353, pl. 138, figs. 15-18. Onniella multisecta (Meek). Hall, 1962, p. 148, pl. 20, figs. 11-31. DeEscrIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- VICIAN. Shell of small size (median length of 35 specimens, 8 mm; median width of 31 specimens, 11 mm), slightly inequivalved, generally biconvex, outline subcircular. Shape only slightly variable, wider than long, greatest width near midpoint between hinge line and anterior margin, length varying between 76 and 82 per cent of width (median of 23 specimens, 78 per cent). Hinge line short, straight; interarea curved, both valves orthocline or anacline. Cardinal extremities rounded. Anterior commis- sure rectimarginate to faintly sulcate; anterior and lateral margins broadly rounded. Multicostellate, costae coarse, broad, rounded; costellae prominent, numerous bifur- cations especially near shell margins. Concentric striae of two distinct types: coarse, widely spaced, concentrated near valve margins; fine, numerous, over entire surface of valve. Pedicle valve broadly convex, umbo inflated, broadly rounded, beak erect. Del- thyrium prominent, large, triangular; deltidium unknown; delthyrial chamber deep; hinge teeth large, crural fossettes deep, anterior-inner edge of hinge teeth well pre- served on latex impression of internal mold (PI. 11, fig. 2) ; dental plates small, extend as faint ridges anteriorly to surround posterodorsal portions of ventral muscle scar. Two diductor scars, elongate, flanking but not entirely enclosing a medial adduc- tor scar. Brachial valve slightly convex, flattened at margins, broadly sulcate. Notothyrial chamber deep, triangular. Cardinalia preserved on latex impression of internal mold (Pl. 11, fig. 3) ; brachiopores at lateral margins of notothyrium, diverge anteriorly, short, erect, razor-like, thickened at base where fused to medial ridge; fulcral plates unknown. Denticle small, narrow, forms posteriolateral lip of deep socket. Cardinal process small, bilobed, extends anteriorly toward center of valve as thickened medial ridge. Dorsal muscle scars prominent, quadripartite, paired posterior and anterior ORDOVICIAN APPALACHIAN ECOLOGY 83 adductors, subround, anterior scars about twice as large as posterior ones. Mantle canal system unknown. Shell microstructure and mineralogy unknown, preservation as internal and external molds. Materiats. The description is based on over 50 specimens from eastern and central Pennsylvania deposited in the Peabody Museum. Discussion. These central Appalachian Upper Ordovician specimens are assigned to Onniella multisecta on the basis of their consistently small size, subcircular outline, well-defined ventral and dorsal muscle scars and delicate cardinal processes. Mis- identification as the similar O. emacerata or O. meeki was avoided, as O. emacerata is a much larger shell with a subrectangular outline and O. meek1, although exhibit- ing a good deal of shape variation, has a prominent large cardinal process which fills the notothyrial chamber of the brachial valve and is visible from the exterior. The Ordovician dalmanellids are one of the more carefully studied brachiopod groups. Unfortunately there has been a general tendency toward genus-making and nomenclatural error since Hall and Clarke (1892) introduced the genus Dalmanella, “Group of Orthis testudinaria.” Subsequent works of particular note are by Bancroft (1928, 1945), Schuchert and Cooper (1932), and the important summary papers of Hall (1962), and Williams and Wright (1963). Many of the previous investigators of the eastern North American Upper Ordovi- cian rocks undoubtedly have identified specimens of O. multisecta as Dalmanella (= Orthis) testudinaria, a European Ordovician species made the type of the new genus Dalmanella by Hall and Clarke (1892, p. 205), but so inadequately defined that it soon came to contain a heterogeneous group of North American dalmanellid species. Sardeson (1897), Raymond (1921) and Foerste (1924) presented an in- creasingly better documented case for the argument that species agreeing with the type Dalmanella testudinaria were unknown to North America. Schuchert and Cooper (1932, p. 126), in their monographic review of the dalmanellid genera, unfortu- nately disregarded the conventions of zoological nomenclature and replaced the type Dalmanella (D. testudinaria) with the common North American species Dalmanella rogata, which was supposed to be the true representative of a widespread Upper Ordovician North American genus. In the process they placed Onnzella Bancroft, 1928, in synonymy with the emended Dalmanella. Cooper (1942, p. 229) recognized the error but no longer believed the species in the “Dalmanella rogata group” were congeneric with Bancroft’s Onniella and felt that this latter genus in North America was restricted to a few species of Richmond age. This, of course, left the “Dalmanella rogata group” without a valid generic designa- tion. Cooper (1944, p. 251-252) subsequently remedied this when he placed the “D. rogata group” in the genus Resserella. Unfortunately Schuchert and Cooper (1932, p. 126) had emended the definition of Resserella Bancroft and had designated a type that placed it in synonymy with Parmorthis; the result of this synonymy was to restrict the term Resserella to a group of Silurian specimens and again leave the distinctive “Dalmanella rogata group” nameless. Cooper (1956, p. 956) thus introduced the new genus Paucicrura with its type Dalmanella rogata and presumably included in the new genus all those Upper Ordovician species originally congeneric with Dal- manella rogata. 84 PEABODY MUSEUM BULLETIN 34 Hall (1962) reviewing the Cincinnatian dalmanellids of the Ohio Valley area, placed Paucicrura in synonymy with Onniella. Hall (1962, p. 139) cited the works of Opik (1933) and Whittington (1938) in considering the Upper Ordovician spe- cies of the “Dalmanella rogata group” as belonging to the genus Onniella. Hall further stated that Paucicrura must be placed in synonymy with Onniella since the generic descriptions given by Bancroft (1928, p. 55) and Schuchert and Cooper (1932, p. 120) are identical. Because Schuchert and Cooper considered “Dalmanella”’ and Onniella to be congeneric and because there is no description of the type for the genus Paucicrura given by Cooper (1956), the earlier definition is the only valid one standing. Williams and Wright (1963, p. 28-29) list quite similar diagnostic features for Onniella and Paucicrura and found only the undifferentiated bilobed cardinal process in Onniella to differ from the differentiated trilobate process in Paucicrura. Hall (1962), however, found bi-, tri- and quadrilobate cardinal processes in Onniella. Howe and Reso (1967, p. 358) submit a reasonable suggestion: if the wide variation of the posterior portion of the cardinal process in Paucicrura can be demonstrated, Paucicrura should be placed in synonymy with Onniella. The distribution of abundant O. multisecta, limited to eastern and central Penn- sylvania, brachiopod province I, shows almost the same zoogeographic pattern (see Table 3) as that of Sowerbyella (Sowerbyella) sericea (see Fig. 14). However, O. multisecta becomes suddenly sparse in south-central Pennsylvania; only rare, scattered specimens are found in northern Virginia (loc. 160, 161, 162, 165, 167, 168). The enclosing rock is commonly a mud or muddy silt; the abundant associated faunal elements are Sowerbyella (Sowerbyella) sericea and crinoids, part of the Orthid—Crinoid Population of the Sowerbyella—Onniella Community. In certain lo- cales Rafinesquina “alternata”, Hallopora and Flexicalymene are common. Infre- quently there occur concentrated patches of Cryptolithus, Sinuites and Receptaculites. O. multisecta, like many of the other central Appalachian Upper Ordovician bra- chiopods, often occurs in highly concentrated patches where entire bedding planes are covered with this one species. The life habits and environmental setting of O. multisecta are as hard to infer as were those for the other orthids and strophomenids. As in the case of the brachiopods, one can assume a normal marine environment, waters of low turbidity and low but sporadic rates of sedimentation. Temperature may be an important factor, as the species was confined to the northeastern parts of the central Appalachians during the Late Ordovician. O. multisecta presumably had a fairly stout functional pedicle by which it was attached to the muddy silt substratum, other shells, or non-preservable material such as worm tubes or algae. Considerable organic stain is evident with the dalmanellids. The patchiness and gregarious nature of O. multisecta are common in Recent shelf brachiopod faunas and are also usual in the other Upper Ordovician brachiopod species. Geographic and stratigraphic evidence points to a habitat some- what north of the major area of terrigenous clastic influx, but in all cases the fauna appears to have been abundant only in the sublittoral, probably outer sublittoral, rela- tively quiet waters dominated by a few numerous, closely bunched species. This shelf portion appears to be assumed elsewhere by Zygospira recurvirostra and some Heber- tella sinuata, brachiopod faunal province III (see Fig. 14), which replace O. multi- secta southward. ORDOVICIAN APPALACHIAN ECOLOGY 85 OrpveER STROPHOMENIDA SuBorRDER STROPHOMENIDINA SUPERFAMILY PLECTAMBONITACEA Famity SOWERBYELLIDAE SuBFAMILY SOWERBYELLINAE Genus SOWERBYELLA Sowerbyella (Sowerbyella) sericea (Sowerby, 1839) Plate 12, figures 3-6; plate 13, figures 1-4 Leptaena sericea Sowerby, 1839, p. 636, pl. 19, figs. 1, 2a, [?]2. Hall, 1847, p. 110, pl, 31B, figs. 2a:h; p. 287, pl. 97, figs. 3a, 3a*, 3b. [not] Hall, 1852, p. 59, pl. 21, figs. la-e. Billings, 1856, p. 41, fig. 2. Billings, 1863, p. 163, figs. 139a-c. Meek, 1873, p: 70, pl.5, figs) 3a=e, ||? |3f-h. Strophomena sericea (Sowerby). Conrad, 1840, p. 201. Emmons, 1842, p. 394, fig. 105.1. Owen, 1844, p. 269, pl. 105, fig. 1. Emmons, 1855, p. 199, pl. 11, figs. 6a-f. [?]Leptaena sericea var. rugosa Meek, 1873, p. 72, pl. 5, figs. 3f-h. [?|Leptaena aspera James, 1874a, p. 151. Plectambonites sericea (Sowerby). Shaler, 1876, p. 28. Hall and Clarke, 1892, pl. 15, figs. 25, 27-29, [?]26. Winchell and Schuchert, 1895, p. 414, pl. 32, figs. 10-12. Cumings, 1908, p. 922, pl. 36, figs. 1, la-c. Bassler, 1909, pl. 14, figs. 1, 2. Parks and Dyer, 1922, p. 35, pl. 7, figs. 15, 16. Foerste, 1924, p. 113, pl. 13, figs. 2a, b, 3. Ruedemann, 1925b, p. 123, pl. 12, fig. 18. [?|Plectambonites sericeus var. asper (James). Ruedemann, 1901, p. 18, pl. 1, figs. 6, 7. [?|Plectambonites sericeus var. typus Ruedemann, 1912, p. 91, pl. 4, fig. 6, [?]figs. 3, 45 Gy [?]Plectambonites rugosa var. clarksvillensis Foerste, 1912, p. 127, pl. 1, figs. 7a, b, {?]7c; pl. 10, figs. 7a-d. [?|Plectambonites rugosa (Meek). Foerste, 1912, p. 123. Bassler, 1919, p. 255, pl. 54, figs. 31-33. [?]Parks and Dyer, 1922, p. 35, pl. 7, fig. 11. Ruedemann, 1925b, pe h235 pl l2, fissn19-21: [?|Plectambonites curdvillensis Foerste, 1912, p. 122, pl. 10, figs. 15a, b. [?|Plectambonites punctostriatus Mather, 1917, p. 38, pl. 1, figs. 15-17. [?]Plectambonites rugosus var. manitoulinensis Foerste, 1924, p. 113, pl. 4, figs. 4a-d. Sowerbyella sericea (Sowerby) . Jones, 1928, p. 414, pl. 21, figs. 1-4. [?|Sowerbyella sericea var. soudleyensis Jones, 1928, p. 417, pl. 21, figs. 5, 6. [?|Sowerbyella rugosa var. triradiatus Butts, 1941, p. 113, pl. 96, fig. 9. [?|Sowerbyella sp. Butts, 1941, p. 113, pl. 96, fig. 10. [?]Sowerbyella rugosa (Meek). Butts, 1941, p. 113, pl. 96, figs. 7, 8. Cooper, 1944, pe ooo, pli2ewhies: 42743. Fiat. [?|Sowerbyella clarksvillensis (Foerste). Cooper, 1944, p. 335, pl. 128, figs. 39, 40. [?|Sowerbyella curdvillensis (Foerste). Cooper, 1956, p. 780, pl. 201A, figs. 1-13. [?|Sowerbyella punctostriatus (Mather). Cooper, 1956, p. 792, pl. 205C, figs. 9-25, pl. 206D, figs. 14, 15. Sowerbyella (Sowerbyella) sericea (Sowerby). Muir-Wood and Williams, 1965, p. H379, figs. 243, la-f. 86 PEABODY MUSEUM BULLETIN 34 DEscrRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN Upper Orpo- vic1AN. Shell of moderately small size (median length of 25 specimens, 8 mm; median width of 29 specimens, 14 mm), inequivalved, outline subcircular. Shape variable, wider than long, greatest width at hinge line, length varying between 44 and 66 per cent of width (median of 20 specimens, 54 per cent). Hinge line long, straight. Cardi- nal angle variable, acute with subalations, usually right angle. Anterior commissure rec- timarginate. Anterior margin broadly curved; lateral margins rounded, subparallel only near hingeline. Parvicostellate, costae closely spaced, narrow, rounded; costellae num- erous, bifurcating, regularly spaced between costae; median ridge on brachial valve faint to absent. Concentric striae faint, widely spaced but crowded near valve margins. Pedicle valve strongly convex, margins nearly flat. Umbonal region not pro- nounced ; beak only slightly above level of hinge line, posterior margin almost straight; cardinal area anacline. Apical foramen unknown, deltidium or pseudodeltidium un- known. Ventral muscle scars well-defined, bilobate, bounded posterolaterally by dental plates, anteromedially by ridges diverging from short, median septum; two adductors, small deeply impressed at posterior extreme of muscle scar; two diductors broad, shal- low impression, divided into two subequal elements by low ridges (Pl. 12, fig. 5; Pl. 13, 16 ea Brachial valve flat to gently concave, noticeably concave near valve margins. Cardinalia simple; crural bases curved, narrow, diverging widely from posterior end of cardinal process. Chilidial plates form well-defined submedial septa, broaden toward anterior, diverge slightly, fused with small socket ridges, flat-lying, flanking median septum (PI. 12, fig. 4). Mantle canal system preserved on internal mold (PI. 13, fig. 1) of brachial valve, lemniscant, inequidistributate (Pl. 12, fig. 3). Shell fibrous, pseudopunctate, punctae regularly spaced in rows between costellae. MaterIALs. The description is based on over 40 specimens from eastern and central Pennsylvania deposited in the Peabody Museum. Discussion. These specimens from the central Appalachian Upper Ordovician rocks are tentatively assigned to Sowerbyella (Sowerbyella) sericea pending a complete taxonomic revision of Sowerbyella (Sowerbyella) and Sowerbyella (Viruella). Previ- ous investigators described and figured species and varieties of Sowerbyella (= Lep- taena; = Plectambonites) from numerous localities in the Upper Ordovician strata of eastern North America. Many of these species and their varieties were named on the basis of slight variations in length-width ratios or poorly defined differences in surface sculpture. The Family Sowerbyellidae and many other Upper Ordovician brachiopod families have bee.» ‘atensely studied for their usefulness as potential stratigraphic in- dicators or guides. In the process artificial taxa were created for the recognition of minute subdivisions of rock units. Earlier authors attempted to define slight differ- ences between forms of Plectambonites and at first produced numerous stratigraphi- cally defined varieties of P. sericea, which later investigators made into distinct species. Foerste (1912, p. 127) was one of the few who recognized at an early date the hope- lessness of this situation when he attempted to redefine P. sericea var. rugosa (Meek) from the Cincinnatian strata of the Ohio River Valley. Although I have not attempted an exhaustive survey of the morphological variation that exists within and among the many world-wide species of Ordovician and Silurian Sowerbyella which are presently ORDOVICIAN APPALACHIAN ECOLOGY 87 recognized, I have included in the present synonymy those species from the Ordovi- cian of eastern North America that I believe to be likely subjective synonyms of S. (S.) sericea based on a review of previously published plates and descriptions. Sowerbyella (Sowerbyella) sericea is abundant only in eastern and central Penn- sylvania (brachiopod faunal province I, see Fig. 14). A few specimens are found in northern Virginia (loc. 160, 161, 166, 178), where S. (S.) sericea constitutes only a very scattered, less significant faunal element. Associated faunal elements are Rafines- quina “alternata” and crinoids, (part of the Strophomenid Population of Sowerbyella— Onniella Community), but S. (S.) sericea is just as often found by itself. Onniella multisecta and Hallopora are less commonly associated faunal elements, and speci- mens of Flexicalymene, Zygospira concentrica and Phragmolites are rare. S. (S.) sericea is most often found in a muddy silt or fine sand. The distribution throughout Pennsylvania and northern Virginia is notably patchy. The life habits and environmental setting of S. (S.) sericea must, of course, be in- ferred from the few studies of living articulate brachiopods and the one possible strophomenid descendant, Lacazella. Strophomenid ecology is reviewed in the discus- sion of Rafinesquina “alternata”, p. 89. S. (S.) sericea adults lived unattached on the sea floor, much like R. ‘“‘alternata’. Williams (1953, p. 2) stated that the young stages also were probably unattached, the valves resting freely on the muddy silts and sands. A normal marine environment, probably outer sublittoral, in an area of fairly low turbulence is most likely. The reasons for the concentration of §. (S.) sericea immedi- ately to the north of and off the major area of terrigenous clastic influx are not obvious. Possibly it results from the presence of a suitable firm muddy silt substratum and a tolerable temperature regime. The extreme patchiness of the distribution is typical of the Upper Ordovician brachiopods and is well-documented in Recent bra- chiopod populations. Local current patterns probably accounted for this patchy nature of distribution, as they account for both nutrient distribution and larval dispersal. SUPERFAMILY STROPHOMENACEA Famity STROPHOMENIDAE SUBFAMILY RAFINESQUININAE Genus RAFINESQUINA Rafinesquina “alternata” (Hall, 1847) Plate 15, figures 1-6 Strophomena Emmons, 1842, p. 403, fig. 112.2 (nomen nudum). Leptaena alternata Hall, 1847, p. 286, pl. 79, figs. 2f-21, [not] 2a-2d. Strophomena alternata (Hall). Emmons, 1855, pl. 17, fig. 2; [?]pl. 11, fig. 3. [?|Strophomena alternata var. fracta Meek, 1873, p. 91, pl. 7, figs. 3a-3c. [2?|Strophomena squamula James, 1874b, p. 335. Rafinesquina alternata (Hall). Hall and Clarke, 1892, p. 282, pl. 8, figs. 6, 7, [?]8-11. Hall and Clarke, 1895, pl. 84, [?]figs. 17, 18. Bassler, 1909, pl. 14, fig. 9. Bassler, 1919, p. 265, pl. 57, fig. 8. Foerste, 1924, p. 114, pl. 13, figs. 6a-c. Ruedemann, 1925); p; 126. Butts,.1941, p. 117, sol. 97, fe. 29. [?|Rafinesquina squamula (James). Hall and Clarke, 1892, p. 283. Foerste, 1914a, p. 264. Bassler, 1919, p. 264, pl. 54, figs. 3, 4; pl. 58, fig. 4. 88 PEABODY MUSEUM BULLETIN 34 [?|Rafinesquina alternata var. fracta (Meek). Cumings, 1908, p. 927, pl. 37, figs. 5: Oa. [?|Rafinesquina mucronota Foerste, 1914a, p. 265, pl. 2, figs. 7a, b. Parks and Dyer, 1922; p. 37. Foerste, 1924, p. 115, pl. 14, fig 1; pl’ 30) fig."6, 7. ’Ruedentanny 1925p; p. 129) ple t2 fies, Volz: [?|Rafinesquina mucronota var. torontonensis Parks and Dyer, 1922, p. 38, pl. 7, figs. 13, 14, 17. [?]Rafinesquina alternata var. centristriata Ruedemann, 1925b, p. 127, pl. 12, figs. 13,14. [?|Rafinesquina alternata var. mediolineata Secrist and Evitt, 1943, p. 363, figs. 13, 14. Description BaseD ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER Orpo- vicIAN. Shell of moderately large size (median length of 39 specimens, 23 mm; median width of 25 specimens, 24 mm), inequivalved, concave-convex, U-shaped outline. Shape variable, slightly wider than long, greatest width near hinge line, width varying between 85 and 129 per cent of length (median of 21 specimens, 102 per cent). Hinge line long, straight. Cardinal angle variable, sharply acute with small alations or broadly rounded, obtusely angular. Anterior commissure rectimarginate. Lateral mar- gins subparallel, broadly rounded; anterior lateral margins smoothly curved. Parvicos- tellate, costae on median part of valve, well-defined, thick; costellae, primary and secondary, bifurcating, highly variable in length, regularly spaced. Concentric striae prominent, two kinds: coarse, widely but regularly spaced; fine, closely spaced, faint. Pedicle valve convex, very broadly curved; beak prominent, pointed; cardinal area anacline; delthyrium prominent, pseudodeltidium unknown; posteroventral muscle scar small, fan-shaped, faint. Brachial valve gently concave, flattened near anterior margin; cardinalia fragile, cardinal process small, details unknown, notothyrium prominent. Shell pseudopunc- tate, punctate, punctae regularly spaced in rows between costellae, preserved on in- ternal mold (PI. 15, fig. 1). Materiats. The description is based on over 50 specimens from Pennsylvania to Tennessee deposited in the Peabody Museum. Discussion. These specimens from the central Appalachian Upper Ordovician rocks are tentatively assigned to Rafinesquina “alternata”’ pending a complete taxonomic revision of the Upper Ordovician Rafinesquininae. Previous investigators working in the central Appalachians had frequently identified these large, concavo-convex stro- phomenids with a distinctive costellate pattern as R. (= Leptaena, = Strophomena) alternata, or as one of its numerous subspecies. It had become customary to group a wide variety of shells under this term. Foerste (1924, p. 114) commented that the extreme variation in size, outline, convexity and internal structures of this long- ranging Middle to Upper Ordovician species made the catch-all R. alternata virtually useless. He informally attempted to restrict R. alternata to those large, plate-like Rafinesquininae of the Upper Ordovician (Maysville) in Canada and in doing so placed only Hall’s Hudson River Group specimens in synonymy. Later Salmon (1942, p. 574) emended the definition of R. alternata in her study of the Mohawkian Rafinesquininae. Her emended description is based only on Hall’s ORDOVICIAN APPALACHIAN ECOLOGY 89 New York Middle Ordovician (Trenton)- specimens, and she suppresses the term R. alternata in favor of R. trentonensis. In the discussion of R. trentonensis, Salmon states that the Upper Ordovician (Cincinnatian) forms previously called R. alternata do not conform to the emended definition. These later forms are larger, much more convex, and have much less regular costellae. Interior structures are supposed to be more prominently displayed in the Upper Ordovician specimens, but Salmon does not elaborate on the details. She concludes that these specimens very closely resemble R. alternata var. ponderosa (Hall). Salmon’s (1942, p. 575) informal designation of all Cincinnatian forms previ- ously called R. alternata as R. ponderosa is not satisfactory. There are numerous refer- ences (see Bassler, 1915, p. 1085) to Upper Ordovician (Maysville) specimens, called R. alternata (Hall), R. alternata var. fracta (Meek) and R. alternata var. centri- striata Ruedemann, which do not resemble R. alternata var. ponderosa, but rather show closer affinity to R. trentonensis (Salmon, 1942, emend.). The material I have collected from the central Appalachian Upper Ordovician also appears to be much more similar to R. trentonensis than to R. ponderosa, although undoubted R. pon- derosa has been identified from one locality (loc. 97). However, use of the term R. trentonensis for my central Appalachian Upper Ordo- vician specimens seems a poor choice: first, because Salmon (1942, p. 573) stated that the Upper Ordovician Rafinesquina are not conspecific with those of the Middle Ordovician and second, because her emended definition does not include Hall’s New York Hudson River Group (Upper Ordovician) R. alternata, which the central Appalachian Upper Ordovician specimens closely resemble. The term R. alternata must therefore be placed in the category of nomen inquirendum, and I will call the specimens from the Upper Ordovician of the central Appalachians R. “alternata”. The term R. alternata var. mediolineata was introduced by Secrist and Evitt (1943, p. 363) for specimens found at Massanutten Mountain, north-central Vir- ginia. I have re-collected from their locality (my locality 167) and have found these specimens to exhibit a prominent median costae much like the New York R. alternata var. centristriata Ruedemann. I am tentatively placing both these taxa in R. “alter- nata”’, because in all other external morphological features these specimens are similar to the other central Appalachian specimens. Rafinesquina “alternata’ is widespread throughout the central Appalachian Upper Ordovician rocks but is most abundant from Pennsylvania to northern Vir- ginia, brachiopod faunal province I (see Fig. 14). It is patchy in its distribution in eastern Pennsylvania (Shochary Ridge), West Virginia and southwestern Virginia. Table 15 lists the associated faunal elements of R. ‘“‘alternata” in each region, includ- ing populations of the Sowerbyella—Onniella Community and the Zygospira—Heber- tella Community. R. “alternata” occurs alone or with the strophomenid Sowerbyella (Sowerbyella) sericea and crinoids in the Strophomenid Population of the Sower- byella—Onniella Community which is by far its most common association. Most speci- mens of R. “alternata” are found in a muddy silt or fine sand. Any interpretations of the life habits of R. “alternata” are hindered not only by our lack of knowledge of the anatomy and ecology of almost all Recent articulate brachiopods, but also by the fact that there are no living representatives of the stro- phomenids with the possible exception of the thecideid Lacazella (Williams, 1953). Elliott (1965, p. H857) believed that the affinities of the order Thecideidina must PEABODY MUSEUM BULLETIN 34 90 SpNUI dUII| -s}is Appnur q[Is-pues uinjeysqng PIO pruswioydois uone[ndog DLISOMALNIVL pidoyaq DLgsoshT D104 0110 sproully D4I9S14INUL D1JSOLINLNIAL paniLas D1]91UUO D104 0710 D1IaSiyjNUL pugsosh7z Dyjatgsamog DaI1Las Danas D1] a1uuo s}UsUIe]9 DipNuUs Dipnuis pyakquamos pyjakquamos DaI1Las Teun 011974999 011914993 (ao1eds A194) sprourir) pyakquamog pezeloossy E81 ‘OST 891 “L9T 801 “FOT srequimt 821 “L21 BLT “LLT 991 ‘O9T LE “GE “IE 8¢ ‘SI “+ AqrTe00T San eee eA “IA Uoprey ‘eA SUA BqMezeyn ‘eA ea ‘eg ‘oSpry ‘uua Ty, ‘“oSpry UsTTeM “4. Uo Nuesseyy “WW esroreosn J, Areyooyusg “IW 2u0'T “IW YON “VW AueiINn ‘aSpry 31g ‘4 uo0D0e Y ee ole lll TTT a——s00 OO “Jessouua TT, UIIYWAOU 0} eruealAsuuag UIOjSVI WOIT ..0IDULI)D,, puinbsauyoy jo sjUsUa[a [eUNe} pozeIOOSse VY, “C{ ATAVL ORDOVICIAN APPALACHIAN ECOLOGY 91 remain uncertain pending a complete restudy of Lacazella, which lives permanently cemented to the substratum by its large, convex ventral valve with the much smaller dorsal valve uppermost (Hyman, 1959, p. 585). Williams (1953) and Rudwick (1965) emphasized the characteristic shell modifications of the strophomenids. The loss of a functional pedicle as shown by the small size of the foramen is critical to any environmental reconstructions. More recent studies by Crickmay (1966, p. 503), who sectioned Upper Ordovician specimens of R. “alternata” from Ohio, point up the possibility that the apical cavity had no primal opening at all. Whether the pedicle was atrophied early in life or was never functional, the mature shell must have lain free on the substratum. An adaptation to a soft substratum is seen in the concavo- convex shell form which probably developed concurrently with the loss of the pedicle. All modern articulate brachiopods are limited to waters of normal marine salinity and appear to be tolerant of some turbulence, but less tolerant of actual sediment influx. R. “alternata” probably was no exception, as it lived on a muddy fine-grained sand and silt substratum, supported only by the gently convex ventral valve. The en- vironmental setting of R. ‘“‘alternata” and the other abundant strophomenid, Sower- byella (Sowerbyella) sericea, was probably quiet water and sublittoral. Both animals would have had considerable difficulty in maintaining themselves unattached where wave or current energies were high. The strophomenid shape is suggestive of some Recent bivalve molluscs; for example, some of the free-living plano-convex pectinoids, such as Aequipecten irradians which inhabits enclosed waters where the substratum is soft mud or firm (not shifting) sand (Gutsell, 1931, p. 573). Perhaps a better bi- valve analogue is the Recent East Indian anomiid Placuna placenta (Hornell, 1909, p. 45-47), which lies freely on the muddy silts in sheltered or quiet water environ- ments. It is strongly concavo-convex and reportedly lies with its hinge line submerged in the sediment; it is extremely common in a muddy silt community. OrpER RHYNCHONELLIDA SUPERFAMILY RYNCHONELLACEA Famity RHYNCHOTREMATIDAE SuBFAMILY ORTHORHYNCHULINAE Genus ORTHORHYNCHULA Orthorhynchula linney (James, 1881) Plate 13, figures 5-8; plate 14, figures 1-5 Orthis(?) linneyi James, 1881, p. 41. Nettleroth, 1889, p. 41 pl. 34, figs. 7-13. Orthorhynchula linneyi (James). Hall and Clarke, 1893, p. 181, pl. 56, figs. 10-13, 19 (13 labeled as 18). Bassler, 1909, pl. 14, figs. 10-12. Foerste, 1910, p. 24, pl. 3, fie 10, Poerste, (912, p.132,pl. Tl, he. 5. Bassler, 1919) pr 27) pl on mes, gale. Ruedemann, 1925b, p. 131, pl. 13, fig. 6. Schuchert and Cooper, 1932, p. 42, pl. 16, figs. 12 ,17, 28-30. Butts, 1941, p. 117, pl. 97, figs. 14-19; p. 119, pl. 97, figs. 39-42. Cooper, 1944, p. 309, pl. 117, figs. 41-47. Cooper, 1956, p. 669, pl. 128F, figs. 32-36. Ager et al., 1965, p. H557, figs. 423.2a-f, 425.3a-c. Platystrophia ponderosa var. stevensoni Grabau, 1913, p. 453, pl. 12, figs. 1-3. Orthorhynchula stevensoni (Grabau). Cooper, 1944, p. 309. Swartz, 1948, p. 111. Swartz, 1955, p. 82. Horowitz, 1965, p. 10. 92 PEABODY MUSEUM BULLETIN 34 DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN Upper Orpo- vicIAN. Shell of moderately large size (median length of 75 specimens, 19 mm; median width of 110 specimens, 23 mm), inequivalved, subpentagonal. Shape variation negligible, slightly wider than long. Cardinal extremities sub-round. Anterior com- missure sulcate. Radial costae pronounced, broadly rounded; interspaces deep, sharply rounded. Pedicle valve broadly convex, medial sulcus prominent. Umbo very prominent, broad, large, elongate; umbonal region inflated, slopes to cardinal extremities steep. Beak erect, curved; beak ridges prominent, preserved on internal mold. Pedicle foramen medium sized, subangular in outline, deltidial plates unknown. Teeth ridge elevated, blunt. Interarea apsacline; hinge line short, straight. Brachial valve sharply convex, medial fold prominent. Cardinalia preserved on latex impression of internal mold (Pl. 13, fig. 6), functions as crural base; cardinal process simple vertical blade; sockets narrow, elongate, curved anterolaterally from cardinal process; outer socket ridge high, thin; crura prominent, elongate, fusion with dorsal septum. Musculature unknown. Shell calcite, fibrous with conical markings on inner shell surface, preserved on internal mold. MatTeRIALs. The description is based on over 900 specimens from south-central Pennsylvania to northern Tennessee deposited in the Peabody Museum. Discussion. These specimens from the central Appalachian Upper Ordovician rocks are tentatively assigned to Orthorhynchula linneyi pending a more complete taxono- mic study. Orthis(?) linneyi was originally described, but not figured, by James (1881) from specimens from the upper part of the Cincinnati Group in Kentucky. The definition was emended by Hall and Clarke (1893, p. 181), who designated it the type of the new genus Orthorhynchula. Since that date Orthorhynchula linneyt has been identified by numerous investigators from the Middle Ordovician (Trenton) in Kentucky and Tennessee and the Late Ordovician (Cincinnatian) of the Mid- Continent and central Appalachians. Specimens of O. linneyi have undoubtedly been misidentified as the superficially similar Rynchotrema capax or Platystrophia ponderosa, although neither of these has the short, straight hinge line or well-defined crura* characteristic of O. linney. Hall and Clarke (1893, p. 182) and Foerste (1910, p. 25) thought that O. linneyi was a characteristic fauna of the south-central Appalachians and was not found north of southwestern Virginia, but Ulrich (1911), Bassler (1919) and Butts (1940) identi- fied O. linneyi as a major faunal component of the Upper Ordovician strata through- out the central Appalachians. Swartz (1948, p. 111) renewed the claim that “O. lin- ney previously identified from central Pennsylvania to southwestern Virginia was not identical to the typical O. linneyi from Kentucky and Tennessee; therefore, he used the term O. stevensont. This name had been introduced by Grabau (1913, p. 453) as a variety of Platystrophia ponderosa, which it most certainly is not. Unfor- tunately Swartz has not attempted to document the specific differences between O. linneyi and O. stevensoni (Swartz, 1948, p. 111; 1955, p. 82). Horowitz (1965, p. 10,91) comments that O. stevensoni evolved from the earlier (i.e., Middle Ordovi- *The crura are two processes that extend from the cardinalia forming the posterior basal support for the spirolophous lophophore. ORDOVICIAN APPALACHIAN ECOLOGY 93 cian) O. linneyi, but again there is no mention of what evolutionary adaptations have taken place. I have re-collected from Grabau’s Platystrophia ponderosa var. steven- sont type locality in Walker Mountain (my locality 151) and have found these brachiopods similar to all the other Orthorhynchula specimens in the central Appala- chian Upper Ordovician rocks. A restudy of this central Appalachian and Mid- Continent material should remove O. stevensoni from the category of nomen in- quirendum. The classification of rhynchonellid brachiopods is reviewed by Cooper (1959) and summarized by Ager et al. (1965). Schuchert and Cooper (1932, p. 26, 42) referred very briefly to O. linney: in their classical study of the orthids and pentamerids, mak- ing a small but important revision of Hall and Clarke’s 1893 definition. More im- portant are their figures of O. linney: from the Maysvillian of Kentucky (Schuchert and Cooper, 1932, pl. 16). Compared to the central Appalachian form, the Upper Ordovician specimens from Kentucky are about one-fourth to one-third smaller and somewhat less ovate, but specific differences in the cardinalia appear slight (see also Foerste, 1910, p. 27; Ager et al., 1965, figs. 425.3a, b and PI. 13, fig. 6, this paper). The most distinctive parts of the rhynchonellid brachiopod shell are the crura, which are moderately long and assume several distinctive patterns or shapes (Cooper, 1959, p. 7). Unfortunately the crura of many of the Paleozoic genera have yet to be described and figured. The preservation of much of the central Appalachian Upper Ordovician material as steinkerns and the lack of sufficient numbers of serial sections through the shell have prevented an accurate definition of the crura, although a few latex impressions of the internal mold of the brachial valve do give some indication of overall size and shape (Pl. 13, fig. 6). Ager et al. (1965, p. H553), however, claim that the morphology of the crura does not seem as valuable in the classification of the Paleozoic rhynchonellids as it is in the Mesozoic and Tertiary species. Unfortunately, there is very little agreement on which morphological features are the most important. Not only does each investigator appear to prefer to employ his own techniques for identification of features, but these features are usually only those which he views as important. Ager et al. (1965, p. 552) have pictured a bleak future of a proliferation of Paleozoic rhynchonellid genera if the trend is not reversed. Cooper (1959), how- ever, has provided a valuable summary of rhynchonellid classification and also has reviewed the morphological characters that should be considered in the definition of any rhynchonellids. Orthorhynchula linneyi is one of the most characteristic and abundant fossils in the central Appalachian Upper Ordovician strata. Bassler (1919, p. 272) felt that this species was so well-represented at the Fairview-Maysville horizon in the Appalachian Valley and Ridge Province that he applied the name “Orthorhynchula Bed” to these rocks. They are mentioned in numerous subsequent publications as the Orthorhyn- chula Zone of the Reedsville or Martinsburg Formation. Butts et al. (1939, p. 26), Butts (1940, p. 208) and Butts (1945, p. 5) reported that O. linney: could be found from Morristown, Tennessee to Tyrone, Pennsylvania. I have found O. linneyt most abundant along the westernmost exposures of the Reedsville Formation from south- western Virginia to south-central Pennsylvania, especially in brachiopod faunal prov- ince II, but specimens also may be common in province III (Fig. 14). It is more scat- tered and noticeably less abundant away from these areas in the central Appalachians; Ruedemann (1925b, p. 131) has found only one specimen in western New York, and 94 PEABODY MUSEUM BULLETIN 34 neither Parks and Dyer (1922) nor Foerste (1914a, 1924) has mentioned it as occur- ring in the Upper Ordovician rocks of southeastern Canada. The central Appalachian O. linneyt is associated with two distinct faunal popula- tions, i.e., the Rhynchonellid Population of the Orthorhynchula—Ambonychia Com- munity and the Orthid Population of the Zygospira—Hebertella Community (Fig. 14), and is found in sediments ranging from sands to lime muds. O. linneyt is, however, most abundant in slightly muddy sands and silts. Table 16 diagrams the associated faunal elements of O. linneyt. The life habits and environmental setting of the central Appalachian Upper Ordovician specimens of O. linneyi can be inferred from the sparse amount of data that has been accumulated on existing genera of rhynchonellids. Hyman, (1959, p. 580), in a brief summation of the work done on Recent Rhynchonellacea, pointed out that the anatomy and shell morphology of some of the genera are fairly well known, but there is little data pertaining to the environmental setting of the rhynchonellids. The overall environmental setting of these Upper Ordovician brachiopods is sum- marized in the chapter on paleoautecology, p. 36. The Recent rhynchonellids are characterized by a strong elongate pedicle, spirolo- phous lophophore, and prominent sulcus and fold. Morse (1902, p. 334) claimed that the unrolled arm tip of the lophophore could actually be extended beyond the margins of the shell. Spicules in the lophophore probably provided support for the extension. Hemithyris psittacea, anatomically one of the best known Recent species, has been dredged by Remy (1928) near Jan Mayen Island in the Greenland Sea where in one clump 100 H. psittacea had been attached to each other or to pebbles. H. psittacea has been found at depths to 2200 meters (Hyman, 1959, p. 599), but is the character- istic circumarctic and circumboreal shelf brachiopod. Hertlein and Grant (1944) have found that the cosmopolitan H. psittacea descends into Puget Sound and onto the Oregon coastal waters; DuBois (1916), working in the same area, reported H. psit- tacea to have its maximum abundance from 54 to 160 meters water depth. Thus rhynchonellids form a characteristic shelf fauna, inhabiting quiet water at moderate depths in the outer sublittoral. O. linneyi is common in the central Appalachian sands and silts and may have been clumped over an extensive area of the inner sublittoral shelf. Between the layers with thickly crowded articulated valves are layers with scattered individuals, possibly indicating some post-depositional reworking or variable rates of deposition, or per- haps representing Late Ordovician distributions which were actually fairly patchy. At a few localities in West Virginia the highest stratigraphic occurrence of O. linneyt is marked by worm tubes covering the surface of some valves (PI. 14, fig. 4). A study of Recent worm borings along the Dutch tidal flats by Boekschoten (1966) has shown occasional concentrated patches of highly bored, loose Cardium edule shells that had been washed shoreward along the flats. The less common occurrence of worm tubes at the inhalant openings of O. linneyi suggests that a few of these were in living posi- tion along the shell bank (Pl. 14, fig. 1). Boekschoten (1966, p. 354) has likewise reported that only 6 per cent of the Cardium edule shells show specific borings at only the inhalant opening, and he believes that this sort of occurrence documents infesta- tion in living position. The worm-encrusted O. linneyi shells represent the nearest- shore occurrence of this rhynchonellid. O. linneyi was probably never intertidal, but apparently could tolerate periods of high sediment influx. The apparent strength of 95 ORDOVICIAN APPALACHIAN ECOLOGY ys Appnur ysis Appnuw q[Is—pues uInjze.ysqng BIO pHjauoyoudyy uoneindog DAISOMQANIAL piigsoghZ épjnsurT suvozoAIg midoy aq sno}eu0}sodez} AVE uaiBe O80 S140] 01pouL piiezeteode S110] 01D OU sisg ojo1pow sisg0j01poW DIDAYINI DIyICuoqup Dsingavsg DIyICUuoquUp DIVIUNA DJUOPOLAYyIST DIVNUIS DI]9}4999 FY pywIunsy DJUOpOsGYIST YiIM JO auoye s}UdUIE[9 [eUNL] poye1oossy sloquinu ISI ‘PBT “6bT “OST “L4T £0 “COZ “102 “661 ITT ‘28 ‘66 ‘86 “ZIT “8 “€9 Aqrjeoo'T i EE EEE ———————————E—E—————————— "eA “IW Uopsey ‘eA M "ed “TW J2qT2M “IIA YOUNTO pue ‘eA “IA 104 YON “VW epeys “IA Assn yy “TA syoef “IA STITM a “eIUISIT A UJBISOMYINOS PUL VIUISITA IS2AA Uo}svO ‘erueayAsuueg [eiqUa0-YyyNos ul sauurz pinyIucysoyjz4—Q) JO syUIWa[a [VuNey pozeloosse oY], “OT ATAvL 96 PEABODY MUSEUM BULLETIN 34 the pedicle and the prominent zig-zag valve edges may have provided the necessary support and efficient protective sensory device for this rhynchonellid to exist in a turbulent environment. Rudwick (1964) claimed that the presence of a zig-zag com- missure did not imply any special environmental conditions. But judging from the abundance of O. linneyi in the silts and sands, the zig-zag opening could be an ad- vantage. This type of opening is also found in Hebertella sinuata, which replaces O. linneyt to the south in the muddy silts and sands. There are only minor changes in the shape of the O. linneyi shell from West Vir- ginia to northern Tennessee. The larger, more rounded shape in the north gives way to a more elliptical and smaller shell in the south, this change coinciding with a dramatic change in the abundant faunal elements. O. linneyi is much less common in the lime muds of the south than in the sands and silts of the north. Thus change in shape may be directly related to local environmental controls. Ager (1965) and Rud- wick (1965) discuss some aspects of brachiopod morphology as it relates to the type of substratum, but little is actually known about the adaptive morphology of brachio- pods. DuBois (1916) has conducted the only successful experiments on phenotypic variation in brachiopod shells as related to current energy. He found that the valves of Terebratalia transversa became shorter and more convex where currents were con- sistently stronger. Unfortunately this type of experimentation has not been continued. It would appear that the more convex northern forms of O. linneyt, abundant in the sands and silts, had been subjected to consistently stronger current energies than the ones in the lime muds of the south. The overall distribution of O. linneyi and its possible mode of dispersal have been briefly touched upon by Ulrich (1911, p. 514), Ruedemann (1925b, p. 131-132) and Horowitz (1965, p. 93), who agree that O. linneyi is found only in Tennessee and Kentucky in the Middle Ordovician. It appears to have migrated northward during the Late Ordovician along the western edge of the central Appalachians as far north as central Pennsylvania, with a few scattered occurrences in New York. Horo- witz (1965) also believed that the rates of evolution were rapid enough for the change of O. linneyi into a distinct Late Ordovician species, O. stevensont. OrpEeR SPIRIFERIDA SusBorDER ATRYPIDINA SUPERFAMILY ATRYPACEA Famity ATRYPIDAE SuBFAMILY ZYGOSPIRINAE Genus ZYGOSPIRA Zygospira modesta (Hall, 1847) Plate 14, figures 6-7 Producta modesta Say, MS (nomen nudum). Atrypa modesta Hall, 1847, p. 141, pl. 33, fig. 15; p. 289. Emmons, 1855, p. 192, pl. lO; fig 15> Zygospira modesta (Hall). Hall, 1862a, p. 154, figs. 1, 2. Hall, 1867, p. 267, fig. 12. Meek, 1873, p. 125, pl. 11, figs. 4a-d. Hall and Clarke, 1893, p. 155, figs. 146-149; pl. 54, figs. 8-10, 12, [?]7. Winchell and Schuchert, 1895, p. 467, pl. 34, figs. 42- ORDOVICIAN APPALACHIAN ECOLOGY 97 44. Cumings, 1908, p. 946, pl. 36, figs. 8, 8a-i. Foerste, 1910, p. 29, pl. 2, figs. 15a, b. Bassler, 1919, p. 274, pl. 54, figs. 20-22; pl. 57, figs. 13-16. Parks and Byer, 1922, -p. 40, pl. 7; figs. 19, 22) Foerste, 1924, p. 127, pl. 10, figs. 21a, b. Invedemann, 1925b, p: 133, ipl. 13, fig: 16: Butts, 1941, p. 118, pl. 97, fig. 28. Secrist and Evitt, 1943, p. 367. Cooper, 1944, p. 317, pl. 120, fig. 72. Boucot et al., 1965, p. H634, fig. 518.2a. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- vicIAN. Shell of small size (median height of seven specimens, 6 mm; median width of five specimens, 8 mm), slightly inequivalved, inflated, biconvex, outline elliptical. Shape variation negligible, slightly wider than long, greatest width near midpoint between hinge line and anterior margin. Hinge line short, straight; interarea of both valves, slightly anacline. Cardinal extremities broadly rounded. Anterior commissure uniplicate to strongly sulcate; anterior margin flattened, lateral margins broadly rounded. Costellate, costae subangular, prominent, numbering about 20; costellae faint, one dorsal, arising from bifurcation of median costae, at anterior margin. Pedicle valve sharply convex, umbo carinated, broad; beak erect, incurved; pro- nounced fold umbo to anterior margin, margin moderately concave, four costae on fold, inner two larger; foramen unknown, deltidial plates unknown. All internal fea- tures of ventral valve unknown. Brachial valve broadly convex; sulcus deep, margins convex; three costae in de- pression, central one large, prominent, flanked by faint, thin costae. All internal fea- tures of dorsal valve unknown. Shell microstructure and mineralogy unknown. MarteriA_s. The description is based on about 20 specimens from central Pennsylvania and northern Virginia deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Zygospira modesta is tentative pending a complete taxonomic review of the North American Lower Paleozoic atrypids. Z. (= Atrypa) modesta was first described and figured by Hall (1847), who subsequently (Hall, 1862a) designated it as the type of the genus Zygospira. It is the most common and widespread North American Upper Ordovician Zygospira and, I believe, has been occasionally confused with Z. recurvirostra and Z. cincinnatiensis. The confusion between Z. recurvirostra and Z. modesta is reviewed in the discus- sion of Z. recurvirostra, p. 99. Z. cincinnatiensis, as originally defined by Meek (1873, p. 126) and elaborated upon by Foerste (1910, p. 29), is quite distinct from Z. modesta and is not just a larger form, as many investigators have implied. The much coarser, broadly bifurcating costae and the notably elongated anterior margin at the fold and sulcus are, at least, specifically distinct. Zygospira modesta is found only in central Pennsylvania and northern Virginia, brachiopod faunal province I (see Table 3; also Fig. 14) and is never as abundant as the congeneric Z. recurvirostra in the south, brachiopod faunal province III. In cen- tral Pennsylvania Z. modesta is found in a fine silt to muddy silt, usually with crinoids and at some locales Isotelus and Flexicalymene, part of the Orthid—Crinoid Popula- tion of the Sowerbyella—Onniella Community. Rare specimens occur in northern Vir- ginia with Sowerbyella (Sowerbyella) sericea and Rafinesquina “alternata”’. It is found as far south as central Virginia (loc. 177, 178) where there are a few specimens 98 PEABODY MUSEUM BULLETIN 34 in a fine silt-sand dominated by Hebertella sinuata of the Orthid Population of the Zygospira—Hebertella Community. Z. modetsa may have differed very little from Z. recurvirostra in life habits and environmental setting, and both probably occupied an outer sublittoral regime. The geographic location, brachiopod faunal province I (Fig. 14), and stratigraphic posi- tion (Fig. 15) of Z. modesta emphasize its outer sublittoral habitat on a muddy silt bottom (see p. 84 and 91 for environmental interpretations of the stratigraphically higher orthids and strophomenids in central Pennsylvania). Another species of Zygospira has been identified in east-central Pennsylvania, bra- chiopod faunal province I (loc. 120). It is Z. concentrica (Ulrich, 1897, p. 14; see Ruedemann, 1925b, p. 134), which is very rare in a black to gray muddy silt domi- nated by Onniella multisecta, Cryptolithus and a few specimens of Sinuites and Sowerbyella (Sowerbyella) sericea, part of the Orthid—Crinoid Population of the Sowerbyella~Onniella Community. This association and the substratum type again seem to indicate a quiet, outer sublittoral environmental setting. Zygospira recurvirostra (Hall, 1847) Plate 14, figures 8-9 Atrypa recurvirostra Hall, 1847, p. 140, pl. 33, figs. 5a-d. Emmons, 1855, p. 191, pl. 10, figs. 5a-d. Rhynchonella recurvirostra (Hall). Billings, 1863, p. 168, fig. 152. [?|Zygospira modesta var. kentuckiensis James, 1878, p. 7. [?|Zygospira kentuckiensis (James). Nettleroth, 1889, p. 138, pl. 34, figs. 21-25. Hall and Clarke, 1893, p. 157, pl. 54, figs. 11, 15, 16. Foerste, 1924, p. 127, pl. 10, figs. 20a-c; pl. 15, figs. 1, 2a-b, 4a-c. Butts, 1941, p. 117, pl. 97, figs. 5-7. Cooper, 1944, 1317; pl 120shes: 54755; Zygospira recurvirostra (Hall). Hall and Clarke, 1893, p. 157, pl. 54, figs. 1-6. Beecher and Schuchert, 1893, p. 77, pl. 10, figs. 7-21. Schuchert, 1893, p. 82, pl. 11, figs. 1-10, Winchell and Schuchert, 1895, p. 466, pl. 34, figs. 38-41. Ruedemann, 1901, p. 27. Weller, 1903, p. 161, pl. 10, figs. 23-26. Bassler, 1909, pl. 7, figs. 4-5. Foerste, 1914b, p. 132, pl. 1, figs. 2a-c. Bassler, 1919, p. 272, pl. 42, figs. 9-12. Butts, 1941yp. 99, pl. 92, [?]fig. 10; p. 100, pl. 92, fig. 23; p. 118; pl) 97 paige: 34-38. Cooper, 1944, p. 317, pl. 120, fig. 56. Cooper, 1956, p. 673, pl. 142H, figs. 34-38. Boucot et al., 1965, p. H364. [?|Zygospira meafordensis Foerste, 1924, p. 128, pl. 15, figs. 3a-c. [?|Zygospira recurvirostra var. aequivalvis Twenhofel, 1927, p. 214, pl. 19, figs. 10-12. DeEscriPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- VICIAN. Shell of small size (median length of 13 specimens, 8 mm; median width of 9 specimens, 9 mm), slightly inequivalved, biconvex, inflated, outline subcircular. Shape variation negligible, length and width almost equal, greatest width near mid- point between hinge line and anterior margin. Hinge line short, straight; interarea of both valves orthocline. Cardinal extremities rounded. Anterior commissure sulcate to uniplicate; anterior margin flattened, lateral margins broadly rounded. Costellate, costae subround, well-defined, numbering 19 to 24; costellae, one dorsal, two ventral, arising from bifurcation of median costae, near anterior margin, more pronounced on ventral fold. ORDOVICIAN APPALACHIAN ECOLOGY 99 Pedicle valve sharply convex; umbo carinated, narrow; beak erect, incurved; pro- nounced fold, extending umbo to anterior margin, margins moderately concave, four costae on fold, two on slopes of fold. Foramen mesothyridid, deltidial plates conjunct. All internal features of ventral valve unknown. Brachial valve broadly convex; sulcus wide, flattened, margin slightly convex to flattened, three costae in depression, two on flanks of depression. All internal features of dorsal valve unknown. Shell fibrous, calcite. Mareriats. The description is based on about 30 specimens from southwestern Vir- ginia and northern Tennessee deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Zygospira recurvirostra must be considered tentative pending a more com- plete taxonomic survey of the North American Lower Paleozoic atrypids. The central Appalachian material does not preserve any internal structures and has permitted comparisons to be made only on external configuration. Species of Zygospira have, however, been previously defined primarily on the basis of size, shape and ornamenta- tion. The taxonomic significance of these characters in Zygospira has yet to be cri- tically explored. Zygospira recurvirostra has long been confused with Z. modesta, a very common Upper Ordovician species, which is the type of Zygospira. Z. recurvirostra has been previously distinguished from Z. modesta by its broader, more shallow mesial depres- sion in the brachial valve, and the five equisized primary costae within the depression (Foerste, 1914b, p. 132; Cooper, 1956, pl. 142H; cf. Pl. 14, fig. 8 in this paper). Z. modesta, although about the same size as Z. recurvirostra and exhibiting the same total number of costae (about 20), has a much more pronounced, deeper mesial sulcus; the costae within the depression are notably more angular, and of the five costae within the depression the medial one is considerably broader than those on either side, which are characteristically faint (Pl. 14, fig. 7). The central Appalachian Upper Ordovician specimens can be segregated into what appear to be internally consistent species groups on the basis of this mesial depression. Some criteria previously employed in discriminating between the two groups were found to exist in both. The total number of costae was not significantly different between the species, and the bifurcation of one or two medial costae near the anterior margin occurs in both. This bifurcation of medial costae was previously thought to be diagnostic of Z. cincinnatiensis (Foerste, 1910, p. 31), but appears to be common throughout the genus Zygospira. Meek (1873, p. 126), Cumings (1908, p. 945), Parks and Dyer (1922, p. 41) and Ruedemann (1925b, p. 134) have described the figured specimens of Z. cincinnatiensis, which I have not found in the central Appalachian Upper Ordovician strata. Z. cincinnatiensis appears to be a distinct spe- cies, although figures identified as Z. cincinnatiensis by Hall and Clarke (1895, pl. 54) and Foerste (1910, pl. 6) closely resemble Z. modesta. Zygospira kentuckiensis, initially described by James (1878) from the Upper Ordovician of Kentucky, was thought to resemble closely Z. modesta, differing mostly by its larger size. Subsequent descriptions and figures of Z. kentuckiensis show a much closer resemblance to Z. recurvirostra, though Z. kentuckiensis is normally one and a half times larger than Z. recurvirostra (Foerste, 1924, p. 127). Some central Appala- chian Upper Ordovician specimens which are as large as previously described Z. 100 PEABODY MUSEUM BULLETIN 34 kentuckiensis show no external morphological differences from the smaller Z. recurut- rostra with which they are found. Zygospira recurvirostra is found abundantly only in southwestern Virginia and northern Tennessee, brachiopod faunal province III (Fig. 14), in rock types varying from lime muds to muddy silts. But Z. recurvirostra is more characteristic of the finer grade substratum and is found with three distinct but intergrading local faunas which are all part of the Spiriferid Population of the Zygospira—Hebertella Community (Table 17). TABLE 17. The associated faunal elements of Zygospira recurvirostra in northern Tennessee and southwestern Virginia. All species are part of the Spiriferid Population of the Zygospira—Heber- tella Community. Lone Mt., Clinch Mt., Tenn. Clinch Mt., Powell Mt., Va. Powell Mt., Tenn. Cumberland Mt., Va. Clinch Mt., Va. Locality numbers 1255) 0265127, “13, 141 133.1135 139, 145, 147, 149 Associated faunal elements Murchisonia? Pterinea (Caritodens) Hebertella sinuata demissa Hallopora Ambonychia cultrata Pterinea (Caritodens) demissa Batostomella Modiolopsis modiolaris Substratum lime mud muddy silt-silt muddy silt-silt — The life habits and environmental setting of Z. recurvirostra are at least as indefi- nite as those of the species of strophomenids and orthids. Probably occupying a normal marine environment, Z. recurvirostra lived on a variety of substrata, apparently pre- ferring muds, and was supported by a functional pedicle. Distribution could have been controlled by water turbulence and by sediment influx. The orthid Hebertella stnuata noticeably begins to outnumber Z. recurvirostra in the fine sands and silts of southwestern Virginia. Thus, Z. recurvirostra appears to prefer a quiet water, shelf environment, probably outer sublittoral, though it may have also occupied an inner sublittoral environment in the southern part of its distribution, where there was little terrigenous influx. GASTROPODA Plates 16-19 Gastropods constitute a numerically important and widespread faunal element throughout the central Appalachian Upper Ordovician strata. Bellerophontacean, pleurotomariacean and murchisoniacean gastropods are most abundant, but the small amount of well-preserved material and the lack of recent studies of the Lower Paleo- zoic gastropods have permitted only tentative identification of much of the Appala- chian material. Dr. Ellis Yochelson of the U. S. Geological Survey has provided in- valuable guidance in the taxonomic assignment of these specimens. Ulrich and Scofield (1897) have presented the only systematic review of the North American Lower Paleozoic Gastropoda. There has been little attempt to revise their systematics, although Foerste (1914a, 1924), Ruedemann (1926), Secrist and Evitt (1943) and Wilson (1951) have made valuable contributions. ORDOVICIAN APPALACHIAN ECOLOGY 101 PuyLtum MOLLUSCA CLiass GASTROPODA OrpveER ARCHAEOGASTROPODA SUBORDER BELLEROPHONTINA SUPERFAMILY BELLEROPHONTACEA Famity BELLEROPHONTIDAE SuBFAMILY PLECTONOTINAE Genus PLECTONOTUS Plectonotus? sp. Plate 17, figures 1-9 DEsScRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER Orpo- VICIAN. Shell of small size (median diameter through the coil of 184 specimens, 6 mm; median width of 112 specimens, 3 mm), bilaterally symmetrical. Whorl profile trilo- bate, preserved as internal mold (PI. 16, figs. 4, 5) ; median lobe prominent, arched or sharply convex; lateral lobes narrow, rounded. Aperture unknown. Umbilical sutures sharply defined, prominent shoulder above each umbilicus. Spiral band at whorl peri- phery preserved on latex impression of external mold, broad, raised, flat (Pl. 16, fig. 3); lunulae unknown. Surface sculpture growth lines fine, paired, intersection with spiral band sharp, swept backwards. All internal features unknown. Shell mineralogy and microstructure unknown. Marteriats. The description is based on over 500 specimens from south-central Penn- sylvania to west-central Virginia deposited in the Peabody Museum. Discussion. Assignment of these central Appalachian specimens to Plectonotus sp. is tentative. Preservation as internal molds is most common; only one latex impression of an external mold was obtained (Pl. 16, fig. 3). A knowledge of the external char- acteristics is extremely important in the classification of bellerophontacean gastropods as well as of all other Archaeogastropoda. The single most important criterion for identification of the Bellerophontidae is the presence of an exhalant channel slit that generates a sweeping of growth lines, forming a peripheral spiral band called a seleni- zone. Boucot and Saul (1963) have reviewed the criteria for identification of a seleni- zone. The central Appalachian specimens exhibit this sweeping of growth lines which seems to indicate a fairly strong re-entrant angle along with a “U”-shaped sinus. The slit appears to have been narrow, but its length is unknown. Although there are no living Bellerophontacea, Recent anatomical analogues can be found in the Pleurotomariacea (Yonge, 1947). The re-entrant notch or slit in the outer lip directs exhalant water currents passing out of the mantle cavity and is ex- pressed in the soft anatomy by the presence of two subequal, bipectinate aspidobranch ctenidia. This fact, extrapolated into the fossil record, makes the presence or absence of the slit and the depth of the re-entrant a critical taxonomic character. Knight, Batten and Yochelson (1960, p. 1175) considered Plectonotus Clarke a subgenus of the sinuitid genus Bucanella. Figured and described by Knight (1941, p. 255-256), Bucanella is a trilobate bellerophontacean, characterized by a well-devel- oped sinus but lacking a slit. Clarke (1899), in his original designation of the genus Plectonotus, suspected that his material had both sinus and slit; the probable slit- bearing selenizone was so poorly preserved that the later authors decided to make 102 PEABODY MUSEUM BULLETIN 34 Plectonotus a subgenus of the non-slit-bearing, but superficially trilobate, Bucanella. Recent findings by Boucot and Saul (1963, p. 1046-1047) and Boucot and Yochelson (1966, p. A7-A8) have uncovered a definite slit-bearing, trilobate bellerophontacean gastropod which they have assigned to the genus Plectonotus, at the same time remov- ing it from the Sinuitidae and placing it in the Bellerophontidae. However, as redefined by Boucot and Yochelson (1966, p. A7), Plectonotus is con- fined to beds of Early to Middle Devonian age. The genus shows some affinities to Ordovician and Silurian trilobate bellerophontacean forms, but these earlier genera are poorly understood. It is possible that many of the Silurian specimens referred to Bellerophon trilobatus Sowerby [see also Sinuites (= Bellerophon) globularis Miller and Faber 1894, p. 28, pl. 1, figs. 21, 22] are slit-bearing plectonotid-like forms. In fact, that they show a cross-section characterized by a high median lobe much like that of these central Appalachian Upper Ordovician specimens. No presently defined Or- dovician bellerophontid with a slit resembles this central Appalachian form; therefore, it is possible that further study will allow an extension downward of the range of the Lower Devonian (?Silurian) genus Plectonotus or the introduction of an earlier slit- bearing genus into the subfamily Plectonotinae Boucot and Yochelson, 1966. The central Appalachian Upper Ordovician Plectonotus? sp. is abundant in West Virginia and south-central Pennsylvania. Figure 16 shows the bellerophontaceans to be common only along the western edge of the Reedsville exposures, gastropod faunal province II; Plectonotus? sp. is the most numerous representative of this superfamily. The associated faunal elements are Tancrediopsis cuneata and Lingula? with lesser numbers of Ischyrodonta truncata, all part of the Linguloid Population of the Ortho- rhynchula-Ambonychia Community. The enclosing sediment is a muddy silt to fine sand, usually with a high organic content. Phosphate grains, many of which are thought to be partial internal fillings of the Plectonotus? sp. shells, are common at some locales. The sediment is often so thoroughly reworked that there are only rem- nant laminae (PI. 1). SuBFAMILY BUCANIINAE Genus BUCANIA Bucania sp. Plate 16, figures 10-11; plate 17, figures 1-3 DEscRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER Orpo- vICIAN. Shell of medium to large size (median diameter through the coil of 17 speci- mens, 14 mm; median width of 8 specimens, 9 mm), bilaterally symmetrical. Whorl profile rounded, broadly arched. Aperture expanded, slightly wide. Umbilicus widely open. Spiral band at whorl periphery faint, preserved as internal mold, bordered by thin flanges (PI. 17, fig. 1); lunulae unknown. Surface sculpture growth lines very faint, striae normal to anterior margin unknown. All internal features unknown. Shell mineralogy and microstructure unknown. MareRIALs. The description is based on about 30 specimens from south-central Penn- sylvania and West Virginia deposited in the Peabody Museum. Discussion. The assignment of these Upper Ordovician specimens to Bucania sp. was ORDOVICIAN APPALACHIAN ECOLOGY 103 made with the aid of plates and descriptions given by Knight (1941), Reed (1920), Wilson (1951) and Ulrich and Scofield (1897). The poor preservation of the cen- tral Appalachian material and the lack of Recent Lower Paleozoic gastropod studies allows only a tentative assignment (see Bellerophon cincinnatiensis Miller and Faber, 1894, p. 29, pl. 1, figs. 23, 24). Knight, Batten and Yochelson (1960, p. 1180) noted that of all the slit-bearing bellerophontid genera, only Tetranota shows a superficial resemblance to Bucania. Tetranota is rare in the central Appalachian Upper Ordovician rocks and has been positively indentified at only one locality in northern Tennessee (loc. 133). Bucania sp. is common only in south-central Pennsylvania and is rare in West Virginia and west-central Virginia, gastropod faunal province II and part of I (see Table 3 for localities and Fig. 16). Bucania sp., although geographically localized, is not everywhere associated with the same faunal elements. In contrast to the more numerous Plectonotus? sp., the only other common bellerophontid, it is not limited exclusively to the western parts of the Reedsville exposures, but occurs across the entire width of the Valley and Ridge Province in south-central Pennsylvania. The wider-ranging Bucania sp. occurs more frequently, however, with the Linguloid Population than with the Rhynchonellid and Strophomenid Populations (Table 18). TABLE 18. The associated faunal elements of Bucania sp. in south-central Pennsylvania and northern Virginia. Population Linguloid Population Rhynchonellid Population Strophomenid Population of the Orthorhynchula- of the Orthorhynchula- of the Sowerbyella- Ambonychia Com- Ambonychia Community Onniella Community munity Associated faunal Plectonotus? sp. Orthorhynchula linneyi crinoid elements Tancrediopsis cuneata Modiolopsis modiolaris Onniella multisecta Lingula? Maclurites? Sowerbyella (Sowerbyella) Ischyrodonta truncata Trochonema sericea Loxoplocus (Lophospira) abbreviata Sinuopea? The geographic distribution of Bucania sp. is believed to be primarily limited by the availability of food and by substratum firmness. Bucania sp. is abundant only where the sediment is composed of a fine sand or silt, and the genus is extremely rare to the south where muds begin to constitute a greater percentage of the sediment. The substratum had to be hard or firm and the bottom waters only slightly turbid in order to allow for the proper functioning of the aspidobranch gill. The one characteristic that distinguishes Bucania sp. from Plectonotus? sp. 1s its larger size. Plectonotus? sp. appears to have been small enough to have lived and browsed on algae, but the larger Bucania sp. may have been too large and heavy to be permanently supported by the algal fronds, unless it existed on that part of the frond which was continually submerged. If this was not the case or if the buoyant effect of the water was not able to offset its weight, Bucania sp. may have had to rely more on plant detritus accumulating on the surface of the substratum. Clumping of the plant detritus is likely and thus may explain in part the characteristic patchy dis- tribution of Bucania sp., even at localities where it is most numerous. 104 PEABODY MUSEUM BULLETIN 34 SuBoRDER PLEUROTOMARIINA SuPERFAMILY PLEUROTOMARIACEA Famity LOPHOSPIRIDAE SuBFAMILY RUEDEMANNIINAE Genus RUEDEMANNIA Ruedemannia? lirata (Ulrich and Scofield, 1897) Plate 18, figures 1-2 [?|Murchisonia uniangulata var. abbreviata Hall, 1847, p. 304, pl. 83, figs. 2a, 2c; [?]2b, 2d. [?|Pleurotomaria semele Hall 1861, p. 36. Lophospira (?Seelya) lirata Ulrich and Scofield, 1897, p. 988, pl. 72, figs. 56, 59. Lophospira (?Seelya) lirata var. obsoleta Ulrich and Scofield, 1897, p. 989, pl. 72, figs. 563 [7 57; [?|Plethospira semele (Hall). Ulrich and Scofield, 1897, p. 1010, pl. 70, figs. 8, 9; [?]10. [?|Ruedemannia abbreviata (Hall). Foerste, 1914a, p. 311. Ruedemannia lirata (Ulrich and Scofield). Foerste, 1914a, p. 312. Knight, 1941, p. 303, pl. 33, figs. 3a, 3b. Knight, Batten and Yochelson, 1960, p. 1209, fig. i alg Lophospira (Ruedemannia) lirata (Ulrich and Scofield) . Bassler, 1919, p. 295, pl. 55, figs:o,-6: [?|Lophospira lirata (Ulrich and Scofield). Ruedemann, 1926, p. 67. [?|Plethospira quadricarinata Ruedemann, 1926, p. 71, pl. 9, figs. 2, 5; [?]3, 4. [not]Lophospira abbreviata (Hall). Ruedemann, 1926, p. 65, pl. 8, fig. 12; [?]11, 13. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER Orpo- vIcIAN. Shell of medium size (height of two specimens, 10 mm and 17 mm), turbini- form. Whorl profile slope about 30 degrees from vertical; whorl surface broadly rounded, two spiral threads; one thread on upper surface raised, rounded, midway between suture and whorl periphery, surface above thread steeply inclined to vertical, concave; another thread below whorl profile, less prominent. Aperture unknown. Umbilicus unknown. Sutures prominent. Spiral bands at whorl periphery rounded, usually three; outline of selenizone prominent, wide, slightly concave; U-shaped sinus broad. Surface sculpture growth lines fine, closely spaced, swept strongly backwards, almost tangential with outer spiral bands; lunulae gently concave forward. All internal features unknown. Shell mineralogy and microstructure unknown. MaterRIALs. The revised description is based on about 10 well-preserved specimens from north-central Pennsylvania deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to the genus Ruedemannia is tentative. Foerste (1914a, p. 312) formally desig- nated Lophospira lirata Ulrich and Scofield, 1897, as the type of the new genus Ruedemannia, which was characterized by subrotund whorls and a trilineate and bilineate peripheral band. Ulrich, however, had figured both trilineate and bilineate L. lirata (Ulrich and Scofield, 1897, pl. 72). Foerste (1924, p. 211) subsequently revised his definition of Ruedemannia to include those rotund Lophospira forms ORDOVICIAN APPALACHIAN ECOLOGY 105 that Ulrich had placed in his L. robusta group (Ulrich and Scofield, 1897, p. 963). But Foerste expressed uncertainty that R. lirata was part of the L. robusta group. The term Ruedemannia was discarded by Ruedemann (1926, p. 67) in favor of Lopho- spira. Knight (1941, p. 87) thought that L. robusta and L. lirata were congeneric and included both in the genus Ruedemannia. Knight (1941, p. 303) and Knight, Batten and Yochelson (1960, p. 1207-209) again defined the genus Ruedemannia and seemed to place the major emphasis on the presence of a ““U”-shaped sinus and a well- defined slit, whereas they described Loxoplocus (Lophospira) as having a “V-shaped sinus and only a short notch, if a notch be present at all. As in the bellerophontacean gastropods, the character of the slit reflects taxonomically important differences. The rotund whorl profile also appears to be in direct contrast to the more angular profile of Loxoplocus (Lophospira). Yochelson (personal communication), however, believes that the genus Ruedemannia must be placed in the category of nomen inquirendum; the quality and amount of material studied and the lack of recent taxonomic studies do not permit the genus to be clearly distinguished from Loxoplocus (Lophospira). Thus I have used the term Ruedemannia? lirata for rotund central Appalachian Upper Ordovician pleurotomariacean gastropods that show either a definite slit- bearing selenizone or a trilineate medial banding pattern. It may be that Ulrich’s L. robusta group, characterized by shells with short rotund whorls, distinctly trilineate medial bands, growth lines and lunulae indicating a wide sinus and slit, is Foerste’s Ruedemannia, but all attempts that I have made to construct even a tentative listing of species that may possibly be assigned to this genus have been unsuccessful. I have in- terpreted the trilineate banding pattern on the more rotund forms as some indication of a definite slit-bearing selenizone, but the value of this trilineate band as a generic character is unknown. Misidentification of these Upper Ordovician specimens as Plethospira or Seelya (Pl. 17, fig. 4) could result because the central Appalachian material shows little or no preservation of the aperture or columellar lip, but Pletho- spira and Seelya do not exhibit the characteristic spiral threads mid-way between the whorl periphery and sutures typical of Ruedemannia and Loxoplocus (Lophospira). Ruedemannia? lirata is found only in north-central Pennsylvania, gastropod faunal province I (loc. 34-A, 50) at the northern limits of the pleurotomariacean distribution (Fig. 16). It is never a dominant faunal element but is locally common. The associated faunal elements are crinoids, Hallopora and Ctenodonta? pulchella, part of the Orthid—Crinoid Population of the Sowerbyella—Onniella Community. Bassler (1919, p. 296) noted fragments of L. (Ruedemannia) lirata in the sandstone debris of the upper part of the Martinsburg Formation in Washington County, Maryland. I was unable to confirm this find, although my locality 124, in the same area, did produce characteristically abundant crinoids and trepostomatous bryozoans, The substratum is composed of muddy silts, never reworked, finely laminated al- though occasionally showing shale pebble fragments. An inner or outer sublittoral, quiet water environmental setting appears to be indicated by the associated fauna, substratum type, geographic and stratigraphic position. R.? lirata, like all other Pleurotomariacea, probably required a firm substratum, non-turbid waters, and fed on macrophagous plant detritus. Only one other gastropod occupies the northernmost portions of the Reedsville exposures, and less than ten specimens were found, all of which occur within gastro- 106 PEABODY MUSEUM BULLETIN 34 pod faunal province I (Fig. 16). It is Cyclonema (loc. 75; Pl. 17, fig. 5), a platycera- tacean with life habits probably quite distinct from those of R.? lirata, although these two species occasionally are associated with similar faunal elements; Cyclonema normally is found with crinoids, Lyrodesma poststriatum, Ambonychia radiata and Rafinesquina “alternata”, part of the Orthid—Crinoid Population of the Sowerbyella— Onniella Community. It is thought that the Upper Ordovician Cyclonema, like the Devonian species of Cyclonema, may have been coprophagous commensals on crinoids (Bowsher, 1955). SuBFAMILY LOPHOSPIRINAE Genus LOXOPLOCUS Loxoplocus (Lophospira) abbreviata (Hall, 1847) Plate 18, figures 4-6 Murchisonia uniangulata var. abbreviata Hall, 1847, p. 304, pl. 83, fig. 2d; [?]2a, 2b2e: [?]Schizolopha moorei Ulrich (in Ulrich and Scofield), 1897, p. 992, pl. 65, figs. 31-37. Lophospira uniangulata var. abbreviata (Hall). Whitfield and Hovey, 1898, p. 52. [?]Ruedemannia abbreviata (Hall). Foerste, 1914a, p. 311. Lophospira abbreviata (Hall). Ruedemann, 1926, p. 65, pl. 8, figs. 11, 13, [?]12. DEscRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- VICIAN. Shell of small size (median height of 12 specimens, 7 mm), conispiral, high spired. Whorl profile slope about 25 degrees from vertical; whorl surface broadly rounded, slight angulation near suture, no pronounced spiral threads. Aperture un- known. Umbilicus unknown. Sutures sharp, deep. Spiral band at whorl periphery raised, angular; lunulae unknown. Surface sculpture fine, faintly preserved as exter- nal molds, intersection with peripheral spiral band broadly angular, not sharp or swept backwards. All internal features unknown. Shell mineralogy and microstructure unknown. MaterIats. The description is based on about 40 specimens from north-central Penn- sylvania and northern Virginia deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Loxoplocus (Lophospira) abbreviata is tentative. A problem of assignment arises from the subsequent designation of lectotypes by Foerste (1914a) and Ruede- mann (1926) from Hall’s Murchisonia uniangulata var. abbreviata material (1847, pl. 83, figs. 2a-2d). Foerste (1914a, p. 311), reworking Hall’s material, formally designated Hall’s figure 2c as the lectotype of the species Ruedemannia abbreviata. His main criterion was that this figure showed the best developed trilineate peri- pheral bands and an overall sub-rotund whorl profile. However, later Foerste (1924, p. 211) failed to mention R. abbreviata in his vague re-definition of the genus Ruede- mannia. The generic problems are further reviewed under the discussion of R.? lirata (see p. 104). Ruedemann (1926), working in western New York, uncovered abundant speci- mens from the upper part of the Whetstone Gulf and lower Pulaski Formations, pos- ORDOVICIAN APPALACHIAN ECOLOGY ~ 107 sibly topotypic with Hall’s Murchisonia uniangulata var. abbreviata, and designated them as Lophospira abbreviata. Ruedemann (1926, p. 66-67) disregarded the term Ruedemannia and Foerste’s formal designation of Hall’s figure 2c (1847, pl. 83) as the type and instead informally designated figures 2a or 2b as the lectotype(s) of the species L. abbreviata, failed to mention figure 2c, and claimed that figure 2d “prob- ably does not belong here”. It is certainly possible that Hall’s syntypes do contain two distinct taxa. Hall’s figure 2c appears more closely related to R.? lirata, and, in fact, Ruedemann’s figure 12 (1926, pl. 8), a fragment of an apparently non-related exterior, showing a definite selenizone with broadly concave lunulae and growth lines sweeping well back along the flanges of the selenizone, also resembles R.? lirata. The central Appalachian Upper Ordovician specimens correspond more closely to Hall’s figure 2d (1847, pl. 83) and Ruedemann’s figures 11 and 13 (1926, pl. 8). They appear to be non-slit-bearing forms and, although broadly rounded, they do not resemble R.? lirata. L. (L.) ab- breviata must be classified as nomen inquirendum pending a complete taxonomic re- view of this material. Loxoplocus (Lophospira) abbreviata is common at localities in south-central Pennsylvania (see Table 3, loc. 101, 106, 107) and in central Virginia (loc. 167, 169, 172; see Fig. 16) always along the eastern edge of the Reedsville exposures, gas- tropod faunal province I. Rare specimens of L. (L.) abbreviata have also been iden- tified to the south and west of these exposures (see loc. 87, 97, 147, 148, 152, 203). The associated faunal elements usually found with L. (L.) abbreviata are L. (L.) ventricosta, L. (L.) perangulata, Sinuopea? and lesser numbers of R. “alternata”, O. linneyi and Modiolopsis modiolaris, which are generally considered part of the Sowerbyella—Onniella Community, but rock samples include occasional species more characteristic of the Rhynchonellid Population of the Orthorhynchula—Ambonychia Community. I have found that specimens of L. (L.) abbreviata are also commonly clumped together. Ruedemann (1926, p. 66) identified L. (L.) abbreviata at only three localities in western New York. He considered it a rare Lorraine fossil, but occasionally very abundant locally near the contact between the Whetstone Gulf Shale and the Pulaski Formation. The probable environmental setting of L. (L.) abbreviata can only be inferred from the ecology of Recent pleurotomariacean gastropods. Pleurotomariacean anat- omy has been studied in detail by Yonge (1947), and in the process he has gathered a small but valuable amount of ecological data. Because these Archaeogastropoda have simple aspidobranch, bipectinate ctenidia, the animal has difficulty in freeing mud-size particles from the gill filaments. The gill structure dictates life on a firm substratum where there is little turbid water. Pleurotomariaceans are commonly macrophagous herbivores that browse on algae or move along the substratum ingest- ing detrital plant material (Graham, 1955, p. 149). Batten (1958, p. 169) noted that Recent Pleurotomariacea live between 50 and 200 fathoms and seem better adapted to colder, possibly deeper waters, though some can tolerate brackish water conditions. The Upper Ordovician Pleurotomariacea are not widespread but probably occu- pied an inner sublittoral, quiet water environment. One of the factors controlling the distribution was probably substratum type, which, in the central Appalachians, is usually a fine, possibly firm silt or sand. The patchiness and local clumping of this gastropod may be associated with the probable irregular distribution of detrital plant 108 PEABODY MUSEUM BULLETIN 34 material by currents moving over the substratum. The influence of water temperature and salinity is difficult to ascertain for any of the Upper Ordovician pleurotomaria- cean species. Loxoplocus (Lophospira) ventricosta (Hall, 1847) Plate 18, figure 3 Murchisonia ventricosta Hall, 1847, p. 41, pl. 10, fig. 3. Emmons, 1855, p. 162. [not] Salter, 1859, p. 23, pl. 5, figs. 2, 2a, 3. [?|Lophospira peracuta Ulrich and Scofield, 1897, p. 976, pl. 73, figs. 15-17. Wilson, 19515 p.oG; pl. 5. ie. Lophospira ventricosta (Hall). Bassler, 1915, p. 766. Wilson, 1951, p. 39, pl. 4, figs. 23, [?]22. [?|Lophospira manitoulinensis Foerste, 1924, p. 213, pl. 36, figs. Sa-d. [?|Lophospira liosutura Secrist and Evitt, 1943, p. 366, fig. 12. DEscRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER OrpDo- VICIAN. Shell of medium size (height of one specimen, 18 mm; diameter of last whorl, 13 mm), conispiral, high-spired. Whorl profile slope about 25 degrees from the verti- cal; whorl upper surface sharply convex, angular, lower surface gently convex, spiral threads absent. Aperture unknown. Sutures prominent, shallow. Spiral band at whorl periphery raised, angular; lunulae unknown. Surface sculpture unknown. All internal features unknown. Shell mineralogy and microstructure unknown. Materiats. The description is based on 10 partial specimens from north-central Virginia deposited in the Peabody Museum. Discussion. Assignment of these central Appalachian Upper Ordovician specimens to Loxoplocus (Lophospira) ventricosta is tentative. The specimens show a promi- nent, raised peripheral band, a sharply convex, non-threaded upper whorl surface and pronounced sutures, all of which are characteristic of numerous Lower Paleozoic Lophospira species, Hall (1847, p. 41) introduced the term Murchisonta ventricosta for some New York specimens; this appears to be the earliest description of a North American species similar to these central Appalachian forms. Wilson (1951, p. 39) remarked that Hall’s illustration of the holotype (1847, pl. 10, fig. 3) is inadequate. She figures two specimens (1951, pl. 4, figs. 22, 23) from the Ottawa area identified by Billings as Murchisonia ventricosta, but only tentatively assigns them to the species. L. (L.) ventricosta must be classified as nomen inquirendum. Abundant L. (L.) ventricosta occur in north-central Virginia, gastropod faunal province I (Table 3, loc. 167, also Fig. 17). This is the type locality of Secrist and Evitt’s Lophospira liosutura (1943, p. 366, fig. 12), which may be conspecific with L. (L.) ventricosta. Dr. Ellis Yochelson kindly made available Secrist and Evitt’s type material deposited in the U.S. National Museum. We have tentatively identified their figured specimens of Lophospira liosutura as occurring in a porous sandstone block labeled “25.6 feet”. The label probably refers to Secrist and Evitt’s “80 foot horizon” of the Passage Creek section (1943, p. 362), which they state is a six-inch porous bed in which Lophospira is very abundant. I have re-collected from this bed which has produced abundant specimens of Sinuopeidae, some Seelya (PI. 17, fig. 4) and the L. (L.) ventricosta (?= Lophospira hosutura). A re-collection and more careful restudy of the gastropods along the eastern edge of the Reedsville exposures ORDOVICIAN APPALACHIAN ECOLOGY 109 in south-central Pennsylvania and northern Virginia where the pleurotomariacean gastropods are most common may show L. (L.) ventricosta to be somewhat more widely distributed, but remaining within this restricted area of the central Appala- chians. L. (L.) ventricosta presumably lived in much the same manner as L. (L.) abbreviata; that is, in a quiet water, shallow sublittoral environment. Loxoplocus (Lophospira) perangulata (Hall, 1847) Plate 18, figures 4 and 7 Murchisonta perangulata Hall, 1847, p. 41, pl. 10, fig. 4. Murchisonia perangulata var. A. Hall, 1847, p. 179, pl. 38, figs. 7a, 7b. Murchisonia bicincta var. perangulata (Hall). Salter, 1859, p. 19, pl. 4, fig. 7. Lophospira perangulata (Hall). Ulrich and Scofield, 1897, p. 972, pl. 73, figs. 1-3, 5-7, [?]4. Ruedemann, 1901, p. 31. Bassler, 1909, pl. 3, figs. 9-13. Wilson, 1951, p. 37, pl. 4, fig. 13. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER Orpo- vic1AN. Shell of small size (median height of four specimens, 7 mm), conispiral, fusi- form. Whorl profile slope about 20 degrees from the vertical; whorl surface broadly rounded, no pronounced spiral threads. Aperture unknown. Umbilicus unknown. Sutures prominent. Spiral band at whorl periphery raised, rounded, preserved as internal mold, lunulae unknown. Surface sculpture unknown. All internal features unknown. Shell mineralogy and microstructure unknown. MateriALs. The description is based on about 10 mostly fragmentary specimens from central Virginia deposited in the Peabody Museum. Discussion. The assignment of these specimens to Loxoplocus (Lophospira) peran- gulata is tentative. Hall (1847, p. 41, 179) introduced the terms Murchisonia peran- gulata for specimens found in the New York Birdseye (Lowville) Limestone, and M. perangulata var. A for specimens in the New York Trenton Limestone. Hall believed the Trenton variety closely resembled M. bicincta, with which it occurred; but he felt that further study would show it to be similar to the Birdseye M. perangulata. Salter (1859, p. 19) informally placed Hall’s Birdseye M. perangulata in synonymy with M. bicincta, stating that it did not differ significantly from small M. bicincta. Salter figured one specimen called M. bicincta var. perangulata (1859, pl. 4, fig. 7), apparently as a representative juvenile form of M. bicincta. The New York Trenton Limestone M. perangulata var. A was considered by Salter a distinct, more elongate species. Ulrich’s subsequent designation of the type Lophospira perangulata (in Ulrich and Scofield, 1897, p. 972) was specifically restricted to Hall’s M. perangulata, Ulrich also considered Hall’s M. perangulata var. A a separate species, but he designated no specific assignment and presented no synonymy. Ruedemann (1901, p. 31), working in the Trenton conglomerate of eastern New York, described specimens which he felt came nearer to Hall’s Birdseye M. perangulata than his Trenton M. perangulata var. A; therefore, he justified the use of the term Lophospira perangulata after Ulrich. The specimens I have collected from the central Appalachian Upper Ordovician appear in closer agreement with Hall’s Trenton M. perangulata var. A, but I have 110 PEABODY MUSEUM BULLETIN 34 used the term L. (L.) perangulata realizing that a complete revision of this taxon is required. The following list may contain some junior subjective synonyms: Loxoplocus (Lophospira) miller [= L. (L.) bicincta (Miller) ] _ (L.) medtalis (Ulrich and Scofield) L. (L.) perangulata (Hall) L. (L.) perangulata var. A (Hall) L. (L.) helicteres (Salter) Abundant specimens of L. (L.) perangulata occur in central Virginia (loc. 174, 177, 179), along the eastern edge of the Reedsville exposures. Specimens are rarely found outside this area. The commonly associated abundant faunal elements are Lingula?, Bucania sp., Ischyrodonta? truncata and L. (L.) abbreviata. The substra- tum is a fine silt and the most probable environmental setting is a quiet water, inner sublittoral environment. The common pattern of clustering is observed as in the other gastropods and again could be associated with the availability of food on the substratum. Recent pleurotomariacean ecology is reviewed under the discussion of L. (L.) abbreviata (p. 106). Famity SINUOPEIDAE SuBFAMILY SINUOPEINAE Genus SINUOPEA? Plate 19, figures 1-2 The identification of these central Appalachian Upper Ordovician specimens was critically reviewed by Dr. Ellis Yochelson, who believes that these pleurotomaria- cean gastropods can be classified only as members of the Family Sinuopeidae and do not resemble any existing genus in that family. The central Appalachian specimens are only suggestive of the genus Sinuopea in their deep sutures and ““U” shaped sinus, and because of the pronounced shoulder of the upper whorl surface of the central Appalachian specimens the present generic assignment is in doubt. The sinuopeid gastropods constitute an abundant faunal element only in south- central Pennsylvania and northern Virginia, gastropod faunal province I (loc. 101, 163, 167, see Fig. 16), along the eastern edge of the Reedsville exposures. The geo- graphic distribution is close to that of Loxoplocus (Lophospira) abbreviata and L. (L.) ventricosta, faunas common to the Strophomenid Population of the Sowerbyella—Onniella Community. Other less common associated faunal elements are Trochonema (PI. 17, fig. 6), Maclurites?, Bucania sp., Ischyrodonta truncata and Orthorhynchula linneyi. A few sinuopeids are also occasionally found with Tancre- diopsis cuneata, Lingula?, Plectonotus? sp. (loc. 84), i.e., the Linguloid Population of the Orthorhynchula-Ambonychia Community, and the crinoids, Onniella multi- secta and Sowerbyella (Sowerbyella) sericea (loc. 107), part of the Strophomenid Population of Sowerbyella—Onniella Community. The two latter faunal associations are found to the west and north of the main pleurotomariacean belt in south-central Pennsylvania, gastropod faunal province I (Fig. 16). The patchiness of the sinuopeid gastropod distribution seems to be characteristic of all Upper Ordovician pleurotomariaceans. The sinuopeid occurrences define a ORDOVICIAN APPALACHIAN ECOLOGY 111 broadly linear north-south belt from south-central Pennsylvania to northern Virginia. The environmental setting of the pleurotomariid gastropods is reviewed under the discussion of L. (L.) abbreviata, p. 106. The sinuopeids are believed to have differed little from the other Pleurotomariacea in their life habits. ?SuBoRDER MURCHISONIIA SUPERFAMILY MURCHISONIACEA Famity MURCHISONIIDAE Genus MURCHISONIA? Plate 19, figures 3-4 The assignment of these Upper Ordovician specimens was reviewed by Dr. Ellis Yochelson, who felt that the quality of preservation permitted classification only as representative of the Family Murchisoniidae. The infrequent, but well-defined, peri- pheral band, the fusiform whorl profile, and the deep sutures are somewhat reminis- cent of the genus Murchisonia, but again the generic assignment is in doubt. The murchisoniid gastropods are found only along Clinch and Cumberland Mountains in northern Tennessee, gastropod faunal province III (loc. 130, 133, 135; see Fig. 16). The rock type is consistently a silty mud or carbonate mud, in direct contrast to the silt-fine sand substratum associated with the bellerophontid and pleuro- tomariid gastropods. The taxonomic diversity of the murchisoniid faunal association is notably lower than in the other two gastropods; Zygospira recurvirostra from the Spiriferid Population of the Zygospira—Hebertella Community is the only abundant associated faunal element, although a few Pterinea (Caritodens) demissa and large Loxoplocus (Lophospira) sp. are present with the murchisoniids. Cox and Knight (1960, p. 1290) reviewed the taxonomic status of the Super- family Murchisoniacea and thought it could be considered an archaeogastropod, a mesogastropod, or a transitional form between the two. The submedial sinus and slit, presumably exhalant in function, point to the Pleurotomariina (Archaeogastropoda) , whereas the high-spired, many-whorled nature of the murchisoniids and their tendency to develop what appears to be an inhalant channel suggests a Cerithiacea (mesogas- tropod) stock. The suborder Murchisoniina was erected by Cox and Knight (1960) for the reception of the Superfamily Murchisoniacea, in the belief that the murchi- soniids still retain the primitive features of the Archaeogastropoda but show some characteristic evolutionary advances along the lines leading to the Mesogastropoda. The morphologically transitional nature of the murchisoniids may be reflected in their Upper Ordovician environmental setting that places them geographically apart from the abundant Archaeogastropoda (Bellerophontacea and Pleurotomaria- cea). Yonge (1947, p. 495) noted that the complex bipectinate aspidobranch cteni- dium of the Archaeogastropoda is easily fouled by sediment, and mud particles can be removed from the ctenidia only with difficulty. Therefore, Recent pleurotomariid gastropods as a whole can exist effectively only in clear waters and on a firm substra- tum. As Lower Paleozoic pleurotomariid populations probably expanded gradually into muddier substrata, those individuals possessing a ctenidial structure from which mud particles could be more easily removed would have had a selective advantage. Along with the development of the monopectinate ctenidium, evolutionary changes advantageous to the mud-dwellers would be the emergence of an extensible inhalant 12 PEABODY MUSEUM BULLETIN 34 siphon and modification of the foot to allow the ancestral mesogastropod to move on or through a soft substratum, BIVALVIA Plates 20-44 The Bivalvia, next to the Brachiopoda, are the most abundant and widespread faunal element in the central Appalachian Upper Ordovician rocks. The class is represented by five superfamilies and ten common species. There are rare and scattered specimens of two additional superfamilies, Nuculanacea (Nuculites and Palaeoneilo) and Cyrto- dontacea (Cyrtodonta?) . The taxonomy and systematics of the North American Ordovician Bivalvia have been neglected for over half a century, but recent studies of Lower Paleozoic nucu- loids by McAlester (1963, 1964, 1968) and ambonychiids by Pojeta (1962, 1966) mark the beginning of renewed interest. Investigations of European species by Isberg (1934) and the excellent survey by Babin (1966) have been of considerable use in this study. Papers dealing with the Ordovician Bivalvia of eastern North America include Hall (1847), Hall and Whitfield (1875), Ulrich (1893, 1894), Bassler (1919), Stewart (1920), Foerste (1924), Ruedemann (1926) and Wilson (1956). Puytum MOLLUSCA Crass BIVALVIA Susctass PALAEOTAXODONTA OrpeER NUCULOIDA SuPERFAMILY CTENODONTACEA Famity CTENODONTIDAE Genus CTENODONTA? Ctenodonta? pulchella (Hall, 1847) Plate 20, figures 1-4 Lyrodesma pulchella Hall, 1847, p. 302, pl. 82, figs. 12a, b, d; [not]12c. Leda pulchella (Hall). Emmons, 1855, p. 173. Tellinomya (Lyrodesma) pulchella (Hall). Hall, 1856, p. 395. Hall, 1857c, p. 136. Ctenodonta pulchella (Hall). Ulrich, 1894, p. 581. Foerste, 1914, p. 305. Ruedemann, 1926, p. 14. DEscrIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- VICIAN. Shell of small size, broadly oval, equilateral (median height of five specimens, 7 mm; median length, 7 mm). Shape variation appears limited to very slight differ- ences in height-length properties. Surface sculpture of fine concentric striae. Taxodont teeth of moderate size, decreasing in size toward the umbo; teeth continuous beneath umbo. Resilifer absent, ligament area otherwise unknown. Original shell microstruc- ture and mineralogy unknown. Marteriats. The description is based on about 20 specimens from north-central Penn- sylvania deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- ORDOVICIAN APPALACHIAN ECOLOGY es mens to the genus Ctenodonta is tentative, pending a thorough restudy of all Upper Ordovician nuculoid bivalves. Until recently all North American Ordovician nuculoid bivalves had been assigned to the genus Ctenodonta, but many of these species do not appear to be congeneric with the type Ctenodonta nasuta (McAlester, 1963). This is true for Ctenodonta? pulchella, which I believe may merit a separate generic desig- nation after a restudy of other North American material, and hence the present generic assignment is questioned. Ulrich (1894, p. 581) placed C. pulchella in his Group IV, ctenodonts typified by C. pectunculoides. Group IV consisted of five species: Ctenodonta pulchella (Hall, 1847) C. pectunculoides (Hall, 1871) C. cingulata (Ulrich, 1879) C. subrotunda (Ulrich, 1892) C. circularis Ulrich 1894 The first three appear to form an internally coherent morphological grouping, but C. subrotunda may be a Palaeoconcha Miller, 1889 and C. circularis is a nomen nudum, as the species was never described or figured. The following is my tentative listing of possible congeneric species. No evaluation of the subjective synonymies that may exist in this list is possible at the present time. Ctenodonta pulchella (Hall, 1847) C. pectunculoides (Hall, 1871) C. cingulata (Ulrich, 1879) C. lorrainensis Foerste 1941 C. borealis Foerste 1924 Ctenodonta? pulchella is abundant at localities 34-A, 35, and 37 in north-central Pennsylvania, bivalve faunal province I, and is very rarely found outside this area (Fig. 17). Associated faunal elements include Praenucula levata, Lyrodesma post- striatum, crinoids and occasionally Hallopora, Zygospira modesta and Onniella multi- secta, part of the Orthid—Crinoid Population of the Sowerbyella-Onmella CGom- munity. The substratum is commonly a finely laminated silt and mud; the environ- mental setting appears to have been sublittoral and subjected to only moderate turbu- lence. By analogy with Recent nuculoid bivalves, C.? pulchella was probably an in- faunal detritus feeding form, a life habit that is locally dominant in these Upper Ordovician offshore mud and silt environments. Genus TANCREDIOPSIS Tancrediopsis cuneata (Hall, 1856) Plate 21, figures 1-7; plate 22, figures 1-6; plate 23, figures 1-5; plate 24, figures 1-3 Tellinomya cuneata Hall, 1856, p. 392, figs. 6, 7. Hall, 1857a, p. 183, figs. 6, 7. Hall, 1857b, p. 143, figs. 6, 7. [not] Hall, 1862b, p. 38, figs. 1, 2. Ctenodonta contracta Salter, 1859, p. 37, pl. 8, figs. 4, 5. Logan, 1863, p. 175, figs. 160a, b. Wilson, 1956, p. 23, pl. 2, figs. 7-9. 114 PEABODY MUSEUM BULLETIN 34 a Ctenodonta (Tancrediopsis) contracta (Salter). Beushausen, 1859, p. 70. [?]Tellinomya contracta? (Salter). Walcott, 1884, p. 76, pl. 11, figs. 15, 15a. Tancrediopsis cuneata (Hall). McAlester, 1963, p. 5, figs. 1-80. Description BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN Upper Orpo- vic1an. Shell of medium size, equivalved, strongly inflated, umbones very prominent (median length of 42 specimens, 14 mm; median height, 9 mm). Shape variable, height ranging from 57 to 76 per cent of length (median of 42 measured specimens, 66 per cent). Surface sculpture of faint, widely spaced concentric striae; sculpture usually obscure because of internal mold preservation. Large, chevron-shaped taxodont teeth; about equal numbers of teeth on either side of, and pointed toward, umbo; teeth are continuous beneath umbo but decrease in size. Resilifer absent, ligament area otherwise unknown. Anterior and posterior adductor muscle scars prominent, empha- sized by sharp ridge on inner side of each scar, more prominent on anterior; pedal retractor muscle scars small but prominent, located at dorsal end of the inner adduc- tor ridges; other internal features unknown. Original shell microstructure and mineral- ogy unknown. Mareria.s. The description is based on over 200 specimens from central Pennsylvania to southeastern Virginia deposited in the Peabody Museum. Discussion. The taxonomic status of Tancrediopsis cuneata was reviewed by Mc- Alester (1963). My central Appalachian specimens can be assigned to this species and exhibit only slight morphological variation from northern to southern localities, bivalve faunal province II (Fig. 17). They remain constantly associated with the same abundant faunal elements, Lingula?, Plectonotus? sp. and occasionally Ischyrodonta truncata, part of the Linguloid Population of the Orthorhynchula-Ambonychia Com- munity. This faunal assemblage dominates inner sublittoral and intertidal environ- ments from central Pennsylvania into central Virginia and is apparently able to tolerate variations in substratum (muddy silts to medium sand), possibly salinity, and temperature. A more complete review of the ecological requirements of this assem- blage is presented in the chapter on paleoautecology (p. 36). Not included in this description are some questionable nuculoid bivalves from localities 135 and 148 in southwestern Virginia and Tennessee, bivalve faunal Province III (Pl. 20, figs. 9-11). They may belong to the genus Palaeoneilo Hall and Whitfield, 1869, although their poor preservation does not permit any positive assignment; only the notable posterior expansion gives any clue to the taxonomic placement of these specimens. They are smaller than the typical T. cuneata (median length of 23 speci- mens, 11 mm; median height, 5 mm) and are found almost to the exclusion of any other faunal elements at localities 135 and 148, but the species may be part of the Zygospira—Hebertella Community. SUPERFAMILY NUCULACEA Famity PRAENUCULIDAE Genus PRAENUCULA Praenucula levata (Hall, 1847) Plate 20, figures 5-8 Nucula levata Hall, 1847, p. 150, pl. 34, figs. la-d, f-i; [?}le, k. ORDOVICIAN APPALACHIAN ECOLOGY 15 Leda levata (Hall). Emmons, 1855, p. 137, pl. 14, fig. 10. Tellinomya (Nucula) levata (Hall). Hall, 1856, p. 395. Hall, 1857c, p. 136. Ctenodonta levata (Hall). Billings, 1863, p. 175, figs. 161a, b. Ruedemann, 1912, p. 100, pl. 6, fig. 1. Wilson, 1956, p. 25, pl. 2, figs. 10-13. Tellinomya levata (Hall). Hall, 1871, pl. 3, fig. 27. Hall, 1872, pl. 7, fig. 27. Hall and Whitfield, 1875, p. 82, pl. 1, fig. 23. [?]Ctenodonta filistriata (Hall and Whitfield). Ulrich, 1894, p. 599, figs. 44a-e. Bassler, 1919, p. 297, p. 54, figs. 26-29. [?]Stewart, 1920, p. 9, pl. 1, fig. 5. Foerste, 1924, p. 134, pl. 18, figs. 7a, b. Ruedemann, 1926, p. 14, pl. 1, figs. 13, 14. Tellinomya (Ctenodonta) levata (Hall). Clarke and Ruedemann, 1903, p. 521. DEscrIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER OrpDo- vicIAN. Shell of small size, equivalved, anteriorly elongated (median length of eight specimens, 7 mm; median height, 5 mm). Shape variable, height ranging from 62 to 84 per cent of length (median of eight measured specimens, 78 per cent) ; distance from anterior extremity to umbo ranging between 57 and 64 per cent of length (median of six measured specimens, 62 per cent). Surface sculpture unknown, pre- served only as internal molds. Prominent taxodont teeth, chevron-shaped, pointed toward umbo; teeth continuous but decreased abruptly in size under umbo; subequal in size on either side of umbo. Resilifer absent, ligament area otherwise unknown. Anterior muscle scar subround, weakly impressed; other internal features unknown. Original shell microstructure and mineralogy unknown. MateErIALs. The description is based on about 10 specimens from central Pennsylvania deposited in the Peabody Museum. Discussion. A survey of the North American Ordovician literature reveals that some species now assigned to the genus Ctenodonta probably belong to the genus Praenu- cula Pfab, 1934. I have tentatively assigned my central Appalachian specimens to this genus pending taxonomic re-evaluation of other North American material. Hall (1847, p. 150) remarked in his description of Ctenodonta (= Nucula) levata that the shell “presents considerable variation in form, even in the same locality.” But it appears that his figures show more than one species; i.e., figures le and 1k (pl. 34) appear to belong to the genus Palaeoconcha Miller, 1889. The other figures seem to be Praenucula, although they show considerable variation in the degree of posterior expansion, Hall designated no type for the species C’. levata. Wilson (1956, p. 25) also has noted that Hall’s material appeared to contain more than one species, but she stated that Ulrich and Ruedemann after examination of Hall’s specimens decided upon a lectotype for C’. Jevata. Wilson further pointed out that the specimen chosen by Ulrich and Ruedemann was figured by Ruedemann (1912, pl. 6, fig. 1), but I have found no subsequent type designation presented by Ruedemann (see 1912, p. 110). Furthermore there is no discussion of the status of Hall’s syntypes by either Ruedemann or Wilson. That plate 6, figure 1 (Ruedemann, 1912) is the subse- quently designated type of C. levata rests on the interpretation of Wilson (1956). No authors have considered the difficulties created by the shape variation that Hall’s specimens show, or faced the obvious problems of preservation that appear to have plagued Wilson (1956, p. 25). What appears to me to have been the supposed “key criterion” for the identification of C. levata, the slightly subangular anterodorsal projection, is rarely preserved. 116 PEABODY MUSEUM BULLETIN 34 McAlester (1968, p. 46) described the type species of the genus Praenucula (Prae- nucula expansa Pfab, 1934) as being of unknown shape variability, although showing a well-defined anterior elongation. I have listed below the North American species that may belong in this genus; there are notable differences in the degree of anterior expansion, but all appear to show subequally sized taxodont teeth on either side of the umbo. Ctenodonta levata (Hall, 1847) C.. donactformis (Hall, 1847) C. abrupta Billings 1865 C. nitida (Ulrich, 1892) C’. medialis Ulrich 1894 . scofieldi Ulrich 1894 . retrosa Ulrich 1893 (1895) . filistriata Ulrich 1894 . albertina Ulrich 1894 . simulatrix Ulrich 1894 maadisonensis Ulrich 1894 calvini Ulrich 1894 perminuta Ulrich 1893 (1895) nuculiformis (Hall, 1847) . (?) hilt (Miller, 1874) ?|C. soctalts Ulrich 1894 ?\C. fecunda (Hall, 1862) SEeE Soro oe) aor > vv SES This group includes most of Ulrich’s C. levata or Group III ctenodonts (1894). Excluded are: Ctenodonta hartsvillensis Safford 1869, probably a Palaeoconcha C’. danvillensis Ulrich 1894, nomen nudum C. tumida Ulrich 1894, nomen nudum C. mundula Ulrich 1894, nomen nudum Those species designated as nomina nuda have never been figured or described. Additions to the list of possible North American Praenucula include the following: Ctenodonta planodorsata (Ulrich, 1892) C’. prossert Ruedemann 1912 . radiata Ruedemann 1912 . recta Ruedemann 1912 . myalta Stewart 1920 . chambliensis Foerste 1924 . hyacinthensis Foerste 1924 SOS Praenucula levata is commonly found with C.? pulchella, Lyrodesma poststriatum and lesser numbers of crinoids, Hallopora and Onniella multisecta, which are part of ORDOVICIAN APPALACHIAN ECOLOGY U7 the Orthid—Crinoid Population of the Sowerbyella—Onniella Community, at localities 37, 52, and 97 in central Pennsylvania, bivalve faunal province I (Fig. 17). Ruede- mann (1926, p.-15) also found what appear to be species of Praenucula and Cteno- donta? commonly associated throughout the Whetstone Gulf Shale in western New York. The environmental setting for the central Appalachian species appears to be in quiet, offshore waters. The substratum is a finely laminated silt and mud which is dominated by small patches of infaunal, detritus feeding nuculoid bivalves. P. levata and C.? pulchella constitute the greatest number of these infaunal forms, although there are scattered specimens of Nuculites and Palaeoconcha. Susctass PTERIOMORPHIA Orpver PTERIOIDA SuBoRDER PTERIINA SuPERFAMILY AMBONYCHIACEA Famity AMBONYCHIIDAE Grnus AMBONYCHIA Ambonychia radiata Hall 1847 Plate 36, figures 1-6 Pterinea carinata Emmons, 1842, p. 204, fig. 111.1. Vanuxem, 1842, p. 64, fig. 9.1. Owen, 1844, p. 376. Emmons, 1855, p. 175, pl. 17, fig. 23. Ambonychia radiata Hall, 1847, p. 292, pl. 80, figs. 4a, b, c, f, [not]figs. 4d, h-l. Hall, 1859a, p. 8; p. 110, figs. 1, 2. Hall, 1859b, p. 269; p. 523, figs. 1, 2. Hall, 1862b, p. 54, figs. 11.1, 11.2. [not]Billings, 1863, p. 215, fig. 219. Hall and Whitfield, 1875, p. 79, pl. 2, fig. 2. Stoliczka, 1870, p. XXI. Stoliczka, 1871, p. 387. Ambonychia carinata (Emmons). Lesley, 1889, p. 22, fig. 111.b. Byssonychia radiata (Hall). Ulrich, 1893 (1895), p. 629. Foerste 1914a, p. 273, pl. 3, figs. 12A-C. Bassler, 1919, p. 282, pl. 57, fig. 26. Stewart, 1920, p. 23, pl. 4, fig. 3. Foerste, 1924, p. 164, pl. 27, figs. 3a, b; pl. 31, figs. 13a, b, c. Ruedemann, 1926, p. 27, pl. 3, figs. 4-7. [not]Butts, 1941, p. 127, pl. 100, figs. 6-8. [not]Wilson, 1948, p. 144, pl. 18, fig. 16. Pojeta, 1962, p. 183, pl. 22, figs. 1-15; pl. 23, figs. 1-14; pl. 24, figs. 1-7. Byssonychia vera Ulrich, 1893 (1895), p. 629, figs. a-c. Bassler, 1919, p. 282, pl. 54, figs. 34-36. Stewart, 1920, p. 25, pl. 1, figs. 23, 24. [not]Butts, 1941, p. 127, pl. 100, fig. 9: Byssonychia bowmani Secrist and Evitt, 1943, p. 363, figs. 4, 5. DEscRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- VICIAN. Shell of small to medium size, moderately inflated, equivalved, rounded pos- terior expansion (median diagonal of six specimens, 24 mm; median length, 20 mm). Shape only slightly variable, length varying between 82 and 85 per cent of the diagonal. Byssal gap prominent, elliptical, small; byssal sinus moderate. Anterior margin rounded; umbones rounded. Surface sculpture of radial ribs, about 50; faint concentric striae. Small cardinal teeth, one or two, radiating from beneath umbo; posterior lateral teeth, two or three, elongate. Ligament longitudinally striated, liga- ment area otherwise unknown. Posterior adductor large, subround; other internal fea- tures unknown. Original shell microstructure and mineralogy unknown. 118 PEABODY MUSEUM BULLETIN 34 MartERIALS. The description is based on over 15 specimens from central Pennsylvania deposited in the Peabody Museum. Discussion. Pojeta (1962, p. 183; 1966, p. 172) discussed in detail the taxonomic status of this species, the type of the genus Ambonychia. The Upper Ordovician Appalachian specimens that I have assigned to this species are abundant at some locales (loc. 72, 78), and are confined geographically to central Pennsylvania, bivalve faunal province I. Localities farther south produce some questionable A. radiata fragments, though the ribbing appears to resemble A. ulrichi (esp. loc. 127). I re- collected from Secrist and Evitt’s (1943) type locality of Byssonychia bowmani (my locality 167) and found most specimens indistinguishable from A. radiata; there were a few specimens that appear similar to A. praecursa but are too poorly preserved for an accurate identification. Almost all of the North American literature seems to emphasize the importance of A. radiata as the characteristic Ambonychia in the central Appalachians, but this is certainly not the case, as A. praecursa is far superior in numbers. I believe that the misidentification of A. praecursa as A. radiata has accounted for much of the dis- crepancy. The variability of shell shape recorded by me must be viewed cautiously because there are few whole A. radiata in the central Appalachian collection. My central Appalachian A. radiata are, however, slightly smaller and more rounded than are most previously figured specimens. A tentative listing of possible subjective synonyms of A. radiata includes the following: Ambonychia obesa (Ulrich, 1893) A. alveolata (Ulrich, 1893) A. retrorsa Miller 1878 A. hyacinthensis (Foerste, 1924) The environmental setting of A. radiata is treated under the discussion of A. prae- cursa, The common associated faunal elements are Rafinesquina “alternata’’, Sowerbyella (Sowerbyella) sericea, Onniella multisecta, crinoids and occasionally Praenucula levata and Ctenodonta? pulchella, all part of the Sowerbyella—Onniella Community. Ambonychia praecursa (Ulrich, 1893) Plate 37, figures 4-5; plate 38, figures 1-2, 4-5; plate 39, figures 1-4; plate 40, figures 1-4; plate 41, figures 1-3; plate 42, figures 3-4 Byssonychia praecursa Ulrich, 1893 (1895), p. 633, pl. 45, figs. 1, 2. Bassler, 1919, p. 283, pl. 57, figs. 28, 29. Stewart, 1920, p. 24, pl. 1, fig. 27. Foerste, 1924, p. 167, pl. 28, figs. 2a, b. Ruedemann, 1926, p. 30, figs. 9, 10. Pojeta, 1962, p. 191, pl. 27, figs. 1-7. Byssonychia walkerensis Grabau, 1913, p. 454. DeEscripTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- VICIAN. Shell of medium size, strongly inflated, equivalved, broad posteroventral elongation (median diagonal of 234 specimens, 38 mm; median length, 25 mm). ~— sat ge ORDOVICIAN APPALACHIAN ECOLOGY 119 Shape variable, length varying between 64 and 78 per cent of the diagonal (median of 234 specimens, 67 per cent). Byssal gap prominent, elliptical; byssal sinus shallow. Anterior margin almost flat, umbones not rounded. Surface sculpture of prominent radial ribs (35 to 40), some ribs bifurcating near the hinge line (PI. 41, fig. 2) ; finer concentric striae, closely spaced, numerous; and prominent concentric striae, wide- spaced, very few. Cardinal teeth two, radiating from beneath umbo; lateral teeth two, short and confined to posterior end of hinge line. Ligament longitudinally striated, ligament area otherwise unknown. Internal features unknown. Original shell microstructure and mineralogy unknown. MarteriAts. The description is based on over 1600 specimens from south-central Pennsylvania to southwestern Virginia deposited in the Peabody Museum. Discussion. The assignment of these specimens to Ambonychia praecursa conflicts with earlier central Appalachian reports in which assignment was made rather vaguely to A. radiata. A re-collection from a locality listed by Grabau (1913, my local- ity 140) has produced topotypes of A. walkerensis which are indistinguishable from A, praecursa. Ulrich (1893, p. 633) in his original definition of A. (= Byssonychia) praecursa was unsure of its exact taxonomic status. He thought it could be either a true species or a variety of A. richmondensis, adding that A. praecursa could be the “forerunner” of A. richmondensis, A. robusta or A. cultrata, and was shaped like A. radiata. Most later authors have accepted A. praecursa as a true species. Unfortunately its systematic relationships to the other Ambonychia mentioned by Ulrich have never been dis- cussed, and the size and shape variability that puzzled Ulrich has never been ade- quately defined. In addition to A. praecursa, collections of Ambonychia specimens from central Appalachian Upper Ordovician rocks yield A. radiata and A. cultrata, An investiga- tion of the general size-shape-variability of the three species points up a possible en- vironmental control on distribution of the species. Medians of the diagonal and length, and the ratio of these two measurements from the central Appalachian specimens are shown in Table 19, The shell shape variations that exist among these three species of Ambonychia are diagrammed in Figure 32. Comparisons of shell morphology, abun- dant faunal associates, and substratum as determined from the central Appalachian species are shown in Table 20. Table 20 and Figure 32 present a very simplified picture of Ambonychia shell morphology as it is probably related to the environmental setting. Each of the three species was most probably an epifaunal, byssally attached, mussel-like bivalve. The prominent byssal gap and equivalved form emphasize an attached upright mode of TABLE 19. Measurements of the diagonal and length of the three common species of the genus Ambonychia. Of particular note is the length-diagonal ratio which is used as a general measure of shape variability and possibly related to environmental setting. Species Diagonal (mm) Length (mm) L/D (%) N A. praecursa 38 25 67 240 A. cultrata 51 37 78 26 A. radiata 24 20 82 12 120 PEABODY MUSEUM BULLETIN 34 TABLE 20. Comparisons of the morphology and abundant associated faunal elements of the genus Ambonychia. This table forms the basis for subsequent interpretations of central Appalachian Late Ordovician environmental setting (see also Fig. 32). Species A. radiata A. praecursa A. cultrata Size small medium large Shape subround moderately elongate subround Byssal gap small, ellipsoidal large, ellipsoidal large, elongate Anterior edge rounded flat flat Dentition weak strong unknown Associated faunal crinoids Modiolopsis Modiolopsis elements Rafinesquina Orthorhynchula Zygospira recurvirostra Praenucula Ischyrodonta Pterinea (Caritodens) Ctenodonta? Trepostomes Populations Orthid-—Crinoid Modiolopsid and Rhynchonellid Spiriferid Population ; Population ; Populations; Orthorhynchula— Zygospira—Hebertella Sowerbyella- Ambonychia Community Community Onniella Community Substratum silty mud—mud fine sand-silt silty mud—mud life. Pojeta (1962, p. 182) finds a Recent analogue in Mytilus and Modiolus; in over- all shape, I believe, it also somewhat resembles Pinna. The fine sand and silt, where numerous A. praecursa are present, is interpreted as one of the most physically exposed environments in the central Appalachian Late Ordovician. A. praecursa, with its more elongate shape, broader and flatter anterior edge of attachment, and possibly more secure articulation seems the best adapted of the three to cope with such an environment. Ambonychia praecursa grades abruptly southward into A. cultrata. There is an accompanying change in substratum from a fine sand-silt to mud. Modiolopsis modto- laris is the only faunal associate common to both species, whereas a small spiriferid brachiopod, Zygospira recurvirostra; a pterioid, Pterinea (Cartiodens) demissa; and trepostomes, part of the Spiriferid Population, Zygospira—Hebertella Community, are most common with A. cultrata. Mixtures of the two species are found at a few localities in south-central Virginia; but to the north only A. praecursa is found, and to the south, only A. cultrata. The larger, rotund shell shape and the narrow elongate byssal gap of A. cultrata appear better adapted to a less turbulent environment. Ambonychia radiata is not much smaller than some A. praecursa but is similar to A. cultrata in shape (Table 19). Its rounded, small shell with a small byssal gap, is probably adapted for environments of little water movement. A. radiata is more common in a silty mud and mud (Table 20) that is characteristic of deposition in low-energy environments. The faunal associates and the stratigraphic and geographic distributions strengthen the interpretations of an exposed inner sublittoral setting for A. praecursa of the Orthorhynchula-Ambonychia Community, a protected inner sublittoral for A. cultrata of the Zygospira—Hebertella Community and an outer sub- littoral for A. radiata of the Sowerbyella—Onniella Community. Ruedemann (1926, p. 31) commented briefly that a slab from the New York Lorraine Group showed one A. praecursa with many A. radiata. This sort of associa- tion is common in central Pennsylvania, bivalve faunal province I, and suggests the 121 ORDOVICIAN APPALACHIAN ECOLOGY "DX uonesassexe s10ysyo 0} aloysuo ‘a10ys 94} Zuole 29Ue}SIP 0} S1ojar gjeos ayy, ‘suauttoeds jo azis [enjoe oie s[issoy Jo sdurmesq “Surjjes [e}UIUIUOIIAUD YIM (SaaTeA Jo ozIs pue odeys [esgued ‘a't) Aqiqeisea [eorso;oydiour Bunvjer109 jo Azr[Iqissod ay} st a30u Iepnonsed yO ‘suvryoeyeddy [es}UId ay} UT URIDIAOPIO 23e'T 94) BuTINp sotseds piy2tuoquyp jo uoNnqiysiqg ‘7g “Old JIYOHSNO IYOHSIIO EO¢DIpos y Auscy =e ee aa” io Y SSS auoysewsy DIUDA/ASUU Bd a ee ajDUS ae ——— DsoIpos'y BUOLSHIIS nS BN Sop Bley ns @uoyspuns ’ QN39317 ossinjabpsid ‘yp 122 PEABODY MUSEUM BULLETIN 34 possibility of reworking a few dominantly inner sublittoral A. praecursa shells from the Orthorhychula-Ambonychia Community into outer sublittoral environs domi- nated by A. radiata of the Sowerbyella—Onniella Community. The opposite of this situation does not occur, in other words a few A. radiata have not been found with many A, praecursa, thereby possibly presenting some clue as to the relative strengths of the onshore and offshore current patterns. In fact, A. praecursa valves are also found within faunal assemblages dominated by numerous outer sublittoral faunal ele- ments of the Sowerbyella-Onniella Community — brachiopods, crinoids and bryo- zoans. Ambonychia praecursa is by far the most widely distributed Ambonychia in the Upper Ordovician clastic facies, bivalve faunal province II (Fig. 17). The usual faunal associates are Modiolopsis modiolaris and/or O. linneyt of the Modiolopsid and Rhynchonellid Populations of the Orthorhynchula-Ambonychia Community, but at three widely separated localities (Table 3, loc. 78, 152 and 203) specimens which resemble A. praecursa, A. cf. praecursa, are found with numerous Tancrediopsis cuneata, Lingula? and Plectonotus? sp., part of the Linguloid Population of the Orthorhynchula—Ambonychia Community. These specimens have not been included in the description of central Appalachian A. praecursa. Twelve specimens of A. cf. praecursa show a median diagonal of 19 mm, almost half that of the central Appala- chian A. praecursa. From all available stratigraphic, sedimentological and paleonto- logical evidence, species of the Linguloid Population probably dominated the nearest- shore Upper Ordovician environments. If these specimens are dwarfed A. praecursa, it is likely that the control may be in reduced or variable salinity (see Hallam, 1965, p. 134). Ambonychia cultrata (Ulrich, 1893) Plate 42, figures 1, 2; plate 43, figures 1-4 Byssonychia cultrata Ulrich, 1893 (1895), p. 632, pl. 45, figs. 5-7. Foerste, 1924, p. 166, pl. 28, fig. 6. Pojeta, 1962, p. 189, pl. 25, figs. 6-13, pl. 26, figs. 1-6. Ambonychia cultrata (Ulrich). Pojeta, 1966, p. 174, pl. 32, figs. 1, 2. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- vicIAN. Shell of large size, slight to moderate inflation, broad posteroventral expan- sion (diagonal dimension of 15 specimens, 51 mm; median length, 39 mm). Shape variable, length varying between 74 and 81 per cent of the diagonal (median of 15 specimens, 78 per cent). Byssal gap narrow, elongate; byssal sinus moderate. Anterior margin flat, umbones not rounded. Surface sculpture of prominent radial ribs (40 to 45) ; less prominent fine concentric striae. Dentition unknown. Ligament broad, elongate, longitudinally striated, ligament area otherwise unknown. Internal features unknown. Original shell microstructure and mineralogy unknown. Materiats. The description is based on over 40 specimens from southwestern Virginia and northern Tennessee deposited in the Peabody Museum. Discussion. The assignment of these specimens to the genus Ambonychia is tentative, for internal features and dentition are lacking. General shell shape and size suggest that this central Appalachian species is conspecific with the types of Ulrich’s Byssony- - ORDOVICIAN APPALACHIAN ECOLOGY 123 chia cultrata from Ohio. The environmental setting of the central Appalachian Upper Ordovician specimens of A. cultrata has been outlined under the discussion of A. prae- cursa (p. 119). A. cultrata is common only in southwestern Virginia and northern Ten- nessee, bivalve faunal province III (Fig. 17). The more northerly localities (Table 3, loc. 145, 147, 149, 151, 184) contains a mixture of A. cultrata and A. praecursa, but farther to the south A. cultrata is the dominant Ambonychia. It may occur entirely without A. praecursa, but is commonly found (loc. 131, 133, 140, 141) with a fauna dominated by Modtolopsis modtolaris, Zygospira recurvirostra, Pterinea (Caritodens) demissa and Monticultpora, from the Spiriferid Population of the Zygospira—Heber- tella Community. ?Ambonychia byrnest (Ulrich, 1893) Plate 38, figure 3 Byssonychia(?) byrnesi Ulrich, 1893 (1895), p. 635, pl. 47, figs. 4, 5. Byssonychia cf. byrnest (Ulrich). Foerste, 1914b, p. 134, pl. 3, fig. 6. Byssonychia byrnesi (Ulrich). Pojeta, 1962, p. 188, pl. 25, figs. 2-5. Ambonychia byrnest (Ulrich). Pojeta, 1966, p. 142, pl. 31, figs. 18-20. DEscRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER OrRpo- vicIAN. Shell of medium size, strongly inflated, broad posterior expansion (median diagonal of three specimens, 43 mm, length one specimen, 36 mm). Shape variability unknown (length 84 per cent of diagonal in one specimen) . Byssal gap small, elliptical ; byssal sinus slight. Anterior margin rounded, umbones rounded. Surface sculpture of prominent radial ribs, about 25; fine concentric striae with a few widely spaced promi- nent concentric striae. Dentition unknown. Ligament area unknown. Shell microstruc- ture and mineralogy unknown. Materiaus. The description is based on three specimens from central Pennsylvania deposited in the Peabody Museum. Discussion. The identification of these few specimens as Ambonychia byrnesi is tentative. The generic status is in doubt because no internal features are preserved, and differentiation from A. actirostris and A. imbricata is uncertain because the shell shape variation is unknown. The specimens come from only one locality (Table 3, loc. 75) and are unlike any other Ambonychia in the central Appalachian Upper Ordovician strata in the strength and numbers of radial ribs. Associated with the more common A. praecursa in a muddy silt, near what appears to be the northern extreme of the A. praecursa distribution, bivalve faunal province II (Fig. 17), their general inflated shell shape, rounded ap- pearance and small byssal gap appear to be suited to a lower energy environment than is indicated by the elongate A. praecursa with a large byssal gap. These specimens were not included in the simplified ecological picture presented under the discussion of A. praecursa because they are so few in number. A. praecursa in this northern environ- ment does show some shape variability, becoming somewhat larger but no less elongate; but I am sure that these specimens called ?A. byrnesi could not be inchided within the variability limits of A. praecursa. 124 PEABODY MUSEUM BULLETIN 34 SuperFAMILy PTERIACEA . Famity PTERINEIDAE Genus PTERINEA Pterinea (Caritodens) demissa (Conrad, 1842) Plate 24, figures 5-7; plate 25, figures 1-5; plate 26, figures 1-7; plate 27, figures 1, 2 Avicula demissa Conrad, 1842, p. 242, pl. 13, fig. 3. Emmons, 1842, p. 404, fig. 2. Hall, 1847, p. 292, pl. 80, figs. 2a, b. Emmons, 1855, p. 175, pl. 17, fig. 10. Pterinea demissa (Conrad). McCoy, 1854, p. 260, pl. 1, fig. 7. Hall and Whitfield, 1875, p. 78, pl. 2, fig. 1. Cumings, 1908, p. 1018, pl. 48, fig. 1. Stewart, 1920, p. 22, pl. 1, fig. 28. Pterinea (Caritodens) demissa (Conrad). Foerste, 1910, p. 71, pl. 1, fig. 10. Bassler, 1919, p. 284, pl. 57, fig. 24. Foerste, 1924, p. 161, pl. 26, fig. 3; pl. 29, fig. 10; pl. (31, fig. 12. Ruedemann, 1926, p. 23, figs. 7-11. Caritodens demissa (Conrad). Foerste, 1914a, p. 269, pl. 1, fig. 10; pl. 3, fig. 11. [?|Pterinea maternata Secrist and Evitt, 1943, p. 365, fig. 15. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN Upper Orpo- victAN. Shell of medium size (median length of 36 specimens, 25 mm; median height of 49 specimens, 22 mm), inequivalved. Left valve convex; right valve slightly convex in umbonal region, flat to slightly concave marginally. Shape extremely variable, height ranging from 60 to 123 per cent of the length (median of 33 specimens, 94 per cent) ; angle formed by line drawn along the mid-part of the umbonal ridge and hinge line ranges between 55 and 75 degrees (median of 34 specimens, 65 degrees) ; lowest angle and obliquely prosoclinal shape most common in smaller specimens (PI. 24, fig. 7, and PI. 25, fig. 2) ; larger shells usually obtuse, rounded (PI. 25, fig. 1, and Pl. 28, fig. 1). Byssal sinus on anterior margin, near hinge line, not pronounced. Anterior auricle and posterior wing, blunt, rounded, length of both variable. Umbones prominent, broad, rounded; posterior margin of umbonal ridge distinct, sharp subangular; anterior part broadly rounded, less prominent than posterior. Surface sculpture of two kinds of concentric striae: coarse, raised, irregular, widely spaced; and fine, regular, closely spaced. Posterior lateral tooth on left valve, corresponding socket on right valve, gently concave toward umbonal ridge, elongate; possible anterior tooth on left valve, short, projecting just beneath and anterior to umbones, Ligament duplivincular, six to eight fine longitudinal striae, amphidetic, narrow, internal. Posterior adductor large, sub-round, located centrally between ventral and dorsal margins, preserved on one right valve. All other internal features unknown. Original shell microstructure and mineralogy unknown. MATERIALS. The description is based on over 80 specimens from West Virginia and Virginia deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Ptertnea (Caritodens) demissa is tentative, because of both the small amount of well-preserved Ordovician material upon which the taxon is defined and, espe- cially, the lack of recent taxonomic studies of lower Paleozoic pterioids. Foerste (1910, p. 71) established the subgenus Caritodens (which he later raised to generic rank) for what he believed to be a distinct Upper Ordovician pterioid that ORDOVICIAN APPALACHIAN ECOLOGY 125 could be distinguished from Pterinea by the absence of the duplivincular ligament and of well-defined multiple anterior and posterior teeth. The type, C. demissa (Conrad), exhibits only one strong posterior “crural” ridge, or “jugum’’, which culminates in a posterior lateral tooth, and also a short, blunt anterior projection. Subsequently Foerste (1914a, p. 269) discovered better preserved Ordovician material that showed a definite duplivincular ligament. Thus the definition of Caritodens rests solely on the presence of the single “crural” ridge. Foerste had failed to figure C. demissa with the posterior “crural” ridge and the loss of the material prior to his 1924 publication makes the documentation less well- established. Ruedemann, however, figured a New York specimen (1926, pl. 2, fig. 8) that does show the characteristic posterior jugum, which I have found to be typical in all my central Appalachian Upper Ordovician material. One of the major problems facing the earlier investigators in the definition and identification of Ordovician pterioids, aside from the characteristic poor preservation, was the extreme shape variation. The definition of a number of Ordovician species was based on slight changes in shape or minor differences in the concentric surface sculp- ture. The following is a list of North American Ordovician pterioid species that may be junior subjective synonyms of P. (C.) demissa. Pterinea insueta (Emmons) P. obtusiformis Ruedemann P. cincinnatiensis Miller and Faber P. rugatula Miller and Faber P. prolifica Billings P. bellilineata Billings P. macronota Ulrich Secrist and Evitt (1943, p. 365, fig. 15) figured a very poorly preserved specimen called P. maternata that was collected from their Passage Creek locality at Massanutten Mountain, north-central Virginia. I have re-collected from this locality (loc. 167) and do not feel that my material can be satisfactorily distinguished from P. (C.) demissa. The problem of shell shape and its significance as a discriminator of species was the topic of lengthy discussions by Foerste (1914a, p. 269; 1924, p. 161) and of a summary statement, with illustrations, by Ruedemann (1926, p. 24-25). Without any knowl- edge of possible allometric growth in Recent pterioid species, Foerste introduced the idea that the younger, smaller P. (C.) demissa are characteristically more oblique, whereas the more mature, larger specimens are more ovate. He concluded that the direction of maximum growth along the shell edge changed drastically through time; “Small specimens appear so different from mature ones as to suggest their belonging to a different species” (Foerste, 1924, p. 161). However, Hynd (1955), working with the Recent Pinctada aibina, an abundant pterioid found along the coastline of north- ern Australia, confirmed this dramatic change in shell shape with age, and found that every one of the taxonomic shape characters usually described is subject to considerable change. Unfortunately Foerste had discovered only about half of the problem; it becomes increasingly apparent from the numbers of central Appalachian Upper Ordovician specimens which I have collected that supposedly mature specimens from the same 126 PEABODY MUSEUM BULLETIN 34 horizon may be ovate or oblique (PI. 25, fig. 1, and Pl. 26, fig. 6). Again, Hynd (1960) described quite significant morphological changes in the shape of Pinctada albina as a result of environmental influences. He did not relate these changes in the character of the shell to any clearly defined environmental conditions. Added to the characteristic allometric growth that invariably shows a pronounced oblique juvenile shell, middle- sized erect specimens and large obtuse forms, Hynd (1960) found that pterioid shells assumed two extreme shapes as the result of environmental influences. One group, found in a “rocky environment” and attached to a hard subsurface, exhibits a relatively stronger projection of the anterior margin and the posterior wing; the posteroventral margin does not project and the shell form is obtuse. The second group, presumably the sandy-bottom dwelling, inner sublittoral specimens, shows no noticeable projection of the anterior margin or of the posterior wing; rather, the posteroventral margin projects strongly and the shell form is oblique or erect. Pterioids from the central Appalachian Upper Ordovician rocks exhibit the obtuse and oblique shell forms as a function of size and possibly of ecological control. Pterinea (Caritodens) demissa is one of the most widespread faunal elements in the central Appalachian Upper Ordovician strata, but is abundant only in southwestern Virginia, bivalve faunal province III (Fig. 17 and Table 3, loc. 141, 147, 149, 184). Here it occurs in a silty mud with numerous Zygospira recurvirostra, Ambonychia cul- trata, various trespostomatous Bryozoa and some Hebertella sinuata, all part of the Spiriferid Population of the Zygospira—Hebertella Community. In these localities where P. (C.) demissa is common both right and left valves are found. In the more northerly exposures where fewer valves are found, only the more convex left valve occurs. Bassler (1919), Foerste (1910, 1914a, 1924) and Ruedemann (1926) have figured only left valves, and Ruedemann (1926, p. 26) thought that the right valve may have been in some way less resistant. The right valves may have been more deli- cate, more easily fragmented by currents, and thus more readily lost through the effects of diagenesis and compaction. Another possibility, perhaps less likely, is that of dif- ferential shell transport. The plate-shaped, probably lighter right valves may have been more easily winnowed and scattered by waves and currents, whereas the convex left valves, larger and somewhat heavier, would tend to remain aggregated and be pre- served essentially in place. Inferences as to life habitats of the central Appalachian Upper Ordovician P. (C.) demissa come from the spare literature available on Recent pterioids. Although there is a fair amount of data concerning their anatomy, there are few references to ecology and environmental setting. Modern pterioids appear to live in a variety of shallow and deep water environments, although they appear most prolific in the inner sublittoral. Attached to a firm sandy substratum or solid object (e.g., reefs, rocks, pilings) by the convex right valve, they exhibit a pronounced byssal notch in the right valve. Newell (1937, p. 18-20) discussed the enigma that no known Paleozoic pterioids or pectinoids have a markedly convex right valve. As is the case in the Ordovician P. (C.) demissa, the right valve is only slightly convex and is, in fact, partially concave at the margin. The byssal notch in the right valve of P. (C.) demissa is no more pronounced than that in the left valve. Whether these Ordovician pterioids rested on their convex left or “flat” right valve remains unknown. The probable environmental setting for P. (C.) demissa is an inner sublittoral, quiet, non-turbid environment where wave and current energy was only strong enough ORDOVICIAN APPALACHIAN ECOLOGY 127 to winnow and scatter the more delicate right valves. The pterioids definitely thrived away from the more northerly influx of clastic terrigenous sediments. There is no significant geographic trend in the shape of P. (C’.) demissa shells, although there are more numerous oblique shells in the southwestern Virginia localities where the pte- rioids are most abundant. This is the more common shell form for Recent pterioids liv- ing on “sandy” bottoms and not attached to a hard substratum. The pronounced alate form apparently common in the Upper Ordovician of southeastern Canada and fig- ured by Foerste (1914a, 1924) is, however, not common in the central Appalachian clastic facies or in the New York Upper Ordovician Lorraine Group (Ruedemann, 1926, p. 25). SuscLass PALAEOHETERODONTA OrveR ACTINODONTOIDA SUPERFAMILY MODIOMORPHACEA Famity MODIOMORPHIDAE Genus MODIOLOPSIS Modiolopsis modiolaris (Conrad, 1838) Plate 31, figures 1-3; plate 32, figures 1-3; Plate 33, figures 1-3; Plate 34, figures 1-3; plate 35, figures 1-4 Pterinea modiolaris Conrad, 1838, p. 118. Cypricardites modtolaris (Conrad). Conrad, 1841, p. 52. Emmons, 1842, p. 403, [?]fig. 4; p. 405, fig. 114.2. Cypricardites augustifrons Conrad, 1841, p. 52. Emmons, 1842, p. 405, fig. 114.1. Cypricardites ovata Conrad, 1841, p. 52. Modiolopsis modiolaris (Conrad). Hall, 1847, p. 294, pl. 81, fig. la-1g, [?]pl. 82, fig. 1. Billings, 1856, p. 44, fig. 8. Billings, 1863, p. 213, fig. 217. Ulrich, 1894, p. 481, figs. 37a, [?]37b. Bassler, 1909, pl. 14, fig. 8. Foerste, 1914a, p. 281, pl. 3, fig. 1; pl. 5, figs. 1, 2. [not]Hall and Whitfield, 1875, p. 83, pl. 2, fig. 17. Bassler, 1919, p. 286, pl. 58, fig. 12. Stewart, 1920, p. 34, pl. 3, fig. 1. Lysonta submodiolaris (d’Orbigny). Emmons, 1855, p. 171, pl. 17, figs. 8, 8a. Modiodesma modiolare (Conrad). Ulrich, 1924, p. 191, pl. 31, fig. 1; pl. 32, figs. 1-3; pl. 33, figs. 3-6. Ruedemann, 1925a, pl. 6. Ruedemann, 1926, p. 32, pl. 4. Modtodesma modiolare var. augustifrons (Conrad). Ulrich, 1924, p. 189, pl. 32, figs. 4,5. Ruedemann, 1926, p. 34, fig. 11. Modiodesma modiolare var. brevoir Ulrich, 1924, p. 189. Ruedemann, 1926, p. 34. [?|Modtodesma scapha Ulrich, 1924, p. 189, pl. 33, figs. 1, 2. [?]Orthodesma sp.? Butts, 1941, p. 114, pl. 96, figs. 19, 20. [?]Rhytimya sp.? Butts, 1941, p. 127, pl. 100, fig. 1; p. 128, pl. 100, figs. 14, 15. [?]|Whiteavesia sp.? Butts, 1941, p. 127, pl. 100, fig. 16. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER OrRpo- VICIAN. Shell of large size (median length of 154 specimens, 51 mm, median height of 171 specimens, 20 mm), inflated, equivalved, extreme posterior elongation. Shape vari- able, height varying between 19 and 62 per cent of the length (median of 120 specimens 42 per cent), much of shape variation results from tectonic distortion (PI. 35, fig. 128 PEABODY MUSEUM BULLETIN 34 4; cf. Ulrich, 1894, p. 481, figs. 37a, b). Byssal sinus shallow, on ventral margin, to- ward anterior. Umbones rounded, near anterior margin; umbonal ridge faint, broadly rounded, flattens toward posterior. Anterior margin sharply rounded, narrow; posterior margin broadly rounded, expanded. Surface sculpture of fine concentric striae, pre- served as external mold, over entire shell, most prominent at postero- and antero- dorsal margins. Edentulous. Ligament broad, elongate, straight to moderately curved, opisthodetic, possibly partially internal. Anisomyarian, anterior adductor large, subcircular to elongate, narrowing at dorsal edge; posterior adductor two times larger than anterior, very faint, subcircular. Pedal retractors small, elongate, directly above anterior adductor. All other internal features unknown. Shell microstructure and mineralogy unknown. Mareriats, The description is based on over 850 specimens from south-central Penn- sylvania to northern Tennessee deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Modtolopsis modiolaris is tentative pending a restudy of Modiolopsis Hall, Orthodesma Hall and Whitfield, and Cymatonota Ulrich. Hall (1847, p. 297) combined Pterinea modiolaris (= Cypricardites modiolaris) Conrad, Cypricardites augustifrons Conrad and Cypricardites ovata Conrad to form Modiolopsis modtolaris, which was defined as the type of Hall’s new genus Modiolopsis. In the definition of M. modiolaris, Hall placed a great deal of emphasis on the extreme shape variability of the New York Ordovician specimens. This variability was thought to result from “natural” and “compressional” forces. Hall probably attributed to “natural forces” the distinct shape variation between forms found in shales and those in sandstones, although he failed to mention specifically what the characteristic changes were. The secondary tectonic or “compressional” forces that altered the origi- nal shell shape were documented by Ulrich (1894, p. 481, figs. 37a, b; Pl. 35, fig. 4, this paper). Distorted M. modiolaris and other associated faunal elements are common at most localities in the central Appalachians. Ulrich (1924, p. 183) reviewed Hall’s type material and attempted to redefine M. modiolaris but incorrectly made it the type of a new genus Modiodesma. Ulrich claimed that Modtolopsis modiolaris had to be removed from the genus Modiolopsis because it did not conform to Hall’s generic definition. Modiodesma modiolaris must be considered a junior objective synonym of Modiolopsis modiolaris. It is certainly possible that Hall’s material contained more than one species, but I doubt that Ulrich’s division of Modiolopsis modiolaris into four separate species representing three genera can be substantiated. I do feel, however, that Hall’s (1847) pl. 82, fig. 1 is probably not Modtolopsis modiolaris. Whether it is another species of Modiolopsis (M. milleri?) or a species of Colpomya must await a more complete taxonomic revision. Newell et al. 1969 have placed the genus Modiodesma in synonymy with Modio- lopsis and have added a number of junior subjective synonyms; one is the genus Or- thodesma Hall and Whitfield, which has been identified previously in the central Ap- palachian Upper Ordovician rocks as occurring with M. modiolaris (Foerste, 1914a, p. 284-285). Hall and Whitfield (1875, p. 93) defined Orthodesma as differing from Modiolopsis in the absence of hinge teeth; Ulrich (1894, p. 516) emphasized the edentulous nature of Orthodesma and its close relationship to Modiolopsis, but felt that the elongate outline, coarser concentric striae and slightly gaping valves were typi- ORDOVICIAN APPALACHIAN ECOLOGY 129 cal of Orthodesma. I have found in the central Appalachian material that misidentifi- cation of Modtolopsis modiolaris as Orthodesma rectum or O. nasuta is simply a func- tion of distortion and selective preservation. The coarser concentric striae are preserved only as an external mold of MM. modiolaris, and the distortion gives rise to the elongate outline and the gaping valves. I am in complete agreement, however, with John Pojeta of the U. S. Geological Survey (pers. comm.) that some gaping, elongate Orthodesma- like bivalves in the Ordovician are distinct from what I believe to be deformed Modio- lopsis. A complete review of the Family Modiomorphidae Miller 1877 (—=Modiolopsi- dae Fischer 1887) should resolve these problems. Modtolopsis modiolaris is one of the most common central Appalachian Upper Ordovician faunal elements and is abundant from south-central Pennsylvania to south- central Virginia, bivalve faunal province ITI (Fig. 17). Associated faunal elements are normally Ambonychia praecursa and, rarely, Orthorhynchula linneyt (Ruedemann, 1925a, p. 6; Pl. 2, this paper), both in the Modiolopsid and Rhynchonellid Popu- lations of the Orthorhynchula—Ambonychia Community. Patches of abundant M. mo- diolaris occurring alone appear common in central Virginia. The substratum is usually a muddy silt-sand, and the patches of concentrated, exclusively Mf. modiolaris are found in a muddier sediment. But most of the M. modiolaris are not clumped but are scattered over the bedding plane, where the valves are often articulated and in various degrees gaping. In southwestern Virginia and northern Tennessee, bivalve faunal province III (Fig. 17), M. modiolaris is a less dominant faunal element, usually smaller (length normally less than 30 mm), less notably elongate and more rectangular (PI. 35, fig. 2). It resem- bles M. concentrica; but I feel that these morphological differences are slight in light of the poor preservation of the southern material and the present wide range of shape variation permitted in M. modiolaris. The substratum is a silty mud in southwestern Virginia and the common associated faunal elements are Ambonychia cultrata, Zygo- spira recurvirostra and Dekayia in the Spiriferid Population of the Zygospira—Heber- tella Community (Table 3, loc. 149, 151, 141). In the lime muds of northern Tennes- see, Mf. modiolaris is found with abundant Zygospira recurvirostra, Hebertella stnuata and a few Ambonychia radiata?. Scattered modiolopsids, possibly M. sinuata (= M. anodontordes?; Pl. 32, fig. 2) are found with abundant Onniella multisecta, crinoids and Lyrodesma poststriatum from the Orthid—Crinoid Population of the Sowerbyella—Onniella Community in north-central Pennsylvania, bivalve faunal province I (Fig. 17). A few small Colpomya and Cymatonota (= ?Psiloconcha) are occasionally found with abundant crinoids in the same general area. Very poorly preserved modiolopsids occur along the eastern edge of the Reedsville exposures in north-central Virginia bivalve faunal prov- ince I (loc. 167, 168, 169), where they are found with abundant Rafinesquina “alter- nata’, numerous pleurotomariacean gastropods and a few Cyrtodonta? (PI. 37, figs. 1-3), part of the Strophomenid Population of the Sowerbyella-Onniella Community. The state of preservation of these modiolopsid-like bivalves precludes even a tentative generic assignment, The environmental setting and life habits of M. modiolaris probably were much like those of some recent species of Modiolus. One, Modiolus rectus, found along the west coast of the United States, is bysally attached in the muddy silts and sands of quiet water, nearshore environments. The mussel is usually solitary and occasionally 1s 130 PEABODY MUSEUM BULLETIN 34 found covering a fairly extensive mud-silt flat, or muddy substratum in 5 to 15 meters of water. It is embedded vertically in the mud with just the posterior tip of the shell projecting above the surface (Fitch, 1953, p. 48; Keen, 1958, p. 56). Small clumps or patches of the related Modiolus modtolus have also been reported by Kuderskii (1962) from the inner sublittoral waters of Onega Bay, the White Sea, U.S.S.R. The central Appalachian Upper Ordovician M. modtolaris is believed to have inhabited a quiet water, inner sublittoral environment, living bysally attached, usually solitary and partially embedded in the muddy silt substratum, Where abundant M. mo- diolaris is found alone and not in common association with Ambonychia praecursa there is usually a change in the substratum, from a muddy silt to a silty mud. This mud may place a limitation on the distribution of the subround ambonychiid but not on that of the more elongate modiomorphid which may, in fact, have lived embedded even more deeply in the muds. I have found little evidence to support the clumping of M. modiolaris into a shell bank. Rare large concentrations of articulated valves may reflect clumping or may have been produced by local current activity. Mortality- growth rate curves may provide further clues to the possibilities of transportation prior to burial. M. modiolaris shows some evidence of infestations by Polydora-like worms; occa- sionally a few specimens exhibit a characteristic, irregular “U”-shaped worm tube at the approximate position of the inhalent current (Pl. 31, fig. 1). This infestation is never extensive and probably had little influence on the distribution of M. modtolaris. And most often the posterior portion of the shell extends beyond the tube, probably indi- cating an adequate relining of shell material over the tube. One interesting note is that collections of Mf. modiolaris in the Peabody Museum from the Upper Ordovician of the Cincinnati region occasionally show identical inhalent worm tubes. Boekschoten (1966, p.. 354), working along the Dutch tidal flat, described Recent Polydora tubes at the posterior margins of some Cardium edule, which appears to be indicative of attack in living position. Only where the valves were separated and lying loose on the substratum were they bored over the entire surface. [?]OrpER TRIGONIOIDA {?]/SupERFAMILY LYRODESMATACEA [?]Famity LYRODESMATIDAE Genus ISCHYRODONTA Ischyrodonta truncata Ulrich, 1890 Plate 27, figures 3-6; plate 28, figures 1-6; plate 29, figures 1-6; plate 30, figures 1-6 [?|Modiolopsis truncatus Hall, 1847, p. 296, pl. 81, figs. 3a, b. Hall and Whitfield, 1875; p186: ple 2o hie 13: [?|Lysonta subtruncata (d’Orbigny). Emmons, 1855, p. 171, pl. 17, fig. 4. Ischyrodonta truncata [not Hall, 1847] Ulrich, 1890, p. 174, figs. 1la-1le. Ulrich, 1893, p. 672, figs. la-le. [?\Ischyrodonta ovalis Ulrich, 1892, p. 242, fig. 27. Ulrich, 1893, p. 674, pl. 54, figs. 12-15. Ulrich, 1894, p. 477, fig. 35-I. [?|Ischyrodonta decipiens Ulrich, 1893, p. 673, pl. 45, figs. 16-19. [?|Modiolodon truncatus (Hall). Ulrich, 1893, p. 656, pl. 51, figs. 9, 10. Bassler, 1919, ORDOVICIAN APPALACHIAN ECOLOGY 131 p. 288, pl. 57, fig. 25. Ruedemann, 1926, p. 39, Butts, 1941, p. 127, pl. 100, nes: 2, 3. [?|Eurymya? truncata (Hall) . Ulrich, 1894, p. 512. [?|Modiolopsis sp.? Butts, 1941, p. 127, pl. 100, figs. 12, 13. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER ORDO- vIcIAN. Shell of medium size (median length of 78 specimens, 29 mm; median height of 107 specimens, 17 mm), inflated, inequivalved, broad, posterior expansion, Shape sub-trapezoidal, variable, height varying between 50 and 70 per cent of the length (median of 73 specimens, 61 per cent) ; distance umbo to anterior margin varying be- tween 22 and 45 per cent of total shell length (median of 73 specimens, 32 per cent). Byssal sinus very faint. Anterior margin broadly rounded; posterior margin flattened, wide, intersection with hinge line sharply rounded. Umbones prominent, sharp, gently pointed toward anterior, curved in toward hinge line; umbonal ridge broad, subangu- lar. Surface sculpture prominent, concentric striae, coarse, widely spaced. Cardinal teeth usually two, radiating from beneath umbo; lateral teeth unknown. Ligament duplivincular, two or three longitudinal striae, narrow, internal, amphidetic (PI. 30, fig. 6). Anisomyarian; anterior adductor muscle large, elongated dorsoventrally, sub- round, with coarse longitudinal furrows; posterior adductor faint, subcircular, twice as large as anterior muscle. Pedal retractor muscle prominent, small, rounded, directly above but separated from anterior adductor. All other internal features unknown. Original shell microstructure and mineralogy unknown. MarteriAts. The description is based on over 250 specimens from Pennsylvania to Tennessee deposited in the Peabody Museum. Discussion. The assignment of these central Appalachian Upper Ordovician speci- mens to Ischyrodonta truncata is tentative pending a complete taxonomic restudy of Ischyrodonta, Modiolodon, Ortonella, Cyrtodonta and Modtolopsis. The strong, well- defined cardinal teeth and the duplivincular ligament presumably set Ischyrodonta apart from Modiolopsis. The lack of any posterior lateral teeth probably separates it from Cyrtodonta and Ortonella, but Ischyrodonta Ulrich (1890, p. 173) and Modiolo- don Ulrich (1893, p. 652; 1894, p. 521) had been considered indistinguishable.. How- ever John Pojeta (pers. comm.) has informed me that silicified topotypic Modiolodon material does not show a duplivincular ligament. Bassler (1919, pl. 57, fig. 25) and Butts (1941, pl. 100, figs. 2, 3, 12, 13) have figured poorly preserved specimens from the central Appalachian Upper Ordovician rocks, which they called Modiolodon truncatus and Modiolopsis sp.?, that resemble the specimens I have collected from the same area. Ruedemann (1926, p. 39), how- ever, claimed that M. truncatus is exclusively an Ohio Valley species and that the New York, Appalachian and Canadian specimens misidentified as this species are really Ischyrodonta (= Anodontopsis) unionoides, a possibility that had been touched upon briefly by Hall and Whitfield (1875, p. 86). The reasons for his reassignment are not clear, although Ulrich (1890, p. 173; 1894, p. 521) suggested the supposedly thicker shell and well-preserved pedal muscle scars, common to the Appalachian specimens, are more characteristic of Ischyrodonta than Modiolodon or Cyrtodonta. Ischyrodonta unionoides has been reported frequently from the Upper Ordovician rocks of eastern North America (Ulrich, 1893; Foerste, 1914a, 1924; Bassler, 1919; 132 PEABODY MUSEUM BULLETIN 34 Stewart, 1920; Ruedemann, 1926), but all the figured specimens are considerably more ovate than the specimens I have collected and have assigned to I. truncata. In fact, I. truncata seems to present something of an intermediate subtrapezoidal shape between the rounded I. untonoides and the notably elongate I. elongata Ulrich (1890), I, misenert Ulrich (1893) and I. modioliformis Ulrich (1893). Ischyrodonta truncata is one of the most common and widespread faunal elements in the central Appalachian Upper Ordovician. It is most abundant from south-central Pennsylvania to southern Virginia, bivalve faunal province II (Fig. 17), and is associ- ated with two distinct faunal populations. In one case O. linneyt from the Rhyncho- nellid Population of the Orthorhynchula~Ambonychia Community is the most abun- dant associated faunal element. J. truncata is also found associated with Tancrediop- sts cuneata, Lingula? and Plectonotus? sp., part of the Linguloid Population of the Orthorhynchula—Ambonychia Community, although O. linneyi rarely occurs with these. The substratum in both cases is a muddy silt-fine sand. Smaller numbers of J. truncata are found with abundant Rafinesquina “alternata”, Onniella multisecta, cri- noids, Hallopora, and Lyrodesma poststriatum, part of the Orthid-Crinoid Population of the Sowerbyella—Onntella Community, in north-central Pennsylvania (Table 3, loc. 77-A, 110) in a fine muddy silt, and in southwestern Virginia and northern Tennessee (loc. 141, 147, 133, 135, 139) with abundant Zygospira recurvirostra, Pterinea (Car- todens) demissa, Murchisonia? and various trespostomatous Bryozoa, part of the Spiriferid Population of the Zygospira—Hebertella Community, in a fine silty mud. The life habits of I. truncata may have resembled those of some Recent Modiolus (especially M. capax), to which I. truncata shows a superficial resemblance. The en- vironmental setting probably was similar to that proposed for Modtolopsis modiolams, in which the mussel lived byssally attached to a silt-sand substratum, partially sub- merged in a quiet, semi-protected, inner sublittoral environment. The distribution rarely shows clumping of individuals. Sardeson (1924) provided evidence for the possibility of an infaunal habit for some mid-continent Cyrtodonta, to which I. truncata shows at least some resemblance in shape, musculature and cardinal dentition. I. truncata may therefore have assumed a partially submerged habit especially in the nearer shore, possibly more turbulent environments. Some tolerance for temporary changes in salinity may be indicated by its association with abundant Lingula? and Tancrediopsis cuneata. Association with abundant O. linneyi probably points to a more normal marine environ- ment. Locally common in I. truncata, when associated with O. linneyt, is the preserva- tion of what appears to be worm tubes at the inhalent opening (PI. 28, fig. 3; PI. 29, fig. 3). Tubes of this type are also commonly found preserved on O. linneyt valve margins at the probable sites of inhalent currents (PI. 14, fig. 1). The ecological significance of this infestation was probably minimal. Genus LYRODESMA Lyrodesma poststriatum (Emmons, 1842) Plate 44, figures 1-7 Nuculites poststriatus Emmons, 1842, p. 399, fig. 4. Nucula poststriata (Emmons). Hall, 1847, p. 151, pl. 34, figs. 2a, b, [?]p. 301, pl. 82, figs. 10a, b. ORDOVICIAN APPALACHIAN ECOLOGY 1350 Cardiomorpha poststriata (Emmons). Emmons, 1855, p. 175, pl. 17, fig. 22. Lyrodesma poststriatum (Emmons). Billings, 1863, p. 176, figs. 167a, b. Nicholson, 1875, p. 36, fig. 11b. Foerste, 1914a, p. 306. Stewart, 1920, p. 26, pl. 4, fig. 5. Foerste, 1924, p. 169, pl. 25, fig. 10a, b; pl. 43, fig. 9. [?]Lyrodesma cannonense Ulrich, 1894, p. 601, pl. 42, figs. 6-8. [?]Lyrodesma schucherti Ruedemann, 1912, p. 103, pl. 6, fig. 5. [?|Lyrodesma poststriatum elongatum Stewart, 1920, p. 26, pl. 4, fig. 5. Foerste, 1924, p. 170, pl. 22, fig. 8. Lyrodesma poststriatum manitoulinense Foerste, 1924, p. 170, pl. 43, fig. 5. DESCRIPTION BASED ON SPECIMENS FROM THE CENTRAL APPALACHIAN UPPER Orpo- vicIAN. Shell cf medium size, pronounced posterior elongation (median length of 19 specimens, 17 mr; median height, 11 mm). Shape variable, height ranging from 61 to 70 per cent of length (median of 19 measured specimens, 62 per cent). Surface sculpture of fine concentric striae, faint except near edges of valves, about six promi- nent coarse radial ribs at posterodorsal edge of shell. Prominent schizodont teeth, nor- mally eight; well-marked longitudinal striae on each tooth (Pl. 44, fig. 4) ; teeth not uniform in size, notable anterior and slight posterior decrease in size away from the umbo. Resilifer absent, ligament area otherwise unknown. Anterior and _ posterior adductor muscle scars rounded, posterior slightly more elongate. Pedal muscle scars rounded, posterior pedal scar slightly larger and more elongate than anterior. Pallial line with distinct impression of a small pallial sinus, posteroventral, preserved as in- ternal mold on two specimens (PI. 44, fig. 5) ; other internal features unknown. Origi- nal shell microstructure and mineralogy unknown. MatTeRIALs. The description is based on about 30 specimens from central Pennsylvania deposited in the Peabody Museum. Discussion. Sixteen species and subspecies described from the Middle and Upper Ordovician strata of North America have been assigned to the genus Lyrodesma (see Wilson, 1956, p. 64, for a concise generic description). This grouping of species can be informally subdivided into three morphological groups on the basis of shell size, shape variation (height to length ratios) and the degree of posterior expansion, Table 21 outlines these three groups. Stewart (1920, p. 26) also mentioned that there ap- TABLE 21. An informal morphological grouping of previously defined Lyrodesma species. The three groups are qualitative and designed only for a clearer understanding of the shape variabil- ity within the central Appalachian Upper Ordovician specimens. 1. Small size, oval, 2. Medium size, suboval, 3. Large size, subellipsoidal no distinct posterior pronounced posterior extreme posterior expansion expansion expansion Lyrodesma cincinnatiense Lyrodesma poststriatum Lyrodesma major L. acuminatum L. poststriatum elongatum L. postplanum L. acuminatum intermedium L. poststriatum manitoulinense L. huguesensis L. planum L. cannonense L. inoratum L. schucherti L. conradi L. grande L. subplanum 134 PEABODY MUSEUM BULLETIN 34 | peared to be three distinct subgroups of the genus Lyrodesma, based on noticeable — differences in height-length ratios; but she did not discuss the distinguishing character- ; istics of these groups. Instead, she mentioned only a characteristic “type” for each group. Most of the Appalachian Lyrodesma specimens can be assigned to Lyrodesma — poststriatum of subgroup 2 (Table 21), but a few specimens show morphological — characteristics that appear to typify one of the other subgroupings and thus may belong to one or more other species. These latter specimens, because they are rare, have not been described. In fact, the shape variation within the genus itself remains poorly known and a complete resurvey of Lyrodesma morphological variability should be undertaken. Thus the three subgroups are not intended as taxonomic groupings in this report, but rather are introduced as a means of emphasizing overall size and shape variability espe- cially with regard to the most common central Appalachian form. Lyrodesma poststriatum is common in central Pennsylvania, (loc. 122, 37, 35, 52, and 97), where it occurs with Praenucula levata, Ctenodonta? pulchella, crinoids and lesser numbers of Rafinesquina “alternata” and Onniella multisecta. The substra- tum is a finely laminated silt or mud, and the most likely environmental setting appears to be in quiet, offshore waters. Lyrodesma is unique in that it is an Early Paleozoic siphonate bivalve. By analogy with Recent siphonate forms, where depth of burrowing appears directly related to the depth of sinuosity of the pallial sinus, Lyrodesma appears to have been a shallow infaunal form. I have also collected a few Lyrodesma specimens from localities 189, 192, 195, and 203, where the fauna is dominated by O. linney, Ambonychia praecursa and Modiolopsis modiolaris in a muddy silt-sand. These rare specimens of Lyrodesma exhibit a more pronounced posterior expansion than the more abundant ones farther north, but unfortunately no pallial lines have been found preserved on these more posteriorly expanded specimens. I suspect, however, that specimens with a more deeply inset pallial sinus might be found, emphasizing a deeper infaunal habit in a more turbulent environment. Locality 1 LOCALITY REGISTER (includes only fossiliferous exposures, location given to nearest 0.5 mile. ) Peabody Museum Number (A-6324) (A-6325) (A-6326 ) (A-6327) (A-6328) (A-6329) (A-6330) (A-6331) (A-6332) (A-6333) (A-6334) (A-6335) (A-6336) (A-6337) (A-6338) (A-6339) (A-6340) (A-6341) (A-6342) (A-6343) (A-6344) Description Road cut 1.0 mile s. of New Tripoli, Pa. along New Tripoli - Lynnville road. Road cut 1.5 miles n. of Lynnville, Pa. along New Tripoli - Lynnville road. Road cut 0.5 mile n. of Lynnville, Pa. along New Tripoli - Lynnville road. Road cut 1.5 miles s. of Pleasant Corners, Pa. along Pleasant Corners - Werley’s Corner road. Road cut less than 0.5 mile s. of loc. 9. Road cut 0.5 mile s. of loc. 11. Road cut 1.5 miles w. of loc. 2 and 4 along a paved road lead- ing sw. from New Tripoli, Pa. Road cut 1.0 mile n. of loc. 15. Road cut 1.0 mile s. of Lynnport, Pa. along Pa. Rt. 863. Road cut less than 0.5 mile s. of loc. 17. Road cut less than 0.5 mile s. of loc. 18. Road cut less than 0.5 s. of loc. 19. Road cut a few hundred yards n. of loc. 22. Road cut a few hundred yards n. of loc. 23. Road cut 2.0 miles s. of Jacksonville, Pa. along Pa, Rt. 737[?]. Road cut 0.5 mile s. of loc. 25. Road cut 1.5 miles w. of Albany, Pa. along Albany - Eckville road. Road cut 2.5 miles w. of loc. 27. Quarry n. of Cedar Springs, Pa., junction Pa. Rts. 64 and 880. Road cut 1.0 mile se. of Rote, Pa. along Pa. Rt. 880. Road cut 0.5 mile n. of Loganton, Pa. along Pa. Rt. 880. Road cut 1.0 mile n. of Carroll, Pa. along Pa. Rt. 880. Road cut 1.0 mile s. of Rauchtown, Pa. along Pa. Rt. 880. 135 136 Locality 34-A 35 36 37 38 39 39-A 42 43 44 45 47 48 49 50 51-A 52 60 62 63 64 68 69 70 71 72 13 PEABODY MUSEUM BULLETIN 34 Peabody Museum Number (A-6345) (A-6346 to A-6357) (A-6358) (A-6359 to A-6363) (A-6364) (A-6365) (A-6366) (A-6369) (A-6370) (A-6371) (A-6372) (A-6374) (A-6375) (A-6376) (A-6377) (A-6379) (A-6380) (A-6381) (A-6382) (A-6383) (A-6384) (A-6388 ) (A-6389) (A-6390) (A-6391) (A-6392) (A-6393) Description Quarry 1.0 mile s. of Rauchtown, Pa. within Pa. State Park grounds a few hundred yards e. of Pa. Rt. 880. Road cut 2.5 miles s. of Antes Fort, Pa. along Pa. Rt. 44. Road cut 2.0 miles se. of Collomsville, Pa. along Pa. Rt. 44. Road cut 0.5 mile n. of Bastress, Pa. along Pa. Rt. 654. Road cut 1.0 mile s. of Duboistown, Pa. along paved road through north limb of Raccoon Mountain. Quarry about 2.0 miles s. of Lamar, Pa. immediately n. of Pa. Rt. 780. Road cut a few hundred yards sw. of loc. 39. Road cut 3.5 miles n. of Livonia, Pa. along Livonia - Green- burr road. Road cut less than 0.5 mile n. of Livonia, Pa. along Livonia - Greenburr road. Road cut 0.5 mile n. of Rebersburg, Pa. along Rebersburg - Tylersville road. Road cut about 5.0 miles e. of Woodward, Pa. along Pa. Rt. 45. Quarry 1.0 mile s. of Nittany, Pa. along Pa. Rt. 445. Road cut 1.0 mile s. of junction of Pa. Rt. 192 and north- south paved road, north limb of Brush Mountain. Road cut 2.0 miles s. of loc. 48, south limb of Brush Mountain. Road cut 1.0 mile s. of Pleasant Gap, Pa. along Pa. Rt. 53. Road cut less than 0.5 mile n. of Bellefonte, Pa. along Pa. Rt. 93: Road cut 1.5 miles n. of Jacksonville, Pa. along Pa. Rt. 445. Quarry at junction of Pa. Rt. 53 and U.S. Rt. 322 at Potters Mill, Pa. Road cut about 1.0 mile se. of Reedsville, Pa. along U. S. 322. Road cut about 1.0 mile se. of Reedsville, Pa. along U. S. Rt. _ 322 Bypass. Road cut 2.5 miles n. of Belleville, Pa. along Pa. Rt. 305. Stream cut 1.0 mile nw. of Allensville, Pa. Road cut 3.5 miles ne. of Mill Creek, Pa. along Pa. Rt. 655. Road cut 1.0 mile s. of Franklinville, Pa. in Colraine State Park, s. of Pa. Rt. 45. Two small quarries 1.5 miles ne. of Lemont, Pa. along Lemont - Oak Hill road. Road cut at Baffalo Run, Pa. along U. S. 322. Road cut 0.5 mile n. of Centennial, Pa. along Centennial - Port Matilda road. Locality 75 77 77-A 78 79 80 81 82 83 84 86 87 89 91 92 93 94 95 96 97 98 99 100 101 102 ORDOVICIAN APPALACHIAN ECOLOGY : 137 Peabody Museum Number (A-6395) (A-6396) (A-6397) (A-6398) (A-6399) (A-6499) (A-6400) (A-6401) (A-6402) (A-6403) (A-6404) (A-6406) (A-6407) (A-6408) (A-6409) (A-6410) (A-6411) (A-6412) (A-6413) (A-6414) (A-6415) (A-6416) (A-6417) (A-6418) Description Railroad cut 1.0 mile se. of Tyrone, Pa. a few hundred yards Sof Pac Rt.350. Road cut 3.0 miles n. of Elberta, Pa. along Elberta - Culp road. Road cut a few hundred yards s. of loc. 77. Railroad cut 0.5 mile s. of Ganister, Pa. a few hundred yards e. of Pa. Rt. 866. Quarry 0.5 mile nw. of Royer, Pa. a few hundred yards off Pa. Rt. 866. Quarry 1.5 miles nw. of Roaring Spring, Pa. along Pa. Rt. 164. Road cut 2.5 miles w. of Ore Hill, Pa. along Ore Hill - Sproul road. Road cut at Brumbaugh, Pa. at junction of Pa. Rts. 867 and 869. Road cut 2.5 miles ne. of Williamsburg, Pa. along Williams- burg - Huntingdon road. Road cut 2.5 miles se. of Clover Creek, Pa. along Pa. Rt. 164. Road cut 0.5 mile e. of Loysburg, Pa. along Pa. Rt. 868. Road cut 4.5 miles s. of Loysburg, Pa. along Pa. Rt. 36. Road cut a few hundred yards e. of Blue Mountain tunnel entrance, Pa. Turnpike. Road cut 8.5 miles e. of Tuscarora tunnel entrance, Pa. Turn- pike. Road cut about 2.0 miles e. of Bedford, Pa., Pa. Turnpike. Road cut at junction of two unmarked, paved roads a few hundred yards e. of Sulfur Springs, Pa., western limb of Wills Mountain. Road cut 1.5 miles e. of Buffalo Mills, Pa., Buffalo Mountain. Road cut 2.0 miles n. of Fossilville, Pa. along unpaved road through southern edge of Buffalo Mountain. Road cut 2.0 miles e. of Bedford, Pa. along U. S. Rt. 30; a few hundred yards w. of junction of U. S. 30 and Pa. Rt. 326. Road cut 1.5 miles s. of Rainesburg, Pa. along unpaved Pa. Rt. 326. Road cut 6.5 miles s. of Loysburg, Pa. along Pa. Rt. 36. Road cut 1.0 mile w. of Everett, Pa., a few hundred yards off U. S. 30 on paved service road. Road cut 1.5 miles w. of Everett, Pa. along Everett - Ashcom road. Road cut 2.5 miles se. of McConnellsburg, Pa. along Pa. Rt. 16. Quarry 0.5 mile ne. of Knobsville, Pa. near junction of nar- row, paved unmarked road and U. S. 522. 138 Locality 103 104 105 106 107 108 109 110 111 112 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 PEABODY MUSEUM BULLETIN 34 Peabody Museum Number (A-6419) (A-6420) (A-6500) (A-6421) (A-6422) (A-6423) (A-6424) (A-6425) (A-6426) (A-6427) (A-6428) (A-6429) (A-6430) (A-6431) (A-6432) (A-6433 ) (A-6434) (A-6435) (A-6436 ) (A-6437) (A-6438 ) (A-6439) (A-6440) (A-6441) (A-6442) (A-6443) Description Road cut 3.0 miles e. of McConnellsburg, Pa. along U. S. 30. Road cut 2.0 miles w. of Fort Louden, Pa. along U. S. 30. Road cut 1.5 miles e. of Fannetsburg, Pa. along Fannetsburg — - Upper Strasburg road. Road cut 1.5 miles w. of Upper Strasburg, Pa. along Pa. Rt. 533[?]. Road cut 1.5 miles w. of Roxbury, Pa. along Pa. Rt. 641. Road cut 7.0 miles w. of Roxbury, Pa. along Pa. Rt. 641. Quarry 2.0 miles s. of Spring Run, Pa. along Pa. Rt. 641 im- mediately n. of Pa. Turnpike overpass. Road cut 4.5 miles e. of Neelytown, Pa. along Pa. Rt. 641. Road cut 2.0 miles e. of Orbisonia, Pa. along paved, un- marked road immediately n. of junction with U. S. 522. Road cut 2.0 miles w. of Mt. Union, Pa. along U. S. 22. Road cut 8.0 miles n. of Lemoyne, Pa. along U. S. 11 and 15. Road cut 1.5 miles n. of Doubling Gap, Pa. along Pa. Rt. 233. Road cut 3.0 miles e. of East Waterford, Pa. along partially paved East Waterford - New German Town road. Road cut 4.5 miles n. of Doylesburg, Pa. along Pa. Rt. 274. Road cut 4.5 miles n. of Clear Spring, Md., near Hanging Rock, Bear Pond Mountains. Road cut 1.5 miles e. of Thorn Hill, Tenn. along U. S. 255. Road cut 3.0 miles w. of Joppa, Tenn. along Joppa - Powder Springs road, Clinch Mountain. Road cut 1.5 miles s. of Rose Hill, Tenn. along Tenn. Rt. 33. Road cut 2.0 miles w. of Ridenour, Tenn. along Tenn. Rt. 61, Lone Mt. Road cut and stream cut 3.0 miles nw. of Yoakum Crossroad, Tenn. along unpaved road across Powell Valley and eastern edge of Cumberland Mountain; road parallels Davis Creek. Road cut and railroad cut 2.0 miles n. of Arthur, Tenn. along unpaved Arthur - Cumberland Gap road. Road cut immediately s. of Cumberland Gap, Tenn. along motel service road parallel to Tenn. Rt. 32 and U. S. 25E. Road cut 2.5 miles w. of Sycamore Hall, Tenn. along unpaved road from Sycamore Hall through Wallen Ridge that junc- tions with unmarked paved road 2.0 miles n. of Tazwell, Tenn. Road cut 2.0 miles sw. of Klondike, Tenn. along Tenn. Rt. 66. Road cut 2.0 miles nw. of Choptack, Tenn. along Tenn. Rt. 66. Road cut 7.0 miles se. of Kyles Ford, Tenn. along Tenn. Rt. 70, Clinch Mountain. Locality 136 137 138 139 140 141 142 143 144 145 147 148 149 150 151 152 153 160 161 162 163 164 ORDOVICIAN APPALACHIAN ECOLOGY 139 Peabody Museum Number (A-6501) (A-6444) (A-6445 ) (A-6446 ) (A-6447) (A-6448 ) (A-6449 ) (A-6450) (A-6451) (A-6452) (A-6453) (A-6454) (A-6455) (A-6456 ) (A-6457) (A-6458) (A-6459) (A-6460) (A-6461 ) (A-6462) (A-6463 ) (A-6464) Description Road cut 0.5 mile s. of Unthanks, Va. along Va. Secondary Rt. 758. Road cut 1.0 mile w. of U. S. 58 near Hagan, Va. along the Hagan - Smiley road. Road cut 3.5 miles se. of Bowling, Va. along Va. Primary Rt. 70 and U. S. Alt. 58. Road cut 2.5 miles nw. of Blackwater, Va. along Va. Primary Rt. 70 and 798[?], Powell Mountain. Road cut 3.0 miles n. of Mendota, Va. along unpaved Men- dota - Collinwood, Va. road. Road cut 3.5 miles nw. of Pattonsville, Va. along U. S. 421 and 58, Powell Mountain. Road cut 1.5 miles nw. of Stickleyville, Va. along U. S. 421 and 58, Wallen Ridge. Stream cut 1.0 mile nw. of Pennington Gap, Va. a few hun- dred yards ne. of U.S. 421. Road cut 1.5 miles se. of Olinger, Va. along paved, unmarked road that junctions with U. S. Alt. 58. Road cut 1.0 mile s. of Rockdell, Va. along Va. Primary Rt. 80, Clinch Mountain. Road cut 1.5 miles se. of Mt. Gate, Va. along Va. Primary Rt. 16, Clinch Mountain. Road cut 12.5 miles n. of Marion, Va. along Va. Primary Rt. 16, Walker Mountain. Road cut about 10 miles n. of Broadford, Va. along unpaved. Va. Primary Rt. 91, Clinch Mountain. Road cut 6.0 miles nw. of Chilhowie, Va. along Va. Primary Rt. 107, Walker Mountain. Road cut a few hundred yards s. of Walker Mountain lookout tower along Va. Secondary Rt. 621, near junction with U. S. 21 and 52. Road cut 1.5 miles s. of Rocky Gap, Va. along U. S. 21 and 52, Wolf Creek Mountain. Road cut 2.0 miles se. of Bluefield, W. Va. along U. S. 21 and 52, East River Mountain. Road cut about 10 miles s. of Wardensville, W. Va. along unpaved road parallel to Waites Run, Great North Mountain. Road cut 3.0 miles e. of Lost City, W. Va. along W. Va. Rt. 59, Great North Mountain. Road cut 4.0 miles n. of Liberty Furnace, Va. along unpaved Liberty Furnace - Perry road. Road cut 1.0 mile w. of Cootes Store along Va. Primary Rt. 259 (Brock’s Gap). Road cut about 15 miles w. of Harrisonburg, Va. at Harrison’s Gap, along Harrisonburg - Fulks Run road. 140 Locality 165 166 167 168 169 170 171 172 173 174 175 177 178 179 180 181 182 183 184 185 186 187 188 PEABODY MUSEUM BULLETIN 34 Peabody Museum Number (A-6465) (A-6466 ) (A-6467) (A-6468) (A-6469) (A-6470) (A-6471) (A-6472) (A-6473) (A-6474) (A-6475) (A-6476) (A-6477) (A-6478) (A-6479) (A-6480) (A-6481) (A-6482) (A-6483) (A-6484) (A-6323) (A-6485) (A-6486 ) Description Road cut 0.5 mile w. of Basore, W. Va. along Basore - Ma- ; thias road. Road cut about 13 miles e. of Wardensville, W. Va. along Va. Primary Route 55, eastern limb of Great North Mountain. Road cut 3.0 miles s. of Water Lick, Va. along Va. Secondary — Rt. 678, Massanutten Mountain. Road cut about 8 miles e. of New Market, Va. along U. S. 211 (New Market Gap). Road cut about 9 miles nw. of Shenandoah, Va. along un- paved road, eastern part of Massanutten Mountain. Road cut and railroad cut at Buffalo Gap, Va. along Va. r Primary Rt. 254, Little North Mountain. Road cut 1.5 miles w. of McKinley, Va. along unpaved Mc- Kinley - Craigsville road. Road cut 7.0 miles nw. of Kerrs Creek, Va. along U. S. 60. Road cut 5.0 miles e. of junction of U. S. 60 and Va. Second- ary Rt. 770, along Va. Secondary Rt. 770, North Mountain. Road cut 0.5 mile nw. of Eagle Rock, Va. along U. S. 220 e. of the James River. Road cut 0.5 mile sw. of Eagle Rock, Va. along U. S. 220 w. of the James River. Road cut 2.0 miles e. of Catawba, Va. along Va. Primary Rt. 311, Catawba Mountain. Road cut 2.5 miles sw. of Fagg, Va. along Va. Secondary Rt. 603. Road cut 3.0 miles s. of Radford, Va. along Va. Secondary Rt. 787, Ingle Mountain. Road cut 2.0 miles s. of Poplar Hill, Va. along Va. Primary Rt. 100, Walker Mountain. Road cut 5.5 miles s. of Mechanicsburg, Va. along Va. Sec- ondary Rt. 738, Walker Mountain. Road cut 3.0 miles s. of Burkes Garden, Va. along Va. Sec- ondary Rt. 623, southeastern limb of Garden Mountain. Road cut at Gose Mill, Va. along Va. Secondary Rt. 623, northwestern limb of Garden Mountain. Road cut 1.0 mile s. of Gratton, Va. along Va. Secondary Rt. 623, Rich Mountain. Railroad cut 1.0 mile n. of McCoy, Va. along Va. Secondary Rt. 652, Walker - Gap Mountain. Road cut 2.5 miles n. of Narrows, Va. along U. S. 460, East River Mountain. Road cut 1.5 miles n. of Mountain Lake, Va. along Va. Sec- ondary Rt. 700, between Salt Pond and Doe Mountains. Road cut 3.5 miles s. of New Castle, Va. along Va. Primary Rt. 42. Locality 189 190 191 192 193 194 fo3 196 197 ogo 200 201 202 203 204 205 206 207 ORDOVICIAN APPALACHIAN ECOLOGY 141 Peabody Museum Number (A-6487 ) (A-6322) (A-6488 ) (A-6489 ) (A-6490) (A-6491) (A-6492) (A-6493) (A-6494) (A-6495 ) (A-6496 ) (A-6497) (A-6498) (A-6301 to A-6321) Description Road cut 4.0 miles s. of Paint Bank, Va. along Va. Primary Rt. 311, southern limb of Little Mountain. Road cut 2.0 miles s. of Sweet Springs, W. Va. along Va. Primary Rt. 311, Peters Mountain. Road cut 0.5 mile se. of Cliffdale, Va. along Va. Secondary Rt. 616. Road cut 11.0 miles nw. of Eagle Rock, Va. along Va. Sec- ondary Rt. 621 (or 613[?]), Rich Patch Mountain. Road cut 4.5 miles se. of Falling Spring, Va. along U. S. 220, Little Mountain. Road cut at Hot Springs, Va. paved road sw. of railroad sta- tion to Bacova Junction. Road cut 1.5 miles e. of junction of U. S. 220 and Va. Primary Rt. 39 along Va. Primary Rt. 39 e. of Warm Springs, Va. Road cut 2.0 miles n. of junction of U. S. 220 and Va. Pri- mary Rt. 39 along U. S. 220 n. of Warm Springs, Va. Road cut 0.5 mile w. of Warm Springs, Va. along Va. Primary Re 39: Road cut 2.0 miles w. of Vanderpool, Va. along Va. Primary Rt. 84, Back Creek Mountain. Road cut 0.5 mile w. of Trimble, Va. along Trimble - Mustoe road, Jack Mountain. Road cut 2.5 miles e. of Hightown, Va. along U. S. 250. Road cut 1.0 mile w. of Hightown, Va. along U. S. 250. Road cut about 12 miles w. of Franklin, W. Va. along U. S. 33, eastern limb of North Fork Mountain. Road cut 1.5 miles w. of loc. 203, west limb of North Fork Mountain. Gas line cut 1.5 miles e. of Mouth of Seneca, W. Va. Road cut 2.0 miles w. of Saumsville, Va. along Va. Secondary Rt. 600. Quarry 2.0 miles n. of Lickdale, Pa. along Pa. Rt. 72 (Swa- tara Gap). LITERATURE CITED Ager, D. V., 1963, Principles of paleoecology: New York, McGraw-Hill, 371 p. 1965, The adaptation of Mesozoic brachiopods to different environments: Palaeogeog., Palaeoclimat., Palaeoecol., v. 1, p. 143-172. Ager, D. V., R. E. Grant, D. M. McLaren and H. Schmidt, 1965, Rhynchonellida, in Moore, R. C., ed., Treatise on invertebrate paleontology, Pt. H, Brachiopoda: p. H552-H632, Law- rence, Kansas, Univ. of Kans. and Geol. Soc. America. American Geological Institute, 1960, Glossary of geology and related sciences, 2nd ed., Howell, J. V., coordinating chairman; Washington, D.C., Kaufmann, 325 p. (72 p. supplement). Atkins, D., 1960, The ciliary feeding mechanism of the Megathyridae (Brachiopoda) and the growth stages of the lophophore: Jour. Marine Biol. Assoc. U. K., v. 39, p. 459-479. Atkins, D. and M. J. S. Rudwick, 1962, The lophophore and ciliary feeding mechanisms of the brachiopod Crania anomala (Miller): Jour. Marine Biol. Assoc. U. K., v. 42, p. 469-480. Babin, C., 1966, Mollusques bivalves et cephalopodes du Paléozoique Armoricain: Brest, Impri- merie Commerciale et Administrative, 470 p. Bancroft, B. B., 1928, On the notational representation of the rib-system in Orthacea - V: Mem. and Proc. Manchester Lit. and Phil. Soc., v. 72, p. 53-90. 1945, The brachiopod zonal indices of the stages Costonian to Onnian in Britain: Jour. Paleontology, v. 19, p. 181-252. Bassler, R.S., 1909, The cement resources of Virginia, west of the Blue Ridge: Va. Geol. Survey Bull. II-A, 309 p. 1915, Bibliographic index of American Ordovician and Silurian fossils: U.S. Natl. Mus. Bull. 92, 1521 p. (2 vols.). 1919, Cambrian and Ordovician deposits of Maryland: Baltimore, Johns Hopkins and Maryland Geol. Survey, 424 p. 1953, Bryozoa, in Moore, R. C., ed., Treatise on invertebrate paleontology, Pt. C: Law- rence, Kansas, Univ. of Kans. and Geol. Soc. America, 253 p. Batten, R. L., 1958, Permian Gastropoda of the southwestern United States, 2. Pleurotomaricea: Portlockiellidae, Phymatopleuridae and Eotomariidae: Am. Mus. Nat. Hist. Bull., v. 114, p. 153-246. Bayer, T. N., 1967, Repetitive benthonic community in the Maquoketa Formation (Ordovician) of Minnesota: Jour. Paleontology, v. 41, p. 417-422. Beecher, C. E. and C. Schuchert, 1893, Development of the brachial supports in Dielasma and Zygospira: Proc. Biol. Soc. Washington, v. 8, p. 71-78. Berry, W. B. N., 1966, Zones and zones — with exemplification from the Ordovician: Am. Assoc. Petrol. Geol. Bull., v. 50, p. 1487-1500. Beushausen, L., 1895, Die Lamellibranchiaten des rheinischen Devon mit Ausschluss der Avicu- liden: Kgl. Preussischen Geol. Landesanstalt Abh., Neue Folge, no. 17, 514 p. Billings, E., 1856, Fossils of the Lower Silurian rocks of Canada: Canadian Naturalist and Geologist, v. 1, p. 39-47. 1863, The geology of Canada: Canadian Geol. Survey, Rept. of Progress to 1863, 983 p., Dawson Bros., Montreal. Boardman, R. S., 1960, A revision of the Ordovician bryozoan genera Batostoma, Anaphragma and Amplexopora: Smithsonian Misc. Coll., v. 140, 28 p. Boardman, R. S. and J. Utgaard, 1966, A revision of the Ordovician bryozoan genera Monticuli- pora, Peronopora, Heterotrypa and Dekayia: Jour. Paleontology, v. 40, p. 1082-1108. Boekschoten, G. T., 1966, Shell borings of sessile epibiontic organisms as paleoecological guides (with examples from the Dutch coast): Palaeogeog., Palaeoclimat., Palaeoecol., v. 2, p. 333- 379. 142 ; 7 * ‘ ‘ ‘ ee ORDOVICIAN APPALACHIAN ECOLOGY 143 Boucot, A. J., J. G. Johnson, C. W. Pitrat and R- D. Staton, 1965, Spiriferida, in Moore, R. C., ed., Treatise on invertebrate paleontology, Pt. H, Brachiopoda: p. H632-H728, Lawrence, Kans., Univ. of Kans. and Geol. Soc. America. Boucot, A. J. and J. M. Saul, 1963, Gastropoda in Saul, J. M., A. J. Boucot and R. M. Finks, Fauna of the Accraian series (Devonian of Ghana) including a revision of the gastropod Plectonotus: Jour. Paleontology, v. 37, p. 1042-1053. Boucot, A. J. and E. L. Yochelson, 1966, Paleozoic Gastropoda from the Moose River synclino- rium, northern Maine — Contributions to paleontology: U.S. Geol. Survey Prof. Paper 503-A, 20 p. Bowsher, A. L., 1955, Origin and adaptation of platyceratid gastropods: Univ. Kansas Paleo. Contr., Mollusca, art. 5, p. 1-11. Bretsky, P. W., 1969, Ordovician benthic marine communities in the central Appalachians: Geol. Soc. Am. Bull., v. 80, p. 193-212. Bretsky, P. W., K. W. Flessa and S. S. Bretsky, 1969, Brachiopod ecology in the Ordivician of eastern Pennsylvania: Jour. Paleontology, v. 43, p. 312-321. Brown, G. D., 1965, Trepostomatous Bryozoa from the Logana and Jessamine Limestones (Mid- dle Ordovician) of the Kentucky bluegrass region: Jour. Paleontology, v. 39, p. 974-1006. Bruevitch, S. V. and E. D. Saitzeva, 1958, On the chemistry of the Bering Sea sediments; Papers Inst. Ocean., v. 26, p. 8-108. Bushinski, G. I., 1964, On the shallow water origin of phosphorite sediments in van Straaten, L. M. J. U., ed., Deltaic and shallow marine deposits: p. 62-70, Amsterdam, Elsevier. Butts, C., 1933, Geologic map of the Appalachian valley of Virginia with explanatory text: Va. Geol. Survey Bull. 42, 56 p. 1940, Geology of the Appalachian valley in Virginia, Pt. I — Geologic text with illus- trations: Va. Geol. Survey Bull. 52, 568 p. 1941, Geology of the Appalachian valley in Virginia, Pt. II — Fossil plates and explana- tions: Va. Geol. Survey Bull. 52, 271 p. 1945, Geologic atlas of the United States - Hollidaysburg and Huntington Quadrangles: U.S. Geol. Survey Geol. Atlas, Folio 227. Butts, C., F. M. Swartz and B. Willard, 1939, Atlas of Pennsylvania - Tyrone Quadrangle: Pa. Topographic and Geol. Survey Atlas 96, 118 p. Calver, J. L., 1963, Geologic map of Virginia: Va. Dept. Conservation and Economic Devel. and Div. of Mineral Resources. Carey, A. G., 1965, Preliminary studies on animal-sediment interrelations off the central Oregon coast: Ocean Science and Ocean Engineering, v. 1, p. 100-110. Chuang, S. H., 1956, The ciliary feeding mechanisms of Lingula unguis (L.) (Brachiopoda) : Proc. Zool. Soc. London, v. 127, p. 167-189. P Clarke, G. L., 1954, Elements of ecology: New York, J. Wiley, 560 p. Clarke, J. M., 1899, The Paleozoic faunas of Para, Brazil, Author’s English Edition (1900), Archives do Museu Nacional do Rio de Janeiro, v. 10 [not seen]. Clarke, J. M. and R. Ruedemann, 1903, Catalogue of type specimens of Paleozoic fossils in New York State Museum: N. Y. St. Mus. Bull. 65, 847 p. Cloos, E., 1941, Geologic map of Washington County, Maryland: Maryland Geol. Survey. Conrad, T. A., 1838, Report on the paleontological department: State of N. Y., Assembly Doc. No. 200, 1838, Communications relative to the Geological Survey, p. 107-119. 1839, Report on the paleontological department: State of N. Y., Assembly Doc. No. 275, 1839, Communications relative to the Geological Survey, p. 57-66. 1840, Third annual report on the paleontological department of the survey: N. Y. Geol. Survey, Ann. Rept. 4, p. 199-207. 1841, Fifth annual report on the paleontology of the State of New York; State of N. Y., Assembly Doc. No. 150, 1841, Communications relative to the Geological Survey, p. 25-57. 1842, Observations on the Silurian and Devonian systems of the United States with descriptions of new organic remains: Jour. Acad. Nat. Sci. Philadelphia, v. 8, p. 228-280. Cooper, G. A., 1942, New genera of North America brachiopods: Jour. Washington Acad. Sci., v. 32, p. 228-235. 1944, Phylum Brachiopoda, in Shimer, H. W. and R. R. Shrock, eds., Index fossils of North America: p. 277-365, New York, J. Wiley. 1956, Chazyan and related brachiopods: Smithsonian Misc. Coll., v. 127, Pt. I text; Pt. II plates, 1042 p. 269 pls. 1959, Genera of Tertiary and Recent Rhynchonelloid brachiopods: Smithsonian Misc. Coll., v. 139, 90 p. 22 pls. Copper, P., 1966, Ecological distribution of Devonian atrypid brachiopods: Palaeogeog., Palaeo- climat., Palaeoecol., v. 2, p. 245-266. 144 PEABODY MUSEUM BULLETIN 34 Cox, L. R. and J. B. Knight, 1960, ?Archaeogastropoda — Suborder Murchisoniina, in Moore, R. C., ed., Treatise on invertebrate Paleontology, Pt. 1, Mollusca I: p. 1290-1296, Lawrence, Kansas, Univ. of Kans. and Geol. Soc. America. Craig, G. Y., 1952, A comparative study of the ecology and paleoecology of Lingula: Trans. Edinburgh Geol. Soc., v. 15, p. 110-120. Craig, G. Y. and N. S. Jones, 1966, Marine benthos, substrate and paleoecology: Palaeontology, v. 9, p. 30-38. Crickmay, C. H., 1966, The external apical cavity of Strophomenacea brachiopods: Canadian Jour. Earth Sciences, v. 3, p. 499-508. Cumings, E. R., 1908, The stratigraphy and paleontology of the Cincinnati series of Indiana: In- diana Dept. Geol. and Nat. Resources, Annual Rept. 32, p. 605-1189. Cumings, E. R. and J. J. Galloway, 1913, The stratigraphy and paleontology of the Tanner's Creek section of the Cincinnati series of Indiana: Indiana Dept. Geol. and Nat. Resources, Ann. Rept. 37, p. 353-479. 1915, Studies on the morphology and histology of the Trepostomata or monticuliporids: Geol. Soc. America Bull., v. 26, p. 349-374. d’Anglejan-Chatillon, B. F., 1965, The marine phosphorite deposit of Baja, California, Mexico: Present environment and recent history: Univ. of Calif., Scripps, Ph.D. Thesis, 195 p. 1967, Origin of marine phosphorites off Baja, California, Mexico: Marine Geology, v. 5, p. 15-44. Davids, C., 1964, The influence of suspensions of microorganisms of different concentrations on the pumping and retention of food by the mussel (Mytilus edulis, L.): Netherlands Jour. Sea Research, v. 4, p. 233-249. Dennison, J. M., 1961, Stratigraphy of Onesquethaw Stage of Devonian in West Virginia and bordering states: West Va. Geol. Survey Bull. 22, 87 p. DuBois, H. M., 1916, Variation induced in brachiopods by environmental conditions: Pub. Puget Sound Marine Station, v. 1, p. 177-183. Durham, J. W., 1950, Cenozoic marine climates of the Pacific coast: Geol. Soc. America Bull., v. 61, p. 1243-1264. Elias, M. K., 1937, Depth of deposition of the Big Blue (Late Paleozoic) sediments in Kansas: Geol. Soc. America Bull., v. 48, p. 403-432. Elliott, G. F., 1965, Order Uncertain — Thecideidina, in Moore, R. C., ed., Treatise on inverte- brate paleontology, Pt. H, Brachiopoda: p. H857—H864, Lawrence, Kansas, Univ. of Kans. and Geol. Soc. America. Emery, K. O. and J. Hulsemann, 1962, The relationships of sediments, life and water in a marine basin: Deep-Sea Research, v. 8, p. 165-180. Emmons, E., 1842, Survey of the Second Geological District, Pt. II, Geology of New York: N.Y. Nat. Hist. Survey, Albany, 437 p. 1855, The Taconic system, in American Geology, v. 1, pt. II, 251 p. Fager, E. W., 1963, Communities of organisms in Hill, M. N., ed., The Sea, v. 2: p. 415-437, New York, Wiley-Interscience. Fitch, J. E., 1953, Common marine bivalves of California: Dept. of Fish and Game, Marine Fisheries Branch State of California, Fisheries Bull. 90, 102 p. Foerste, A. F., 1909, Preliminary notes on Cincinnatian fossils: Denison Univ. Sci. Lab. Bull., v. 14, p. 209-228. 1910, Preliminary notes on Cincinnatian and Lexington fossils of Ohio, Indiana, Ken- tucky and Tennessee: Denison, Univ. Sci. Lab. Bull., v. 16, p. 17-87. 1912, Strophomena and other fossils from Cincinnatian and Mohawkian horizons, chiefly in Ohio, Indiana and Kentucky: Denison Univ. Sci. Lab. Bull., v. 17, p. 17-174. 1914a, Notes on the Lorraine faunas of New York and The Province of Quebec: Denison Univ. Sci. Lab. Bull., v. 17, p. 247-340. 1914b, The Rogers Gap fauna of central Kentucky: Jour. Cincinnati Soc. Nat. Hist., v. 21, p. 109-156. 1924, Upper Ordovician faunas of Ontario and Quebec: Geol. Survey Canada Mem. 138, 255 p. Ford, J. P., 1965, Bedrock geology in southwestern Hamilton County, Ohio: Ohio State Univ, Ph.D. Thesis, 101 p. 1967, Cincinnatian geology in southwest Hamilton County, Ohio: Am. Assoc. Petrol. Geol. Bull., v. 51, p. 918-936. Grabau, A. W., 1913, Early Paleozoic delta deposits of North America: Geol. Soc. America Bull., v. 24, p. 399-528. ——— xxx CLC ORDOVICIAN APPALACHIAN ECOLOGY 145 Graham, A., 1949, The molluscan stomach: Trans. Roy. Soc. Edinburgh, v. 61, p. 144-159. 1955, Molluscan diets: Proc. Malacological Soc. London, v. 31, p. 144-159. Gray, C., 1960, Geologic map of Pennsylvania: Pa. Topog. and Geol. Survey. Gutsell, J. S., 1931, Natural history of the bay scallop: Bur. Fisheries Bull., v. 46 (1930) ; Bur. Fisheries Doc. 1100, p. 569-632. H._ 1, C. A., 1964, Shallow water marine climates and molluscan provinces: Ecology, v. 45, p. 226-234. Hall, D. D., 1962, Dalmanellidae of the Cincinnatian: Palaeontographica Americana, v. 4, p. 131-165. Hall, J., 1847, Natural History of New York — Paleontology of New York: New York Geol. Sur- vey, v. 1, 338 p. 1852, Paleontology of New York, v. II, Containing descriptions of the organic remains of the lower middle division of the New York System: C. Van Benthuysen, Albany, 362 p. 1856, On the genus Tellinomya and allied genera: Canadian Naturalist and Geologist, v. 1, p. 390-395. 1857a, On the genus Tellinomya and allied genera: 10th Ann. Rept. of the Regents of the Univ. of the St. of N.Y. on the condition of the State cabinet of Nat. Hist., N.Y. Senate No. 109, p. 181-186. 1857b, On the genus Tellinomya and allied genera, in Descriptions of new species of Paleozoic fossils, etc., extracted from 10th Ann. Rept. of Regents of the Univ. of the St. of N.Y. p. 141-146. 1857c, Descriptions of Paleozoic fossils: N.Y. St. Cabinet of Nat. Hist., Ann. Rept. 10, p. 39-180. 1859a, Notice of the genera Ambonychia, Palaearca and Megambonia: 12th Ann. Rept. of the Regents of the Univ. of the St. of N.Y. on the condition of the State cabinet of Nat. Hist., N.Y. Assembly No. 186, p. 8-14 [Supplementary note on the genus Ambonychia, p. 110]. 1859b, Paleontology, v. III, containing descriptions and figures of the organic remains of the lower Helderberg group and the Oriskany sandstone: Geol. Survey N.Y., Nat. Hist. of N.Y., Albany, C. Van Benthuysen, [text, pt. 1, 1859, 533 p.; plates, pt. 2, 1861, 120 pls.]. 1861, Descriptions of new species of fossils from the investigations of the survey: Geol. Survey Wisc., Rept. of the Superintendent, Jan. 1, 1861, p. 11-52. 1862a, Observations upon a new genus of Brachiopoda: 15th. Annual Report of the Regents of the Univ. of the St. of N.Y. on the condition of the State cabinet of Nat. Hist., N.Y. Senate No. 116, p. 154-155. 1862b, Physical geography and general geology; Remarks upon the condition of the fossils, etc., in Hall, J. and J. D. Whitney, Rept. Geol. Survey Wisc., v. 1, p. 1-72, 425-448. 1867, Observations on genera of Brachiopoda: N.Y. St. Cabinet Nat. Hist., Ann. Rept. 20, p. 241-281. 1872, Description of new species of fossils from the Hudson River group, in the vicinity of Cincinnati, Ohio: N.Y. St. Mus., 24th Ann. Rept. on the condition of the State cabinet of Nat. Hist., p. 225-232 [Advance printing in 1871]. 1883, Brachiopoda, plates and explanations: Rept. of the State Geologist for the year 1882, pls. 34-61. Hall, J. M., and J. M. Clarke, 1892, An introduction to the study of the genera of Paleozoic Bra- chiopoda: Paleontology of New York, v. 8, pt. 1, 367 p. pls. 1-20. 1893, 1895 (1894), An introduction to the study of the genera of Paleozoic Brachiopoda: Paleontology of New York, v. 8, pt. 2, p. 1-317 (1893) ; p. 319-394, pls. 21-84 (1895). Hall, J. M. and R. P. Whitfield, 1875, Descriptions of invertebrate fossils, mainly from the Silurian System: Geol. Survey Ohio, v. 2, pt. 2, p. 67-179. Hallam, A., 1965, Environmental causes of stunting in living and fossil marine benthonic inverte- brates: Palaeontology, v. 8, p. 132-155. Hatai, K., 1940, On some Recent Brachiopoda from Seto, Province Kii: Rec. Oceanog. Wks. Japan, v. 10, p. 100-111. Hedgpeth, J. W., 1957, Classification of marine environments, in Hedgpeth, J. W., ed., Treatise on Marine Ecology and Paleoecology: Geol. Soc. America Mem. 67, v. 1, p. 17-27. Hertlein, L. and U. S. Grant IV, 1944, The Cenozoic Brachiopoda of western North America: Publ. Univ. Calif. Los Angeles, Math. and Physical Sciences, v. 3, 236 p. Hornell, J., 1909, Marine zoology of Okhamandel in Kattiawar, Pt. I: London, Williams and Norgate, 148 p. Horowitz, D. H., 1965, Petrology of the Upper Ordovician and Lower Silurian rocks in central Pennsylvania: Pa. State Univ., Ph.D. Thesis, 214 p. 146 PEABODY MUSEUM BULLETIN 34 1966, Evidence for deltaic origin of an Upper Ordovician sequence in the central A palachians, in Shirley, M. L. and J. A. Ragsdale, eds., Deltas in their geologic framework: p 159-169, Houston, Houston Geol. Soc. Howe, H. J. and A. Reso, 1967, Upper Ordovician brachiopods from the Ely Springs Dolomite in southeastern Nevada: Jour. Paleontology, v. 41, p. 351-363. Hutchins, L. W., 1947, The bases for temperature zonation in geographical distribution: Ecologi- cal Monographs, v. 17, p. 325-335. Hyman, L., 1959, Smaller coelomate groups, in The Invertebrates: v. 5, New York, McGraw- Hill, 783 p. Hynd, J. S., 1955, A revision of the Australian pearl shells, genus Pinctada (Lamellibranchia) : Australian Jour. Marine and Freshwater Research, v. 6, p. 98-137. 1960, An analysis of variation in Australian specimens of Pinctada albina (Lamarck) (Lamellibranchia) : Australia Jour. Marine and Freshwater Research, v. 11, p. 326-364. Ingram, R. L., 1954, Terminology for the thickness of stratification and parting units in sedimen- tary rocks: Geol. Soc. America Bull., v. 65, p. 937-938. Irving, E., 1964, Paleomagnetism and its application to geological and geophysical problems: New York, J. Wiley, 399 p. Isberg, O., 1934, Studien iiber lamellibranchiaten des Leptaenakalkes in Dalerna: Lund, Hakan Ohlssons Buchdruckerei, 492 p. James, U. P., 1871, Catalogue of Lower Silurian fossils, Cincinnati group: Cincinnati, 14 p. 1874a, Descriptions of one new species of Leptaena, and two species of Cyclonema from the Lower Silurian rocks, Cincinnati group: Cincinnati Quart. Jour. Sci., v. 1, p. 151-154. © 1874b, Descriptions of new species of Brachiopoda from the Lower Silurian formation, Cincinnati group: Cincinnati Quart. Jour. Sci., v. 1, p. 333-335. 1878, Descriptions of newly discovered species of fossils from the Lower Silurian Forma- tion — Cincinnati group: The Paleontologist, no. 1, p. 1-8. 1881, Contributions to paleontology: Fossils of the Lower Silurian Formation: Ohio, Indiana and Kentucky: The Paleontologist, no. 5, p. 33-44. Johnson, R. G., 1962, Interspecific associations in Pennsylvanian fossil assemblages: Jour. Geol., v. 70, p. 32-55. Jones, N. S., 1950, Marine bottom communities: Biol. Reviews, v. 25, p. 283-313 . Jones, O. T., 1928, Plectambonites and some allied genera: Geol. Soc. Great Britain Mem., v. 1, p. 367-527. Jorgensen, C. B., 1966, Biology of suspension feeding: Oxford, Pergamon Press, 357 p. Keen, M., 1958, Sea shells of tropical west America: Stanford, Calif., Stanford Univ. Press, 624 p. King, P. B., 1959, The evolution of North America: Princeton, N. J., Princeton Univ., 189 p. Kinne, O., 1963, The effects of temperature and salinity on marine and brackish water animals — I. Temperature, in Barnes, H., ed., Oceanography and marine biology: An annual review: v. 1, p. 301-340, London, Allen and Unwin. i Knight, J. B., 1941, Paleozoic gastropod genotypes: Geol. Soc. America Sp. Paper 32, 510 p. Knight, J. B., et al., 1960, Mollusca 1, in Moore, R. C., ed., Treatise on invertebrate paleontol- ogy, Pt. I: Lawrence, Kansas, Univ. of Kans. and Geol. Soc. America, 351 p. Krumbein, W. C., and L. L. Sloss, 1963, Stratigraphy and sedimentation: San Francisco, Freeman, 660 p. Krynine, P. D., 1960, Sedimentation near University Park (State College): University Park, N.S.F. summer conferences on stratigraphy and structure of the Appalachians. Kuderskii, L. A., 1962, Benthic community of Modiolus modiolus from Onega Bay of the White Sea: Trudy Kael’sk Fil. Akad. Nank. SSSR, v. 33, p. 67-81. Lagaaij, R. and Y. V. Gautier, 1965, Bryozoa from the Rhone delta: Micropaleontology, v. 11, p. 39-58. Laporte, L., 1967, Carbonate deposition near mean sea-level and resultant facies mosaic: Manlius Formation (Lower Devonian) of New York State: Am. Assoc. Petrol. Geol. Bull., v. 51, p. 73-101. Lesley, J. P., 1889-1890, A dictionary of the fossils of Pennsylvania and neighboring states, 3 vols. : Geol. Survey Penns., Rept. P-4, 1283 p. [v. 1, A-M, 1889; v. 2, N-R, 1889; v. 3, S-Z, 1890). Logan, W. E., et al., 1863, Geology of Canada: Geol. Survey of Canada, Rept. of progress from its commencement to 1863, etc., Montreal, Dawson Bros., 983 p. McAlester, A. L., 1963, Revision of the type species of the Ordovician nuculoid pelecypod genus Tancrediopsis: Yale Peabody Museum, Postilla 74, 19 p. ————— 1964, Preliminary suggestions for a classification of nuculoid bivalves: Jour. Paleontology, v. 38, p. 397-400. ORDOVICIAN APPALACHIAN ECOLOGY 147 1968, Type-species of Paleozoic nuculoid bivalve genera: Geol. Soc. America Mem. 105, 143 p. ’ McBride, E. F., 1960, Martinsburg flysch: Johns Hopkins Univ., Ph.D. Thesis, 324 p. 1962, Flysch and associated beds of the Martinsburg Formation (Ordovician), central Appalachians: Jour. Sed. Petrology, v. 32, p. 39-91. McCoy, F., 1854, Description of the British Paleozoic fossils in the Geological Museum of the Univ. of Cambridge, in Sedgwick, A. and F. McCoy, British Paleozoic rocks and fossils, 644 p. McKee, E. D., and G. W. Wier, 1953, Terminology for stratification and cross-stratification in sedimentary rocks: Geol. Soc. Am. Bull., v. 64, p. 381-389. Mather, K. F., 1917, The Trenton fauna of the Wolfe Island, Ontario: Ottawa Naturalist, v. 31, p. 33-40. Mattox, N., 1955, Observations on the brachiopod communities near Santa Catalina Island: Essays in the natural sciences in honor of Capt. Allan Hancock: p. 73-86, Los Angeles, Univ. Southern Calif. Press. Meek, F. B., 1873, Descriptions of invertebrate fossils of the Silurian and Devonian Systems: Rept. Geol. Survey Ohio, v. 1, pt. 2, p. 1-243. Miller, S. A., 1875, Monograph of the class Brachiopoda of the Cincinnati group: Cincinnati Quart. Jour. Sci., v. 2, p. 6-62. Miller, S. A., and C. L. Faber, 1894, New species of fossils from the Hudson River Group and remarks upon others: Jour. Cincinnati Soc. Nat. Hist., v. 17, p. 22-33. Morse, E., 1902, Observations on living Brachiopoda: Boston Soc. Nat. Hist. Mem., v. 5, p. 313-386. Muir-Wood, H. and A. Williams, 1965, Strophomenida, in Moore, R. C., ed., Treatise on inverte- brate paleontology, Pt. H, Brachiopoda: p. H361—H521, Lawrence, Kans., Univ. of Kans. and Geol. Soc. America. Nettleroth, H., 1889, Kentucky fossil shells; a monograph of the fossil shells of the Silurian and Devonian rocks of Kentucky: Ky. Geol. Survey, Frankfort, 245 p. Newell, N. D., 1937, Late Paleozoic pelecypods: Pectinacea: Kansas Geol. Survey, v. 10 (text), 123 p. 1965, Classification of the Bivalvia: Am. Mus. Nat. Hist. Novitates 2206, 25 p. Newell, N. D., J. Imbrie, E. Purdy and D. Thurber, 1959, Organism communities and bottom facies, Great Bahama Bank: Am. Mus. Nat. Hist. Bull., v. 117, p. 183-228. Newell, N. D., et al., 1969, Mollusca 6, in Moore, R. C., ed., Treatise on invertebrate paleontology, Pt. N: Lawrence, Kansas, Univ. of Kans. and Geol. Soc. America, 951 p. (2 vols. ). Nicholson, H. A., 1875, Report upon the paleontology of the Province of Ontario: Toronto, 96 p. Opdyke, N. D., 1962, Paleoclimatology and continental drift in Runcorn, S. K., ed., Continental drift: Chap. 2, p. 41-65, New York, Academic Press. Opik, A., 1933, Uber einige Dalmanellacea aus Eastland: Acta et Comment. Univ. Tarta, Ser. A, v. 25, p. 1-25. Owen, D. D., 1844, Review of the New York Geological Reports: Am. Jour. Sci. Art, v. 48, p. 354-380. Parker, R. H., 1960, Ecology and distributional patterns of marine macroinvertebrates, northern Gulf of Mexico, in Shepard, F. P., ed., Recent sediments, northwest Gulf of Mexico: p. 302- 337, Tulsa, Oklahoma, Am. Assoc. Petrol. Geol. Parks, W. A., and W. S. Dyer, 1922, The stratigraphy and paleontology of Toronto and vicinity, Pt. II Molluscoidea: 30th. Ann. Rept. Ontario Dept. Mines (1921), v. 30, pt. 7, 58 p. Peck, J. H., 1966, Upper Ordovician formations in the Maysville area, Kentucky: U. S. Geol. Survey Bull. 1244-B, 30 p. Petersen, C. G., 1914, On the distribution of the animal communities of the sea bottom: Rept. Danish Biol. Station, v. 22, 7 p. Pierce, K. L., 1966, Bedrock and surficial geology of the McConnellsburg quadrangle, Pennsy]l- vania: Pa. Topog. and Geol. Sur., 4th. Ser., Atlas 109a, 111 p. Pojeta, J., 1962, The pelecypod genus Byssonychia as it occurs in the Cincinnatian at Cincinnati, Ohio: Palaeontographica Americana, v. 4, p. 169-216. 1966, North American Ambonychiidae (Pelecypoda) ; Palaeontographica Americana, v. 5, p. 131-241. Purdy, E. G., 1964, Sediments as substrates, in Newell, N. D. and J. Imbrie, eds., Approaches to paleoecology: p. 238-271, New York, J. Wiley. Rader, E. K. and J. J. Ryan, 1965, Martinsburg Formation in west-central Virginia: Va. Minerals, v. 11, p. 32-34. 148 PEABODY MUSEUM BULLETIN 34 Raymond, P. E., 1921, A contribution to the description of the fauna of the Trenton Group: Dept of Mines and Geol. Survey Canada, Mus. Bull. 31 (Geol. Ser. 38), 64 p. Read, K. R. H., 1964, Comparative biochemistry of adaptations of poikilotherms to the the environment: Symposium on experimental marine ecology, Occas. Pub. 2, p. 39-47. Reed, F. R. C., 1920, A monograph of the British Ordovician and Silurian Bellerophontacea, I: Palaeontographical Soc. London (1918), 48 p. Remy, P., 1928, Materiaux zoologiques recoltés dans les mers arctiques: Ann. Sci. Nat. Zool., Sér. 10, v. 11, p. 209-243. Rodgers, J., 1953, Geologic map of east Tennessee with explanatory text: Tenn. Div. Geol. Bull. 58, Pt. 1 maps: Pt. 2, text, 168 p. Ross, J. P., 1963, The bryozoan trepostome Batostoma in Chazyan (Ordovician) strata: Jour. Paleontology, v. 37, p. 857-866. Rudwick, M. J. S., 1962, Filter-feeding mechanisms in some brachiopods from New England: Jour. Linnean Soc. London, v. 44, p. 592-615. 1964, The function of the zigzag deflections in the commissures of fossil brachiopods: — Palaeontology, v. 7, p. 135-171. 5 1965, Ecology and paleoecology, in Moore, R. C., ed., Treatise in invertebrate paleontol- ‘ ogy, Pt. H, Brachiopoda: p. H119-H214, Lawrence, Kansas, Univ. of Kans. and Geol. Soc. America. Ruedemann, R., 1901, Trenton Conglomerate of Rysedorph Hill Rensselaer County, New York, and its fauna: N.Y. St. Mus. Bull. 49, Paleontology Pap. 2, 114 p. 1912, The Lower Siluric shales of the Mohawk valley: N.Y. St. Mus. Bull. 162, 151 p. 1925a, The Utica and Lorraine Formations of New York, Pt. 1 — Stratigraphy: N.Y. St. Mus. Bull. 258, 175 p. 1925b, The Utica and Lorraine Formations of New York, Pt. 2 — Systematic paleontol- ogy 1. Plants, sponges, corals, graptolites, crinoids, worms, bryozans and brachiopods: N.Y. St. Mus. Bull. 262, 171 p. 1926, The Utica and Lorraine Formations of New York, Pt. 2 — Systematic paleontology 2. Mollusks, crustaceans and eurypterids: N.Y. St. Mus. Bull. 272, 227 p. Salmon, E. S., 1942, Mohawkian Rafinesquinae: Jour. Paleontology, v. 16, p. 564-603. Salter, J. W., 1859, Canadian organic remains: Geol. Survey Canada, dec. 1, 47 p. Sanders, H. L., 1956, The biology of marine bottom communities, in Oceanography of Long Island Sound, 1952-1954: Bingham Oceanog. Collection, v. 15, p. 345-414. 1958, Benthic studies in Buzzards Bay I: Animal-sediment relationships: Limnology and Oceanog,, v. 3, p. 245-258. 1960, Benthic studies in Buzzards Bay III: The Structure of the soft-bottom community: Limnology and Oceanog., v. 5, p. 138-153. Sardeson, F. W., 1897, The Galena and Maquoketa series, Pt. III, on Orthis testudinaria: Am. Geologist, v. 19, p. 91-111. 1924, Habit of an Ordovici pelecypod: Pan-American Geol., v. 42, p. 345-356. Savilov, A. I., 1959, Biological aspects of bottom fauna grouping in the north Okhotsh Sea, in Nikitin, B. N., ed., Marine biology: p. 67-136, Washington, D. C., American Inst. Biol. Sci. Schuchert, C., 1893, On the development of the shell of Zygospira recurvirostra: Proc. Biol. Soc. Washington, v. 8, p. 79-82. Schuchert, C. and G. A. Cooper, 1932, Brachiopod genera of the suborders Orthidea and Penta- meroidea: Peabody Mus. Nat. Hist. Mem. 4, 270 p. Secrist, M. H. and W. R. Evitt, 1943, The paleontology and stratigraphy of the upper Martins- burg Formation of Massanutten Mountain, Virginia: Jour. Wash. Acad. Sci., v. 33, p. 358-368. Shaler, N. S., 1876, On the fossil brachiopods of the Ohio Valley: Kentucky Geol. Survey, Mem. 1, pt. 3, 44 p. Sowerby, J. deC., 1839, Chap. 46, Shells of the Lower Silurian rocks, in Murchison, R.I., The Silurian system, p. 634-644, J. Murray, London. Sparck, R., 1937, The benthonic animal communities of the coastal waters: The Zoology of Iceland, v. 1, 45 p. Speden, I. G., 1966, Paleoecology and the study of fossil benthonic assemblages and communities: New Zealand Jour. Geol. and Geophys., v. 9, p. 408-423. Spjeldnaes, N., 1960, Ordovician climatic zones: Norsk. Geol. Tidsskr., v. 41, p. 45-77. Stach, L. W., 1936, Correlation of zoarial form with habitat: Jour. Geol., v. 44, p. 60-65. Stevens, C. H., 1966, Paleoecological implications of early Permian fossil communities in eastern Nevada and western Utah: Geol. Soc. America Bull., v. 77, p. 1121-1130. Stewart, B. H., 1920, The stratigraphy and paleontology of Toronto and vicinity, Pt. 1, Pelecy- poda: 29th Ann. Rept. Ontario Dept. Mines, v. 28, 58 p. ORDOVICIAN APPALACHIAN ECOLOGY 149 Stoliczka, F., 1870-1871, Cretaceous fauna of southern India, the Pelecypoda: Geol. Survey India, Palaeontologia Indica, Memoir, v. 3, ser. 6, 537 p. Stose, G. W., 1932, Geologic map of West Virginia: W. Va. Geol. Survey. Sutton, R. G., Z. P. Bowen and A. L. McAlester, 1966, Multiple-approach environmental study of the Upper Devonian Sonyea Group of New York: Geol. Soc. America New Orleans Ann. Meeting (1966), p. 214 (abs.). Swartz, F. M., 1948, General characters of the Paleozoic sediments from western to central Penn- sylvania and to western New York, in Field conference northern portion of the Appalachian basin: p. 91-115, Pittsburgh Geol. Soc. Guidebook (1948). 1955, Description of the Paleozoic sediments in western and central Pennsylvania, in Field Guidebook of Appalachian geology, Pittsburgh to New York: p. 70-86, Pittsburgh Geol. Soc. Guidebook (1955). Thompson, A. M., 1967, Facies succession in a marine-continental transition in the Upper Ordovi- cian of central Pennsylvania: Geol. Soc. America Northeast Section Meeting (1967), p. 61 (abs. ). Thorson, G., 1957,-Bottom communities (sublittoral or shallow shelf), in Hedgpeth, J. W., ed., Treatise on marine ecology and paleoecology: Geol. Soc. America Mem. 67, v. 1, p. 461-534. Twenhofel, W. H., 1927, Geology of Anticosti Island: Canadian Geol. Survey, Mem. 154, 481 p. Twenhofel, W. H., et al., 1954, Correlation of the Ordovician formations of North America: Geol. Soc. America Bull., v. 65, p. 247-298. Ulrich, E. O., 1879, Descriptions of new genera and species of fossils from the Lower Silurian about Cincinnati: Jour. Cincinnati Soc. Nat. Hist., v. 2, p. 8-30. 1890, New Lamellibranchiata — 2, On two new genera and six new species: Am. Geol., v. 6, p. 173-181. 1892, New Lower Silurian Lamellibranchiata chiefly from Minnesota rocks: Minn. Geol. Nat. Hist. Survey, 19th Rept., p. 211-248. 1893, (1895), New and little known Lamellibranchiata from the Lower Silurian rocks of Ohio and adjacent states: Rept. Ohio Geol. Survey, v. 7, chap. 7, p. 627-693. Ulrich, E. O., 1894, (1897), The Lower Silurian Lamellibranchiata of Minnesota: Geol. of Minn., v. 3, pt. 2 of the Final Rept., chap. 6, p. 475-628. 1911, Revision of the Paleozoic systems: Geol. Soc. America Bull., v. 22, p. 281-680. — 1913, The Ordovician-Silurian boundary: Inter. Geol. Congress XII, p. 593-667. 1924, Modiodesma new genus, and the genotype of Modiolopsis Hall: Geol. Survey Canada Mem. 138, p. 183-190. Ulrich, E. O. and W. H. Scofield, 1897, The Lower Silurian Gastropoda of Minnesota: Geol. of Minn., v. 3, pt. 2 of the Final Rept., chap. 10, p. 813-1081. Utgaard, J. and T. G. Perry, 1964, Trepostomatous bryozoan fauna of the upper part of the Whitewater Formation (Cincinnatian) of eastern Indiana and western Ohio: Ind. Dept. of Conservation Geol. Survey Bull. 33, 111 p. Valentine, J. W., 1961, Paleoecologic molluscan geography of the California Pleistocene: Univ. of Calif. Pub. in Geol. Sci., v. 34, p. 309-442. Vanuxem, L., 1842, Geology of New York, Pt. III, comprising the survey of the third geological district: Albany, 306 p. Walcott, C. D., 1884, Paleontology of Eureka district [Nevada]: U.S. Geol. Survey Mon. 8, 298 p. Weller, S., 1903, Report on Paleontology, v. III, The Paleozoic faunas: Geol. Survey New Jersey, 462 p., J. L. Murphy Pub. Co., Trenton, N. J. Wentworth, C. K., 1922, A scale of grade and class terms for clastic sediments: Jour. Geol., v. 30, p. 377-392. Whitfield, R. P. and E. O. Hovey, 1898-1901, Catalogue of the types and figured specimens in the paleontological collection of the geological department, American Museum of Natural His- tory: Am. Mus. Nat. Hist. Bull. 11, 500 p. Whittington, H. B., 1938, New Caradocian brachiopods from the Berwyn Hills, North Wales: Ann. Mag. Nat. Hist., v. 2, p. 241-259. 1966, Phylogeny and distrbiution of Ordovician trilobites: Jour. Paleontology, v. 40, p. 696-737. Willard, B., 1943, Ordovician clastic sedimentary rocks in Pennsylvania: Geol. Soc. Am. Bull., v. 54, p. 1067-1121. Williams, A., 1953, The classification of the strophomenid brachiopods: Jour. Wash. Acad. Sci., v. 43, p. 1-13. 1962, The Barr and Lower Ardmillan Series (Caradoc) of the Girvan district, south-west Ayrshire, with descriptions of the brachiopods: Geol. Soc. London Mem. 3, 267 p. 150 PEABODY MUSEUM BULLETIN 34 Williams, A. and A. D. Wright, 1963, The classification of the “Orthis testudinaria Dalman” Group of brachiopods: Jour. Paleontology, v. 37, p. 1-32. 1965, Orthida, in Moore, R. C., ed., Treatise on invertebrate paleontology, Pt. H., Bra- chiopoda: p. H299-H359, Lawrence, Kans., Univ. of Kans. and Geol. Soc. America. Williams, A., et al., 1965, Brachiopoda, in Moore, R. C., ed., Treatise on invertebrate paleontol- ogy, Pt. H: Lawrence, Kans., Univ. of Kans. and Geol. Soc. America, 927 p. (2 vols.). Wilson, A. E., 1951, Gastropoda and Conularida of the Ottawa Formation of the Ottawa — St. Lawrence lowland: Geol. Sur. Canada Bull. 17, 149 p. 1956, Pelecypoda of the Ottawa Formation of the Ottawa — St. Lawrence lowland: Geol. Sur. Canada Bull. 28, 102 p. Wilson, C. W., 1948, The geology of Nashville, Tennessee: Tenn. Dept. of Conservation, Div. of Geol., Bull. 53, 172 p. 1949, Pre-Chattanooga stratigraphy in central Tennessee: Tenn. Div. Geol. Bull. 56, 347 p. Wilson, D. P., 1952, The influence of the nature of the substratum on the metamorphosis of the larvae of marine animals, especially the larvae of Ophelia bicornis Savigny: Ann. de I’Instit. Oceanog., v. 27, p. 49-156. Winchell, N. H. and C. Schuchert, 1895, The Lower Silurian Brachiopoda of Minnesota: Geol. of Minn., v. 3, pt. 1 of the Final Rept., Paleontology, chap. 5, p. 333-474. Woodring, W. P., M. N. Bramlette and W. S. W. Kew, 1946, Geology and paleontology of the Palos Verdes Hills, California: U.S. Geol. Survey Prof. Pap. 207, 145 p. Woodward, H. P., 1951, The Ordovician System of West Virginia: W. Va. Geol. Survey, v. 21, 627 p. Yatsu, N., 1902, On the habits of Japanese Lingula: Annot. Zool. Japonenses, v. 4, p. 61-67. Yeakel, L. S., 1962, Tuscarora, Juniata and Bald Eagle paleocurrents and paleogeography in the central Appalachians: Geol. Soc. America Bull., v. 73, p. 1515-1540. Yochelson, E. L., 1960, Permian Gastropoda of the southwestern United States, 3. Bellerophon- tacea and Patellacea: Am. Mus. Nat. Hist. Bull., v. 119, p. 205-294. Yonge, C. M., 1939, The protobranchiate Mollusca; a functional interpretation of their struc- ture and evolution: Phil. Trans. Roy. Soc. London, v. 230, ser. B, p. 79-147. 1947, The pallial organs in the aspidobranch Gastropoda and their evolution throughout the Mollusca: Phil. Trans. Roy. Soc. London, ser. B, v. 232, p. 443-518. Youssef, M. I., 1965, Genesis of bedded phosphates: Econ. Geol., v. 60, p. 590-600. Zangerl, R. and E. S. Richardson, 1963, The paleoecological history of two Pennsylvanian black shales: Fieldiana, Geol. Mem., v. 4, 352 p. Ziegler, A. M., 1965, Silurian marine communities and their environmental significance: Nature, v. 207, p. 270-272. PLATES Abbreviations used in explanations: YPM — Peabody Museum of Natural History, Yale University, New Haven, Connecticut Loc. — Locality All illustrated specimens are deposited in the Peabody Museum of Natural History and were collected for this study. All magnifications are given in linear dimensions. PLATE 1 (XS) A-6304 — Disrupted laminae presumably due to biogenic reworking, phosphate grains seen as subround dark clasts—Locality 203. Section cut about 70 feet below Oswego— Reedsville contact. ” 4 . as a .t SEA es ay Stole a. tw 2 Seat Bes a2 PLATE 2 (0.67) A-6304 — Bedding plane with abundant Ambonychia praecursa and a few Modiolop- sis modiolaris essentially “in place’ and forming a small, clustered mussel-like bank. Viewed from underside of bedding plane. YPM 26065 — Locality 203. PLATE 3 All figures are 30 except fig. 3 (50). Figs. 1-3..Genus Monticulihora . ... «ovis « «= p5-0+ 0st ee p. 1. YPM 25848, Loc. 141 (A-6448), transverse section. 2. YPM 25849, Loc. 141 (A-6448) , longitudinal section. 3. YPM 25848, Loc. 141 (A-6448) , longitudinal section, same speci- men as fig. 1. Fig. 4. Genus Dekayid 2 iis... ws oes 6 1 ce i p. ¥a 4. YPM 25850, Loc. 128 (A-6436) , longitudinal section. 70 care ame 4 bled ee J r - Mig A Mh: 2 i e *. «+«s 004 te eee p. 74 4. YPM 25864, Loc. 141 (A-6448) , transverse section. 6. YPM 25865, Loc. 141 (A-6448) , longitudinal section. PLATE 8 All figures are X30 except fig. 3 (50) SPERM CLANS A MICXO PONG... die. . S tiie hs sone de artciasee wielen dae Maen p. 74 1. YPM 25866, Loc. 131 (A-6439), longitudinal section. 2. YPM 25866, Loc. 131 (A-6439) , longitudinal section, same speci- men as fig. 1. 3. YPM 25866, similar to fig. 1 only higher magnification. 4. YPM 25863, Loc. 131 (A-6439), tangential section, same speci- men as pl. 7, fig. 3. PLATE 9 All figures are X30 except fig. 5 (50). Figs, 1-6. Genus Hallopiora: ... 22 oi. ctecwa cs ove ps sue Ot p. 1. YPM 25867, Loc. 127 (A-6435) , tangential section. 2. YPM 25868, Loc. 34-A (A-6345), tangential section. 3. YPM 25869, Loc. 147 (A-6453) , longitudinal section. 4. YPM 25867, Loc. 127 (A-6435) , longitudinal section, same speci- men as fig. 1. . YPM 25870, Loc. 34-A (A-6345) , transverse section. 6. YPM 25871, Loc. 147 (A-6453), tangential section. 75 on PLATE 10 All figures are 4. Ree MERGERS AIDE? e/6 1. YPM 25872, Loc. 98 (A-6414). 2. YPM 25873, Loc. 203 (A-6309). 3. YPM 25874, Loc. 179 (A-6478). 4. YPM 25875, Loc. 203 (A-6314). 5. YPM 25876, Loc. 203 (A-6309). Figs. 1-6. Figs. 7-8. PLATE 11 All figures are 4 except figs. 7, 8 (2). Onntella mulitsecta. (Meek) .. ..< sa» cage anne ene eee p. Gz 1. YPM 25877, Loc. 35 (G) (A-6352), brachial valve external. Image reversed. 2. YPM 25878, Loc. 39 (A-6365), pedicle valve internal, latex im- pression of fig. 5, showing large hinge teeth and deeply impressed crural fossettes, 3. YPM 25879, Loc. 35 (B) (A-6347), brachial valve internal, latex impression of fig. 4. 4. YPM 25879, Loc. 35 (B) (A-6347), brachial valve internal mold (natural). 5. YPM 25878, Loc. 39 (A-6365), pedicle valve internal mold (natural). 6. YPM 25880, Loc. 39 (A-6365), brachial valve internal mold (natural). Hebertella sinuata (Hall)... 3c. ou. s anieen.c sp a p. 78 7. YPM 25881, Loc. 147 (A-6453), pedicle valve internal mold (natural) . 8. YPM 25882, Loc. 147 (A-6453), brachial valve internal mold (natural). » a vw Me. ; ¥ WAY ° a *? i ay Pa Va? Fig. 1. Fig. 2. Figs. 3-6. PLATE 12 All figures are X4 except figs. 1,2 (2). lebertella sinuata’ (lal): sc wc oss ene lone sob 6 or veprc © wlerad eee ng are p 78 1. YPM 25883, Loc. 147 (A-6453), pedicle valve internal mold (natural). Rropable Hebertellasinuata: (Tall), 2). a. oeseew wets eae motes p. 78 2. YPM 25884, Loc. 15 (A-6330), ?brachial valve external, latex impression. Sowerbyella (Sowerbyella) sericea (Hall) ............... 0.00 ee Pp: -69 3. YPM 25885, Loc. 31 (A-6341), brachial valve internal mold (natural). 4. YPM 25886, Loc. 31 (A-6341), brachial valve internal, latex im- pression showing well-defined submedial septa and curved crural bases. 5. YPM 25887, Loc. 31 (A-6341), pedicle valve internal mold (natural) showing well-defined ventral muscle scars. 6. YPM 25888, Loc. 31 (A-6341), pedicle valve external, latex im- pression. PLATE 13 Figures 1-4 (4), Figures 5-8 (2). Figs. 1-4. Sowerbyella (Sowerbyella) sericea (Hall) ..........0 cece cease -p. 85% 1. YPM 25889, Loc. 31 (A-6341), brachial valve internal, latex im- pression showing flat-lying submedial septa flanking median sep- tum. Lighting from lower right. 2. YPM 25890, Loc. 31 (A-6341), pedicle valve internal mold (natural) showing well-defined ventral muscle scars. ‘ 3. YPM 25891, Loc. 31 (A-6341), brachial valve external. 4. YPM 25892, Loc. 31 (A-6341), brachial valve internal mold (natural). Figs. 3-8. Orthorhynchula linneyi (James) «...02.5.0s.+000008 00 p. 91 5. YPM 25893, Loc. 203 (A-6303), brachial valve up. 6. YPM 25894, Loc, 203 (A-6307) , posterior internal latex impres- sion showing prominent crura in brachial valve; impression of fig. 7. 7. YPM 25894, Loc. 203 (A-6307), internal mold (natural) , umbo very prominent. 8. YPM 25895, Loc. 203 (A-6306), internal mold (natural). PLATE 14 Figures 1-5 (2), Figures 6-9 (4). BecemieonOrtnornynchula linneys (JAMES)... 61 oo... ey le eee ee ot pa ol 1. YPM 25896, Loc. 203 (A-6308), external mold (natural), con- centration of worm tubes along anterior inhalent margins. Image reversed. 2. YPM 25897, Loc. 203 (A-6303), brachial valve up. 3. YPM 25898, Loc. 203 (A-6307), internal mold (natural) pedi- cle valve up. 4. YPM 25899, Loc. 203 (A-6308), latex impression of external mold showing small worm tubes covering surface of valve; tubes concentrated along each radial interspace. 5. YPM 25900, Loc. 185 (A-6484), pedicle valve left. MamOs/aeey cos pia modesta (Ela) co... ois 5 ee we os cee yes was oe ee eee ~ 26 6. YPM 25901, Loc. 110 (A-6425). 7. YPM 25902, Loc. 110 (A-6425). meawa-omeeveospiurarecurivostra (Hall)... 3 hc ses eno ae tee eee me 98 8. YPM 25903, Loc. 141 (A-6448). 9. YPM 25904, Loc. 141 (A-6448). PLATE 15 All figures are 2. Figs. 1-6. Rafinesquina “alternata” (Hall) ............... see p.. Gal 1. YPM 25905, Loc. 37 (4) (A-6363), pedicle valve internal mold (natural). 2. YPM 25906, Loc. 31 (A-6341), pedicle valve external. . YPM 25907, Loc. 31 (A-6341), pedicle valve external. 4. YPM 25908, Loc. 98 (1) (A-6414), pedicle valve internal mold (natural). . YPM 25909, Loc. 183 (A-6482), pedicle valve internal mold (natural). 6. YPM 25910, Loc. 49 (A-6376), pedicle valve internal mold (natural). io) S| PLATE 16 All figures are <4. Seen Se CVONOLUS AST alge car « UNA ajo side apni ee ss Bh elene we ee p. 101 1. YPM 25911, Loc. 203 (A-6316). 2. YPM 25912, Loc. 203 (A-6310). 3. YPM 25911, Loc. 203, (A-6316) , latex impression of the external mold of fig. 1. YPM 25913, Loc. 148 (A-6454). YPM 25914, Loc. 203 (A-6316). YPM 25915, Loc. 203 (A-6316). Specimen lost. YPM 25916, Loc. 203 (A-6308). YPM 25917, Loc. 203 (A-6316). YPM 25918, Loc. 203 (A-6316). eaeee OSU PDUGAIRARSI. <).cac, poe REO pdares, 91s l Ram da cathe ves Ne Mee ahe eee p- 102 10. YPM 25919, Loc. 87 (A-6404). 11. YPM 25920, Loc. 87 (A-6404). SS Re eee me inte PLATE 17 All figures are X4 except fig. 2 (2). Figs, 1-3. Bucania apy. oc. 00. cescnnsecieese bs teen ouster p. 102 1. YPM 25921, Loc. 203 (A-6303). 2. YPM 25922, Loc. 87 (A-6404). 3. YPM 25923, Loc. 87 (A-6404). Figs. 4 Genus Seelya oo... cc censecvek cuss au vale en 0d gee p. 105 4. YPM 25924, Loc. 167 (A-6467). Figs. 9; Genus Cyclonema .... 00.005 cs0e uns elm =» enn p. 106 5. YPM 25925, Loc. 75 (A-6395). Figs. ©. Genus Trochonema ..:. : 2... 6c ct vec sx e's oe Oo ee p. 110 6. YPM 25926, Loc. 101 (4) (A-6417). Figs. 1-2. Fig. 3. Figs. 4-6. Figs. 4, 7. PLATE 18 All figures are 4. Reaedemannia®? lrrata (Ulrich & Scofield) 2.2.0... 5.0. 2 5sc5 + on ds p. 1. YPM 25927, Loc. 50 (A-6377), latex impression showing pro- nounced trilineate banding. 2. YPM 25928, Loc. 34-A (A-6345), bilineate banding and fine growth lines well-preserved. axoplocus.(Lophospira) ventricosta (Hall) .......0: 3's... 58 p. 3. YPM 25929, Loc. 167 (A-6467) , latex impression. axoplocus (Lophospira) abbreotata (Hall) . i... 25.2.2 .5 02.50. p. 4. (right) — YPM 25931, Loc. 179 (A-6478). 5. YPM 25932, Loc. 167 (A-6467). 6. YPM 25933, Loc. 203 (A-6316). Loxoplocus (Lophospira) perangulata (Hall) .................. p. 4. (left) — YPM 25930, Loc. 179 (A-6478). 7. YPM 25934, Loc. 179 (A-6478). 104 108 106 109 PLATE 19 All figures are 4 except fig. 3 (2). Figs, 1-2. Genus Sinuopea? ... cies « cpnes sini ee an nearelnl eh eee p. 110 1. YPM 25935, Loc. 167 (A-6467). 2. YPM 25936, Loc. 167 (A-6467) , latex impression. Figs. 5-4. Genus Murchisonia? . ... 0. .cen cess even ease Evin een p. 111 3. YPM 25937, Loc. 133 (A-6441). 4. YPM 25938, Loc. 133 (A-6441). ~~ PLATE 20 All figures are <4. memo .Crenononta: pulchella’ (Hall). .wec5 se cae scicctus dete oe ee er p. YIP ME 25939, Loc: 37 (A-6359).. 2. YPM 25940, Loc. 37 (A-6359). 32) VPM 25941, Loc. 37 (A-6359). mica. Probable Cienodonta? pulchella (Hall) «.......0020.n0%...4... p. 4, YPM 25942, Loc. 34 (A) (A-6345). ieamo-G.eruenuctia icdata, (Hall)... . 3.05. Ne ee see is esate s HO are EEA 3 p. 5. YPM 25943, Loc. 37 (A-6359). 6. YPM 25944, Loc. 97 (11) (A-6413). 7. YPM 25945, Loc. 77-A (A-6397). 8. YPM 25946, Loc. 37 (A-6359). Hise bropable Genus Palaconeilo. . 2. . Ysa sen y teats Dee ee een p. 9. YPM 25947, Loc. 135 (A-6443). 10. YPM 25948, Loc. 135 (A-6443). 11. YPM 25949, Loc. 148 (A-6454). 112 112 114 114 PLATE 21 All figures are <4. Figs. 1-7. Tancrediopss cuneata (Hall) .........:.5.00) 002 se p..113 1. _ YPM 25951, Loc, 203 (A-6317). _ YPM 25952, Loc. 203 (A-6316). . YPM 25953, Loc. 84 (A-6402). . YPM 25954, Loc. 75 (A-6395). _ YPM 25955, Loc. 82 (A-6400). . YPM 25956, Loc, 82 (A-6400). SND OW SS W PO YPM 25950, Loc, 203 (A-6316). PLATE 22 All figures are 4. Sermea: Gancrediopss cuncata (Hall). ..0. 20.5% 2.tscstsihy. some G eta p. alia 1. YPM 25957, Loc. 203 (A-6309). . YPM 25958, Loc. 188 (A-6486). . YPM 25959, Loc. 203 (A-6308) . . YPM 25960, Loc. 203 (A-6304). . YPM 25961, Loc. 201 (A-6497). . YPM 25962, Loc. 193 (A-6490). Dok oO PN PLATE 23 All figures are «4. Figs. 1-5. Tancrediopss cuneata (Hall) .....:.. 052.00. ones p. 113 1. YPM 25963, Loc. 203 (A-6313). 2. YPM 25964, Loc. 200 (A-6496). 3. (right) — YPM 25966, Loc, 203 (A-6316). (left) — YPM 25965, Loc. 203 (A-6316). 4. YPM 25967, Loc. 203 (A-6316). 5. YPM 25968, Loc. 203 (A-6316). PLATE 24 All figures are 4 except figs. 5, 6 (2). bigs, sled. Lancrediopsis cuneata (Hall) o.....464.080bme ews oo5 BOE CaaS pills 1. YPM 25969, Loc. 97 (4) (A-6413). 2. YPM 25970, Loc. 84 (A-6402). 3. YPM 25971, Loc. 75 (A-6395). Bret MM ETUIS CV CULES | ints vate Goran Glave a puerta Wagers ate Gee ae Re Saat pe ily 4. YPM 25972, Loc. 34-A (A-6345). Figs. 5-7. Pterinea (Carttodens) demissa (Conrad) ............0.00 ee eees p. 124 5. YPM 25973, Loc. 152 (A-6548), internal mold (natural) of right valve showing pronounced posterior lateral socket. 6. YPM 25974, Loc. 152 (A-6548), internal mold (natural) of right valve showing partial impression of large posterior ad- ductor. 7. YPM 25975, Loc. 203 (A-6303), shape characteristic of smaller species. showing obliquely prosoclinal PLATE 25 All figures are <2 except fig. 3 (4). Figs. 1-5. Pterinea (Caritodens) demissa (Conrad) ........+.-. esse ceeees p. 124 ie 2. 3. YPM 25976, Loc. 203 (A-6303) , showing obtuse, rounded shape characteristic of larger specimens. YPM 25977, Loc. 149 (A-6455). YPM 25976, similar to fig. 1 only higher magnification showing the duplivincular ligament. . YPM 25978, Loc. 150 (A-6456). . YPM 25979, Loc. 203 (A-6303), internal mold (natural) of left valve showing impression of posterior lateral tooth or jugum, PLATE 26 All figures are 2. Figs. 1-6. Ptertnea (Caritodens) demissa (Conrad) ..............0. 0.0005. p. 124 Fig. 7. i: YPM 25980, Loc 2. YPM 25981, Loc 3. YPM 25982, Loc 4, 5 6 YPM 25983, Loc . YPM 25984, Loc . YPM 25985, Loc . 185 (A-6484). . 203 (A-6309). . 203 (A-6304). . 147 (A-6453). . 186 (A-6323). . 203 (A-6306). Probable Pterinea (Caritodens) demissa (Conrad) .............. py 124 7. YPM 25986, Loc. 181 (A-6480). Fig. 1. Fig. 2. Figs. 3-6. PLATE 27 All figures are X 2. Pterinea (Caritodens) demissa (Conrad) ............0eeeeseeee p. 124 l. YPM 25987, Loc. 170 (A-6470). Probable Pterinea sp. . .. «cs. -- +0045 suns whines ane p. 124 — YB YPM 25988, Loc. 178 (A-6477). Ischyrodonta truncata Ulrich .........25..s5004 00 vee p. 130 3. . YPM 25990, Loc. 203 (A-6306). . YPM 25991, Loc. 203 (A-6311). . YPM 25992, Loc. 203 (A-6302) , internal mold (natural) showing ao > YPM 25989, Loc. 192 (A-6489). impression of small, rounded pedal retractors. PLATE 28 All figures are X 2 except fig. 5 (4). Boom -owisciyroaonta truncata Ulrich {Fo So. ek ee ee ee eee eas p. 130 Ne Pe Sf 4. YPM 25993, Loc. 98 (A-6414). YPM 25994, Loc. 200 (A-6496). YPM 25995, Loc. 203 (A-6307), showing impression of possible worm tubes at the inhalent opening. (top) — YPM 25996, Loc. 203 (A-6309). (bottom) — YPM 25997, Loc. 203 (A-6309) . . YPM 25998, Loc. 87 (A-6404), internal mold (natural) of left valve showing impression of cardinal dentition. . YPM 25998 — Similar to fig. 5, except lower magnification. PLATE 29 All figures are <2. Figs. 1-6. Ischyrodonia truncata Ulrich . : :.. 3. 6 ni ees os eb eee p. 130 1. YPM 25999, Loc. 152 (A-6458). 2. YPM 26000, Loc. 38 (A-6364). 3. YPM 26001, Loc. 182 (A-6481), latex impression showing pos- sible worm tubes at the inhalent opening. 4. YPM 26002, Loc. 203 (A-6309). . YPM 26003, Loc. 99 (A-6415). 6. YPM 26004, Loc. 203 (A-6310). uo PLATE 30 All figures are 2. Migs, Jou scnyyodonra truncata WICH 5 coc 16. san sad wobe s 0s bea p. 130 1. YPM 26005, Loc. 152 (A-6458). . YPM 26006, Loc. 140 (A-6447) , latex impression. . YPM 26007, Loc. 203 (A-6308). . YPM 26008, Loc. 203 (A-6309). . YPM 26009, Loc. 98 (A-6414). . YPM 26010, Loc. 203 (A-6303), showing amphidetic, dupli- vincular ligament. Dok OO NP PLATE 31 All figures are 2 except fig. 3 (1.5). Figs. 1-3. Modtolopsis modtolars. (Conrad). 4... .9:1 2 dee oe ee p: 12% 1. YPM 26011, Loc. 203 (A-6303), showing impression of an ir- regular ‘“‘U”-shaped tube at the approximate position of the in- halent current. 2. YPM 26012, Loc. 203 (A-6303). 3. YPM 26013, Loc. 203 (A-6307). PLATE 32 All figures are <2. Bigs. 1, 52 Modiolopss modtolans (Conrad). cc sens Sone na nae aan’ pei2y, Fig. 2. 1. YPM 26014, Loc. 63 (B) (A-6383). 3. YPM 26016, Loc. 203 (A-6305), internal mold (natural) show- ing impression of elongate, broad opisthodetic ligament. Probable Modtolopsis modiolaris (Conrad) ........... 00.0.0 005. p: 127 2. YPM 26015, Loc. 52 (A-6380), possibly another species (cf. M. sinuata). PLATE 33 All figures are <2 except fig. 2 (1.5). Figs. 1-3. Modiolopsis modiolaris (Conrad) ........«.++18 anes ak Dee p. 127 1. YPM 26017, Loc. 203 (A-6303). 2. YPM 26018, Loc. 171 (A-6471). 3. YPM 26019, Loc. 203 (A-6303). ry ak ie a =, ~~ PLATE 34 All figures are <2. Pigs wl-oseModtolopsts modtolaris (Conrad)... 520025 gs cue dn duet wees paal2d 1. YPM 26020, Loc. 149 (A-6455). 2. YPM 26021, Loc. 203 (A-6301), latex impression. 3. YPM 26022, Loc. 186 (A-6323). PLATE 35 All figures are <2. Figs. 1-4. Modtolopsis modiolaris (Conrad) ............ecceceeseeuceces p. 127 i rf x 4, YPM 26023, Loc. 147 (A-6453). YPM 26024, Loc. 125 (A-6433), possibly another species (cf. M. concentrica). YPM 26025, Loc. 87 (A-6404). YPM 26026, Loc. 203 (A-6302), showing shape variation result- ing from tectonic distortion. PLATE 36 All figures are <2. ieswicorambvonycnia madtata. Tall)... 0% yw wo bit aistomaeme nie vom eee poll? Oo PB OF DD . YPM 26027, Loc. 62 (H) (A-6382) , showing striated ligament. . YPM 26028, Loc. 77-A (A-6397). . YPM 26029, Loc. 82 (A-6400) , showing posterior lateral teeth. . YPM 26030, Loc. 37 (A-6359). . YPM 26031, Loc. 75 (A-6395), internal mold (natural) show- ing impression of cardinal and lateral teeth and part of posterior adductor muscle scar. . YPM 26031, external mold (natural) of fig. 5. Lighting from bottom. PLATE 37 All figures are <2 except figs. 2,3 (1). Figs. 1-9. Cyriodonta? ....6 cae cto cess suse» op ak 6 oe a p. 129 1. YPM 26032, Loc. 167 (A-6467). 2. YPM 26033, Loc, 167 (A-6467). 3. YPM 26034, Loc. 167 (A-6467). Figs. 45. Ambonychia praecursa (Ulrich) .........=»=5en see p. 118 4. YPM 26035, Loc. 203 (A-6302). 5. YPM 26036, Loc. 203 (A-6303). PLATE 38 All figures are X2 except fig. 1 (4). esle2 4-5. Ambonychia praccursa (Ulrich) ..... 2.0.00 0000 ¢. ees eee nen p: 118 Fig. 3. 1. YPM 26037, Loc. 87 (A-6404), internal mold (natural) show- ing impression of cardinal dentition. 2. YPM 26037, same as fig. 1 only lower magnification. 4, YPM 26039, Loc. 177 (A-6476). 5. YPM 26040, Loc. 75 (A-6395), showing impression of lateral teeth confined to posterior end of hinge line. PAmbany chia ioyriest (UIC) ter oo. ccs k ss ec ce te ee es eee ees p. 123 3. YPM 26038, Loc. 75 (A-6395). PLATE 39 All figures are <2. Figs. 1-4. Ambonychia praecursa (Ulrich) . «1.2.00: y.05s>s 5000 ese eee p. 118 1. YPM 26041, Loc. 93 (A-6409), showing impression of posterior lateral teeth, 2. YPM 26042, Loc. 203 (A-6306) , prominent byssal gap. 3. YPM 26043, Loc. 203 (A-6303). 4. YPM 26044, Loc. 203 (A-6303). PLATE 40 All figures are <2. Hiesmied Ambonychia praccursa (Ulrich) 2 .... 05.262 cee ees waees p: Lis 1. YPM 26045, Loc. 75 (A-6395). 2. YPM 26046, Loc. 203 (A-6303). 3. YPM 26047, Loc. 203 (A-886). 4. YPM 26048, Loc. 203 (A-6301). PLATE 41 All figures are 2. Figs. 1-3. Ambonychia praecursa (Ulrich) ......... 5. "=.=ses dee p. 118 1. YPM 26049, Loc. 203 (A-6302). 2. YPM 26050, Loc. 75 (A-6395), bifurcation of some ribs near the hinge line. 3. YPM 26051, Loc. 75 (A-6395). PLATE 42 All figures are X 2. Beweie. Ambonyonia cultrata (Wirich) 222 o38 veil. ee ses oe wae ee oe p. 122 1. YPM 26052, Loc. 145 (A-6452). 2. YPM 26053, Loc. 152 (A-6458), showing impression of longi- tudinally striated ligament. Eiceua- ae ambponychia praccursa. (Wirich)..0.%2 22. 6. Sas onda ee ns oe p. 118 3. YPM 26054, Loc. 203 (A-6308). 4. YPM 26055, Loc. 203 (A-6303) . PLATE 43 All figures are X 2 except fig. 1 (4), fig. 4(X1). Figs. 1-4. Ambonychia cultrata (Ulrich) .....5... dss 4505s eee p. 122 1. YPM 26056, Loc. 141 (A-6448), impression of longitudinally striated ligament. 2. YPM 26056, same as fig. 1 only lower magnification. 3. YPM 26057, Loc. 141 (A-6448) , impression of striated ligament. 4. YPM 26058, Loc. 141 (A-6448). 5 a Y PLATE 44 All figures are 4 except figs. 1,5 (2). icsi-ye eyrodesma postsiriatum (EMMons) «22.6.2. eye os oa es Ss a. p. 132 1. YPM 26059, Loc. 37 (A-6359). 2. YPM 26059, same specimen as fig. 1 only higher magnification showing impression of adductor and pedal muscle scars and promi- nent schizodont teeth. 3. YPM 26060, Loc. 97 (11) (A-6413). 4. YPM 26061, Loc. 77-A (A-6397), showing impression of well- marked longitudinal striae on each tooth. 5. YPM 26062, Loc. 37 (A-6359) , showing impression of pallial line with distinct impression of a small, posteroventral pallial sinus. 6. YPM 26063, Loc. 149 (A-6455), showing impression of coarse radial ribs at posterodorsal edge of shell. 7. YPM 26064, Loc. 37 (A-6359). NORTH N\ 120 208 | to 29]/e 209 UPPER ORDOVICIAN LOCALITIES — CENTRAL APPALACHIANS a ey _ EY r MARTI = ALL Mietees parrtan i TINSBURG FM.- GREAT V cael oe EDSVILLE FM.- VALLEY AN ; f \ NORTH =. 9 4 SO MILES 9gb89 on v2 ¢9 99 | b Lb b i¢ € (rs ee = 8 is = : : = g &o i) aa = — nN oe 3 w — a : or ‘ cre : >t Rodgers— 1953 - 8 - Stose—1932 5 oe \ Ds re a fe boiene | is efezo) — VIRGINIA ie? iw) ’ PETERS MT.— POTTS MT. CATAWBA MT WOLF CREEK MT. POWELL MT. RICH MT.—EAST RIVER MT. BIG WALKER MT.— ‘CLINCH MT. a4a4a e538 13223 ~ * ww hp ° “ ~ ad ‘a7 TENNESSEE CUMBERLAND MT... CLINCH MT. 5) $323 54.3 5 1 23 5 11 $ 1 1 1 2 11 1 11 11 rT EES Ui bs 1d PVE) SB 3 22 3 233 “Onniello multisecta | BRACHIOPODA Lingula? | } Orthorhynchula linnayi : Rafinesquina “alternata” Sowerbyella (Sowerbyella) pericea t Hebertella sinuata — | (GASTROPODA) Zygospira modesta ~ | 4 J Zygospira recurvirostra ae ae Sc | 2 a | Se BRYOZOA | j Dekayia ) — NE eS ee Hallopora Batostomella | Monticulipora Amptexopora sees) MOLLUSCA (BIVALVIA) “Ambonychia radiata’ Ambonychia cultrata Ambonychia praecursa Amtonychiebyrnresit——_—____ 77 Ischyrodonta? truncata Lyrodesma poststriatum Pterinea (Caritodens) demissa Modiolopsis modiolaris Tancrediopsis cuneata Praenucula levota Ctenodonta? pulchella — Plectonotus? sp Bucania sp. Ruedemannia? lirata Loxoplocus (Lophospira) abbreviata Loxoplocus (Lophospira) ventricosta Loxoplocus jLophospira) perangutgte Sinuopesu? Murchisonia? TRILOBIT A 1 . Cryptolithus Flexicalymene tsotetus 7 ; T CRINOIDEA Crinoid columnals UPPER ween BO vine OF CENT Re pas PALINSPASTI' (AFTER DEN ADDITIONAL SOURCES FOR MEASURED GEOLOGIC SECTIONS BASSLER-1919 BRENT -1960 BUTTS - 1941 COOPER, B.N.-1944 GRABAU - 1913 HOROWITZ- 1965 MILLER & BROSGE- 1954 MILLER & FULLER - 1954 PIERCE - 1966 SECRIST & EVITT-1943 SWARTZ -1957 WILLARD- 1943 WOODWARD -195| rs wT} ____ PENNSYLVANIA —MARYLAND I IRGINIA WEST RGN VIRG ee AN N N RSM | 'USCARORA MT. CATAWBA MT-—WOLF CREEK MT! poweLL MT. __ NITTANY MT. | ond | JACK MT.—NORTH MT. (So) : NORTH (N) : ITTATINY-BEARPOND MT. RICH MT.—EAST RIVER MT. SHADE Wi BRACHIOPODA Lingulo? | 1 | Orthorhynch a linn | Mavivhaquina alterndta® Beha Ske SO tie y2asn's 25 s j | Peat srt os ie tyere Nyt 2 5 aor Hebertella sinuata / Onniella multisecta _ Zygospira modesta Zygospira recurvirostra 625 453 31 i 1) y124 a .3f2'3 1 “Le ery ae cl Gees | tate any | 3.5) 5523\543 ot BRYOZOA | Dekayia Hallopora Batostomella Monticulipora Amp oporat—i—t } | MOLLUSCA (BIVALVIA) th Nea _ Ambonychia radiata Ambonychia cultrata Ambonychia praecursa it ro byrnesi | Ischyrodonta? trun¢ata | Plrinent poststriatum | i Jn222455 1 We | it : 2 bey 5 3424231 3 3241 1. i sit 7. 1 1 1 | i a5 4 43 3 1 Tt 31-5 §$4342523455335 ’ 1 Tal (et | 1 Modiolopsis modiolaris Tancrediopsis cuneota Proenucula jevata — Ctenodonta’ pulchella 32151135 SSSTI! 4 if (GASTROPODA) | Plectonotus? sp ' Bucania sp. Ruedemannja? lirata Loxoplocus (Lophospi Loxo onat | | ) 52 1 23 15555435124 i a Weran ane we Murch isonia? | 1 | | | | ——FRILOBITA Cryptolithus. Flexicalymene | 4 CRINOIDEA Crinold columnals eS1S511355325555355 TABLE 3 — Distribution of central Appalachian Upper Ordovician faunas | Sowerbyella (Sowerbyelia) Bericea 4 ea (Caritodens) demissa 70) obbrevioto locus (Lophospira) ventricosta locus (Lophospira) perangulala UPPER ORDOVICIAN STRATIGRAPHY | - SETS eee ee OF THE sara CENTRAL APPALACHIANS loo reer NORTH PALINSPASTIC BASE (AFTER DENNISON, 1961) 50 | 94-97-98 25 0) - 202-203 145-147-149 ee 197-200-201 182-183-184 === ee ADDITIONAL SOURCES FOR MEASURED 190-191 GEOLOGIC SECTIONS BASSLER-1I919 BRENT -1960 BUTTS- 1941 COOPER, B.N.- 1944 GRABAU - 1913 HOROWITZ-1965 MILLER & BROSGE- 1954 MILLER & FULLER- 1954 208-120-121 123 (107-108) 167-169 160-166 PIERCE - 1966 SECRIST & EVITT-1943 SWARTZ -1957 WILLARD- 1943 LESH IND WOODWARD - | a LITHOLOGY STRATIGRAPHIC NAMES Conglomerate Senate SILURIAN Sandstone Tuscarora - T MILES Cross-bedding wy Massanutten - YY b F de Siltstone ORDOVICIAN 5 Shale = Juniata- J Limestone == Sequachie- S Oswego - O (including Bald Eagle) Reedsville-R Martinsburg- MA Unconformity eh ey cme IAN STRATIGRAPHY | THE . oe VERTICAL SCALE \PPALACHIANS 100 FEET A 75 | > BASE NISON, 1961) 50 25 0 202-203 145-147-149 197-200-201 148 is! ae 178 125-126-133 140 fel eke rIGURE~ 2 UPPER ORDOVICIAN FAUNAL ASSOCIATIONS Ge ALAE CENTRAL APPALACHIANS NORTH 35-37-34A eS PALINSPASTIC BASE SCALE tS 2 (AFTER DENNISON, 1961) 78-82-84-86 100 FEET 94-97-98 MILES 75 po 4 (0) 50 100 202-203 a. 145-147-149 197-200-201 * 182-183-184 25 = 0 =) 130 {e) SP » 208-120-121 ; 6 123(107-108) att {60 132-136 LEGEND FAUNAL ASSOCIATIONS SOWERBYELLA -ONNIELLA COMMUNITY Strophomenid Population - Ss 174-175 177-178 n BM Orthid-Crinoid Population-OC i) s evar ORTHORHYNCHULA- AMBONYCHIA COMMUNITY SP Linguloid Population- L 0 Rhynchonellid Population—R Modiolopsid Population-M (0) ZYGOSPIRA-HEBERTELLA COMMUNITY Spirtferid Pomme on - SP Orthid Population-o { Stratigraphy and Paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin Area, Wyoming and Montana_ John H. Ostrom Bulletin 35 PEABODY MUSEUM — OF NATURAL HISTORY YALE UNIVERSITY Stratigraphy and Paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin Area, Wyoming and Montana JOHN H. OSTROM Peabody Museum of Natural History and Department of Geology and Geophysics, Yale University BULLETIN 35 ° AUGUSmi, 1970 PEABODY MUSEUM OF NATURAL HISTORY YALE, UNIVERSITY NEW HAVEN, CONNECTICUT Bulletins published by the Peabody Museum of Natural History, Yale University, are numbered consecutively as independent monographs and appear at irregular in- tervals. Shorter papers are published at frequent intervals in the Peabody Museum Postilla series. The Peabody Museum Bulletin incorporates the Bulletin of the Bingham Oceano- graphic Collection, which ceased independent publication after Vol. 19, Article 2 (1967) Publications Committee: John H. Ostrom, Chairman Theodore Delevoryas Willard D. Hartman Keith S. Thomson Thomas Uzzell Charles G. Sibley, ex officio Editor: Nancy A. Ahlstrom Asst. Editor: Elise K. Kenney Asst. Editor: Elizabeth G. Weinman, editor this volume Communications concerning purchase or exchange of publications should be ad- dressed to the Publications Office, Peabody Museum of Natural History, Yale Uni- versity, New Haven, Connecticut 06520, U.S.A. © Peabody Museum of Natural History Printed in the United States of America CONTENTS PSO AG CIRISS: 65 c's ais nae ccnyeidee 6 serene cus terete ees ator “LAUSD CG] B81 2d O92 \@] Bl So ee oe AS ee ee AN Oe ee ee A, ees Pete EVAR ANS 05-565 Se clan 5 FS cay a «ec oe Reeds AOL Loe SAREE: RPO EY TAU GES: 255 0.0542 chess, Wiens sb OMe RR Aare: aces PisinOr TOCALIEY IMAPS io 2 a sectr acted i cuiorade sy corcieussey eae aseeen BpoRAG TS (English, German, Russian) 2... 2 yee b acaitycani ds eae ROU CEE TON, oc ccs a c-02o eta ee a ee Ee eee FACIE OW LEDGE MENTS: 6 foc's-¢ foe a. 8 ean ess u eer haste ope 232 Locality Map B05 6.ccisyececsantxcch se canoe ied Oan oie eee eee 233 Locality Man ©) i... 5 vs ssaia tien cones tee CRs ted ce ee a ee eee 234 Locality, Mag Desi cc voces ose s eebbieenesis ORES oe oak One 213 Locality Man Bots cce vases cesuuctss ean Onywesee shekaieiaa ss ie terme 214 Locality Magy Fo. oic.0.0s asisiass ie hunes en's nnd ewe clerly arti og eeans en 215 Locality. Map Gis: cisicewvid.e ete n tie sek cope slash PII Oar eta seen 216 Lorahtgian Fh viis:cesn svcd a ie dein as enererda dene eee tape ee 217 Locality: Map lca sice suv e's eniviccwsiecntea Wiiote ee ne dpras Ve 225 Locality Mags J.” s:eeucis sisis's's Ven s mwrsewnnts bibceir sips Series. keene 226 Locality Man EB. «3 ii2:¢ disaive oexiivre ivaae> deck Lenasgilets by pee 227 Locality: Mag Les:sii's « sic sates 0'n eb cwatklanw wa orwnd oats Lip am bored eee 228 Lotality, Mai OA «5ciss sins Keo decile ca als aide Eo 0 ¥en eae ee 229 Locality Mag NN iis :a505s «i's > ».de hich aie say arena demdiipts Fiber eee 231 Locality Man O wis ditvcs venir a ocd dklsiiy rene acess ole einen ae ee 230 Bccnitty Riga PD. cise ietaaies « « » + sida Ret auaidgn 60 9. 00 hoe 208 Locetity Mab © 0 352.) ili «eaten d +s 3s 0's enaeanels eee 224 SSOCHMR GAR TR 5 i'd so iy nis vk on an gnets § Ca hn @ dan ggg 223 Locate Mari Ge. s aise i ainnip = Seis sits wn so oan ae ce ee 222 ECR DART os bile tiy's sie 0 a ales sy x am x wn Mino oro dupiece sis ly ne 221 aapcaity MRD TS ss oi iia oie ws ks 45 kn da ee ee 207 MCHC Y BERD VY mais:ii vidiccas v.00» » ¥en» ae 0% «9 5 ¥n pares don 220 RCH MAID WY a's. 0s s Sip bin np 0-0-5 0 iw 0s 9. 0-000, 9 Os eee a 219 ROGMMEY AMID is bie obo nic ws cs eds bss 94 one + rithm a ye ere oe 209 Vill YALE UNIveERSiITy PEABODY MusEuUM OF NATURAL History BULLETIN No. 35, 234 p., 27 pxs., 9 Fics., 1970 ABSTRACT The nonmarine strata of the Bighorn Basin, lying between the Late Jurassic Sundance Formation and the Early Cretaceous Thermopolis Shale, have been subdivided into three formal units: the Morrison, Cloverly and Sykes Mountain Formations. Applica- tion of these terms to actual outcropping rock units has been quite inconsistent, and considerable confusion and disagreement exist over formation boundary positions. Traverses around the periphery of the Bighorn Basin and across adjacent areas to the north, west and south established the existence of seven distinctive lithic units. These are: a lowermost, drab gray, calcareous claystone; a massive, brilliant white, quartz- chert sandstone (in the southern part of the Basin) ; a variegated gray-green or pink, calcareous claystone; a massive, black chert, coarse sandstone or conglomerate (in the northern part of the Basin) ; a drab gray to white or pastel-colored, bentonitic and non- calcareous claystone rich in chalcedonic and baritic concretions; a discontinuous series of coarse, yellow to ochre-colored, clay-rich, feldspathic channel sands; and a brightly variegated, noncalcareous, bentonitic claystone rich in polished, siliceous pebbles and cobbles (“‘gastroliths” of some authors). These seven units have been designated here by informal terms: Unit I to Unit VII. Units I through III are considered as the Morrison Formation. Units IV through VII correspond wholly or in part with the Pryor Conglomerate, Little Sheep Mudstone and Himes Mudstone Members of the Cloverly Formation, as that formation was defined by Moberly (1960). Units VI and VII and the lower sands (Unit VIII) of the overlying Sykes Mountain Formation correspond to the Cloverly Formation as it was defined by Darton in 1906. Some authors have applied the term Morrison to the entire nonmarine sequence and limited the Cloverly Formation to basal sands (Unit VIII) of Moberly’s Sykes Mountain Formation. In order to provide a meaningful stratigraphic foundation for placement of the paleon- tologic collections obtained, the stratigraphic sections and terminology usage of pre- vious workers are compared in detail with the informal lithic units recognized in this study. Extensive collections of fossil vertebrate remains were made from Units V, VI and VII. The fauna, as presently known, is considerably less diverse than that of the Morrison Formation of other regions. It includes a new species of Ceratodus (C. fraziert), an indeterminate amioid, two baenoid turtles (Naomichelys speciosa Hay, 1908 and Glyptops pervicax Hay, 1908), a possible testudinid, indeterminate meso- suchian crocodilians, and several theropods (Deinonychus antirrhopus Ostrom, 1969; Microvenator celer [new genus and species]; an undefinable species of Ornithomimus; and an undefinable, but distinctive, large theropod. Also, of greatest abundance, are remains of a titanosaurid sauropod, a new genus and species of iguanodontid ornitho- pod (Tenontosaurus tilletti) and a new genus and species of acanthopholid ankylo- saur (Sauropelta edwardst). Despite extensive washing and sieving, no mammalian or other microfaunal remains were recovered, 1 2 PEABODY MUSEUM BULLETIN 35 The Cloverly fauna is totally distinct from that of the classical Morrison Forma- tion. With the possible exception of the crocodilian remains, not a single Cloverly specimen is referable to a taxon presently known from the Morrison Formation. On the other hand, the few fragmentary vertebrate fossils that have been recovered from Units I, II and III in the study area are referable to well-established Morrison taxa. In addition, all specimens now known from the Cloverly Formation (Units V, VI and VII) appear to have closer affinities with Late Cretaceous taxa than with Morrison species. ‘This may be explained by either a major environmental change or a signifi- cant time hiatus between Morrison and Cloverly time, or both. Comparison with fau- nas from the Arundel Formation of Maryland, the Glen Rose Formation (Trinity Group) of Texas and Oklahoma, and the Wealden beds of northwestern Europe in- dicate at least partial contemporaneity of the Cloverly and Glen Rose Formations and a somewhat greater age for the Arundel and Wealden beds. The age of the Cloverly, on the bases of fossil invertebrate and paleobotanical evidence, as well as the fossil verte- brates, is probably Late Aptian and Early Albian. ZUSAMMENFASSUNG Die nichtmarine Schicht des Bighornbeckens, die zwischen der Spat-Jura Sun- dance Formation und dem Frith-Kreide Thermopolis Schieferton liegt, wurde in drei wesentliche Gruppen unterteilt: Die Morrison, Cloverly und Sykes Mountain Formationen. Die Anwendung dieser Bezeichnungen auf die gegen- wartig zutage tretenden Gesteinsgruppen ist ziemlich unsicher, und es besteht viel Unklarheit und Uneinigkeit tiber die Formationsbegrenzungen. ‘Traversen entlang des Randes des Bighornbeckens sowie durch angrenzende Gebiete im Norden, Westen und Siiden lassen sieben wesentliche Gesteinsschichten erken- nen: zuunterst grauer, kalkhaltiger Tonstein; massiger, diamantartig glanzender weisser Quarz-Kieselschiefer Sandstein (quartz-chert) (im stidlichen Becken- teil); bunter grau-griin oder rosa kalkhaltiger Tonstein; massiger, schwarzer Kieselschiefer, grober Sandstein oder Konglomerate (im nérdlichen Becken- teil) ; grau-weisser oder pastellfarbiger bentonischer, kalkarmer ‘Tonstein, hoch- haltig an chalzedonischen und _ baritischen Konkretionen; unterbrochene Schichten von grobem, gelb-ockerfarbigem tonreichem, feldspathaltigem Fluss- bettsand; und hellbunter, kalkarmer bentonischer ‘Tonstein, hochhaltig an polierten Gerdllen und Kieseln (von einigen Autoren “gastrolithen” genannt). Diese sieben Schichten wurden hier inoffiziell als Stufen I bis VII bezeichnet. Stufen I bis III geho6ren der Morrison Formation an, Stufen IV bis VII ent- sprechen ganz oder teilweise den Pryor Konglomeraten, Little Sheep und Himes Schlammsteinverbindungen der Cloverly Formation—so benannt von Moberly (1960). Stufen VI und VII sowie die unteren Sande (Stufe VIII) der dariiber- liegenden Sykes Mountain Formation entsprechen der Cloverly Formation wie sie Darton 1906 bezeichnete. Einige Autoren verwendeten die Bezeichnung Morrison fiir die gesamte nichtmarine Schichtenfolge (sequence) und beschrank- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY a ten die Cloverly Formation auf die Sandbasis (Stufe VIII) von Moberly’s Sykes Mountain Formation. Um eine sinnvolle stratigraphische Grundlage zur Klassi- fizierung von paladontologischen Sammlungen zu erhalten, wurden hier die stratigraphischen Zonen und die Fachsprache von fritheren Wissenschaftlern genau verglichen mit den inofhiziell bezeichneten Gesteinsstufen in dieser Studie. Umfangreiche Sammlungen von versteinerten Wirbeltiertiberresten kamen aus den Stufen V, VI und VII. Soweit bis heute bekannt ist, ist diese Fauna bei weitem nicht so vielfaltig wie die der Morrison Formation anderer Bezirke. Sie enthalt eine neue Art von Ceratodus (C. frazieri), ein unbestimmbarer Amioid?, zwei baenidische Schildkréten (Naomichelys speciosa Hay, 1908 und Glyptops previcax Hay, 1908) méglicherweise ein Testudinid, unbezeichnete Mesosuchia Krokodile, und verschiedene Tetrapoden (Deinonychus antirrhopus Ostrom, 1969); Microvenator celer (eine neue Gattung und Art); eine un- bestimmbare Art von Ornithomimus; und ein unbestimmbarer aber ausge- sprochener grosser Thercpod. Ausserdem sind in grosser Menge Uberreste von titanosaurischen Sauropoden enthalten, eine neue Gattung und Art von iguano- donischen Ornithopoden (Tenontosaurus tillettt) sowie eine neue Gattung und Art von acanthopholischen Ankylosaurier (Sauropelta edwardsi). Obwohl alles griindlich gewaschen und gesiebt wurde, wurden keine Saugetier- oder anderen mikrofaunischen Uberreste aufgefunden. Es besteht ein sehr wesentlicher Unterschied zwischen der Cloverly Fauna und der klassischen Morrison Formation. Mit der moglichen Ausnahme von Krokodiltiberresten steht kein einziger Cloverlyfund in Beziehung zu einer taxonomischen Einheit der Morrison Formation wie sie bis heute bekannt ist. Andererseits stehen die wenigen fragmentarischen Wirbeltierversteinerungen aus den Stufen I, II und III des untersuchten Gebietes in Beziehung zu den gut geordneten Morrison Einheiten. Weiterhin scheint es, dass alle bis heute bekannten Fundstiicke aus der Cloverly Formation (Stufen V, VI und VII) eréssere Ahnlichkeiten besitzen mit solchen aus der Spiat-Kreide als denen der Morrison Formation. Das ist eventuell zu erklaren mit einer Veranderung in der Umgebung oder einer zeitlichen Liicke zwischen Morrison und Cloverly Formationen, oder beidem. Vergleiche mit den Faunen der Arundel Formation von Maryland, der Glen Rose Formation (Trinity Gruppe) von Texas und Okla- homa und den Wealden Schichten Nordwesteuropas zeigen zumindest teilweise eine Gleichzeitigkeit der Cloverly und Glen Rose Formationen und einen erdsseren Altersunterschied mit den Arundel und Wealden Schichten. Man schatzt das Alter der Cloverly Formation auf Grund von evertebraten Ver- steinerungen und paladobotanischen Funden sowohl als auch Wirbeltierver- steinerungen als Spat-Aptian und Frih-Albian. 4 PEABODY MUSEUM BULLETIN 35 PE3WHME Hemopcrnue naacTs BurxopHcKoro Oacceiiva, 3acerawnyve Mex AY Wo3sqHewpcKon cBU- TOM CaHaHe HM HWKHEMeAOBLIM TEPMONOAHCOBBIM ClaHHeM, POPpMadtbHO NOfpas3yeteHsl Ha TPH HaMMeHOBAHHA: CBHTHI MapHCOK, KAOBepAM MH Calikc MayHTeH. I]pumeHenue THX HasBaHuit Kk LelCTBUTeIbHO BBIXOAAMAM Ha MOBeEPXHOCTb W1acTaM OBO BeCcb- Ma IIpOTHBOPe4YHBEIM, HM cymecTByeT OoIbM0e pasHoraacne 10 BOIpOCy 0 pasrpa- HuveHuH cBUT. Hadswjenusa 10 Hepudpepuu Burxopuexnoro Oacceiina u B IpHazeraw- mux paiionax kK ceBepy, B3allaqy HM Wry OOOCHOBEIBAWT CyIeCTBOBaHHe ceMu OTIMYATCIDHBIX MAAaCTOB: CaMBbIfi HAWVKHHH, TYCKIO-cepoBaTHi, M3BeCTKOBO-TrIMHu- CTH ClaHell; MaCCHBHBIli, O1ecTame-OeIb, KBapleBO-KpeMHUCTHH WecuaHHK (B OKHOH uacTH OacceiiHa); MecTpo-cepo-3e1¢HbEIi WIM PO30BHIi, WH3BeECTKOBO-IrIu- HUCTHM ClaHell; MaCCHBHBIM, UepHBIM uwepT, rpyOosepHUCTHH WecuaHuk WAM KOH- ri0MepaT B CeBepHo uacTu Oaccelina; TYCKIO-cepoBaTHH, Nepexoqamuli B OernIf HIM WacTeIbHbIM, OCHTOHHTOBHIA WH HEU3BECTKOBO-TIMHUCTHM ClaHell ¢C XaleOHO-u OapuToOOraTHIMH KOHKPeUMAMH; IpepbIBUCTaA CepHA TpyOO8epHUCTHIX, iKeATHIX TepeXOMAMUX B OXPOBHI WBeT, TIMHOOOTATHIX, NOJEBOMMATOBEIX PYCIOBBIX IeCKOB, HW TecCTpbii, HeM3BeCTKOBO-OCHTOHUTOBHIM TIMHUCTHH caaHell OoraTH oTMmUo- BaHHBIMM KPeCMHUCTHIMH TadbkaMu (“‘TacTpOIHTHI” Y OTeIbHEIX AaBTOPOB). ITU CeMb I1acTOB OOO3HAYeHBI B HacTOAMel padote yc1OBHbIMM TepMuHaMn: IInacr |] — IIaact VII. Iaactsr J — III ornocatca & cBute mopucon. Uaactar IV — VII noa- HOCTbWO HIM YWCTHYHO COOTBETCTBYWT IIPHOPCKOMY KOHTIOMepaTy, ATA WuincKon WA1OBKe WV XalMCKUM UAOBKOBBIM TWaukaM CBUTH KAOBePAM, Kak ONpeeIuA sTY CBUTY Mo6depau (1960). Inactsr VI a VII 1 nuanne necku (Iaact VIII) sarmerexameti CBUTHI CalikC MAYHTeH, COOTBETCTBYIOT CBUTe KAOBePAN, Kak ee Opesetua JapTou B 1906 r. OTTeIbHbIe ABTOPH 0OO0O3HAYHAM HasBAaHHeM MOPHCOH BCH HEMOPCKYW TOJ- Illy U OrpaHwunin CBUTY KIOBepsiN OasaitbHBIMA Meckamu (IImact VIII) cBursr cafixc mMayHTeH Mo6epan. Jaa Toro, YTOOHI WpeAAOHUTH alekBaTHYW cTpaTurpaduyeckyyw OCHOBY JIA Pa3sMeNLCHHA MOTYYeCHHBIX WateOHTOAOTMYeCKUX KOIIeERUME, cTpaTurpa- (pUUeCKHe eMHHITEE U TEPMHHOIOTUA IPeAbILYMUX Uccre_oBaTedei MOAPoOOHO CpaB- HUBAWTCA C IPMHATHIMH B VTOH paboTe yCIOBHEIMH WiacTaMH. OOMMpHe KOAICKIMM HCKOMAeCMBIX OCTATKOB T103BOHOUHBIX OBIIM COCTABIeCHEI u3 Inactop V, VI un VII. dra dayHa ropa3qo MeHee pa3HooOpasHa, YeM ayHa CBH- THI MOPHCOH B pyrux pafionax. K Hel OTHOCATCA HOBHIMt BU, Ceratodus (C. Frazieri), HeolpeleeHHbIii aMHMONI, 1Be OaeHanOBble Yepettaxu (Naomichelys speciosa Hay, 1908 u Glyptops pervicax Hay, 1908), Bo3sMO#KHEIM TeCTYIMHU, HeompeseiéHHEe Me30- BYXOBBIE KPOKOMIOBIe, HM HECKOABKO Teponos0B (Deinonychus antirrhopus Ostrom, 1969) ; Microvenator celer [HOBEIi pox U BUA]; HeoupexeteHHE BU Ornithomimus; HeompeeIeHHEI, HO OTAMYNTeIBHBIM, KpyNHBI Teponoz. Take B HanOOTbINeM KO- IMYeCTBe MMeITCA OCTATKH OHOTO TUTAHOZABPUa (AMepOHOTUX), HOBOTO posa H Bua UryaHOAOHTHAa (mTHMeHOrux) (Tenontosaurus tilletti), HOBOTO powa HM Bua akaHTOPOIMAOBOTO aHKHIOBaBpa (Sauropelta edwardsi). HecmoTpa Ha oOmupHOe IIPOMBIBAHHe UW WpoceuBaHve He Yaloch OOHAPYKUTH HAKAKUX OCTATKOB, HH Mie- KOMMTAWNMX, HU {pyro muKpodayHeEl. PayHa KAOBepAW BO BCeX OTHOMeHHAX OTAMYAeTCA OT ayHB KAaccHyecKoH CBHUTEI MOPHCOH. 3a BO3MOZKHBIM UCKIIOUCHHEM KPOKOAWAOBHIX OCTATKOB HeT HH OHOTO OOpasila KIOBePAU, KOTOPEIi He OTHOCHTCA K TaKCOHY U3BeCTHOMY OT CBHTBI mMopucon. © pyro cTopoubl, Te HEMHOTOUNCAeHHbIe (parMeHTapHble HCKOMAeMBIe OCTATKH IO03BOHOUHBIX, OOHapyKeHHEe B IInactax I, II u III B uccaeqyemom paiione OTHOCATCA K XOPOMO U3BeECTHEIM TakCOHAaM MOpHcoHa. Kpome Toro, Bce 40 cHx Top W3BECTHHIE OOPaslbl U3 CBUTHI KAOBepan (IIaactsr V, VI u VII), noBuyuMomy, uMe- OT Oonee OAMBKHE CXOACTBA C BEPXHEMEAOBLIMM TAKCOHAMH, YeM C BHaMH MOPHCOH. ITO OOYCAOBAMBAeTCA HIN KPYMHBIM U3MeHeEHHEM BO BHEMHeH Cpese HAM 3HAYMTeIb- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 5 HHIM BPCMeHHBIM MpobeIOM MexKAY MOPHCOHOM HM KAOBePAM (HIM OOCMMM IpHunHaMnH ). Cpapnenue ¢ dayHoft cBuTH apyHyea Mopuaenga, canto P'sen Pos (rpynma Tpon- wa) Texaca H OktaXOMBI, Y9IeHCKUX NIacTOB ceBeposalaqHo Epponsl cBuyjeTesb- cTByeT 110 Kpalinefi Mepe 0 4acTHUHO OHOBpeMeHHOCTH CBUT KIOBepan u T'nen Pos, 0 CPaBHUTeIbHO CTaplieM BOspacTe WlacTOB apyHed u yoaten. BospacT Ka0Bepasn, Ha OCHOBAHHM HCKOMAeMBIX OesI03BOHOUHBIX HM WateoOOTAHHYeCKHX J[aHHBIX, Kak H HCKOMAeMBIX MO3BOHOUHBIX, MOBUHMOMY, IpHypounBaercA K O3sqHeMy allry H pauH- HeMy aiboy. ~ai ate, ae nays: © bana _— Sutin gr ie eepeeneres A a> » anes : aeoerryte & oe. . a are ie tae e ° an a sawe ' v + ar > ete : , iuyeree » & ; : eiage wif . eee e > 4 s e 1. INTRODUCTION The Mesozoic section in much of the western interior of the United States is charac- terized by a prominent sequence of nonmarine, variegated claystones and sandstones measuring up to 700 feet (200+ m) in thickness that is generally considered to be of Late Jurassic and Early Cretaceous age. The lower part of this sequence, widely re- ferred to as the Morrison Formation, has produced perhaps the most significant and diverse terrestrial vertebrate fauna known from all of the Mesozoic. The upper part of the sequence is variously referred to as the Cloverly, Kootenai, Dakota, Inyan Kara, Lakota-Fuson, Gannett, Lytle, Cedar Mountain or Burro Canyon Formation, but until now it has contributed less than half a dozen fragmentary fossil vertebrate speci- mens to our published knowledge. After years of debate, the age of the Morrison Forma- tion is now generally accepted as Kimmeridgian to Early Portlandian (Simpson, 1926; Baker, Dane and Reeside, 1936) ; the overlying nonmarine strata are considered as Aptian or Early Albian (Peck, 1941, 1951; Peck and Craig, 1962; Stokes, 1952). The apparent absence of fossil vertebrates in strata overlying the Morrison Forma- tion, together with the fact that Early Cretaceous vertebrates are exceedingly rare and poorly known from all regions of North America, prompted the present investigation. Added to these were the efforts of several individuals, particularly during the 1930's and 1940’s, that resulted in intriguing collections purportedly from the Cloverly For- mation of Montana. None of this early work has been reported, but the nature of the materials indicates that a fauna quite distinct from that of the Morrison Formation apparently does exist in the upper part of this nonmarine sequence. In spite of inade- quate stratigraphic data, it appeared that these collections might well represent the most significant evidence available of Early Cretaceous vertebrates in the Western Hemisphere. Aside from these earlier unreported collections from the “Cloverly”, the sum total of our knowledge of Early Cretaceous terrestrial vertebrates in North America rests on very fragmentary or isolated materials from: 1) the Arundel Formation of Maryland (Marsh, 1888; Lull, 1911a, 1911b; Gilmore, 1921), 2) the Trinity Group of Texas and Oklahoma (Larkin, 1910; Stovall and Langston, 1950; Patterson, 1951, 1955, 1956; Slaughter, 1965), 3) the “Lakota” of South Dakota (Lucas, 1901, 1902; Gil- more, 1909), 4) the Kootenai of Montana (Olson, 1960), and 5) the Dakota of Kansas (Eaton, 1960). In addition, a solitary specimen, often cited as Late Cretaceous in age but almost certainly from the Dakota sandstone capping Como Bluff in south- ern Wyoming, the type of Nodosaurus textilis, was described by Marsh (1889). These constitute the published record of Early Cretaceous vertebrate life in North America. Although the Late Jurassic-Early Cretaceous continental sequence is widespread throughout most of the western interior (exposures of part or all of this sequence 7 8 PEABODY MUSEUM BULLETIN 35 occur locally in New Mexico, Arizona, Texas, Oklahoma, Colorado, Utah, Wyoming, Montana, Idaho, South Dakota and Kansas), the present study was restricted to a relatively small area in north-central Wyoming and south-central Montana (Fig. 1). Reconnaissance of several possible areas by the writer during the summers of 1957 and 1958 indicated that the periphery of the Bighorn Basin and adjacent regions offered the most extensive exposures of the critical upper part of the section. Another decisive factor was the unreported collections mentioned above of Barnum Brown, Roland T. Bird, A. Silberling and J. W. Stovall from this and nearby areas in Mon- tana. The area selected comprises parts of Hot Springs, Washakie, Big Horn and Park Counties in Wyoming and Carbon, Big Horn and Yellowstone Counties in Montana. The precise area is shown in Figure 2 (in pocket). Within this area the upper part of the continental sequence is referred to as the Cloverly Formation (Darton, 1904, 1906), although in the northern sectors it is sometimes termed the Kootenai. Limited investigations were also carried out in parts of Fremont and Teton Coun- ties, Wyoming, and Wheatland County, Montana; some of the results are included in this report. Stratigraphic comparisons, but no collecting, were also extended to Weston, Albany, Johnson, Natrona, Carbon and Sheridan Counties in Wyoming and to Judith Basin and Fergus Counties in Montana. FIG. 1. Index map showing the location of the area including in this study. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 9 ACKNOWLEDGEMENTS The cooperation and assistance of a great many individuals contributed immeasurably to the successful completion of this study. It is not possible to mention each contribu- tor by name—the list is much too long—but I am indebted to everyone who aided us in this project. I am grateful to Drs. Edwin H. Colbert and Bobb Schaeffer of the American Museum of Natural History for making available the field records and notes of Bar- num Brown and Roland T. Bird and for permission to borrow and study the Cloverly collections made by these two men. I am also indebted to Dr. Glenn L. Jepson of Princeton University for permission to study the two fine specimens collected by A. Silberling and to Dr. David B. Kitts of Oklahoma University for arranging the loan of two specimens collected by Drs. J. W. Stovall, Wann Langston and Donald Savage. My thanks also go to Dr. Langston of the University of Texas for providing informa- tion pertaining to the sites of these last two specimens. Field exploration and collecting cannot be carried out without the cooperation and consent of local residents and landowners. I am grateful to the scores of individ- uals in the Bighorn Basin and Crow Indian Reservation who greatly facilitated our work and who on more than one occasion extended a generous and most welcomed helping hand to save us from gumbo, broken axles and camp cooks. I especially wish to acknowledge the assistance and hospitality of Dr. Harold McCracken, Director of the Whitney Gallery of Western Art in Cody, Wyoming; the Tillett family of Lovell, Wyoming—Lloyd, Royce, Ab, Marion and Bess; the Wilford Frazier family of Billings, Montana; Thor Lande, Tom and Nell Edwards, Paul Petersen, Richard Leavitt and Lee Hoffmann. On behalf of all the crew I extend sincere thanks. A major part of the area investigated lies within the Crow Indian Reservation in southern Montana. Exploration of these areas was facilitated by the Crow Tribal Council and officials of the Bureau of Indian Affairs: Superintendent Otto Weaver, Director of Area Affairs Ned O. Thompson, Realty Officers Robert Seitz, R. S. McDermott and Geneva Miller. Reconnaissance of limited areas in the Wind River Reservation of Wyoming was approved by the Arapahoe-Shoshone Joint Tribal Coun- cil, Superintendent Clyde Hobbs, and Realty Officers Robert Schoewe and Geneva Miller. Field assistants during the five field seasons (1962-1966) were: Ray Breuninger, Thomas Churchill, Jon Hall, Larry Spencer, Gary Wright, Stephen Burrell, Harold Brown, Robert Bakker, Marc Hecht, Peter Parks, Roger Rice, Frederic Mulhauser, Roseanne Leidy Pilbeam, Ralph Molnar, Donald McGuire, Scott Frazier, John Thomson, John Russell, John Marr, Farish and Eleanor Jenkins and Grenville Thoron. These students were ably supervised by Roy Winslow, Thomas Walsh, Grant Meyer, Peter Parks, Ronald Brown and Clyde Weinman of the Peabody Museum staff. I am grateful to each for a job well done. I am indebted to Dr. Douglas Coombs of the University of Otago, Dunedin, New Zealand, for petrographic analyses of concretion samples from the middle part of the Cloverly Formation. 10 PEABODY MUSEUM BULLETIN 35 The illustrations were prepared by Ward Whittington and Roseanne Rowan, the maps and charts by Mary Ann Clow, Judy Chaney and Daphne Zachary. Rebekah Smith ably assisted in the preparation of charts and maps and in data compilation. Photographs in Plates 1-21 are by John Howard, A. H. Coleman, Thomas Brown and the author. Photographs of Plates 22-27 are by Elwood Logan of the Division of Photography, The American Museum of Natural History. I am grateful to Louise Holtzinger, who typed the entire manuscript, and to Jeanne E. Remington and Elizabeth G. Weinman, Editors of Peabody Museum publications. Finally, I am most appreciative of the efforts and advice of Drs. Karl M. Waage, J. D. Love, Eugene Gaffney, Bobb Schaeffer and Edwin H. Colbert who have read and criticized various parts of the manuscript. They are in no way responsible for the conclusions and interpretations presented here: these are solely the responsibility of the author. This investigation was supported by grants from the National Science Founda- tion (G-23624, GB-1015, GB-3638 and GB-5451), the John T. Doneghy Research Fund of the Peabody Museum and the Sheffield Scientific Fund of Yale University. I am also indebted to the John Simon Guggenheim Foundation for the fellowship which enabled me to study extensive collections from the European Wealden and Greensand Formations. This report is published with the aid of a National Science Foundation Publication Grant (GN-528). Abbreviations: Institutional names have been abbreviated as follows throughout this report: AMNH — American Museum of Natural History, New York City, New York BB — Buffalo Bill Museum, Cody, Wyoming BM (NH) — British Museum (Natural History) , London CM — Carnegie Museum, Pittsburgh, Pennsylvania FMNH — Field Museum of Natural History, Chicago, Illinois IRSNB — Institut Royal des Sciences Naturelles de Belgique, Brussels NMC — National Museum of Canada, Ottawa, Ontario OU — J. Willis Stovall Museum of Science and History, University of Okla- homa, Norman, Oklahoma Pw — Princeton University Museum, Princeton, New Jersey ROM — Royal Ontario Museum, Toronto, Ontario SM — Sedgewick Museum, Cambridge University, Cambridge UKM — University of Kansas Museum, Lawrence, Kansas USNM — United States National Museum, Washington, D.C. YPM — Peabody Museum of Natural History, Yale University, New Haven, Connecticut Zoo Rey PGR APE Several factors require that a detailed analysis of the stratigraphy, including a review of previous investigations, be presented before consideration is given to the systematic paleontology. First and most important of these is the necessity of providing a frame- work in which to record the precise stratigraphic occurrence of all fossil collections. Second, because of the many conflicting interpretations and diverse definitions by past workers (Fig. 3), there is considerable confusion as to exactly what has been, or may be, intended by past and current use of the terms “Cloverly, Morrison, Greybull, Pryor, rusty beds”, etc. Consequently it is essential that stratigraphic terminology as used in this report be clearly defined and compared as precisely as possible with the usage of previous workers. To accomplish this, it was necessary to visit the sites of all previously published measured sections. Charts 1 to 7 compare these earlier interpre- tations of specific sections with the terminology of this report. The sole purpose of the lengthy stratigraphic discussion which follows is to elimi- nate diverse or inconsistent applications of terminology as a source of confusion, so that the collections reported here can be placed in any or all stratigraphic contexts (Darton’s, Lee’s, Fisher’s, Hewett’s or Moberly’s, etc.). It is not important to me at this point which usage the reader prefers. What is important is that stratigraphic data relating to our collections be accurately and unmistakably translatable into terms that have been used by others. Darton’s Cloverly Formation exists as a formal term, at least, and has been applied by numerous geologists to rock strata within the western in- terior. It has not yet been demonstrated, however, whether or not his specific lithic units can be recognized with certainty outside the immediate vicinity of his type area. Most geologists after Hewett and Ziegler believed that they could distinguish between Dar- ton’s Cloverly and the Morrison Formation; a few, however, have declined to select a boundary. Whether or not this nonmarine sequence should be subdivided into two for- mations is not of primary concern in this report (although it is my own opinion that such twofold division is both useful and warranted on stratigraphic grounds). The primary concern is whether Darton’s Cloverly Formation can be recognized with cer- tainty throughout the Bighorn Basin and adjacent regions, My conclusion is that it can. In the discussions that follow it will be evident that identification and correlation of specific lithic units within the Morrison-Cloverly sequence are often extremely diffi- cult. Persistent key horizons are rare or difficult to recognize in widely separated ex- posures. Few lithic units seem traceable over great distances with any degree of con- fidence. Correlations between spot localities are questionable, to say the least, due to pronounced lateral and vertical facies changes, wedging and erosional gaps in the section. The only practical method upon which to establish correlations is by walking out exposures, but, in spite of an abundance of exposures in the study area, outcrops are discontinuous and in some places separated by several miles or more. Fortunately (or unfortunately), the only means of discovering fossil vertebrate remains is by walk- ing out exposures, and in the course of our search the entire outcrop belt of the Morrison-Cloverly sequence encircling the Bighorn Basin (Fig. 2, in pocket) was tra- versed. The generalized stratigraphic section that follows is based on observations and data collected on this traverse. Documentation is presented at the back of this report in 11 12 PEABODY MUSEUM BULLETIN 35 Darton Darton Fisher Fisher |Washburne Lupton Ziegler Hores Hewett | Bouer & Moulton & Lupton | Robinson & Knappen 1904 1906 1906 1908 rm ISI6 1917 ISI7 1917 1923 1927 Southern & or a bermce: Pryor esi 0a ane a | cosy | sence | % [eos | ae | iovery prior Min s Benton Formation __ Ee Lower Benton Fm. Benton Fm. Thermopolis sn | Thermopolis Sh. ermopolis sn | Rusty Series 2 = TION Ze = ! Cloverly Formation & | | Cloverly Formation Cloverly Formation Cloverly Formation Cloverly Formati Cloverly Formation Cloverly Formation ' i Me) et iol esi E. ic i ee) 2 Q oO Morrison Formation Morrison Formation | Morrison Formation Morrison Formation Morrison Formation Morrison Formation Morrison Formation Fic. 3. Comparison of Upper Jurassic - Lower Cretaceous nonmarine the 28 measured sections of Appendix A (see also Fig. 4, in pocket) and in several pho- tographs at critical localities (Plates 1 to 7). The Mesozoic sequence is extensively exposed in the study area along the eastern, southern and northwestern margins of the Bighorn Basin and around the western and northern flanks of the Pryor Mountains. Outcrops occur in low cuestas, prominent hogbacks and extensive badlands bordering the Bighorn, Owl Creek, Pryor and Absaroka—Beartooth Mountain uplifts and in numerous subsidiary anticlinal structures. Near the middle of this section is a sequence of 200 to 600 feet (60 to 180 m) of varie- gated, often brightly colored, claystones, fine-grained to conglomeratic sandstones, shales and channel sands of continental origin. These beds are usually mapped as a single unit “Morrison-Cloverly undivided’, although most discussions treat the two formations separately, Of the two, only the Cloverly Formation is based on local stud- ies and can be referred to a local type section. The term “Morrison” has been ex- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 13 Johnson Thom, Holl, Wilson |Lommers | Pierce & | Love, Gordner, | Andrews | Pierce Rogers, | Richards | Moberly | Mirsky Wedgeman & Moulton Andrews ef al et al & Eargle et al 1934 1935 1936 1939 1940 1945 1946 1947 1948 1948 1955 1960 |19620b Crow Sy Carbon Co. Big Horn | Park Co, Bs ek Cody Pryor Leghorn | Montana Pryor Min Hae is Poper err] Thermopolis Sh. Thermopolis Sh. Thermopolis ss | Thermopolis Sh. c ° = ~ Ww 4 7 2 s.1e E35 E Selge —E |®o _ 9-2 4 Seis jan 9 Pea gS 8 3S GC AG x is) reybull |Greybu e i) E S. SS a g Po j.3 Te nn nee = s : 5 5 5 i 2) — ee as “| (=| \ sai 2 o Wa) (i ° 6 ie oi Sie ral ANA = qe oti wht ma ~ wD I o eS © il i 2 lh <4 ins io pi S re) ed =| = ee = le se.) ee A lg ie 5 o \|£ Otter Cr 1) Seiten é SS. 5— ee — ne ud bit} oS c=] o (S) Oo Cloverly Formation Morrison Formation | Morrison Formation | | . a Morrison Formation | | son Formation Morrison Formation Morrison Formation Morrison Formation Morrison Formation Morrison Formation Morr Morrison | Fm. Sundance |Sundance|Sundance |Sundance|Sundance |Sundance |Sundance} Ellis Sundonce |Sundance}Sundance} Swift | Sundance |Sundance | Sundance Fm Fm Fm Fm Fm Fm Fm Fm Fm Fm Fm Fm Fm Fm Fm stratigraphic terminology as used by previous workers in the Bighorn Basin area. tended to this area through common practice from the classic Morrison exposures in Colorado, chiefly on the basis of nearly continuous surface exposures and of well logs that show Morrison type lithologies are present in the subsurface. Only Mook (1916) has published regional studies comparing the Morrison facies between Colorado and northern Wyoming. In the study area, the nonmarine sequence lies with apparent conformity on glau- conitic, calcareous sandstones and shales commonly rich—even coquinoid—in marine invertebrate remains, In this study the base of the nonmarine sequence was placed at the highest occurrence of marine invertebrate fossils because of the highly variable lithologies immediately above that level. The Morrison-Cloverly sequence is overlain conformably by some 300 to 600 feet (90 to 180 m) of fissile, black, bentonitic, marine shale. The underlying unit is referred to as the Upper Sundance Formation; the over- lying unit as the Thermopolis Shale. 14 PEABODY MUSEUM BULLETIN 35 GENERALIZED STRATIGRAPHIC SECTION It is almost superfluous to note that the Morrison-Cloverly sequence varies considera- bly from one place to another, but this is by far its most prominent feature. Variation consists of changes in rock type and color, topographic expression and differences in sequence and thickness. Yet within this variable sequence is a broad pattern that is quite persistent—at least within the study area. The lower half of the section is nor- mally calcareous, regardless of lithology. Claystones are calcareous and locally contain calcareous nodules or thin freshwater limestone strata. Sandstones usually feature cal- careous cement. On the other hand, the upper half of the section is rarely calcareous. Instead it is rich in authigenic silica and bentonite. Moberly (1960) noted this dis- tinction, but otherwise it apparently has been overlooked in the Bighorn Basin. The nonmarine sequence can be divided into eight recognizable major units within the study area. Although one or more may be absent at a given locality, several are remarkably persistent throughout the region and most can be recognized in particular outcrops. Some of these have been noted by other workers and a few have been for- malized as formations or members. These eight subunits are persistent enough and sufficiently distinct to serve as useful reference units for placement of the paleonto- logic materials and for consideration of stratigraphic interpretations. In order to avoid the multiple meanings that are associated with the classical terms now in use, numeri- cal designations are applied to these units in this report. The lower, calcareous part of the Morrison-Cloverly sequence has been subdi- vided here into three units (labeled Units I, II, and III) based chiefly on exposures in Hot Springs, Big Horn (Wyoming) and Carbon (Montana) Counties. Units I and III are massive or poorly stratified, drab-yellow to gray-green, silty claystones. They are very similar to each other, so similar in fact they cannot be distinguished in limited exposures or in the absence of Unit II. Unit II consists of 20 to 75 feet (6 to 23 m) of brilliant white to buff or yellow-green quartz sandstone, usually massive, cross- laminated, poorly jointed and calcareous with chalky-white chert grains. The upper, noncalcareous part of this sequence is subdivided here into four ele- ments (Units IV, V, VI and VII). Of these, the uppermost is by far the most persist- ent and prominent—in fact, it is the only part of the entire nonmarine sequence that apparently is not absent anywhere within the study area. These four units consist of a lower conglomerate or conglomeratic sandstone (Pryor Conglomerate of some au- thors) , a lower claystone (Unit V), an upper, discontinuous, channel sandstone which occasionally is conglomeratic (Unit VI) and an upper claystone (Unit VII). In con- trast to the claystones of the lower half of the sequence, Units V and VII are readily distinguished even in the absence of any of the other units. As will be shown, Unit V is everywhere characterized by frequent to abundant chalcedony and barite concre- tions, whereas these are absent in Unit VII and apparently in nearly all exposures of the lower claystones. Unit VII on the other hand contains rare to abundant, highly polished and rounded “‘gastrolith”’-like pebbles. While it may be argued that the occurence of chalcedony, like any other single character, should not be considered an absolute or distinctive feature upon which to CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 15 identify a particular stratigraphic unit, after traversing nearly all of the relevant exposures, I am satisified that this character can be so used in this region. The most significant evidence for this conclusion is the apparently constant stratigraphic posi- tion of chalcedony-concretion-bearing claystone within the Morrison-Cloverly se- quence. The Pryor Conglomerate (or an identical, black chert pebble conglomerate) , when present, always lies immediately beneath this claystone. And a brightly colored, non-chalcedony-bearing claystone always overlies it, frequently with a coarse, poorly sorted, feldspathic sandstone (Unit VI) lying between them. The origin of these chalcedony (and barite or calcite) concretions is not known. Chert concretions usually are characteristic of carbonate rocks and are thought by some to have resulted from selective replacement of calcareous matrix by amorphous silica. Chert concretions are much less common in detrital rocks, but when present appear to be secondary structures resulting from local concentration of silica during diagenesis. Detrital materials and primary bedding structures are preserved within such nodular bodies. The present examples, however, show no primary sedimentary structures, contain few or no recognizable detrital grains, and consist entirely of amor- phous chalcedonic chert, barite, or (in lesser amounts) calcite. They occur as widely scattered, isolated features, or are concentrated in restricted zones or local concentra- tions. A detrital origin seems improbable for there are no signs of abrasion and they are never associated with pebbles, cobbles or other coarse detrital fragments. The evidence seems to indicate a primary origin, presumably as a hydrous silica gel accu- mulated in irregular masses at various times during accumulation of volcanic ash and the detrital clay. Whatever the origin, the chalcedony-barite concretions are by far the most useful criterion for field recognition of the upper subdivisions of the Morrison- Cloverly sequence. As noted previously, Unit VII differs from Unit V in the abundant occurrence of scattered, well-rounded and highly polished chert or quartzite pebbles, held by some to be dinosaur stomach stones or “‘gastroliths”, and the complete absence of chalced- ony-barite concretions. In addition, Unit VII is generally much more brightly col- ored and is rarely bentonitic. The so-called gastroliths range from less than 1 inch (2.5 cm) to more than 6 inches (30 cm) in maximum dimension, but usually fall within the 1 to 2 inch (2.5 to 5 cm) range. Sample collections consisted of less than 3 percent nonsiliceous material. The source of these objects is not known, but no evi- dence was found during the course of this investigation to support the popular, but improbable, thesis that they represent dinosaur gizzard stones. Although often en- countered during quarry operations, not a single “gastrolith” was found closely asso- ciated with any of the numerous articulated skeletons collected by Yale expeditions. Dorr (1966) has presented evidence suggesting that such polished pebbles are wind- polished, but the general absence of even poorly defined facets on most pebbles from Cloverly exposure suggests other factors. Conclusive evidence has not yet been found, but the most plausible explanation to date attributes such highly polished pebbles to normal sedimentary processes (Stokes, 1942). Unit I. The lowermost unit consists of calcareous claystones? and siltstones, usually 1 The term claystone is applied to fine-grained sedimentary rock in which clay-sized grains pre- dominate, there is no bedding structure or it is obscure, and the rock is nonfissile, having blocky or conchoidal break in fresh samples. The term shale is applied to similar fine-grained sedimentary rock that possesses conspicuous parallel stratification and is fissile. 16 PEABODY MUSEUM BULLETIN 35 greenish in color with prominent red-brown banding locally and containing occa- sional or frequent, usually thin, discontinuous, calcareous sandstone lenses. It rests conformably, and at some places gradationally, on glauconitic sandstone, gray-green shale or limestone containing marine invertebrates. Thick, massive, nonresistant clay- stone or poorly stratified shale predominate, but locally resistant sandstones 1 to 10 feet (0.3 to 3.0 m) thick and thin limestone strata occur. Sandstone lenses are rarely clean, usually contain abundant clay matrix, and are marked by cross-laminations and occasional ripple-marked surfaces. Moberly (1960: p. 1168) reported the dominant clay mineral to be illite. Unit I varies from 70 to 170 feet (21 to 51 m) in thickness and corresponds to the lower part of the Morrison Formation of most workers. Unit IT. Overlying Unit I on a surface of some relief is a prominent, massive, white sandstone ranging from 10 feet (3 m) to more than 80 feet (24 m) in thickness, but normally about 45 feet (14m) thick. It varies from medium- to coarse-grained, locally with pebbles up to 10 mm in diameter. The coarse fraction consists predominantly of well-rounded grains of quartz and white chert, the latter making up 15 to 20 percent. The cement is calcite; the clay matrix is negligible except in the lower 1 to 3 feet (0.3 to 0.9 m). It weathers to pale greenish yellow, light tan or brilliant white, forms smooth, steep slopes or large, rounded knobs. Jointing is rare and vertical exposures accordingly are infrequent. Unit II generally is exposed in massive 10 to 20 foot (3.0 to 6.0 m), cross-laminated beds, but thinly bedded strata are present locally, especially near the top. It is a prominent ledge-former in the western and southern parts of the study area but has not been recognized with assurance in the northern areas, Unit II falls within the lower part of the Morrison Formation as it is defined by most students of this region. Unit IIT. This unit consists of 30 to 120 feet (9.0 to 36 m) of nonresistant, varie- gated claystone that weathers to greenish gray, pale yellow, light gray and pink. In general it resembles Unit I and in the absence of Unit II cannot be readily distin- guished from that unit. Locally, red-brown bands occur, but these are not as vivid or as common as those in Unit I. Fresh rock is dark to medium gray and gray green and breaks into irregular small chips. It is universally calcareous and silty. Thin, discon- tinuous calcareous sandstone strata are common and white limestone beds up to 1 foot (0.3 m) thick occur locally. At some localities, white to dark-gray calcareous concre- tions are abundant. The dominant clay mineral is illite, according to Moberly (1960: p. 1168). The unit commonly weathers to low-angle slopes except where it is pro- tected by an overlying resistant sandstone or conglomerate. Unit III corresponds to the upper part of the Morrison Formation as it has been redefined by Moberly (1960) and to the middle part of that formation as it has been interpreted by others. Unit IV. Overlying Unit III, particularly in outcrops along the west flank of the Bighorn Mountains north of Shell Creek and along the west and northwest flanks of the Pryor Mountains, is a thick, massive and very resistant conglomeratic sandstone and conglomerate, which has been formally recognized as the Pryor Conglomerate. Here it is designated Unit IV. Exposures are particularly well developed in the vicin- ity of Sykes Mountain, Crooked Creek, Red Dome and Bluewater Creek, but the same facies is present at about the same level near the type Cloverly section and northeast of Thermopolis. The unit varies from about 10 feet (3.0 m) to more than 50 feet (15.0 m) thick, generally weathers to a dark gray or gray brown and consists of coarse sand, pebbly sand and conglomeratic lenses. Pebbles and sand grains consist chiefly of CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 17 black, dark gray, or brown chert. Some light-gray quartzite and white quartz is present in northern exposures. Feldspar grains constitute less than 2 or 3 percent of the sand fraction. Clay matrix is generally lacking or only a minor component, but when pres- ent consists of kaolinite (Moberly, 1960: p. 1168). Pebble fraction varies greatly both laterally and vertically, pebbles generally being concentrated in 2 to 10 inch (5.0 to 25 cm) zones or in restricted (4 to 8 foot long [1.2 to 2.4 m]) wedges or cross-beds. Pebbles range from pea size to 2 inches (5.0 cm) in diameter. In the Pryor Mountain area, Unit IV caps many of the ridges and cuestas. The basal contact is sharp and may be unconformable regionally. C. J. Hares (1917) is credited with coining the term Pryor Conglomerate and was one of the first to adopt this unit as the basal mem- ber of the Cloverly Formation. Several subsequent studies have followed this usage (apparently equating it with the “conglomerate sandstone” described by Darton at the base of the Cloverly), but others place the Morrison-Cloverly contact well above this unit. Unit V. Unit IV is overlain by a rather persistent, predominantly unstratified, non- calcareous claystone, which varies from drab neutral, light to medium gray to pastel and sometimes rather brightly variegated colors. It is the variable nature of weathered coloration of this unit that apparently has caused much of the difficulty in subdividing the section. Where drab in color it resembles the claystones of Unit III; where brightly variegated it resembles overlying claystone that is here labeled Unit VII. In the ab- sence of intervening coarse clastic facies, no precise division can be made between Unit V and Unit VII. The claystone is typically medium to dark gray, sometimes greenish or with a purple tinge on fresh exposures. It is highly bentonitic, particularly in the upper part, and usually is rich in chalcedony, calcitic and barite concretions. Concretions occur either in distinct zones, or scattered throughout the entire thick- ness, and vary in abundance from rare to extremely abundant. Concretions usually are about fist size and range from white, milky gray, blue, lilac to yellow. Some are nearly opaline in appearance. In composition, they vary both locally and stratigraphically from pure chalcedony, quartz and chalcedony with minor amounts of calcite and/or barite, to nearly pure calcite or barite. The entire sequence varies from 20 (6.1 m) to nearly 200 feet (61 m) in thickness and features occasional, fine-grained, quartz sand- stone lenses and thin, finely crystalline, white limestone layers, both ranging up to 18 inches or 2 feet (0.45 to 0.61) m) in thickness. Occasional channel sands up to 30 feet (9 m) across and 6 to 12 feet (1.8 to 3.6 m) thick also occur, At some localities selenite crystals and white, pink or orange satin spar veins are common. Along the eastern perimeter of the Bighorn Basin, specifically in the Shell Creek, Cloverly and Sheep Mountain areas, a thin, highly weathered, fragmental tuff occurs in the upper part of Unit V. Ranging from less than 6 inches (15 cm) to more than 28 inches (70 cm) in thickness this tuff is prominently exposed as a brilliant white band in the upper third of Unit V. No sign of this unit was recognized in the northern, western or southern margins of the basin. Plates 1: A and B, 2: A and 3: A and B show this volcanic unit as a conspicuous white band near the top of Unit V. Unfor- tunately, this tuff is so highly altered that radiometric dates could not be obtained. Unit V typically weathers into low, rounded, pale-purple, gray or nearly white, sometimes pinkish-gray, vegetation-free, gumbo hills with very soft, “popcorn” surfaces strewn with chalcedony concretion fragments. At some localities the section is rather vividly colored, but at most exposures the colors are pastel or drab neutral 18 PEABODY MUSEUM BULLETIN 35 colors. Fresh rock is generally dark gray with little or no mottling; it breaks into ir- regular, waxy-lustered chips. Unit V corresponds to the upper part of the Morrison Formation of some authors and the lower or middle parts of the Cloverly Formation of others. It represents the middle portion of the Morrison Formation of at least two interpretations. Moberly (1960: p. 1145) has proposed this unit as the Little Sheep Mudstone Member of his redefined Cloverly Formation. Unit VI. Unit VI is a coarse-grained, discontinuous channel deposit that is almost always present at the top of the chalcedony-concretion-rich claystone (Unit V). The unit consists of 2 to 75 feet (0.6 to 25 m) of olive, yellow or brown, sometimes tan, “salt and pepper” sandstone. Locally it is pebbly, but rarely would it be considered a conglomerate. Sand grains are subangular to angular and consist largely of feldspar, quartz and some dark minerals. Coarse fragments are gray or yellow chert and light- colored quartzite in northern exposures, but chiefly white chert in southern outcrops. Unit VI is typically impure with considerable clay matrix that Moberly (1960: p. 1168) reports as predominantly montmorillonite. Locally, this sandstone may be well indurated, forming a massive, resistant ledge, but usually it is rather friable, disinte- grates readily, and is often concealed or poorly exposed at the base of steep cliffs or slopes formed by the overlying claystones. Parallel stratification is usually obscure; cross-laminations are common. The basal contact is sharp and irregular with relief up to 5 or 6 feet (1.5 to 1.8 m) over a 100 foot (30 m) distance. Clay pebbles and angu- lar fragments are common in the lower 2 to 6 inches (5 to 15 cm). The contact with the overlying claystone is usually gradational. Although the unit is discontinuous and clearly represents multiple channel sands, informal stratigraphic designation is justi- fiable because of the nearly universal occurrence of this facies at what appears to be a constant stratigraphic level. Unit VI corresponds to the basal sandstone of the Cloverly Formation as described by Darton (1906), but other students have included it in the middle or upper part of the Morrison while Moberly considers it part of his upper (Himes) member of the Cloverly. Unit VII. The most persistent, and one of the most prominent facies of the entire nonmarine sequence is the 20 to 100 feet (6 to 30 m) of brightly colored, variegated claystone that everywhere overlies Unit VI. These claystones are gradational with the underlying sands at most localities. Usually they weather into steep, “fluted” slopes or cliffs and occasional badlands with maroon, red, orange, deep-purple and red-brown colors predominating. Neutral grays and pastel shades occur rarely and locally. Chal- cedony concretions are lacking, satin spar occurs rarely, but highly polished pebbles commonly referred to as “gastroliths” are almost always present throughout the region and at some localities are extremely abundant. The pebbles often are concentrated at the base of the claystone cliffs or on the gentle slopes below, where they are associated with concentrations of chalcedony concretions, but they are derived from the steeper outcrops of Unit VII. (A random collection of these “gastroliths” consisted of 97 per- cent silica—quartz, quartzite, chert, chalcedony.) Fresh rock is generally light gray green to yellow and pale purple with dark gray-green and red-brown mottling. It breaks into large, irregular blocks with conchoidal fracture and abundant slickensides. Bedding is obscure or absent, except in the highest portions where it sometimes grades into thin-bedded sandstones or fissile shale. The unit is often sandy, rarely calcareous and only locally bentonitic. Sandstone strata and wedges from 2 to 6 feet (0.6 to 1.8 m) thick are common, consisting of quartz with some feldspar usually in well-rounded CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 19 grains. Unit VII represents the middle member of Darton’s Cloverly but has been in- terpreted as both the upper member of that formation and of the Morrison Formation. Unit VIII. Capping the vividly colored claystone of Unit VII is a persistent, but variable, sequence of up to 30 feet (9 m) of massive and/or thinly bedded sandstones and siltstones interbedded with gray to black, fissile shales. The entire sequence weath- ers to a yellow or rust-brown color and is often rich in ironstone concretions, black hematite laminae and abundant hematite and limonite staining. Where massive sand- stones occur, it stands up as a resistant cap rock. The sandstones consist of fine- to medium-grained, well-rounded quartz grains. Ripple marks and fucoidal impressions are abundant, locally occurring on virtually all bedding planes. True cross-beds are rare. Precise thicknesses are difficult to obtain because of the highly gradational nature of the contact with the overlying, black, bentonitic shale of the Thermopolis Forma- tion. No recognizable, persistent contact or horizon was found on which to separate one from the other. Unit VIII corresponds to the lowest part of the “rusty beds” of many authors. Moberly (1960) has proposed formalization of the “rusty beds” as the Sykes Mountain Formation based on exposures near the Montana-Wyoming state line north of Lovell. Where a massive sandstone is present, Unit VIII equals the Greybull sandstone of some authors. A major point I wish to make with regard to this generalized stratigraphic section is that it is possible to distinguish the two upper claystone sequences from each other and in most instances from either of the two lower claystones, regardless of whether or not intervening coarse clastic units are present. This separation is possible on the basis of the apparently constant disparate distribution of in situ chalcedony, calcite or barite concretions and highly polished “gastrolith” pebbles. During the course of this study, the two were never found in positive in situ association. “Gastroliths” (here- after referred to as polished pebbles or cobbles) were encountered only in the upper claystone (Unit VII), whereas chalcedony, calcite or barite concretions were never found above the level of Unit V. The two are frequently found in association on the surface, but this clearly is a secondary association due to concentration of polished pebbles on lower angle slopes beneath the usually steep exposures of Unit VII. Not a single chalcedony concretion was found on the surface above Unit V, nor were any concretions found in place in the nearly 60 fossil quarries that we excavated in Unit VII and the upper part of Unit VI. Polished pebbles, on the other hand, were fre- quently, although never abundantly, discovered in these excavations. It must be pointed out that only eight excavations were opened in Unit V, compared with nearly 60 above that Unit, so I must admit to the possibility that polished pebbles do occur below Unit VI. None were encountered, however, either in our excavations or in fresh rock exposed while measuring stratigraphic sections. This apparently constant relationship not only constitutes the most reliable crite- rion for distinguishing the two upper claystones but also permits recognition of the two middle sandstones or conglomerates (Units IV and VI). Thus, the Pryor Con- glomerate (Unit IV), which everywhere lies below a chalcedony-concretion-rich clay- stone, cannot be equated with the conglomeratic sandstone described by Darton at the base of his Cloverly type section which lies above a chalcedony-concretion-rich clay- stone. The boundary between the Cloverly and Morrison Formations in nearly all published reports has been placed at the base of a pebbly sandstone or conglomerate. Whether stated or not, the implication is that the sandstone selected corresponds to 20 PEABODY MUSEUM BULLETIN 35 Darton’s basal Cloverly facies. The following discussion, together with the 28 meas- ured sections at the end of this report (Appendix A), will show many of these corre- lations to be in error. Specifically, whereas Darton (1906) described what I have here labeled as Unit VI as the basal clastic facies of the Cloverly Formation, Hares (1917), Bauer and Robinson (1923), Lee (1927), Knappen and Moulton (1930), Thom, Hall, Wege- mann and Moulton (1935), Wilson (1936), Lammers (1939), Love et al. (1945), Gardner et al. (1946), Richards (1955) and Moberly (1962) have referred to a lower bed—my Unit IV (the Pryor Conglomerate of some authors) —as the lowest unit of the Cloverly Formation (Fig. 3). On the other hand, Hewett (1914), Ziegler (1917), Pierce and Andrews (1940), Pierce (1948), and Rogers et al. (1948) adopted the uppermost, transitional sandstones (rusty beds of Darton and others), or what I have here labeled as Unit VIII, as the basal Cloverly facies. In other words, depending on which of the three uppermost clastic units was present, or most prominent in the re- gions studied, all three upper sandstones (Units IV, VI and VIII) have been used as the basal Cloverly sandstone. Hintze (1915), Lupton (1916), Hewett and Lupton (1917), Lee (1927, in part), Thom, Hall, Wegemann and Moulton (1935, in part), Andrews and Eargle (1947) and Mirsky (1962a, b) seem to have adopted the same (or at least a similarly positioned) coarse sandstone as did Darton for the basal facies of the Cloverly Formation. Our traverses have established that all three sandstones are discontinuous—and of doubtful correlation even when present. In contrast, the intervening, fine-grained facies appear to be not only widespread but continuous and distinctive. This applies particularly to Units V and VII, which constitute the greatest part of the Cloverly Formation as defined by Moberly (1960) and in this report. My opinion at this point is that claystone fractions of nonmarine sequences may be of far greater value in sub- division and correlation of continental strata than are the coarse sandstone facies that are more conspicuous and traditionally relied upon. PREVIOUS STUDIES The earliest investigations of these nonmarine strata are those of Darton (1904, 1906). In his first report, Darton compared the stratigraphy of the Black Hills, Bighorn Mountains and Rocky Mountain Front Range regions. In the Bighorn area he recog- nized lithologies that he considered to be the same as those of the Morrison Formation in Colorado and adjacent to the Black Hills. Overlying the “Morrison”, he described (1904: p. 398) a “thin bed of sandstone which, from its stratigraphic relations and character, is believed to represent the Lakota of the Black Hills, overlain by and merg- ing into clays resembling the Fuson formation . . . it has been thought best to give this series a separate designation. Accordingly, ‘Cloverly’ is proposed, a name derived from a postoffice on the eastern side of the Bighorn basin.” No type section was cited and only the following general description was given (p. 398-399) : The sandstone member of the Cloverly formation usually gives rise to a line of knobs or low ridges on the divide along the eastern slope of the Bighorn uplift. Ordinarily it is a coarse grained, buff or dirty gray, cross-bedded, massive sand- stone, averaging 30 feet in thickness, but varying from 10-60 feet. The overlying CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 21 clay is rarely exposed, but in a few outcrops it is seen to be a reddish to ash- colored clay, locally of darker gray color and with a thickness of from 30 to 40 feet. Notice that this description was based on the exposure along the east flank of the Big- horn Mountains and that while it does correspond generally with the section exposed around the margins of the Bighorn Basin, the relationship to topography and the na- ture of the exposures are quite different. West of the Bighorns, the “basal sand” rarely forms ridges or topographic highs and commonly is concealed. The overlying clay- stone, on the other hand, is rarely concealed and usually forms steep, brightly colored, fluted slopes or cliffs. Darton’s original description of the Cloverly was followed in 1906 by a more ex- tensive discussion of general features, a detailed section recorded in the vicinity of the Cloverly Post Office (Fig. 2), which we may consider the type section (see my Plate 1:A), and brief descriptions of the Cloverly Formation at a number of other sites in the Bighorn region. Following publication of Darton’s 1906 report, a number of investi- gations were undertaken by others in other sectors of the Bighorn area, usually with reference to natural resources. Few of these were regional in scope, most dealt with only a limited area with little or no reference to adjacent areas. Many, in fact, merely cited Darton’s findings (apparently without examination of his sections) in subdivid- ing and labeling sections in their own areas. Because of the provincial nature of most of these earlier reports, the following discussion is similarly organized, treating local sectors separately within the total study area. CLOVERLY-SHELL CREEK AREA, The Cloverly-Shell Creek area encompasses the central part of Big Horn County, Wyoming, and includes the outcrops along Shell Creek, around Sheep and Little Sheep Mountains and the extensive but discontinuous bad- lands extending in a northwest-southeast-trending belt between Shell Creek and the junction of the Bighorn and Shoshoni Rivers. Describing the Cloverly Formation along the west flank of the Bighorn Mountains, Darton (1906: p. 52) wrote: “In the vicinity of Cloverly the formation varies in thickness from 50 to 125 feet, and to the east and north of that place it consists of sandstones which outcrop extensively in cliffs of massive buff-colored beds, mostly of moderately coarse-grained material. To the west the middle and lower portions of this sandstone change to a maroon color and some clay is intermixed with the sand. This rock weathers into badlands.” The section given by Darton (following page) was located 1.5 miles (2.4 km) west of Clo- verly, Wyoming. In his 1904 report, Darton defined the Cloverly Formation as consisting of a lower sandstone facies and an upper, brightly colored clay facies. He did not include an up- per sandstone. In his discussion of the overlying Benton Formation, however, he de- scribed (p. 399) the basal member as: “dark gray shales, in part sandy and of rusty brown color with occasional thin beds of brown sandstone. Locally, the sandstone expands into a bed of moderate thickness. It is possible that this portion of the forma- tion [Benton] represents the Dakota sandstone of other regions... .”” In his 1906 re- port, Darton altered his original definition to include a massive or thinly bedded sand- stone overlying the bright clay member of the Cloverly Formation, this in turn being overlain by a “rusty series” of the Benton Formation, Regarding correlation he wrote (p. 53): “The Cloverly formation is believed to represent the Lakota sandstone, Fuson formation and Dakota sandstones of the Black Hills region.” 22 PEABODY MUSEUM BULLETIN 35 This report Darton’s report Unit VIU: Light-buff sandstone (overlain by Benton shale) ... 10 Her (Man-colored: sandstone \4-%)45-5 <8 see ee eee 10 Maroon ielay <2). iatretasiiectepe ls. Seta ved ae een ies Reddish and tan-colored sandy clay .............. 10 ee Drabisandy clay! . setae a daegan ee ade eee op eee LOr te ; Deep manoon: sandyaclay. Sts, iturin 20555 a oa Hardatan-colored, sandstones: ay apretci ee Sane Siti Deep maroon to purple variegated clay ........... APs Lenses of, maroon sandstone). i .eusectsee ame Siam Deep umaroomsandy,clays)..0: isan ares 20) a Olive-green, soft, cross-bedded sandstone with hard Unit VI: layers (lying on maroon and drab-gray Morrison I 612) (8 aaa aR Aa LM ear i a it otal es Lysine 1A2 (RPS see Fisher (1906), working under Darton’s direction, relied on the latter’s sections along the eastern side of the Basin, simply quoting Darton’s descriptions of sections. Washburne (1908, 1909) thought the basal sand and middle clay members of the Cloverly were absent at many localities and attributed this to erosion prior to deposi- tion of the “rusty beds”. In discussing the gas-producing horizon in the Basin-Greybull area, Washburne (1908: p. 350) wrote: The “rusty beds” are a constant feature of the base of the marine Cretaceous. Seemingly they are as a group a true basal sandstone, resting upon a rather smooth surface of erosion. Beneath this erosional surface at some localities is a heavy sandstone, probably the lower sandstone of the Cloverly formation; but at most places the Cloverly sandstone is absent and the “rusty beds” rest upon ma- roon, pink, or bright-green shales which are regarded as part of the Morrison formation, though they may belong to the Cloverly. There can be no doubt as to the lenticular nature of the Cloverly sandstone and its absence over most of the area. The field evidence indicates that the sandstone was removed by erosion be- fore the deposition of the overlying marine strata of the Upper Cretaceous. The “lenticular sandstone” (Unit VI) is absent locally; for example, at several points in the extensive exposures between Bear Creek and North Fork Beaver Creek some 3 to 5 miles (4.8 to 8 km) north of the former Cloverly Post Office site, locally along the Cherry Anticline south of Shell Creek, in certain exposures west of Ther- mopolis and at several localities in the Beauvais Creek area of the Crow Indian Reser- vation. In the immediate vicinity of Cloverly, to the south at Shell Creek Dome and in the badlands along the south side of Shell Creek, this ‘basal Cloverly sand” is ever present, although it varies from less than 3 to more than 30 feet (0.9 to 9.0 m) thick. The field evidence mentioned (but not identified) by Washburne, which supposedly indicated that this sand was removed prior to deposition of the marine (Thermopolis) sequence, was never recognized by us, for whether or not the “basal Cloverly sand” is present, the brightly colored, polished pebble-bearing claystone (Unit VII) is present everywhere within the study area beneath the sandstone (Unit VIII) of the “rusty CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 23 series”. Thus Washburne’s second thought that the maroon shales beneath the “rusty beds” possibly belong to the Cloverly Formation would seem to be correct. Washburne repeated his interpretation in 1909 (p. 168) at the conclusion of his description of the section near the Montana state line: “In all other places examined none of the [Cloverly] formation above the basal sandstone is certainly present, and in most places the entire formation is absent. This hiatus is due to an unconformity separating the Cloverly formation from the overlying marine Colorado shale.” This statement is contrary to our findings. During the course of the present investi- gation, the entire outcrop belt of the Morrison-Cloverly sequence was walked out in the area shown in Figure 2. Throughout this area the “rusty series”, with or without a massive sandstone at its base, lies on variegated, maroon to red-brown or purplish claystone rich in polished pebbles (Unit VII). This in turn lies on either a massive, cross-bedded sandstone up to 70 feet (21 m) thick (Unit VI), or on drab, chalcedony- concretion-rich, bentonitic claystone (Unit V). Contrary to Washburne’s interpretation, we found no evidence to substantiate a post-Cloverly, pre-Colorado (Thermopolis) ero- sion surface in this area. Local absence of Unit VI is attributed to lack of deposition rather than erosion, for Unit VII is universally present in this vicinity. Hintze (1915), who formalized the term Greybull sandstone, described (p. 14-15) the Cloverly Formation in the Shell Creek area as consisting of sandy shales and clays, often brightly colored, tan, maroon, or purple, lying between two sandstone members, in typical section. It is to be noted, however, that the upper one of the sandstones is often wanting, and in such sections the outcrop is apt to be less conspicuous. This condition is noticeable on the south side of Shell Creek three miles east of the Sheep Mountain section above referred to, where the “Rusty Beds” of the lower part of the Colorado rest directly upon the variegated shales and clays of the central part of the Cloverly. The absence of the upper sandstone may be due to nondeposition or to erosion previous to the deposition of the Colorado sediments, . . . The absence of a massive sandstone at the base of the “rusty beds” (usually labeled as the Greybull sandstone) was noted at a number of sites west of Cloverly, along Crooked Creek near the Montana state line, and particularly within the Crow Indian Reservation. It appears that this unit grades laterally from a massive sandstone to thinly bedded strata interbedded with thin laminae of fissile, black shale. Hintze, how- ever, accounted for the absence of the upper massive sandstone by a pre-Colorado erosion episode in accordance with Washburne’s suggestion. The term Greybull sand, long used by drillers to refer to the gas-producing hori- zon in various fields along the eastern margin of the Bighorn Basin, was first formally applied to surface exposures by Hintze (1915: p. 15), who identified it with the prominent sandstone at the base of the “rusty series” in the Basin-Greybull area. Sub- sequent studies of surface geology have generally followed this usage, but identifica- tion of the Greybull sandstone in subsurface appears to have been inconsistent. The usual practice seems to have been to apply this term to the first massive sandstone below the Muddy Sandstone Member of the Thermopolis Shale, whether it was one of the discontinuous sands within the lower Thermopolis, a sand at the base of a “‘rusty series” (Unit VIII), or the “basal Cloverly sand” (Unit VI). 24 PEABODY MUSEUM BULLETIN 35 Hewett and Lupton (1917: p. 68) referred to only one section in this area, giving a brief description of the exposures in Shell Creek Dome. They list 25 feet (7.5 m) of conglomeratic sandstone, 75 feet (21.5 m) of variegated red “‘shale” and 25 feet (7.5 m) of upper sandstone, referred to as the Greybull sand, in their Cloverly Formation. These correspond to Units VI, VII and VIII (see Chart 1) of our section at Shell Creek Dome (Section 12 of Fig. 4). Lee (1927: Pl. 2) described a section measured 2 miles (3.2 km) west of the for- mer Cloverly Post Office site, near Darton’s type section. His section corresponds closely to that of Darton, except that it is slightly thicker (see Chart 1). Lee recorded the “basal Cloverly sand” as 35 feet (10.6 m) thick (compared with Darton’s 11 feet) and the overlying variegated claystone member, including a 10 foot sandstone, as 105 feet (32 m) (compared with Darton’s figure of 82 feet). We found exposures which closely approach Lee’s description approximately 1 mile (1.6 km) north of the small reservoir on Beaver Creek (see Plate 1:A). Of particular importance here is Lee’s notation that he did not observe a lower ‘“‘brown conglomeratic sandstone” below the “basal Cloverly sandstone” such as he observed in exposures near Hyattville (p. 62) and Thermopolis (p. 59). However, we found just such a lower conglomeratic sand- stone (Section 14 of Fig. 4) about 3.5 miles (5.6 km) east of the type exposures, which is indistinguishable from the Pryor Conglomerate. This latter unit, with its abundant black chert pebbles, has tentatively been labeled Unit IV. The absence of a second or lower conglomeratic sandstone in the type area may be a significant contributory factor in the conflicting placements by various students of the Morrison-Cloverly boundary throughout the Bighorn area. To the north, the base of the Cloverly is most frequently placed at the base of the Pryor Conglomerate, which lies well below the level of Darton’s basal sandstone. On the west side of the Basin, the boundary is placed at the base of the most prominent conglomerate, or in the absence of a conglomerate, at the top of the variegated claystones. In the south, if a conglomerate is present, the boundary is placed there; otherwise it may be placed almost anywhere in the variegated claystone sequence. I think it is important to note here that while Darton did describe his basal sandstone member as conglomeratic at certain localities, he did not describe it as such in the Cloverly type area. The type basal sand can be traced to sites where it is conglomeratic, but clearly it is not persistently conglomeratic, nor is it continuous. It is also important, and unfortunate, that most of the continental section below Darton’s basal Cloverly sand is no longer exposed at the type section (a small dam across Beaver Creek has flooded this critical spot). However, a complete section is exposed in the twin buttes approximately 3.5 miles (5.6 km) to the east and here a Pryor-like conglomerate 18 feet (5.5 m) thick is well exposed approximately 100 feet (30 m) below Darton’s basal sand. This exposure is perhaps the most critical evidence indicating that the Pryor Conglomerate and Darton’s basal Cloverly sand- stone are not identical (see Sections 13 and 14 of Fig. 4). A second section recorded by Lee (1927: Pl. 2) is located 8 miles (12.8 km) northwest of Greybull on the west limb of the Sheep Mountain Anticline. This is in the vicinity of Section 17 given at the end of this report (Appendix A). In this section, Lee assigned 293 feet (94 m) (+ 100 feet of overlying Greybull sandstone) to the Cloverly Formation and 260 feet (79 m) to the Morrison; the total is more than 250 feet (76 m) thicker than we observed for the nonmarine section anywhere in this area. The uppermost 35 to 95 feet (9.5 to 30 m) of variegated claystone of Lee’s section are CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 25 here equated with Unit VII, the underlying 200 feet (61 m) with Unit V. Lee’s 260 feet of “Morrison” may correspond with the lower part of Section 17 (Fig. 4), which may be either Unit III or I (Chart 1). A very different usage is given by Pierce (1948) in his geologic map of the Basin- Greybull area. Pierce does not separate the Morrison-Cloverly sequence, but in his columnar section he includes the Greybull sandstone as the lower member of the Cloverly, with the overlying “rusty beds’ composing the remainder of this Formation (Chart 1). Moberly (1960), in the most recent and comprehensive stratigraphic analysis of this sequence, redefined the Cloverly Formation to include the underlying 150 to 300 feet (45 to 90 m) of sandstones and claystones beneath Darton’s type Cloverly, restrict- ing the Morrison Formation to the lowermost + 200 feet (61 m) of nonmarine sedi- ments overlying the Sundance Formation. In general terms, Moberly’s new alignment compares with Darton’s 1906 classification and that used here as follows: Darton, 1906 ‘Dakota-like’”’ sandstone + “rusty beds” Variegated middle claystone member, Cloverly Fm. Basal sandstone member of the Cloverly Formation Morrison Formation (part) Morrison Formation (part) Morrison Formation (part) Sundance Formation Moberly, 1960 Sykes Mountain Fm. Himes Member of the Cloverly Formation “Tithic wacke”’ of the Himes Member, Cloverly Fm. Little Sheep Mudstone Member, Cloverly Fm. Pryor Conglomerate Member, Cloverly Fm. Morrison Formation Sundance Formation This Report Unit VIII + “rusty beds” Unit VII Unit VI Unit V Unit IV Units I, II, III Sundance Formation Moberly (1960: p. 1142) justified this expansion of the Cloverly Formation on the following grounds: A formation is a genetic lithic unit, and because of its genetic and economic sig- nificance, lithic constitution of a sequence is fundamental to subdivision into formations. Frequently, expediency for mapping an area has determined which lithic characters are selected for determining formational boundaries. However, as understanding the origin of a series of sedimentary rocks becomes of more value in the historical interpretation of an area, lithologic characters of greatest genetic significance, rather than those most easily mapped, must be selected for the determination of a formation. But for the final remark, I would agree with most of Moberly’s statement. Rock units, to varying degrees, reflect their genesis, and genetic characters may, and should, be utilized when establishing formal stratigraphic units. But the purpose of formalizing a stratigraphic sequence into formations and members is not to define paleoenviron- ments any more than it is to establish rock ages; it is to classify or separate a variety 26 PEABODY MUSEUM BULLETIN 35 of lithic entities into practical, easily identifiable units. The fundamental objective is identity—the clear, unmistakable identification by everyone concerned. Formalization of a stratigraphic sequence, to this end, requires that it be based on the most conspicu- ous, reliable and persistent features available, whether or not they have recognized significance for any particular hypothesis of origin or theoretical lithotope. As noted earlier, my objective in these discussions is to equate our stratigraphic sections and the precise levels of the vertebrate fauna with the stratigraphic interpre- tations of others. It is unfortunate that so few of the early reports include detailed measured sections (or precise locations for sections), for without these data it is im- possible to arrive at an accurate equation. In the absence of detailed sections, the reader is forced to guess at the data that are the bases of an author’s interpretations and stratigraphic subdivisions. Chart 1 summarizes part of the above discussion by equating the few published sections from the Cloverly-Shell Creek area with the major subdivisions of the Morrison-Cloverly sections used in this report. These are based on observations made at the section sites mentioned or in the immediate vicinity of those sections. A total of seven localities (Locality Maps D, E, F and G) were discovered in the general area of the Cloverly Post Office site, Shell Creek valley, and Sheep and Little Sheep Mountains, which produced fragmentary but identifiable fossil vertebrate ma- terial. These materials are reported in the following section on systematic paleontol- ogy. Three of these localities (YPM 62-4, 62-5 and 62-6) are situated in the extensive outcrop area south of Shell Creek. Two of them occur in the lower part of Unit VII, from 5 to 15 feet (1.5 to 4.5 m) above its base. The third (YPM 62-6) is in Unit V approximately 30 feet (9 m) below the base of Unit VI. A fourth site (YPM 62-10) is situated at the south end of Sheep Mountain Anticline and is in Unit VI approxi- mately 10 feet (3 m) above its base. Three more localities (YPM 62-11, 62-12 and 62-13) are located approximately 18 miles (29 km) west of the Cloverly Post Office site on the south limb of Little Sheep Mountain Anticline near Himes, Wyoming (Locality Map G). All three lie in the upper 2 or 3 feet (0.6 to 0.9 m) of Unit VII. In addition, a number of other localities were recorded in this area, particularly west of “Cloverly”, south of Shell Creek and along both east and west flanks of Sheep Mountain, where abundant bone fragments were weathering out of the middle and lower parts of Unit V. No collections were made at these sites because exploratory excavations indicated that these bone concentrations were surface lag accumulations, the resistant residue left after removal of the bone-bearing claystone. The American Museum’s famous Howe Quarry (Brown, 1933, 1935) lies within this area in NE 4 sec. 9, T.54 N., R.91 W., (see my Fig. 2), and because Brown re- ported this site to be within the Cloverly Formation, it was carefully checked during our first field season. Exposures are poor and discontinuous in the area and faulting or slumping has disturbed the section sufficiently to make precise correlation difficult and uncertain. However, on both lithic and stratigraphic grounds I have concluded that the Howe Quarry lies well below the Cloverly Formation, and at least 150 feet (45 m) below Unit VI. Comparison with the Cedar Creek Section (measured Section 14 of Fig. 4), 1.5 miles (2.4 km) to the southwest, places this site near the middle of the lower claystone sequence (Unit III or I?), approximately 40 feet (12 m) below Unit IV. If the latter Unit is correctly identified as the Pryor Conglomerate, the Howe Quarry falls outside of the Cloverly (contrary to Brown’s [1933] statement), regard- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 27 less of whose usage is adopted. This placement appears to be consistent with the mate- rials collected there. The Howe Quarry collection is not given detailed analysis here, but the collections made there consist entirely of sauropod remains that are referable to Morrison taxa Camarasaurus and Diplodocus. HYATTVILLE-TENSLEEP-NOWOOD CREEK AREA. This region includes the southern part of Big Horn County and the central part of Washakie County. Outcrops parallel No- wood Creek from the northern county boundary to the common corner of Washakie, Hot Springs and Fremont Counties. In the north they form a long ridge along the west limb of Cherry Anticline. Badland type exposures are rare in this area, most outcrops occurring in low cuestas or prominent hogbacks. Darton (1906) was the first to con- sider the Morrison-Cloverly section in this area, describing (p. 52) the Cloverly For- mation at three localities as follows: On Nowood Creek, south of Tensleep, the formation consists of a massive light- colored sandstone about 40 feet thick, overlain by 30 to 60 feet of light-colored shale, mostly massive, and at the top a thin bed of buff to reddish-brown sand- stone 8 to 10 feet thick. A mile west of Tensleep the basal sandstone is nearly pure white in color, coarse grained, and cross-bedded. The overlying shale and clay are 60 feet thick and at the top are 8 feet of sandstone varying in color from white to buff and brown. In the vicinity of Hyattville the following members are exposed: At the base 40 feet of buff cross-bedded sandstone overlain by 130 feet of clays, reddish near the bottom, greenish and sandy higher up, maroon toward the top, and gray and sandy at the top. These clays are overlain by a 15 foot bed of hard, buff, partly massive sandstone succeeded abruptly by dark Benton shales with thin, brown sandstone layers. The first two sections coincide with our observations in those areas, the units men- tioned corresponding to Units VI, VII and VIII (Chart 2). The section at Hyattville, however, is interpreted differently here (Section 10 of Fig. 4). Within the 130 foot (39 m) claystone sequence mentioned by Darton, we found the lower 36 feet (11 m) consisted of pale-maroon to gray calcareous claystone apparently lacking in chalced- ony concretions. This is overlain by 38 feet (11.6 m) of brightly colored, variegated, red, deep-maroon, red-brown and gray claystone, partly bentonitic, with frequent chalcedony concretions. The upper 35 to 40 feet (11 to 12 m) is very similar to the underlying claystone except that chalcedony concretions were not found, whereas pol- ished pebbles are common, although not abundant. The universal absence of chalced- ony concretions above the level of Unit V elsewhere in the study area, and the ap- parent restriction of polished pebbles to claystones above this level, suggests that Dar- ton’s Cloverly claystone in the Hyattville area includes both Units V and VII, and that the lower 30 to 40 feet (9 to 12 m) overlying his ‘“‘basal sandstone” may repre- sent Unit III. At some exposures, particularly to the south and west of Hyattville, a thin, 1 to 6 foot (0.3 to 1.8 m), medium-grained, quartz-feldspar sandstone occurs approximately 35 to 50 feet (10.5 to 15 m) below the top of the claystone sequence. This may be a local wedge of Unit VI. The “basal sandstone” described by Darton in the Hyattville area, lying below a chalcedony concretion zone, appears not to corre- late with his basal sandstone in the type exposures; lithologically it is very similar to 28 PEABODY MUSEUM BULLETIN 35 the lowest prominent sandstone in the Thermopolis area (Unit II). On these grounds it is tentatively correlated with that Unit. Hewett and Lupton (1917) provide only the briefest general description of the Morrison-Cloverly sequence (p. 19) together with occasional comments on exposures in various anticlinal structures in this area. Referring to exposures in Paintrock, Mer- cer, Nowood and Bud Kimball Anticlines (p. 85, 91, 99 and 117-118), they note a uniform thickness of 125 feet (38 m) for the Cloverly Formation and 200 to 250 feet (61 to 76 m) for the Morrison. The latter is described simply as variegated “‘shales” and sandstones, the Cloverly as consisting of upper and lower sandstones, both 20 to 25 feet (6 to 7.5 m) thick (the lower one usually conglomeratic) and a middle varie- gated shale 75 to 80 feet (23 to 24.5 m) thick. Although we did not find the section to be so uniform, the comments generally agree with our findings at these structures. For example, at Bud Kimball Anticline south of Tensleep we measured the lower con- glomeratic sandstone (Unit VI) as 55 feet (16.5 m), the middle claystone, which contains abundant polished pebbles, as 35 feet (10.5 m) and the upper sandstone (Unit VIII) as 5 to 10 feet (1.5 to 3 m). At Paintrock Anticline the upper “gastro- lithic” claystone (Unit VII) is 45 to 50 feet (13.5 to 15 m) thick and underlain by a 4 to 6 foot (1.2 to 1.8 m) sandstone that I believe represents Unit VI. Beneath this is 125 to 135 feet (38 to 41 m) of variegated claystone (Unit V), 45 feet (13.5 m) of coarse, light-tan sandstone (Unit II?) and 175 feet (53.5 m) of drab, gray-green claystone and sandstones (Unit I). Throughout their report, Hewett and Lupton apply the term Greybull sandstone to the sandstone at the base of the “rusty series”, but they make an erroneous reference (p. 19) to the ““Greybull sandstone” illustrated in their Plate IVA, which they describe as lying unconformably on “variegated shales of the Morrison Formation near Tensleep”. The sandstone illustrated, however, is the basal sandstone (Unit VI) of Darton’s Cloverly and is overlain by brightly colored, varie- gated, polished pebble-bearing claystone (Unit VII)—not the “rusty series”. Lee (1927: p. 60-62) included descriptions of sections at Nowood, Tensleep, Hyattville, near Bonanza Anticline and north of Hyattville (Mercer Anticline?) (see my Chart 2). His description of the Cloverly section at Nowood, approximately 30 miles (48 km) south of Tensleep, matches my Units VI, VII and VIII, but Lee omits information about the thickness of his “Cloverly members”, thus these correlations cannot be verified. Lee’s Tensleep section lists a 70 foot (21.3 m) conglomeratic basal Cloverly sandstone, a 30 foot (9.1 m) middle “shale”? member and 10 + feet (3 m) for the upper (Greybull) Cloverly sandstone. These have been identified as Units VI, VII and VIII, although we obtained slightly different thicknesses. For some unex- plained reason, the above description does not match Lee’s Tensleep column (PI. 2) which lists these units at 45, 63 and 9 feet (13.5, 19.2 and 2.7 m), respectively. Of particular interest is Lee’s reference (p. 61) to a second conglomerate 7 feet thick beneath his “basal Cloverly sandstone”, which he judges as not part of the Cloverly Formation but corresponding to the coal-bearing part of the Kootenai. He does not attempt to equate this with a similar but thicker lower conglomerate that he (and we) noted 3.5 miles (5.6 km) northeast of Thermopolis, although this is an obvious possibil- ity. The fact that Unit V is apparently absent in exposures in the Tensleep vicinity (see Section 9, Fig. 4) may be significant and appears to lend support to this latter interpreta- tion. Except that it is significantly coarser grained and less brilliant white in color, I could find no evidence for separating the lower 6 to 12 feet (1.8 to 3.6 m) from the overly- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 29 ing 40-odd feet (12 m) of sandstone at this site, but it is entirely possible that this prominent massive unit represents both Units IV and VI of our classification. Lee’s descriptions of the Cloverly exposures immediately south of Hyattville seem to cor- respond to elements that we labeled VI, VII and VIII (Section 10, Fig. 4), but again he provided no thicknesses. North of the Bonanza Anticline, probably in the north end of the Paintrock Anticline, Lee estimated the lower Cloverly sandstone at more than 100 feet (30 m) thick and the “red, sandy shales containing many polished pebbles or ‘stomach stones’ ”’ at about 200 feet (60 m) thick. Overlying these he listed a 5 to 15 foot (1.5 to 4.5 m) sandstone (Greybull). We did not record a section at this lo- cale, but at no place in the Paintrock Anticline did we encounter thicknesses for these units of more than 50 and 135 feet (15 and 41 m), respectively. At this area, Lee again noted a brown conglomerate (which he compared with that near Thermopolis) 1 to 10 feet (0.3 to 3.0 m) thick, overlain by a carbonaceous shale, lying beneath his “lower sandstone member of the Cloverly”. I have tentatively identified it as Unit IV, correlating it with the Pryor Conglomerate to the north. In exposures 1 or 2 miles (1.6 to 3.2 km) to the south near Paintrock Creek, we found no sign of this lower, dark conglomerate. Furthermore, we found that only the upper 45 to 55 feet (13.5 to 18.5 m) of the variegated claystone sequence definitely represented Unit VII; the underlying 125 to 135 feet (38 to 41 m) of claystone is rich in chalcedony concretions and thus represents Unit V (and perhaps part of Unit III). No chalcedony concre- tions were found either above or below Lee’s “100 foot thick” Cloverly sandstone at the north end of this anticline, but polished pebbles are infrequently present in the overlying claystones. On this basis, Lee’s Cloverly Formation here is equated with Units VI, VII and VIII (Chart 2). Another critical section is exposed in the Mercer Anticline approximately 6 miles (9.6 km) northwest of Hyattville. Lee (1927: p. 62) described the section in a small dome (not identified by name, but presumed to be the above structure) in this locale as follows: Here a brown conglomerate consisting chiefly of pebbles of chert and ranging in thickness from 1 to 25 feet rests on variegated shale of the dinosaur-bearing Morrison formation. Above the brown conglomerate is a brown to black shale 5 to 20 feet thick containing carbonized plant remains and thin seams of brown lignite. The variation in thickness seems to be due to erosion, for the overlying conglomeratic sandstone rests on the shale with sharp irregular contact... . The higher conglomeratic sandstone is gray, massive, and cross-bedded and is 50 feet or more in thickness. It is the lower part of the Cloverly of northern Wyoming and is the lower conglomeratic sandstone of the group of rocks which the writer correlates with the Dakota group of Bellvue, Colo. Overlying the upper conglomeratic sandstone is 50 to 65 feet (15 to 20 m) of varie- gated claystone locally rich in polished pebbles that we identified as Unit VII, capped by massive and thinly bedded, buff to rusty-brown sandstone (Unit VIII). Exposures in the Mercer Anticline are generally poor, but we found no evidence of chalcedony concretions in the area, indicating that Unit V probably is absent here. Moreover, the upper conglomeratic sandstone could not be traced to other exposures north and south, between Shell Creek and Hyattville. However, I believe Lee’s interpretation is 30 PEABODY MUSEUM BULLETIN 35 correct and have assigned this sandstone to Unit VI. Thus Lee’s interpretation of the Cloverly in the Mercer Anticline corresponds to Units VI, VII and VIII of our classi- fication. The underlying lignitic shale and lower, brown conglomerate resemble very closely the sections in the north end of Paintrock Anticline and 3.5 miles (5.6 km) northeast of Thermopolis (see Section 6 of Appendix A and Fig. 4). At all three sites this conglomerate is characterized by black, dark-gray or brown chert and gray and brown quartzite pebbles. The sand fraction is also predominantly dark chert and quartzite. The resemblance to the Pryor Conglomerate is evident; accordingly, it is here designated Unit IV. It should be apparent to the reader that this part of the sec- tion also seems to correspond to part of the Tensleep section as interpreted by Lee. The sequence below this ‘“‘Pryor-like’” conglomerate is very poorly exposed in the Mercer Anticline, but presumably it represents either or both Units I and III. Rogers et al. (1948), in their geologic map of the Worland-Hyattville area do not designate a specific boundary between the Morrison and Cloverly Formations, al- though they do list the ‘““Greybull sandstone” (“5 to 70 feet of light-gray to brown resistant sandstone”) as the Jower member of the Cloverly! They describe the ““Grey- bull sandstone” as being overlain by “‘sandstone, siltstone and shale and several thin, interbedded ironstone or ‘rusty beds’ ” and underlain by a sequence of gray, red and light-purple claystone and shale and interbedded brown, lenticular sandstone contain- ing the so-called gastroliths. From this description it is clear that their “Greybull sandstone” corresponds to our Unit VIII, and that their Cloverly Formation (they list 125 feet [38 m]) consists chiefly of the overlying “rusty series”, Their Morrison For- mation thus includes our Unit VII and all underlying nonmarine elements. Moberly (1960) extended his redefined Cloverly Formation (equaling Units IV, V, VI and VII) to the vicinity of Hyattville, but no specific sections were described from this area (see Chart 2 for a summary of these previous interpretations) . Mirsky (1962a and 1962b) has presented the most detailed stratigraphic sections within this area. His initial contribution contained 20 measured sections, 6 of which are located in the Morrison-Cloverly outcrop belt between Nowood and Tensleep. These latter sections are duplicated in Chart 2 and correlated with the terminology used in this report, based on our examination of exposures in the vicinity of Mirsky’s sections, The same 20 sections form the bases of Mirsky’s more extensive paper on the stratigraphy of nonmarine Upper Jurassic and Lower Cretaceous strata (1962b) along both east and west flanks of the Bighorn Mountains. In brief, Mirsky recognized four major units, which he believed to be the same basic units recognized by Darton (1904). They are a lower, variegated mudstone, which Mirsky considered to be the Morrison Formation; a white to gray, cross-bedded sandstone, which he formalized as the Otter Creek Sandstone member of the Cloverly Formation; an upper, variegated mudstone, which he identified as the upper member of the Cloverly Formation (including an overlying sandstone) ; and an uppermost sequence of interbedded black shales and thin sandstones (“rusty series”), which he considered to be the basal strata of the Thermopolis Shale. Mirsky’s first unit, which varies from 210 to 265 feet (64 to 80.5 m) thick, corresponds to Units I, II?, and III of this report. The Otter Creek Sandstone corresponds to Unit VI, although there is some doubt as to whether or not this is the same as Darton’s type basal Cloverly sand- stone. The lower part of Mirsky’s mudstone member of the Cloverly corresponds to our Unit VII, and the upper sandy part of that member is equated with our Unit VIII. Thus Mirsky’s Cloverly Formation here corresponds to Units VI, VII and VIII. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 31 The Otter Creek Sandstone occupies the same stratigraphic position as the basal sandstone described by Darton at the type Cloverly exposures, but it cannot be dem- onstrated that it is the same unit. Lithologically it is quite different from Unit VI in the area north of Shell Creek, but it closely resembles the upper of two middle sand- stones at Thermopolis. In the outcrops between Tensleep and Thermopolis, the chalcedony-rich claystone (Unit V) is absent and the Otter Creek Sandstone lies dis- conformably on rather drab, calcareous and sandy claystone. At Tensleep, it is under- lain by 6 to 12 feet of gray, conglomeratic sandstone that resembles the Pryor Con- glomerate (Unit IV) of more northerly exposures. At Thermopolis (Sections 5 and 6 of Fig. 4), a thick sandstone resembling the Otter Creek Sandstone is underlain by a similar, dark-gray conglomerate that I have tentatively labeled as Unit IV, and which very closely resembles the Pryor Conglomerate. Certainly it is significant, I think, that a Pryor-like conglomerate occurs at the appropriate level in exposures at Mercer and Paintrock Anticlines, and at Tensleep (also Thermopolis), as well as near the type Cloverly exposures. Elsewhere between Thermopolis and the type Cloverly area this conglomerate (Unit IV) is absent, as is Unit V—the overlying chalcedony-rich clay- stone. In the vicinity of Nowood Creek at least there appears to be a parallel absence of Units IV and V. Correlated with this is the presence of a thick, coarse sandstone (Otter Creek Sandstone). It appears the absence of Units IV and V is the result of extensive erosion prior to or at the time of deposition of the Otter Creek Sandstone. There does not appear to be a significant angular discrepancy between strata above and below this level, but more data are required. Only two fossil vertebrate localities were found in the Hyattville-Tensleep area (Locality Maps B and C). The first (YPM 66-3) is located approximately 2 miles (3.2 km) southeast of Hyattville in gently dipping exposures north of Cedar Moun- tain. The stratigraphic level could not be determined precisely, but it is clearly within the limits of Unit VII at least 30 feet (9 m) below Unit VIII. Locality YPM 66-4 is in the southern end of Paintrock Anticline, approximately 6 miles (9.6 km) southwest of Hyattville. Again, the low angle of dip and the breadth of exposures made precise stratigraphic placement uncertain, but there is no doubt that it lies within Unit VII. THERMOPOLIS AREA. This area includes the central part of Hot Springs County, Wyo- ming. Outcrops of the Morrison-Cloverly section are limited to a sinuous cuesta flank- ing the Owl Creek Mountains and the Thermopolis and Warm Springs or Red Springs Anticlines. Interpretation of the stratigraphy in this area poses many questions, for exposures, although common, are discontinuous and often partly covered. Moreover, the Cloverly-Morrison sequence here is more variable and includes facies not represented (or recognized) in other areas. However, most of the eight major units have been identified. Fisher (1906) was the first to describe the Mesozoic strata exposed along the north flank of the Owl Creek Mountains, but his brief description of a Cloverly section at the west end of the Thermopolis Anticline is not adequate for comparison with sec- tions recorded by others or observed by us. Fisher’s 1908 report contained a more detailed section that he measured 3.5 miles (5.6 km) north of Thermopolis (probably not far from the site of measured Section 5 of this report). In his 1908 section (p. 85-86), Fisher recorded 40 feet (12 m) of variegated “shale” (Unit VII) beneath 32 PEABODY MUSEUM BULLETIN 35 ¢ 24 feet (7.3 m) of thin-bedded and massive sandstones and blue, drab “shale” (Unit VIII). The variegated “shale” rests on 38 feet (11.5 m) of massive, light-colored, cross-bedded, conglomeratic sandstone (Unit VI), which in turn lies on 59 feet (17.8 m) of greenish-brown “shale” (Unit III?). Beneath this, according to Fisher, lie 130 feet (39.6 m) of yellowish-gray, massive sandstone (Unit II). Fisher included this entire section, totaling 290 feet (88.5 m), in the Cloverly Formation (Chart 3). Hewett and Lupton (1917: p. 138) gave extremely brief descriptions of the Mor- rison and Cloverly Formations as exposed in Red Spring (Warm Springs?) and Lucerne Anticlines. Their Cloverly Formation appears to correspond to Units VI, VII and VIII of this report, but their descriptions are not adequate for detailed comparisons. Lee (1927: Pl. 2 and p. 58), in a section located 2 miles (3.2 km) northwest of Thermopolis, recorded 42 feet (12.7 m) of conglomeratic basal Cloverly sandstone (Unit VI), 82 feet (25 m) of variegated claystone (Unit VII) and 60 feet (18.3 m) of ripple-marked, rusty-brown sandstone (Unit VIII). Three and a half miles (5.6 km) north of Thermopolis, Lee registered (Pl. 2 and p. 58) a 90 foot (27.5 m) thick conglomeratic, basal (Cloverly) sandstone (Unit VI and possibly IV), overlain by 55 feet (16.5 m) of red and bluish sandy “shale” (Unit VII), topped by 53 feet (16 m) of thinly bedded sandstones interbedded with variegated “shales” (Unit VIII). A mile (1.6 km) to the east of this last section, Lee noted (p. 59) 25 feet (7.6 m) of brown chert pebble conglomerate (Unit IV) and 20 feet (6.1 m) of carbonaceous shale with plant remains, beneath a 75 foot (22.8 m) thick conglomeratic sandstone (Unit VI) that he correlated with the basal Cloverly sandstone of exposures to the west. Notice that this section correlates almost unit for unit with the sections described earlier at Paintrock and Mercer Anticlines, and possibly with Lee’s interpretation of the exposures 1 mile (1.6 km) west of Tensleep (see Section 6 of Appendix A and Fig. 4). These three sections, together with exposures in the type Cloverly area, are considered critical for correlation of the eight listed major units around the margins of the Bighorn Basin. J. D. Love and others (1945) published a series of stratigraphic columns of the Lower Cretaceous and nonmarine Jurassic rocks in central Wyoming that included a column measured approximately 4 miles (6.4 km) north of Thermopolis. The column included some 18 feet (5.5 m) of variegated claystone (Unit VII) beneath the “rusty beds”, underlain by a massive 25 foot (7.6 m) thick conglomeratic sandstone (Unit VI) resting on more than 50 feet (15 m) of variegated claystone. The claystone overlies some 38 feet (11.5 m) of conglomeratic sandstone (Unit IV?) resting on light and dark-green siltstones (Unit III?). This rests on 150 feet (45 m) of massive gray sandstone (Unit II). It appears likely that Love’s lower conglomeratic sandstone is the same as the lower, brown chert pebble conglomerate of Lee’s third section, and the one noted by us at the sites of measured Sections 5 and 6. Love et al. did not subdi- vide the nonmarine section, but they noted a zone of “sparkly, clean, porous, soft sand- stone with lenticular chert pebble conglomerate” and related this to a quartz crystal sandstone at the base of the Cloverly in areas outside the Bighorn Basin. The sugges- tion is made that the base of this quartz sandstone may represent the contact between the Morrison and Cloverly Formations here. It is evident from these reports that two conglomeratic sandstones occur at least locally in the Thermopolis area (one locale at which the lower of these is absent is CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 53 Warm Springs [Red Springs?] Dome approximately 10 miles (16 km) east of Ther- mopolis, as noted by Lee), separated at some places by 10 to 50 feet (3 to 15 m) of drab-green, lignitic claystone. At exposures on the west side of U. S. Highway 20, approximately 3.5 miles (5.6 km) north of Thermopolis, we found both of these con- glomerates represented (but not separated) although they apparently were not rec- ognized by either Fisher or Lee, both of whom recorded measured sections in this immediate vicinity. The intervening claystone is absent at these outcrops, but as re- corded in Section 5 (Fig. 4), the lower 15 feet (4.5 m) of the prominent massive sandstone facies weathers dark gray to brown and consists largely of black and brown chert pebbles up to 1 inch (2.5 cm) in diameter—identical to the lower con- glomerate exposed less than a mile (1.6 km) to the east across the Bighorn River. The overlying 35 feet (10.6 m) of sandstone weathers white to tan, is conglomeratic in its lower third with pebbles predominantly of light-colored quartzite and white chert— identical with the upper conglomerate across the river. This upper conglomerate is interpreted here as the “basal Cloverly sandstone” (Unit VI) and may also be corre- lated with the Otter Creek Sandstone Member of Mirsky (1962b). The lower one, on both lithologic and stratigraphic grounds, appears to correspond to the Pryor Con- glomerate of more northerly exposures and is here labeled Unit IV. The chalcedony-rich claystone facies (Unit V), which occurs between two very similar conglomeratic sandstones to the north in Big Horn County, is absent in the Thermopolis area and in outcrops to the east and north at least as far as Hyattville (it occurs locally in Paintrock Anticline and exposures immediately south of Hyatt- ville [see Section 10 of Fig. 4], but not in Mercer Anticline northwest of Hyattville) . But, Unit V is everywhere present in exposures west of Thermopolis and north of Mercer Anticline. Absence of Unit V in this area should not be considered reason for discounting the possible equivalency of the lower, chert pebble sandstone with the Pryor Conglomerate, for stratigraphic relationships in the Thermopolis area clearly indicate a significant erosion surface exists at the base of the upper conglomeratic sandstone (Unit VI), as suggested by Lee, (1927: p. 59, 62). The variable presence and thickness of carbonaceous shale between these conglomerates (see Lee’s sections at Paintrock and Mercer Anticlines, and east of the Bighorn River at Thermopolis; also our Sections 5 and 6 of Fig. 4), support such an interpretation. It is probably significant that this erosion surface also correlates with the absence of Unit V and, at some places (Warm Springs Dome), Unit IV. It appears that removal of Unit V, part or all of Unit IV and perhaps the upper part of Unit III occurred during influx of the conglomeratic phase of Unit VI in the southeastern part of the Bighorn Basin. It is perhaps significant that in this area wherever Unit V (and sometimes Unit IV) is absent, Unit VI is usually conglomeratic and has near-maximum thickness (see Sec- tions 5, 6, 7, 8 and 9 of Fig. 4). Wherever Unit V is present, Unit VI is almost always thin (or absent) and is rarely conglomeratic. Section 5 of Appendix A (and Fig. 4), taken at the prominent exposures on the west side of U. S. Highway 20, 3.5 miles (5.6 km) north of Thermopolis, includes an up- per, brightly colored, variegated claystone 67 feet (20.4 m) thick (with infrequent pol- ished pebbles) lying between two coarse, buff sandstones, the lower one of which is conglomeratic. The latter is identified as Unit VI, the overlying “gastrolithic” clay- stone as Unit VII, and the uppermost sandstone is correlated with Unit VIII. At the base of the lower sandstone are 12 to 15 feet (3.6 to 4.5 m) of dark-gray, chert pebble 34 PEABODY MUSEUM BULLETIN 35 conglomeratic sandstones. I interpret these as distinct from the overlying sandstone chiefly on the basis of identical facies separated from the overlying sandstone by 12 feet (3.6 m) of shale in outcrops less than a mile (1.6 km) to the east across the Big- horn River (see Section 6 of Fig. 4), and correlate them with Unit IV. A section measured approximately 7 miles (11.2 km) west of Thermopolis at Rattlesnake Gulch and another 12 miles (19.2 km) northwest of Thermopolis at the west end of Thermopolis Anticline appear to corroborate the erosion surface interpre- tation presented above. In both sections, and in nearly all outcrops west of Thermopo- lis, polished pebbles and chalcedony concretions are common in the nearly 100 feet (30 m) of brightly colored, variegated claystone beneath the “rusty series”, but the former are restricted to the upper 50 to 60 feet (15 to 18 m), the latter to the lower 20 or 35 feet (6 to 10.5 m). No intervening sandstone (Unit VI) is present at either of these two sites (Sections 3 and 4 of Fig. 4), or at most other exposures west of Thermopolis. The presence of Unit V here seems to be correlated with the absence of Unit VI—just the reverse relationship that is preserved immediately north of Thermopolis only a dozen miles (18 km) or less to the east. All exposures in the Thermopolis area feature a prominent, although not always resistant, light gray-green or buff to brilliant white sandstone ranging up to 150 feet (45 m) in thickness in the lower part of the nonmarine sequence. A similar facies out- crops at several sites in the Hyattville-Tensleep, Cloverly-Shell Creek and Cody areas. Unit II of our classification was established on the distinctive character of this lower sandstone in the Thermopolis area. For a summary of previous stratigraphic interpretations in the Thermopolis area compared with designations used in this report, see Chart 3. Only one minor fossil vertebrate site (YPM 66-2) was discovered in the Ther- mopolis area, possibly because exposures in the region are not as clean or as exten- sive as those to the north. Locality 66-2 lies approximately 5 feet (1.5 m) above a resistant sandstone lens in a reddish, variegated claystone (Unit VII) 52 feet (15.8 m) below the lowest sandstone strata of Unit VIII. The locality is 9 miles (14.4 km) northwest of Thermopolis on the north limb of the Thermopolis Anticline, about 200 yards (180 m) east of the point where Coal Draw cuts through the Cloverly hogback (Locality Map A). copy AREA. The Cody area encompasses all of the Morrison-Cloverly outcrops along the western margin of the Bighorn Basin from south and west of Cody northward to Clark Fork of the Yellowstone River. Exposures comparable to those along the east- ern side of the Basin do not occur in this area, except in the Shoshone River Canyon and along the east limb of Horse Center Anticline south of Cody. Fisher (1906) was the first to consider the Mesozoic section along the western margin of the Bighorn Basin. In a very brief account of exposures south of Cody (p. 27) he noted a 50 foot (15 m) thick, basal, coarse-grained, pebbly sandstone overlain by softer, gray sandstone of undetermined thickness, in turn overlain by highly colored clay, succeeded by the “top [Cloverly] sandstone member” and a rust-colored sand- stone. The entire sequence was referred by him to the Cloverly Formation (Chart 4). This description corresponds to exposures approximately one mile (1.6 km) south of Cody (Plate 7:A) that were prospected and measured by the author (Section 1 of Fig. 4). In my opinion, Fisher’s “basal Cloverly sandstone” does not correspond with CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 35 the basal sandstone in the type Cloverly area. Lithologically it is more similar to the lowest thick sandstone (Unit II) in the southern part of the Bighorn Basin, but more important, chalcedony concretions are extremely abundant in the overlying 230 feet (70 m) of variegated claystone, whereas they are completely lacking below. Thus, his pebbly “basal” sandstone may represent either Unit IV or II, but not Unit VI. Over- lying this chalcedony-rich claystone is an 8 foot (2.4 m) thick, tan to light-brown, nonconglomeratic sandstone that may or may not represent Unit VI. This is overlain by 80 or more feet (24 m) of brightly colored, variegated claystone containing fre- quent polished pebbles but no chalcedony concretions. I believe this corresponds to the middle claystone member of Darton’s Cloverly and have accordingly labeled it Unit VII. The Cloverly Formation (sensu Darton) on the west side of the Bighorn Basin appears to have thicknesses comparable to those on the east side, 50 to 100 feet (15 to 30 m) thick (Sections 1 and 2 of Fig. 4) rather than 300 feet (91 m) or more as listed by Fisher and others. Fisher did not give a specifie section for the Morrison Formation in this area, sim- ply remarking that it consisted of about 150 feet (45 m) of alternating gray, fine- grained sandstone and dark-gray sandy “shale”. This approximates the lower part of the nonmarine section as it is exposed in Horse Center Anticline, which I have desig- nated Unit I in this report. Hewett (1914) interpreted the Morrison-Cloverly section along the Shoshone River at Cody quite differently, restricting the Cloverly to the predominantly sandstone por- tion of the “rusty series” and expanding the Morrison to include all the underlying nonmarine sediments. Unit VIII of the present classification corresponds to the lower sandstone part of Hewett’s Cloverly Formation, all other Units (I to VII) repre- senting facies of his Morrison Formation (Chart 4). In discussing this section, Hewett comments (p. 94) : “As no fossils other than saurian bones from the middle portion have been found in either this formation [Morrison] or the overlying ‘Cloverly,’ the upper limit is taken to be the base of the sandstone overlying the uppermost maroon clay.” He further noted the absence of a basal conglomerate corresponding to that de- scribed by Darton as marking the upper limit of the Morrison Formation. However, Fisher (1906), Lee (1927) and I observed a pebbly sandstone situated approximately 300 feet (91 m) below the lowermost massive sandstone of the “rusty beds”. As noted above, I have interpreted this as Unit II and not corresponding to the basal Cloverly sandstone of Darton. This interpretation cannot be verified by walking out exposures, but it appears to be substantiated by the abundant presence of chalcedony concretions in the overlying 230 feet (70 m) of variegated claystone. Lee (1927: p. 64-65), challenged Hewett’s interpretation and limited the Mor- rison Formation to the lower 240 feet (73 m) of nonmarine beds, correlating a 25 foot (7.6 m) thick, massive and locally conglomeratic sandstone at this level with the basal sandstone of Darton’s Cloverly. According to Lee, this is overlain by 260 to 315 feet (79 to 96 m) of variegated, brightly colored claystones containing dinosaur bones, petrified wood and polished “gastroliths”. Lee’s section was measured approximately one mile (1.6 km) south of the site of our measured Section 1. Here his basal sand- stone is much thinner than at our Section 1, but it can be traced to Unit II of Section 1. Thus Lee’s subdivision of the nonmarine sequence is identical with that of Fisher, with the Cloverly Formation consisting of Units II, V, VI?, VII and VIII and the Morrison being limited to Unit I (Chart 4). 36 PEABODY MUSEUM BULLETIN 35 Johnson (1934: p. 820) concluded that no reliable criterion exists for differentiat- ing the Morrison and Cloverly Formation, noting that the combined formations may be described in three subunits: 110 feet (31.5 m) of buff, thin-bedded to massive sandstone (Unit VIII plus the “rusty series”), 440 feet (134 m) of varicolored clay with many sandstone lenses (Units VII, VI?, V and II), and 180 feet (55 m) of green sandy shale (Unit I). This condensed description apparently was based on the sec- tions exposed in the Shoshone River Canyon at Cody. Pierce and Andrews (1940: p. 117), in describing the geology south of Cody, “follow the usage of Hewett and place in the Morrison formation the lenticular con- glomerate or grit beds and overlying purple and lilac colored shales that have pre- viously been included [by Fisher and Lee] in the lower part of the Cloverly.” Of the two “Cloverly” sections presented by them, however, one clearly does not con- form to this decision. In Sec. 19, T.52 N., R.101 W. they recorded 118 feet (36 m) of gray, buff and brown sandstone and shale, ripple-marked and iron-stained, which they labeled as Cloverly Formation. This actually is the “rusty series” of other workers, including an equivalent of the Greybull sandstone at the base (Unit VIII). A second section recorded in Sec. 23, T.52 N., R.102 W., less than 3 miles (4.8 km) away on the opposite (west) limb of Horse Center Anticline, lists 192 feet (58.5 m) of Clo- verly, which includes more than 60 feet (18 m) of red and gray “shale” underlain by cross-bedded sandstone and conglomerate. From personal observations in this vicinity, I have concluded that the lowest sandstone recorded in the first section equals Unit VIII and that of the second section corresponds to Unit VI (with the red and gray “shale” representing Unit VII). The top 85 feet (26 m) of the latter section corre- sponds to Unit VIII plus 70 feet (21 m) or more of overlying “rusty series”. Reporting on the Morrison Formation in the vicinity of their second Cloverly sec- tion, Pierce and Andrews included 388 feet (114 m) in the Morrison, the upper 70 feet (21 m) of which they describe as variegated “shale” with nodular, siliceous limestone concretions, underlain by 24 feet (7.3 m) of conglomeratic sands. These two facies (and the underlying 68 feet [20.7 m] of claystone) are placed in Unit V. Beneath these they noted an 85 foot (26 m) sandstone and 141 feet (43 m) of “shale” and shaly sandstones that correspond to Units II and I of our measured Section 1. Thus, in their section on the west limb of Horse Center Anticline, Pierce and Andrews separated Morrison from Cloverly at the top of a chalcedony-concretion-bearing clay- stone (Unit V) and below a conglomeratic sandstone (probably Unit VI), but on the east limb they placed the boundary at the top of the nonmarine section (between Units VII and VIII) (Chart 4). Pierce and Andrews noted (p. 115) the abundance of both chalcedony concretions and “gastroliths” in the upper part of the Morrison (their inconsistent application of the terms Morrison and Cloverly destroys any mean- ing this might have), but they did not say whether these occur together or not. Our own observations in these locales established that the former occur below the “gas- troliths” and at many places a cross-bedded, sometimes pebbly sandstone occurs be- tween the two zones, as has been observed at many other localities in the Bighorn Basin area. Pierce and Andrews’ sections are duplicated in Chart 4, together with those of Fisher, Lee, Hewett and Johnson and are compared with the classification used in this report. Although fragmentary fossil bone was encountered at several levels, chiefly within Unit V, no significant fossil vertebrate localities were discovered in the Cody area. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 37 CROOKED CREEK—GYPSUM CREEK—WARREN AREA. This region, which includes that part of Big Horn County, Wyoming, that lies north of the Shoshone River and adja- cent areas of southernmost Carbon County, Montana, proved to be one of the most productive regions discovered during the course of this investigation. Large collec- tions of fossil vertebrates were made from a series of sites along the northwest-south- east-trending Cloverly hogback, particularly in T.58 N., R.95 W. (Locality Map H) approximately 8 miles (12.8 km) north of the Shoshone River and 10 miles (16.0 km) northeast of Lovell, Wyoming. The first stratigraphic report to consider the Mesozoic section of this area in any detail is that of Washburne (1909). On page 168 of that report, Washburne described the Cloverly section at Gypsum Creek as follows: At the base of the Cloverly formation in its typical development on Gypsum Creek, north of Lovell, Wyoming, there is 40 to 50 feet of massive sandstone, locally containing shale partings and a thin coal bed. . . . Overlying this sand- stone are 100 to 150 feet of bright variegated clays and soft sandstones, with con- cretions of limestone and chert. The top member of the formation is a massive gray sandstone about 70 feet thick overlain by 15 feet of dark purplish shale. Fisher (1908: p. 85), attempting to correlate this same Gypsum Creek section and one near Thermopolis with the much thicker and quite different section of the Koo- tenai Formation near Great Falls, Montana, similarly recorded the basal sand of the Cloverly Formation at approximately 50 feet (15 m) thick, overlain by 40 feet (12 m) of chert pebble sandstone, which in turn was overlain by 132 feet (40 m) predomi- nantly “shale”, the upper part of which contained limestone and chert (chalcedony?) concretions. Overlying this he noted a 70 foot (21.3 m) thick chert pebble sandstone succeeded by 15 feet (4.5 m) of dark-purple “shale”. The similarity between Wash- burne’s and Fisher’s section is obvious, the most conspicuous difference being the ab- sence of a chert pebble sandstone immediately above the “‘basal sandstone”, as de- scribed by Fisher. The local absence of conglomeratic facies associated with this sandstone in the Gypsum Creek area was substantiated by our observations (Section 21 of Fig. 4 and Appendix A at the end of this report). The above Gypsum Creek sections have been located approximately and measured by the author, the sequence having been traced to this locality from the type Cloverly area. The “basal Cloverly sandstone” of Washburne and Fisher (with the overlying conglomerate [= Pryor Conglomerate]) corresponds to Unit IV, the overlying 100 to 150 feet (30 to 45 m) of concretionary clays and sands to Unit V, the 70 foot (21 m) gray chert pebble sand- stone to Unit VI and the 15 foot (4.5 m) thick, purple “shale” to Unit VII (Chart 5). It should be pointed out that this Gypsum Creek section is not typical for the area. A more typical section may be found in the hogbacks between the Crooked Creek and Dryhead roads. Here the lower pebbly sandstone (Unit IV) ranges from 10 to 30 feet (3.0 to 9.1 m) in thickness, with 25 feet (7.6 m) being an approximate average. The overlying low-slope-forming, chalcedony-rich claystone (Unit V) totals approximately 130 feet (39.6 m) , and the sometimes pebbly sandstone (Unit VI) above averages about 20 feet (6.1 m) (Section 20 of Fig. 4). The cliff-forming, brightly colored, purplish claystone (Unit VII) ranges from 15 to 70 feet (4.5 to 21.3 m). Similar values were obtained to the south and northwest. Both Fisher and Washburne adopted a 38 PEABODY MUSEUM BULLETIN 35 Morrison-Cloverly boundary in this area well below that designated by Darton (1906: p. 52), placing it between Units III and IV rather than between Units V and VI (Chart 5). Again, the chalcedony-rich claystone unit provides the most reliable traceable evi- dence permitting correlation between the type Cloverly area and the Crooked Creek exposures. Ziegler’s (1917) report on the Byron oil and gas field, although dealing with sub- surface stratigraphy at a point some 14 miles (22.4 km) southwest of the Crooked Creek exposures, requires mention here because it adopts a usage quite different from that of Fisher and Washburne. Ziegler, following Hewett’s (1914) lead in the Cody area, saw no good reason for dividing the variegated claystone sequence and placed the base of the Cloverly Formation at the base of the massive sandstone overlying the highest variegated clays (Hintze’s Greybull sandstone or Unit VIII of this report). He argued (p. 187) that “since climatic and physical conditions have apparently been constant during the entire time of deposition of these clays . . .”, it is more logical to include all variegated clays in the Morrison Formation. There is considerable merit in Ziegler’s conclusion, but not for the reasons quoted, which are purely hypothetical. In fact, Moberly (1960) has shown that environmental changes did occur between accumulation of the Morrison (Units I to III) and the Cloverly (Units IV to VII) Formations. Lee (1927: Pl. 2 and p. 63) presented a very brief description of the Morrison- Cloverly section 4 miles (6.4 km) north of Kane, Wyoming (probably at the promi- nent plunging hogback southeast of Sykes Mountain, about 7 miles [11.2 km] south- east of the Crooked Creek quarry sites). Lee recorded 290 feet (64 m) of Morrison (without description), 50 feet (15 m) of coarse-grained, massive, cross-bedded, basal Cloverly sandstone (which I have identified as Unit IV), approximately 150 feet (45 m) of red, sandy “shale” constituting the middle Cloverly member (Units V, VI and VII), and 75 feet (22.5 m) of upper Cloverly or Greybull sandstone (Unit VIII). The most recent study in this area is that of Moberly (1960), referred to earlier. Moberly’s redefined Cloverly Formation includes the Little Sheep Mudstone Member, based on excellent exposures 4 miles (6.4 km) south of Kane (p. 1145), and the Himes Member based on exposures along the west limb of Little Sheep Anticline be- tween Himes and Lovell, Wyoming (p. 1148). Moberly also proposed the overlying “rusty beds” (including the Greybull sandstone of Hintze and others) as the Sykes Mountain Formation, based on exposures between Gypsum and Crooked Creeks (NE Y Sec. 25, T.58 N., R.96 W.). Detailed stratigraphic sections of these units are pre- sented here (Sections 18, 19, 20 and 21 of Fig. 4). During the course of tracing this sequence from the type Cloverly area, we established that Moberly’s Little Sheep Mudstone Member equals Unit V, the Himes Member equals Units VI and VII and the lower sandstones of his Sykes Mountain Formation (at least in part) equal Unit VIII. The coarse chert pebble sandstone or conglomerate cited by Moberly at the base of his Little Sheep Member of the Cloverly and identified by him as the Pryor Conglomerate is here equated with our Unit IV. For a summary of previous terminology applications at specific localities, see Chart 5, and the comparison on pages 12-13. During the 1962 and 1963 field seasons a total of 33 fossil vertebrate sites were dis- covered in this area, principally along the east slope of the Cloverly hogback immedi- ately east of Crooked Creek (Plate 4). In addition, the site of A. Silberling’s 1949 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 39 collection for Princeton University (Locality PU 49-1) was located through the help of Mr. Lloyd Tillett. Extensive collections were made from ten of these sites (Locality Map H). Localities YPM 62-14, 63-22, and PU 49-1 lie within the upper 40 feet (12 m) of Unit V, 20, 2 and 35 to 40 feet (6.0, 0.6, and 10.5 to 12 m) respectively, below the base of Unit VI. Localities YPM 63-16 and 63-32 are situated just below the top of Unit VI (1 to 3 feet [0.3 to .09 m]). All other sites lie within the lower 10 feet (3:0 m) eof Unit VII. BRIDGER-WESTERN PRYOR MOUNTAIN AREA. Included here is the eastern part of Carbon County, Montana, situated between the eastern county boundary and the val- ley of Clark Fork of the Yellowstone River. The Morrison-Cloverly outcrop belt ex- tends from northeast of Warren, along the west flank of the Pryor Mountains to Blue- water Creek and then eastward to the north slope of West Pryor Mountain. Within the area 41 sites were discovered that produced large collections of fossil vertebrates (Locality Maps I, J, K, L, M, N and O and the Locality Register at the end of this report). In 1917, C. J. Hares made an informal report to the Geological Society of Wash- ington, D.C. on “Gastroliths in the Cloverly formation”. Although not intended as a stratigraphic presentation, the publication of his remarks constituted the first pub- lished reference to the Pryor conglomerate. He stated (1917: p. 429): “These gas- troliths occur in the shale portion of the Cloverly between the Pryor conglomerate member at the base and the greybull sandstone member.”’ Although black chert peb- bles occur locally and infrequently in the sandstone here labeled Unit VI, and despite the presence of conglomeratic sandstones at various levels, the Pryor Conglomerate is sufficiently distinct that there is little disagreement over its identity. On the other hand, there is considerable difference of opinion as to whether the Pryor Conglom- erate is, or should be, considered part of the Cloverly Formation or of the Morrison. This first arises in Hares’ comments quoted above, wherein he identifies the Pryor Conglomerate as the basal member of the Cloverly. He did not, nor has anyone else to date, establish the equivalency of the Pryor Conglomerate and Darton’s basal con- glomeratic sandstone. Nor did he suggest a redefinition of the Cloverly Formation. Hares assumed, and others have followed the same assumption, that these were one and the same unit. Consequently, the Pryor Conglomerate is often cited as the basal member of the Cloverly Formation. The most recent instance is the report by Moberly (1960), but Moberly clearly states that he is redefining the Cloverly Formation to in- clude the black chert pebble conglomerate commonly identified as the Pryor Con- glomerate. Unfortunately, Moberly never explicitly states that the Pryor Conglomerate and Darton’s basal Cloverly sandstone are the same or different units, although he indicated the latter in his representation of Darton’s stratigraphic section at the type Cloverly area (Fig. 2). However, other sections of Darton’s (those south of Tensleep, at Hyattville, west of Tensleep, at Sheldon’s ranch and west of Shell) reproduced in this same figure indicate that Darton selected a basal sandstone at the level of the Pryor Conglomerate in four of his sections—the exceptions being the type Cloverly section and the one at Sheldon’s ranch (Shell Creek Dome). However, this is only Moberly’s inter- pretation of how Darton subdivided the sections at these localities. Personal examination of the outcrops in question has led me to conclude that Moberly erred in his interpreta- tion of Darton’s sections at two of the sites. The basal Cloverly sandstone selected by 40 PEABODY MUSEUM BULLETIN 35 « Darton south of Tensleep and west of Tensleep, as well as at Shell Creek Dome and at the type section, is definitely the upper sandstone (Unit VI) that overlies the chalcedony concretion-bearing claystone. Only at the exposures west of Shell and immediately south of Hyattville did Darton refer to a lower sandstone (perhaps at the level of the Pryor Conglomerate) as the basal Cloverly sandstone. At both of these latter sites, the strata described by Darton underlie the chalcedony-rich claystone (Unit V), and the upper sandstone (Unit VI) is absent or very thin. See Charts 1 and 2 for a comparison of Darton’s sections with the classification used here. Bauer and Robinson (1923) in their “Comparative stratigraphy in Montana” adopted Darton’s Cloverly section and his correlations with the Dakota, Fuson and Lakota Formations of the Black Hills region. They further stated that (p. 172): “the shale member below the upper sandstone [‘rusty series’, Greybull sandstone, or Unit VIII of this report] in the Crow Reservation is the equivalent of the upper Kootenai of northern Montana and the thick conglomeratic sandstone below it is the equivalent of the thick sandstone of the Kootenai of the central and northern part of the state. . .” They listed a thickness of 313 feet (95 m) for the variegated “shale” between the upper and lower sandstones of their “Cloverly” on the west side of the Pryor Mountains (no precise location is given), and note the “basal sandstone” is conglom- eratic around the north end of the Bighorn Mountains where its thickness ranges from 58 to 130 feet (17.7 to 39.6 m). Their Cloverly Formation thus totals 371 to 443 feet (112.8 to 135 m). Discussing the Morrison Formation (p. 173-174), they gave a thickness of 294 feet (89.7 m) in the “Pryor-Beartooth Mountain” area. No comment was made as to whether these Cloverly-Morrison thicknesses were measured anywhere near each other, and the supposition here is that they were not. The maximum thick- ness obtained by us for the entire nonmarine sequence in this area is 512 feet (156 m) at Bluewater Creek (Section 24 of Fig. 4), or more than 150 feet (45 m) less than the minimum total thickness cited by Bauer and Robinson. It is unfortunate that no precise location was given by Bauer and Robinson for their data, because without this information precise correlation with our observations cannot be made. However, throughout this area there is only one persistent and dis- tinctive black chert pebble conglomerate within the nonmarine sequence. Accordingly, this must represent their basal Cloverly facies, It equals Unit IV of our classification and has been traced between this area and more southerly exposures where it clearly is not Darton’s basal Cloverly member. Overlying this conglomerate (the Pryor Con- glomerate) we found variegated gray, purple and bluish claystone, rich in bentonite and chalcedony concretions, ranging from 60 to 112 feet (18 to 34 m) thick, that is traceable to the nearly identical Unit V in the type Cloverly area. Above this clay- stone we found a variable, soft, yellow to brown sandstone, sometimes containing occasional black or gray chert pebbles, ranging from 3 to nearly 60 feet (0.9 to 18 m) in thickness. I believe this corresponds to Darton’s basal Cloverly sandstone and ac- cordingly have labeled it Unit VI. Overlying this is 20 to 90 feet (6 to 27 m) of brightly colored, variegated, polished pebble-bearing claystone (Unit VII) capped by a variable thickness of tan to rusty-brown, thinly or massively bedded sandstone (Unit VIII). Thus Bauer and Robinson’s Cloverly Formation appears to correspond to Units IV through VIII of our classification (Chart 6). One of the early attempts to correlate the Morrison-Cloverly section of the Pryor Mountain region with sections outside the Bighorn Basin is that of W. T. Lee (1927). CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 41 Lee compared 13 sections scattered between Thermopolis and Pryor with other sec- tions at Lewistown and near the Big Snowy Mountains of central Montana and a section at Bellvue, Colorado. Included is a section at Red Dome (p. 65) near Bridger, Montana, based on data supplied by R. S. Knappen. This latter section agrees with one of our measured sections (22 of Fig. 4) and with the general description of the Cloverly Formation given by Bauer and Robinson (1923) and Knappen and Moulton (1930). Again, it is my opinion, based on extensive examination of the exposures in the Red Dome and adjacent areas, that the basal conglomerate of Lee’s Bridger sec- tion is the same as that of Bauer and Robinson and corresponds to Unit IV of the present study and therefore does not correspond to the basal sandstone (Unit VI) described by Darton (1906). Thus Lee’s Cloverly Formation in this area includes our Units IV, V, VI, VII and VIII. Knappen and Moulton (1930) noted a 589 foot (180 m) thickness for the non- marine sequence in Carbon County, but they did not include a measured section (a slightly thinner measured section is included from near Pryor 20 miles (32 km) to the northeast). Knappen and Moulton divided this nonmarine section at the base of a black chert pebble conglomerate (not identified by them as the Pryor Conglomerate) that almost certainly is the same one selected by Bauer and Robinson and by Lee, and labeled here as Unit IV. Their overlying Cloverly clay member (90 to 240 feet [27.5 to 73 m]) includes our units V, VI? and VII and their Greybull sandstone member corresponds to Unit VIII (see Chart 6). Of particular interest is the following comment by Knappen and Moulton (1930: p. 25): “A very lenticular, coarse, soft brown sandstone is present at many places about 30 feet below the top of the bright colored, variegated clay. This sandstone ranges from a feather edge to 60 feet in distances of 1000 feet.”” The authors do not record whether the sandstone contains black chert pebbles, but personal observa- tions have established that a sandstone matching their description commonly present at about this level is pebbly locally and does contain infrequent dark chert pebbles. The unit is discontinuous, but it always lies between the chalcedony-rich claystone and the overlying polished pebble-bearing claystone. It is my conclusion that this sand- stone probably represents Unit VI and thus is equivalent to the basal sand of Darton’s type Cloverly. In the absence of detailed measured sections by Knappen and Moulton these correlations cannot be confirmed, but the following observations by them do seem to support my interpretation. They describe (1930: p. 24-25) the lithologies above their conglomeratic basal member of the Cloverly as “bright red, green, purple, yellow and dull black clays... . Much of the clay swells like bentonite when wet and forms gumbo mud which is porous and collapses under pressure after drying.” They further note the amazing abundance of polished, well-rounded stones which “some geologists hold are gastroliths”. Unfortunately, they do not present any details on the stratigraphic distribution of these polished stones within the 90 to 240 feet (27.5 to 75 m) of clays above their basal conglomerate, or on the distribution of the collapsible gumbo muds. Our analysis at the same locale found the so-called gastroliths restricted (tn situ) to the upper cliff-forming claystones (which here are reddish to purplish) and the collapsible gumbo clays (which usually are drab gray and pale green) limited to the lower part of the section and always below the soft, brown sandstone described above. These characteristics are consistent with those observed in more southerly out- crops within the study area and seem to confirm the persistence and distinctiveness of 42 PEABODY MUSEUM BULLETIN 35 Units V and VII. Knappen and Moulton’s basal Cloverly member thus would seem to correspond to our Unit IV. Like that of their predecessors, their Cloverly Formation clearly appears to be an expansion of that formation over Darton’s 1906 definition. Wilson (1936: p. 1167) recorded a composite section between Bowler (now an abandoned town near the southwest boundary corner between Yellowstone and Car- bon Counties) and Dry Creek (South Fork of Bridger Creek?) in which the “Clo- verly” claystone is 150 feet (45 m) thick and the brown and yellow, black chert pebble-bearing sandstone beneath is 50 feet (15 m) in thickness. Wilson lists the total nonmarine section here (excluding the sandstones of the “rusty series”) at about 400 feet (122 m) thick. These values are very close to values we obtained at Red Dome (Section 22 of Fig. 4) and indicate that Wilson subdivided the Morrison and Cloverly Formations at the same horizon as his predecessors (the base of Unit IV), but Wil- son’s data are not sufficiently detailed to permit accurate comparison with earlier works or with our data. Lammers (1939) discussed the origin and correlation of the ““Cloverly conglomer- ate’, but in the absence of detailed measured sections and the exact stratigraphic level of his “Cloverly conglomerate” at any particular locality, it is impossible to ascertain which of the coarse clastic units in this region he was referring to, or to make mean- ingful comparison with the sections recorded here. On the basis of his description, it is most probable that his “Cloverly conglomerate” is synonymous with Pryor Con- glomerate (sensu Hares), in which case Lammers’ Cloverly Group includes our Units IV through VIII. Lammers (p. 131-132) correlated the “Cloverly conglomerate” of this area with the coarse-grained sandstone overlying the Kootenai coal beds in cen- tral Montana and with the basal conglomerate of the Blairmore Formation in Alberta. Gardner et al. (1945: p. 79-80) published a measured section on Five Mile Creek (NE % Sec. 35 and SW 4 Sec. 36, T.5 S., R.24 E. and N % Sec. 1, T.6 S., R.24 E.) about 5 miles (8 km) east of our measured Section 24 and in the vicinity of Locality YPM 64-65. Their section has been duplicated in Chart 6. From our observations in the immediate area, rocks that they assigned to the Kootenai Formation include Units IV, V and VI. They omit any mention of the upper variegated claystone (Unit VIT) although it is prominently exposed locally in the area. Their basal conglomeratic sandstone is the Pryor Conglomerate of other authors (Unit IV). The Morrison Formation as recognized by Gardner et al. includes our Units III and possibly I, totaling 125 feet (38 m) of sandstones and claystones. A 10 foot (3 m) resistant sandstone near the middle of their Morrison section may represent Unit II of more southerly exposures, but this cannot be verified. Lateral variations in thick- ness and changes in grain size indicate it probably represents a local channel deposit. Moberly (1960) provides no measured sections in the area under consideration here, but in a geologic map of the Red Dome area (Moberly, Fig. 7) he recognized the same subunits that he proposed for the nonmarine sequence exposed in Bighorn County, Wyoming. Presumably, his subunits in the Red Dome area can therefore be equated with our classification exactly as is listed on pages 12-13 of this report. The stratigraphic interpretations of most of these workers, compared with termi- nology used here, is summarized in Chart 6. A total of 41 fossil sites was discovered in the Bridger-Pryor Mountain area dur- ing the 1964 field season. Each site was explored and evaluated, and extensive quarry- ing and collecting were carried out at 16 of the sites. The sites are pinpointed on CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 43 Locality Maps I through O. The fossil-bearing horizon at each locality (with the ex- ception of YPM 64-54) lies in or above Unit VI; the precise level of each is recorded in the Locality Register (Appendix B) at the end of this report. PRYOR-BEAUVAIS CREEK AREA. This area includes the northwestern part of Big Horn County and the southernmost part of Yellowstone County, Montana, and lies entirely within that part of the Crow Indian Reservation west of the Bighorn River. The region is characterized by broad, nearly flat-topped plateaus or “benches” bounded by 100 to 300 foot (30 to 90 m) high scarps, low to moderately high cuestas and broad stream valleys. The underlying strata are nearly horizontal in much of the area with dips increasing to 15 or 25° approaching the Bighorn and Pryor uplifts. Exposures of the Morrison-Cloverly sequence occur in erosional scarps bounding the plateaus and on the back slopes of cuestas. The outcrop belt follows the southern limit of the high plateaus north of the town of Pryor and along the valley of Pryor Creek in the western sector, then roughly parallels the course of Beauvais Creek eastward to its junction with Horse Coulee, from which point it swings southeastward toward Grapevine Creek and the Yellowtail Dam site on the Bighorn River (Fig. 2). The earliest reference to the Morrison-Cloverly section in the region is that of Bauer and Robinson (1923). They presented (p. 172) a thickness of 105 to 151 feet (32 to 45 m) for the variegated “shale” between the upper and lower sandstones of their “Cloverly” on the east side of the Pryor Mountains (presumably somewhere in the vicinity of Beauvais Creek) and the conglomeratic sandstone at its base as 58 to 130 feet (17.7 to 39.6 m) at the north end of the Bighorn Mountains. No precise locality was given, however, and we failed to find any exposures in which the con- glomeratic sandstone exceeded (or even approached) their minimum value. Bauer and Robinson correlated the “shale” member (Units V to VII?) below the upper sandstone with the Upper Kootenai of northern Montana and the thick conglomeratic sandstone (Unit IV?) beneath with the prominent, thick sandstone of the Kootenai in central and northern Montana. The Morrison Formation, according to these au- thors, varies from 100 to 150 feet (30 to 45 m) in thickness and consists chiefly of hard, greenish-gray “shale” with some pink and purple “‘shales”, and gray-green, white and yellow sandstones. Because no measured sections or precise localities are given, it was impossible for us to make any meaningful comparisons with our data. However, their thicknesses cited above for the Cloverly and Morrison Formations are thicker and thinner, respectively, than those which we recorded in this area. I believe that the sec- tion assigned by Bauer and Robinson to the Cloverly Formation includes Units IV through VII (they gave no thickness for the upper sandstone—the equivalent of our Unit VIII—but they apparently considered this as the upper member of their Clo- verly Formation), and the 100 to 150 feet (30 to 45 m) assigned by them to the Morrison Formation includes only Units I through ITI. W. T. Lee (1927) published a geologic section (Pl. 2), measured by W. T. Thom, Jr., at exposures near Pryor, Montana, which consisted of 20 feet (6 m) of basal con- glomerate, 106 feet (36 m) of colored “‘shales” and 20 feet (6 m) of sandstone at the top, the entire sequence being assigned to the Cloverly Formation. This approximates the section observed by us in the vicinity of Pryor, and it appears that these three ele- ments are the same as those that we have labeled VI, VII and VIII. However, in view of the nature of the exposures at this locale, I suspect that Lee selected the most con- 44 PEABODY MUSEUM BULLETIN 35 spicuous conglomerate as his basal conglomerate. A massive and thick conglomerate is prominently exposed west and south of Pryor and, although exposures do not per- mit determination of its position relative to the chalcedony-concretion-bearing clay- stone, it is my opinion that this is the Pryor Conglomerate, and I have correlated it with Unit IV (see Section 25 of Fig. 4). Hence, it is quite possible that Lee’s Cloverly in this vicinity includes Units IV through VIII. The most extensive study of the geology in the Crow Indian Reservation is that of Thom et al. (1935). They note several measured sections of the Morrison-Cloverly complex. One of these (p. 45), located in SW 1% Sec. 13, T.5 S., R.25 E. approxi- mately 4 miles (6.4 km) southwest of Pryor, identified a Cloverly section that is iden- tical with that reported by Lee and agrees with our Units VI, VII and VIII as re- corded west of Pryor (see Section 25 of Fig. 4). As noted above, however, their basal unit may correspond to our Unit IV. A second section (p. 45) (located in Sec. 22, T.9 S., R.34 E., south of the Little Bighorn River on the east side of the Bighorn Mountains) is far removed from the area considered here and was not checked dur- ing the present investigation. At that site, they list 185 feet (56.5 m) of Cloverly, the upper sandstone totaling 12 feet (3.6 m) and the basal sandstone 24 feet (7.2 m). This section may include Units IV and V as well as one or more of the overlying units for they note the “great numbers of concretions formed of chalcedony and calcite” occuring in a soft, light gray “shale” 64 feet (19.5 m) above the “lower sandstone” and that “gastroliths are also found at this horizon”. Except for surface associations, the latter is contrary to our findings elsewhere. As I have noted before, in the process of quarrying at more than 50 sites in Units VI and VIII, polished pebbles were fre- quently encountered, but not a single chalcedony, calcite or barite concretion was found. In contrast, such concretions are abundant almost everywhere in Unit V. MacClintock (1957: p. 27 and 36) recorded a similar, non-overlapping distribution of polished pebbles and chalcedony nodules at several localities along the eastern flank of the Big- horn Mountains between Mayoworth and Arminto. The description given by Thom et al. of the above section (pink, red, and purple shale above the chalcedony level and gray shales below) suggests that Unit VI may be absent or very thin at their section site and that what they refer to as the basal sandstone may actually correspond to Unit IV of this report or to some other coarse clastic unit. In addition to these sections, a number of well logs are cited by Thom et al. from Pryor-Beauvais Creek area. It is apparent that subsurface placement of formation boundaries in at least some instances is not consistent with the usual placement of the same boundaries in nearby surface exposures. One of their logs is cited here because it happens to have a critical location in the Beauvais Creek Valley in the immediate vicinity of a number of our fossil vertebrate localities where large collections and de- tailed stratigraphic sections were obtained (see Locality Map U and Sections 27 and 28 of Fig. 4). The well (‘56 Petroleum Corporation’s Well 1, Beauvais Creek Up- lift) raises a problem that we could not resolve: that is, either the location given (SW Y%4, NE % Sec. 28, T.4 S., R.29 E.) is in error or the log has been grossly misinter- preted. According to the log, the top strata penetrated by this well are identified as Cloverly (Thom et al., 1935: p. 110), but the location given places the well in the valley bottom between Beauvais and Buster Creeks some 150 to 200 feet (45 m to 60 m) below the “upper sandstone” of the nonmarine sequence that crops out as the capping rim-rock on both sides of the valley. The valley width at this point is between CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 45 5,000 and 7,000 feet (1,525 and 2,135 m) and there is no evidence of downwarping or faulting in the immediate area. The exposures on both sides of the valley include Units VI, VII and VIII and locally the upper part of V. Unit VIII ranges from 20 to 50 feet (6 to 15 m) thick, Unit VII from 31 to 80 feet (9.5 to 24.4 m) and Unit VI from 0 to 15 feet (0 to6 m) (Sections 27 and 28 of Fig. 4). This gives a total maxi- mum thickness of 135 feet (31 m) for the section that I consider to correspond to Darton’s Cloverly Formation. The base of Unit VI on both sides of the valley is well above the level of the given well site, yet the log (reproduced below) identifies 228 feet (70 m) of Cloverly in subsurface, overlying 134 feet (40 m) of Morrison. If the well is situated in the Beauvais Creek Valley where indicated (we were not able to locate such a well), some 150 or 200 feet (45 to 60 m) below the top of the non- marine section, then the Cloverly Formation (as identified in this log) at this point has a thickness close to or exceeding 400 feet (120 m) and the total nonmarine section has a thickness of 514 to 564 feet (160 to 180 m). The maximum thickness found by us in exposures in the Beauvais Creek area was 209 feet (63 m) for the entire non- marine section (Section 27 of Fig. 4) approximately 2 miles (3.2 km) southwest of the listed well site (Sec. 5, T.5 S., R.29 E.) (see Plate 5:B). Thus it appears that the following well log has been identified with the wrong well (which seems unlikely), 56’? Petroleum Corporation’s Well no. 1, Beauvais Creek Uplift. (Thom et al., 1935: p. 110) Cloverly Formation Thickness Depth eyes hg VE 11s) Aa Oe Aan ORE os eee ee coe ee ee 5 25 Shalet re dipy trl sns5 22) beet sree sem eee cad bastnttesceneatedte tect 20 45 LG) UST see Ne de RS eee on roe TO ee Recent ewe err) Meme 3 48 SUES EE es [tS ce Nee eect ee eer eae eee Cee 22 70 54] ee ERC ECs I 0) mem a ee 8 apg te es ee 12 82 Suge Ege pa et el eet aA te ee edi cr pig ke ee Mn 23 105 Dialer bbe! | Mee ia ce eld deen pectic Rae eee cat aoe teens 10 tS Shaleserayet..2 Behe s ee i ae Bae eC ate anadinn pati 33 148 NS aa et doar cae OE crcehaccdl tan eh MN tet Me I ts scsi eaten 6 154 Sand slighteray, nojwater = s.isccccacct ences eaten eaes 94 248 Morrison Formation SiMe Oi fy erst Ee Ae he eee de Re eae oe 40 288 1 IE ek A eter mene re ey et en. tof te mee eee ee nO Core eee 7 295 5S) ee Hi ey ae i pn lt dt. ee een aloo 5 300 AS) NEI OD 5 al al ah ed ar eee oe tear iri 45 345 D(a Ago ale ee ne one dene a eae ce ri TEES Rem LES Oi 28 373 Shale tena yiyyet aise ee bt or tbh ot cet cela ada onal ee 9 382 Sundance Formation Sliel belie fe eS ee ee TLS Pe UO Sion ence 4+ 386 Shalevioray rah cutcecten tess eh Me aii sal Boe ce Ree eal se, at 64 450 Shaleysandy blues wees eee cca ereetestestscesectee aah censeenencv meneame ener 5 455 Sanay ight oray and Ware scene Melts tute aay eat emced 5 460 1 ia Oe Pretec ee a ee rt RE SA cet cp Oe pe ac i er 23 483 Shales Di Uey secant Dats en ae ate 181 664 15 eval] o(s(0 fy pias MeO RA hee Oe ete Man eA ee ben N aA ee ae pee EM ane aE ee 22 686 Shell limes ctl A st Spee i eee, Bie oe 16 702 [O50 age ene Octeer DETER meen RR CHEE PAU APRePHL a AL Me re WR fn Wet A 90 792 Chugwater Formation 46 PEABODY MUSEUM BULLETIN 35 the well location is in error, or the formation boundaries have been misplaced. Com- parison of surface exposures in the area with the following log has led me to conclude that the last explanation is the most probable. Of particular interest in the above log is the 94 foot (28.7 m) thick light-gray sand listed at the base of the “Cloverly”. A sandstone matching this description occurs near the middle of the Sundance Formation in outcrops 3 to 4 miles (4.8 to 6.4 km) south of Beauvais Creek, but nothing approaching the thickness cited was found in the non- marine section anywhere near the well site. Another significant fact is that we found shell fragments (Gryphaea) on the surface (but not in situ) in the lowest exposures in “Cashen pocket” approximately 200 feet (61 m) below Unit VIII (see Plate 6:B), which indicate that the Sundance probably lies very close to the surface at this point only a mile (1.6 km) northeast of the well site and at an elevation close to that listed for the well. On these grounds, it appears quite probable that little if any of the well log given above includes any part of the nonmarine section, and the lithologies listed for both the Cloverly and Morrison Formations are referable to the Sundance Formation, Richards (1955: p. 41-42), reporting on the geology of the Hardin-Bighorn Can- yon area, listed thicknesses for the Morrison Formation of 140 to 280 feet (42.7 to 85.4 m) and for the Cloverly Formation of between 300 and 400 feet (91 and 122 m) in the region south of the Bighorn River along the east side of the Bighorn Mountains. Our investigation did not extend to this area, so no precise comparisons are made in this report. However, Richards included the “rusty series” as the uppermost member of the Cloverly Formation on the basis that it represents the stratigraphic equivalent of the Fall River Sandstone of the Black Hills region and that the overlying Thermopo- lis Shale corresponds to the Skull Creek Shale of that region. Inclusion of the “rusty series” in the Cloverly Formation follows some earlier interpretations but is at vari- ance with certain recent works and current definition by the United States Geological Survey which consider these as transitional transgressive marine facies closely related genetically to the overlying marine Thermopolis Shale. The variable nature and even absence of the “Greybull” or “upper sandstone” (as a distinctive massive bed) at this level makes it impossible to use this unit as a marking horizon between the Cloverly and the overlying marine shale. However, conspicuous parallel stratification, usually reflected in the highly fissile character of the “rusty series”, is in sharp contrast to the obscure bedding of the variegated claystones immediately beneath. This character may serve as a practical criterion for separating the Cloverly Formation from the overlying Sykes Mountain or Thermopolis Formations. Waage (1955, 1958, 1959a, 1959b) has cited the frequent occurrence of siderite spherulites just below the trans- gressive disconformity separating the Late Jurassic — Early Cretaceous nonmarine and marine sections in Colorado and the Black Hills region; he correlated (1959a: p. 57) this siderite zone with the initial transgression of marine conditions. We occasionally found such spherulites in the upper 2 to 4 feet (0.6 to 1.2 m) of Unit VII or the lower 6 to 8 feet (1.8 to 2.4 m) of Unit VIII. It is quite possible that this spherulite zone is much more persistent than we found it to be (unweathered siderite spherulites are difficult to recognize), in which case it might serve as a more effective marking horizon in the Bighorn Basin for delimiting the Cloverly and Sykes Mountain or Thermopolis Formations. For a comparison of previous interpretations and the present classification see Chart 7. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 47 A total of 44 fossil vertebrate localities were discovered in this area during the 1964 field season. Of these, 23 produced important collections. In addition, a number of collections were made by American Museum parties in 1903, 1904, 1931, 1932, 1933, 1938 and 1955 and by the University of Oklahoma in 1940. Some of the Ameri- can Museum localities, particularly in the Cashen ranch area on Beauvais Creek, were relocated with the help of oblique aerial photographs, prepared by Barnum Brown, that pinpointed a dozen sites (see Plate 6); he also recorded the specimens collected at each place. These sites were verified by personal inspection, which showed signs of prior excavation, abundant fresh bone fragments, and “artifacts” left by earlier collectors. Most of the American Museum sites outside of the immediate vi- cinity of Cashen ranch could be only approximately located, except for two localities (AMNH 31-9 and 31-10) north of Pryor that were relocated with the assistance of Roy Marsh of Pryor, who had aided Barnum Brown in quarry operations at both sites. The two University of Oklahoma sites south of Cashen ranch were relocated approxi- mately through information provided by Dr. Wann Langston of the University of Texas. These localities are recorded on Locality Maps P through X. The stratigraphic levels of the bone-bearing horizons vary considerably among the localities. Many, but not all, of the American Museum sites have been found to lie within Unit V. The University of Oklahoma sites also occur in the upper part of this Unit. The majority of Yale sites are situated in Unit VII but a few occur in Units V and VI. The precise stratigraphic levels of the fossil horizons of nearly all of these localities are recorded in the Locality Register (Appendix B) at the end of this report. MIDDLE DOME AREA. Middle Dome is one of three domal structures on the west end of the Shawmut Anticline in Wheatland County, Montana. It lies outside of the princi- pal study area shown in Figure 2 approximately 50 miles (80 km) to the northwest, about 8 to 10 miles (12.8 to 16 km) SSE of Harlowton (Fig. 1). It is included in this report because of collections made in the area, purportedly from the Cloverly Forma- tion, by the American Museum of Natural History in 1933. Bowen (1919: p. 197-198) described the Middle Dome exposures as having “. . . at the top 50 feet of thin-bedded, fine-grained, platy sandstone of somewhat rusty appearance [Unit VIII?]. .. . Below this sandstone is 45-50 feet of drab to greenish gray shale, which is succeeded by alternate beds of maroon and white shale contain- ing some interbedded sandstone. The lowest member exposed is a coarse gray sand- stone that roofs over the centers of middle and west domes of Shawmut anticline.” These strata are generally similar to the Morrison-Cloverly sequence to the south, but we were unable to distinguish with certainty most of the units we established in the Bighorn Basin. Bowen’s upper sandstone probably represents our Unit VIII and the lower sandstone closely resembles and is presumed to be continuous with the Pryor Conglomerate (Unit IV). The intervening variegated claystones may represent one or more of the expected Units (V, VI and VII). Polished pebbles were found locally, but only as surface features on low-angle slopes in the lower third of the claystone sec- tion. Chalcedony concretions are rare and the few that were found could not be traced to a definite stratigraphic horizon. The claystone sequence approaches 150 feet (45 m) in thickness, the upper 20 to 40 feet (6.1 to 12.2 m) being gray-green medium- gray and weathering to yellow or orange brown. The middle part (80 to 100 feet [24 to 30 m]) is brightly variegated, weathering to deep maroon and brick red with 48 PEABODY MUSEUM BULLETIN 35 pale-lavendar and light-gray zones. The lower 20 to 50 feet (6.1 to 15 m) usually is neutral dark gray, on both fresh and weathered surfaces, and is highly bentonitic. The latter is thought to correspond to our Unit V. The more brightly colored section above probably equals our Unit VII. Gardner et al. (1945, 1946) published a series of stratigraphic sections from south- ern and central Montana, but the closest of these is more than 25 miles (40 km) to the north. No detailed attempt was made to correlate the Middle Dome section with any of their sections. However, those authors and most other students working in central Montana place the lower boundary of the Kootenai Formation at the base of a resist- ant, massive, gray, frequently conglomeratic sandstone. This basal unit has been cor- related by most authors with the Pryor Conglomerate on both lithic and stratigraphic grounds. Thus the Kootenai of central Montana probably corresponds to Units IV, V, VI? and VII of the Bighorn Basin. Our principal objective in extending the investigation to the Middle Dome area was to rediscover the locations and stratigraphic positions of the American Museum localities. Our efforts were largely unsuccessful. Only one site (AMNH 33-1) was re- located and that was possible only because its position had been recorded by Barnum Brown on a photograph (see Plate 7:B). Locality AMNH 33-1 is situated in the upper 10 to 20 feet (3 to 6 m) of the variegated maroon “shale” noted by Bowen, some 100 feet (30 m) above the basal Kootenai sandstone (Unit IV?). This level probably cor- responds to the middle or upper part of Unit VII. The site is located on the north rim of Middle Dome approximately 0.25 mile (0.4 km) east of the north-flowing stream that drains the Middle Dome depression. None of the other American Museum sites at Middle Dome could be found, and several days of prospecting in the area netted only indeterminate bone fragments. DISCUSSION: PREFERRED TERMINOLOGY Early in our investigation it became apparent that we faced a major problem—the near impossibility of placing our paleontologic collections within a generally accepted stratigraphic framework. Except for the contact between the Morrison-Cloverly se- quence and the underlying marine Sundance Formation, there appeared to be no uni- versally recognized datum to which we could refer our collections. While that contact is perhaps the most reliable, it was of little value for such purposes because few of our collection sites occur near exposures which reveal this datum. Recently, Waage (1955, 1958, 1959a, 1959b) and others have established the regional extent of a transgressive disconformity separating the Upper Jurassic-Lower Cretaceous continental sequence from the overlying marine strata. This datum has been recognized in many parts of the study area, but again, as with the Sundance datum, it is rarely preserved or ex- posed in the vicinity of our collection sites. Consequently it was necessary to obtain other stratigraphic data in order to establish a framework to which our collections could be referred and that could be related to the stratigraphic data and terminology of previous workers. These data have been presented in the preceding pages. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 49 At this point it is appropriate to ask which—if any—of the various terminological usages that have been applied to the Morrison-Cloverly sequence is preferred? Should we adopt a restricted application of the term Cloverly (sensu Darton, 1906), or a more expanded usage (after Moberly, 1960), or should the entire nonmarine se- quence be placed in a single formation (as suggested by Hewett, 1914) ? I have striven to present the preceding stratigraphic information in a form free of the usual classical labels, but now I must conform to more usual stratigraphic practices. Certainly it would simplify things greatly if the entire nonmarine sequence could be accepted as a single formation, as suggested or implied by several workers. However, the majority of stratigraphers that have considered these strata seem to favor subdivision into two formations. Most recently, Moberly (1960) has cited significant lithic evidence in favor of this position and now our studies show that there is substantial paleontologic evidence to support such subdivision. The question now resolves itself to the matter of placement of the interformational boundary. Darton did not specify a type section for his Cloverly Formation but he did locate the site of his detailed measured section (1906: p. 52). Consequently, there can be no doubt as to precisely what part of the nonmarine section Darton assigned to his new formation. On the basis of his measured section, we have established that Darton’s Cloverly Formation corresponds to Units VI, VII and VIII of the present report. In the years that followed, most geologists failed to recognize the strata specified by Darton, or chose to adopt different definitions. A few of these reports (Hewett, 1914; Johnson, 1934; Moberly, 1960) clearly indicate that their usage constitutes a redefi- nition of the formations, but most do not, and the supposition here is that the latter reports contain misapplications of Darton’s terminology. Whatever the sources of the diverse applications summarized in Figure 3, our efforts have demonstrated to my satisfaction that the Cloverly Formation as defined by Darton is both widespread and recognizable throughout the Bighorn Basin region and thus might well be retained as a valid formation. To return to Darton’s usage, however, would probably add further to the con- fusion that has plagued work on this part of the stratigraphic column. Whether by intent or through error, a majority of stratigraphic reports dealing with this region have placed the Morrison-Cloverly contact at the base of the Pryor Conglomerate (or a nearly identical conglomerate at approximately the same stratigraphic level). In some reports it is clear that the author erroneously equated the Pryor Conglomerate with Darton’s basal sandstone. Prevalent usage would seem not to favor returning to Darton’s definition. Most recently, Moberly (1960) has proposed a formal redefini- tion of the Cloverly Formation within the Bighorn Basin, placing the lower boundary at the base of the Pryor Conglomerate or at the base of the lowest strata which show “evidence of significant additions of volcanic debris”. His evidence of volcanic debris (p. 1145) includes “‘bentonites, partly bentonitic mudstones and claystones, highly sili- ceous rocks such as cherty siltstones, tuffaceous mudstones and spotted to white cherts, and variegated rocks especially colored shades of pale-red, light to dark-purple, pale- greenish-yellow and neutral gray.” Moberly’s analysis presents the most detailed evi- dence so far available and constitutes the best reasons for subdividing this section in the study area. Accordingly, I have followed Moberly’s terminology in this report. Units I, II and III are assigned to the Morrison Formation and Units IV, V, VI and VII are included in his redefined Cloverly Formation. The sandstones (Unit VIII) 50 PEABODY MUSEUM BULLETIN 35 at the top of the nonmarine section (Greybull sandstone of some authors) are in- cluded in the transitional series (“rusty beds’’) which Moberly has formalized as the Sykes Mountain Formation. A comment regarding the latter unit is in order here, although it is peripheral to the main objectives of this study. For many years there has been a lack of precision as to what has been meant by the term “rusty beds”. It is evident, as I have shown in the preceding pages, that Darton included a massive to thin-bedded sandstone at the base of the “rusty series” as the uppermost element of his Cloverly Formation (as defined by him in 1906). Ever since Moberly (1960) formalized the “rusty series”, including the lowest sandstone (our Unit VIII), as the Sykes Mountain Formation, a debate has developed as to whether the new terminology should be adopted or whether Dar- ton’s inclusion of the “rusty series sandstone” (Greybull sandstone) should be re- tained. Some favor recognition of the Sykes Mountain as the upper member of the Cloverly Formation as being most consistent with prevalent usage in the literature. Others argue that since this unit (at least in many places) contains the siderite spher- ulite zone that is judged to mark the transition from terrestrial to marine conditions, it is more logical to separate the Cloverly Formation from the overlying transitional and marine strata at this level—or at the base of the sandstone. Clearly there is merit in both positions. It is not my intention to evade the problem, but in view of the fact that none of our fossil vertebrate collections were obtained from Unit VIII, and because we did not extend our searches or our sections more than a few feet above the underlying claystone, I feel unqualified to adopt a formal position here. I have not had to concern myself with stratigraphic placement of fossil collections within the Sykes Mountain Formation. I have listed the Sykes Mountain as a formation in the included columns and re- ferred to it as such in discussions only because it is my impression that this application is less ambiguous than are many of the older terms that have been applied, at least within the area we studied. 3. STRATIGRAPHIC DISTRIBUTION OF FOSSIL VERTEBRATES Perhaps the most important product of this investigation, aside from the collection of a previously little known and unpublished fauna, is data on the distribution of fossil vertebrates found in the Morrison-Cloverly sequence. Two distinct vertebrate faunas are present, apparently with no overlap. The new fauna appears to be restricted to the Cloverly Formation (sensu Moberly), at least within the study area, while a typical Morrison fauna is limited to Units I, II and III. Our collections were made primarily from Unit VII and secondarily from Units VI and V. No collections were obtained from Unit IV. Excluding the famed Howe Quarry of the American Museum (which produced only Morrison taxa), as far as I know all collections from this sequence made by other institutions were collected from Unit V or above. With the exception of fragmentary crocodilian remains similar to “Goniopholis”, not one specimen in all these collections is referable to a Morrison taxon. (The status of the genus Goniopholis is far from established and it is probable that many specimens have been referred to that genus that should not have been.) Although we did not carry out extensive exploration of Units I, II and III, a number of identifiable specimens (all fragmentary) were found in these lower units during the course of our traverses. All of them were referable to Morrison taxa (Stegosaurus, Camptosaurus, Allosaurus and Apatosaurus). If elements of the Cloverly fauna are present in these lower units, we did not recognize them. The precise level of the Morrison-Cloverly faunal change is difficult to establish be- cause of the rare occurrence of vertebrate remains in all parts of the sequence. The best assessment at present is that the Cloverly fauna is not known below Unit V and the Morrison fauna is unknown above Unit III. The change thus appears to coincide approximately with Unit IV—the Pryor Conglomerate. Unfortunately, identifiable remains have not been found in the Pryor Conglomerate so it is not known whether the faunal change took place before or after accumulation of that Unit. Nevertheless, it is clear that these faunal distributions approximate the revised stratigraphic align- ments proposed by Moberly. It seems unlikely, in view of the lithotopic evidence pre- sented by Moberly, that this is due to chance. The stratigraphic distribution of these faunas thus seems to add significant new evidence in support of Moberly’s redefined Morrison and Cloverly Formations in the Bighorn Basin area. The extreme rarity of most vertebrate taxa within the Cloverly Formation makes it difficult to establish actual stratigraphic ranges. Figure 5 summarizes the known stratigraphic distributions of the major Cloverly taxa plotted against a generalized stratigraphic column. These taxa are described in the following section on systematic 51 52 PEABODY MUSEUM BULLETIN 35 paleontology. For precise stratigraphic occurrences of individual specimens see the stratigraphic data of the appropriate locality listed in Appendix B. Unfortunately, only three taxa are represented by large enough samples to provide meaningful stratigraphic ranges. These are Tenontosaurus tilletti (gen and sp. nov.), Sauropelta edwardsi (gen. and sp. nov.) and Deinonychus antirrhopus. Tenontosaurus appears to occur at all levels within Units V, VI and VII but is most common in the upper part of V and the lower part of VII. Sauropelta also appears to range through- out most of the same three units, but again the most common occurrences are in the upper few feet of Unit V and the lower part of Unit VII. Deinonychus is limited to the upper 30 feet (9 m) of Unit V, Unit VI and the lower part of Unit VII. It is most common in the latter. All three taxa appear to be distributed through the se- quence without regard to lithology. As might be expected, fossil remains from Unit VI occur as isolated and water-worn elements. The only articulated specimens were found in the finer grained claystones of Units V and VII. The remainder of the Cloverly fauna is known only from the upper part of Unit V or above. This probably does not represent a true lower limit for these elements of the fauna for several reasons. We expended considerably more effort on the upper part of the sequence (upper half of Unit V, Units VI, and VII) for the simple reason that these strata are more abundantly exposed than are the lower strata. Exploration of the lower part of Unit V, however, was relatively unproductive, and it is my im- pression that it is much less fossiliferous than the overlying beds. In view of the low occurrence of both Tenontosaurus and Sauropelta, the two most common taxa, I sus- pect that many, if not all, of the less common elements of the fauna also range close to the base of Unit V. I regret that we were unable to establish this suspicion as fact, but the effort required would be excessive, for even the fossiliferous levels of Unit VII— our most productive zone—would be considered barren by most standards. STRATIGRAPHIC DISTRIBUTION OF CLOVERLY VERTEBRATES GENERALIZED SECTION NORTHERN WYOMING vertical SOUTHERN MONTANA fealetsntgah 80 Thermopolis Shale 20 SYKES a Scat med FORMATION ARS RH SN % a 40 B 3| 18 S 2 = ES & o & op) a S H < 8 w Wy) Fe= o STS afst 2) z|sQ| £ 3 S Sime Zips enn TE =) © |j== ns = Sto S Sad =) sandstone == |(ne i Aa | | AS rt z s 3 S 5 | 5|S 2 x crossbedded sandstone = Sv “VO S| Oo oe a ~ = < _ = Vi | S S 2 S 3 5 A EE2] conglomeratic sandstone j =n] SIS & re} S N S o ) S) Fa Shrine re iS S$ = S > = S [==] claystone a ao = i i— So eo Shee ws ST a a Ea FE siltstone | | aes] (i : S Q S oS o a a = : 8 5 S [2 al chalcedony-barite concretions lJ WW 3 S (o) cS = = uy W 3 5 & calcareous concretions o a |2S i ite-satinspar) oO ie = +" ] gypsum (selenite-satinspar = = ee bentonite =) = = [e ¢} “gastrolith” Oo a [a 4 hematite concretions FIG. 5. Stratigraphic distribution of Cloverly vertebrates. 4. SYSTEMATIC PALEONTOLOGY The extensive collections obtained by American Museum expeditions during the 1930’s and Peabody Museum of Natural History expeditions during the 1960's consist of a large number of partial or nearly complete skeletons, isolated teeth and bones, and fragmentary elements. Most of these represent new species of saurischian and ornithischian dinosaurs. Some of the remains, notably of chelonians, crocodilians and sauropods, are known only from fragments or isolated teeth and postcranial bones. The latter are described and illustrated where appropriate, but some are only tenta- tively referred to a family or other category because existing material is not adequate for more definite assignment. Despite these difficulties, the sauropod material is de- scribed in some detail because it appears to represent the most significant sauropod remains from the Lower Cretaceous of the Western Hemisphere and as such is of particular importance. Crass OSTEICHTHYES SuscLtass SARCOPTERYGII OrpbeR DIPNOI Famity CERATODONTIDAE Gill, 1872 Ceratodus Agassiz Ceratodus Agassiz, 1837. TYPE SPECIES: Ceratodus latissimus Agassiz, 1837. TYPE LOCALITY: Near Bristol, England. KNOWN DISTRIBUTION: Rhaetic of Europe. Ceratodus frazieri, new species Plate 8: B; Plate9: A ETYMOLOGY: Ceratodus frazieri; named for the Wilford Frazier family of Billings, Montana, to whom I am indebted for much assistance. TYPE SPECIMEN: YPM 5276, a left mandibular dental plate. TYPE LOCALITY: Approximately 225 feet (75 m) southeast of Princeton University locality 49-1, NW 14 Sec. 34, T.58 N., R.75 W., Big Horn County, Wyoming. (See Locality Map H.) 58) 54 PEABODY MUSEUM BULLETIN 35 DOUBTFUL REFERRED SPECIMENS: YPM 5537, AMNH 8661? (See Discussion below. ) HORIZON: Unit V, approximately 50 feet (15.2 m) below Unit VI, Cloverly Formation. KNOWN DISTRIBUTION: Unit V, Cloverly Formation, northern Wyoming. DIAGNOSIS: Dental plate very large, broad and thin with four broad and apparently non-tuberculated radial ridges. The ridges are not sharp crested distally as in C. guentheri, nor do they extend to the medial margin of the plate. Externally, these ridges end in broad projections separated by shallow notches. Anterior ridge the larg- est, ends in the longest distal projection. Posterior ridge very faint, terminates distally in a very slight lateral projection. These radial ridges so subdued, apparently by exces- sive wear, that the typical ceratodontid radiating pattern is not clear, except near the external margin. Internal margin broadly rounded and not angled as in most other ceratodontids. Maximum length 58.5 mm, greatest width 28 mm, greatest thickness only 10 mm. DISCUSSION: YPM 5276. As yet no analysis has been made of variation or ontogenetic differences in ceratodontid tooth plates. The situation is further complicated by the fact that wear appreciably alters the gross morphology of these tooth plates. Founda- tion of a new species on the present specimen would seem unwarranted under these circumstances, except for the fact that a large proportion of fossil lung fish are based on such isolated tooth plates. The Cloverly specimen is clearly distinct from any of the tooth plates known from the Morrison Formation, as well as from those of other North American Mesozoic species. Accordingly, until the range of variability, ontogenetic change, and effects of wear are clearly established the distinctiveness of the present specimen is best expressed by formal taxonomic designation. YPM 5276 (Plate 9: A) is considerably larger than any of the Jurassic or Creta- ceous ceratodontid specimens I have seen, and is almost as large as the largest Triassic plates, specifically those of Ceratodus latissimus from the Rhaetic and Ceratodus run- cinatus of the Keuper (both of Europe). It is almost three times as large as the type of the Morrison species, C. guenthert (YPM 205) that measures 20 mm, 10 mm and 6 mm, respectively, in maximum length, width and thickness (Plate 9: B) and is at least twice as large as typical dental plates from the Morrison Formation. All of these specimens are distinct from C. frazieri in the presence of well-defined, sharp-crested ridges that extend nearly or entirely across the plate to the internal margin and in the deep notches separating the external extremities of these ridges. Also, the internal margins of Morrison specimens are moderately to sharply angled (Plate 9: B, C, D). There seems to be nothing distinctive about the size, spacing or arrangement of the dentinal osteons in C. frazieri. There is no evidence of a superficial enamel layer or of palial dentine, except along the external surface, and the tooth plate is composed al- most entirely of osteodentine. The absence of enamel or palial dentine is presumably due to loss by wear, as evidenced by the subdued, broadly rounded topography of the radial ridges, the absence of tubercles, and the surprisingly thin construction of such a large plate. C. frazieri is distinct from the fragmentary type of C. robustus Knight (1898), presumably from the Morrison Formation of Albany County, Wyoming, in the size and spacing of the external projections. The latter specimen, however, appears CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 55 to be a palatal plate rather than a mandibular plate as described by Knight. C. ameri- canus Knight (1898), also from the Morrison Formation, is based on an incomplete mandibular plate that corresponds very closely to Marsh’s (1878) type of C. guenthert. C. eruciferus Cope and C. hieroglyphus Cope of the Fort Union (Hell Creek?) of Montana (Cope, 1876), and C. crosbiensis Warthin (1928) and C. dorothea Case (1921), both from the Triassic Dokum Formation of Texas, are much smaller (21 mm or less in length) and bear several more ridges than C. frazieri. The present specimen is the only positive evidence of Dipnoi that we found during our extensive searches of Cloverly exposures—a surprising circumstance. A possible second specimen exists, however, and because of its interesting history and taxonomic importance, it warrants special comment. “Ceratodus brownt” (Wieland) Brown, 1938: p. 131 This specimen (AMNH 8661) was collected by Barnum Brown from the Cloverly Formation along Beauvais Creek in Big Horn County, Montana, a locale where we recovered extensive collections (see Locality Register of Appendix B and Locality Map U). Brown apparently thought it was invertebrate or plant and turned it over to the Curator of Invertebrate Fossils where it was catalogued as AMNH 24123. Wie- land (1934) subsequently identified it and described it as a new species of shelf fungus, Polyporites brownt. In 1938 Roland Brown of the United States National Museum suspected that Wieland’s type specimen was not a fungus, and his subsequent inves- tigations “resulted in the elimination of every available possibility except the dental plates of Jurassic and Cretaceous species of lung-fish, Ceratodus.” The correspon- dence, detail for detail, with these [fish] remains is so close that there is little, if any, doubt that Polyporites brownt represents Ceratodus. The specimen is therefore re- named “Ceratodus brownt”’ (Wieland) Brown, n. comb. (Brown, 1938: p. 131). Article 2 of the International Code of Zoological Nomenclature states: “If a taxon is transferred to the animal kingdom, its name or names enter into zoological nomen- clature with the original date and authorship.” It seems to me that this would hold true only if other criteria of availability (Articles 10, 11, 12, 13, 14 and 15) are satis- fied at the time of transfer. Article 13, for example, requires accompaniment of “a statement that purports to give characters differentiating the taxon—or a biblio- graphic reference to such a statement” for names proposed after 1930. It is absurd to consider Wieland’s description establishing a fossil fungus as a distinctive diagnosis of a lungfish, and since Roland Brown failed to amend the description so as to distin- guish his species of Ceratodus from other Ceratodus species, C’. browni does not seem to satisfy the Code. The type of C. browni (now recatalogued as AMNH 8661) unfortunately is a badly abraded fragment that cannot be referred with certainty to any animal group. No definitive gross character is preserved, the shape being entirely the result of broken or worn surfaces. There is no evidence of radial ridges or of lateral projections. Only the microscopic “polypore” structure exists and, although it does resemble that of lungfish tooth plates in a superficial way, it is not the same (see Plate 8: A). This specimen may well be a ceratodontid, but it certainly lacks all the usual diagnostic characters and is thus inadequate as a type specimen. I therefore consider Ceratodus browni a nomen dubium. 56 PEABODY MUSEUM BULLETIN 35 SuscLtass ACTINOPTERYGII OrpER AMIIFORMES. SuBorDER PAMIOIDEI Plate 15: C-E REFERRED SPECIMEN: YPM 5519, a partial left dentary of an indeterminate species. LOCALITY: YPM 64-40, approximately 500 m east of Push Creek, Big Horn County, Montana. (See Locality Map R.) HORIZON: Unit VII, 12 feet (3.6 m) above Unit VI, Cloverly Formation. DESCRIPTION: The above specimen consists of a fragment of an edentulous left dentary which is generally similar to, but quite distinct from that of Amza. It appears to in- clude part of the symphyseal surface, but this is uncertain because of abrasion. The length of the fragment is 37.5 mm, maximum vertical and transverse dimensions are 7 and 5 mm, respectively. It tapers very gradually anteriorly and is distinctively bowed, convex laterally. In cross-section, it is triangular with a sharp, narrow ventral apex that reflects a sharp-crested medio-inferior margin. The external surface (Plate 15: E) is slightly convex both vertically and longi- tudinally and faces out and down. It is smooth and unsculptured, but there are a num- ber of distinct foramina irregularly spaced and arranged in two poorly defined rows. The lower of the rows is the more prominent and appears to represent the mandibular lateral line. The internal surface (Plate 15: D) is more strongly convex (vertically) than the external surface and is marked by a narrow, shallow, open Meckelian groove just beneath the upper margin. There is no evidence whatsoever of a splenial or any other post-dentary element, nor is there is any indication of a median gular. The dorsal surface (Plate 15: C) is broad and gently convex, the width being nearly uniform throughout the length. A total of 14 alveoli are arranged in a single row along the external margin of the dorsal surface and separated from the medial margin by a flat shelf 1 to 3 mm wide. The alveoli vary considerably in size but not in a regular or progressive manner. The sixth through ninth (from the front) alveoli are the smallest, ranging from 0.9 mm to 1.5 mm in minimum diameter, whereas those in front and behind are significantly larger. The 12th alveolus is the largest, measuring approximately 2.5 by 3 mm. This irregular variation in alveolar size may be comparable to the irregular size variation of marginal dentary teeth that is characteristic of amioids. Nearly all alveoli are oval, the transverse diameter being greater than the longitudinal dimension. The alveoli are not deep, but are regularly spaced and well defined. Tooth implantation was clearly subthecodont. Despite the absence of both functional and replacement teeth, this fragment is well preserved. The alveolar dimensions relative to height and width of the fragment sug- gest that probably no more than 30 percent of the dentary is missing—if that much. This would indicate a mandible approximating 50 mm in maximum length. DISCUSSION: With the fragmentary evidence at hand, it is impossible to assign the CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 57 specimen with certainty. In shape, size, triangular cross-section and the line of exter- nal foramina it most closely resembles the dentary of Amzia. It differs from the latter in its greater depth and robustness and in the absence of accessory teeth medial to the marginal tooth row. Although the fragment is possibly of amiid affinity, I have re- ferred it questionably to the Amioidei. Crass REPTILIA Orpver TESTUDINATA Numerous fragments of turtle carapaces, plastra and limb bones are present in the Cloverly collections of the American Museum and the Peabody Museum. Most of these are not identifiable, but some are tentatively assigned here to the following taxa, chiefly on the basis of sculpture patterns. SuBoRDER CRYPTODIRA? SUPERFAMILY BAENOIDEA Williams, 1950 ?Famity GLYPTOPSIDAE Marsh, 1890 Naomichelys Hay, 1908. TYPE SPECIES: Naomichelys speciosa Hay, 1908. TYPE LOCALITY: “25 miles east of Pryor, Montana’; “Morrison Formation’ ?* (= AMNH 04-10?). KNOWN DISTRIBUTION: Units V, VI and VII of the Cloverly Formation, Montana and Wyoming. DIAGNOSIS: Same as for the type and only species. Naomichelys speciosa Hay Plate 9: Eand F 2 Gaffney (1969) restricts usage of the term Amphichelydia to those early turtles that include the common ancestors of the Cryptodira and Pleurodira, as originally suggested by Lydekker (1889c). His study of the Baenoidea indicates a close relationship with the cryptodires and I follow Gaffney in placing the baenoids in the Cryptodira. 3 This would place it in the vicinity of Beauvais Creek, near other Cloverly Formation sites of the American and Peabody Museums. (See Locality Map U.) 4 Brown specified Morrison Formation in 1904 when he collected this specimen. The term Cloverly was proposed by Darton that same year and in subsequent years Brown referred to that part of the stratigraphic section exposed in the Beauvais Creek area as the Cloverly Formation. I have shown in a previous section (pages 44-45 and Measured Section 28, Appendix A) that there is very little of the Morrison Formation exposed in the Beauvais Creek area. 58 PEABODY MUSEUM BULLETIN 35 Naomichelys speciosa Hay, 1908. TYPE SPECIMEN: AMNH 6136, entoplastron illustrated by Hay, 1908, Plate 40: figs. Dee: TYPE LOCALITY: “25 miles east of Pryor, Montana, Cloverly Formation” (= AMNH 04-10?). REFERRED SPECIMENS: Right and left epiplastra (YPM 5385, 5431); fragmentary pleurals (YPM 5432, 5433, 5434) ; humerus head, femur head and many shell frag- ments (YPM 5437, 5518) ; shell fragments (AMNH 3052). LOCALITIES: YPM 63-19, 64-18, 64-39, 64-56. KNOWN DISTRIBUTION: Units V, VI and VII of the Cloverly Formation, Montana and Wyoming. REVISED DIAGNOSIS: External ornamentation consists of variable, but generally closely spaced, cylindrical to oval tubercles or pustules ranging from 0.5 to 1.2 mm in diam- eter and 0.3 to 0.5 mm in height. The upper pustule surfaces flat to rounded and pus- tule bases constricted in diameter. Pustules commonly broken off leaving small cir- cular scars. Arrangement appears to be random with no distinct lineation and adjacent tubercles do not coalesce. Entoplastron diamond shaped and slightly longer than wide. The posterior apex is longer than the anterior apex. Entoplastron slightly underlapped ventrally by the epiplastra and extensively overlapped by the hyoplastra. Ventral sur- face is marked by clear narrow sulci defining a long, narrow, wedge-shaped intergular and the medial portions of the humeral scutes. The intergular appears to have extended to the anterior extremity of the entoplastron, but falls short of the posterior extremity. Epiplastra variable with a very short interepiplastral suture and a broad ornamented marginal band on the dorsal surface. Epiplastra more robust (14 mm thick) than ento- plastron. Sulci show the gular scutes to have been much longer in transverse dimension than in longitudinal dimension, and the posterior seam with the humerals is subparallel to the anterior epiplastron margin over much of the seam length. Pleurals inadequately known, but are relatively thin and not strongly arched transversely. Pleurals are not parallel sided, but taper slightly proximally, The rib is represented by a broadly convex ridge on the underside of the pleural. DISCUSSION: These several isolated carapace and plastron elements are believed to belong to a single species, Naomichelys speciosa, because of the unusual ornamenta- tion that is identical to that of the type specimen. Ordinarily I would consider such evidence unsound, but examination of numerous collections of Mesozoic turtles has revealed a conspicuous lack of ornamentation of this type. One specimen does suggest that this type of ornamentation may not have been constant. AMNH 3052, consisting of numerous shell fragments collected from 40 feet (12 m) below the Lakota (Unit VIII) at an unrecorded site at Middle Dome, Montana (Wheatland County), has this distinctive Naomichelys type of ornamentation. One fragment, however, has typical Glyptops type of sculpture and is devoid of pustules. There is no way to establish whether this solitary fragment is from a second specimen or a different region of the shell. I am inclined to favor the former on the grounds that no single fragment or CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 59 specimen presently known shows gradation of Naomichelys and Glyptops types of or- namentation. Nevertheless, such gradation is possible and until more complete speci- mens are available, the following assignments are tentative. In addition to the type specimen, which almost certainly is from the Cloverly For- mation, several dozen fragments have been recovered from the upper part of that formation (Units VI and VII), all with the peculiar pustulose ornamentation. The type specimen corresponds very closely with the entoplastron of a nearly complete turtle (FMNH PR273) in the Field Museum collections from the Trinity Formation of Texas. The similarities include gross shape and dimensions, a long, narrow, wedge- shaped intergular and the same pustulose ornamentation that is present on all external surfaces of both the plastron and carapace. Interestingly enough, the Trinity and Clov- erly Formations have been considered approximate correlatives for some time. The Chicago specimen has not been studied as yet, but it most probably is referable to Naomichelys spectosa. Very similar pustulose ornamentation is also characteristic of the several species of Tretosternon from the Wealden of the Isle of Wight and Belgium. Tretosternon, which has arbitrarily been placed in the Dermatemydidae, may not be close to Naomichelys, but the similarity of sculpture is extraordinary. The only other chelo- nian that I am aware of with ornamentation of this general type is Helopanoplia distincta Hay (1908), a trionychid from the Lance Formation. In that species, the tubercles are more closely spaced, and commonly several tubercles are coalesced to form short, curved ridges. In the Cloverly specimens the spacing between tubercles is usually greater than tubercle diameter, and there seems to be no coalescing of adja- cent pustules. The two epiplastra (YPM 5385, 5431), although approximately of the same size, differ in several features. In YPM 5385 the ornamented marginal upper surface is broader than in 5431 and is marked by a distinct furrow in its lateral extremity. That part of the upper surface that is ornamented in YPM 5431 is convex throughout its length. The position of the gular-humeral sulcus differs also, with the gular scute over- lying a large fraction of the epiplastron and extending over the entire marginal length of YPM 5385, whereas in YPM 5431 it covered a much smaller portion of the inferior surface and did not extend to the lateral extremity of the epiplastron. For the present, I consider these differences as individual variations and refer both varieties to Naomichelys speciosa until additional data are available. Glyptops Marsh Glyptops Marsh, 1890. TYPE SPECIES: Compsemys plicatulus Cope. Glyptops plicatulus Cope Compsemys plicatulus Cope, 1877. Glyptops ornatus Marsh, 1890. 60 PEABODY MUSEUM BULLETIN 35 TYPE LOCALITY: Garden Park, Colorado. KNOWN DISTRIBUTION: Atlantosaurus beds (= Morrison Formation). “Glyptops” pervicax Hay Glyptops pervicax Hay, 1908. TYPE SPECIMEN: AMNH 1910, incomplete carapace and nearly complete plastron, the latter figured by Hay, 1908, fig. 32. TYPE LOCALITY: “Brush Creek”, 10 miles (16 km) east of Pryor, Montana (see fol- lowing Discussion). REFERRED SPECIMENS: Incomplete plastron and carapace (AMNH 6071; YPM 4893, 4894, 4891, 48895435, and 5277). LOCALITIES: YPM 62-11, 62-13, and 66-3. KNOWN DISTRIBUTION: Unit VII, Cloverly Formation and lower part of “Graneros” shale (Sykes Mountain Formation?) , northern Wyoming and southern Montana (see following Discussion). DISCUSSION: Except for AMNH 6071, none of the referred specimens are referable to Glyptops pervicax with certainty. All are too fragmentary. The faint, winding sculp- ture pattern, however, is similar to that of Hay’s species. Gaffney (1969) has studied the type specimen and a referred specimen (AMNH 6071) and concluded that “Glyptops pervicax’ is not determinable beyond assignment to the Baenoidea, but the ornamentation indicates it may be distinct from G. plicatulus and Naomichelys. Gaff- ney (personal communication) suspects that G. pervicax may be referable to a new genus he is describing from the Trinity Group of Texas. At this date, more than 60 years after Barnum Brown collected the two American Museum specimens (AMNH 1910, 6071) there is little likelihood that the precise localities and stratigraphic positions will ever be determined. Hay (1908) gave Brown’s locality for the type specimen as 10 miles (16 km) east of Pryor, Montana on “Brush Creek”. The records in the American Museum catalogue read the same. That region was extensively explored by our field parties, and I myself am very familiar with the area. At present there is no stream in the area known as “Brush Creek”. Al- though we cannot establish the name in use in 1903, the name Push Creek is now applied to the first major tributary of Beauvais Creek, 13 miles (20 km) almost due east of Pryor. Outcrops along the lower 2 miles (3.2 km) of Push Creek consist of the Morrison, Cloverly, Sykes Mountain, and Thermopolis Formations. Thus, it ap- pears probable that “Glyptops pervicax” came from either the Sykes Mountain (rusty beds) or the lower part of the Thermopolis Shale (rather than the Graneros Shale as indicated in American Museum records) from somewhere along Push Creek. The second specimen apparently came from the Sykes Mountain Formation in the vicinity of Cashen ranch on Beauvais Creek, approximately 25 miles (40 km) east of Pryor. Other fragments obtained by Yale expeditions were all found in the uppermost unit CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 61 (VII) of the Cloverly Formation from several localities in Wyoming. On the basis of these tentative identifications, it appears that at least one Cloverly taxon may have survived the initial marine transgression. SUBORDER CRYPTODIRA ? FAMILY incertae sedis Plate 9: I-L DESCRIPTION: A large turtle is represented by the proximal and distal ends of a large right humerus (YPM 4900; locality YPM 63-27). The shaft is missing so length and complete form are not known. Morphologically, these fragments (Plate 9: I-L) com- pare most closely with certain living emydines, particularly Terrapene and Clemmys, and appear to represent a large terrestrial or semiaquatic tortoise. Except for the much larger size, the fragments are identical, point for point, with the humerus ex- tremities of Terrapene: the oval, and slightly twisted head, the broad and sharply defined external (anterior) shelf facet adjacent to the head, the large, tapered inter- nal tuberosity and the smaller deltopectoral crest at nearly right angles, and positioned proximally, close to the head, the short but deep fossa between these proximal proc- esses, the sharply defined and raised trochlear surface extending slightly onto the dor- sal surface, the relative sizes and convexities of the radial and ulnar condyles, the form and location of the ectepicondyle foramen and groove, and the reduced size of the ent- and ectepicondyles. In several of these features there is a close comparison with Glyptops plicatulus?, but in the latter the head is more nearly spherical, the long axis of the head is perpendicular to the deltopectoral crest rather than oblique, and the external articular shelf is narrow and not so sharply defined. The internal tuberosity and deltopectoral crest also are of different shape, and the deltopectoral crest is rela- tively more massive and at more than 90° to the internal tuberosity in the present specimen. Also, the ectepicondyle and entepicondyle are larger in the present speci- men and the trochlea more expanded with both condyles being well rounded, but the ra- dial condyle is the smaller of the two. The proximal ectepicondyle foramen is situated well proximal to the trochlear facet, in contrast to Glyptops plicatulus, and the en- tepicondyle is much larger in Glyptops. The only feature (other than size) that ap- pears to distinguish the specimen from Terrapene is a moderate-sized, deep fossa on the dorsoanterior surface of the deltopectoral crest. I have not recognized this con- dition in any other turtle. LOCALITY: YPM 63-27. HORIZON: Unit VII, Cloverly Formation. DISCUSSION: These fragments cannot be assigned to any family with certainty, but they suggest testudinid affinities. If correct this would be the earliest record of that family. Hay (1908) described Gyremys spectabilis, from a carapace and plastron from the Judith River Formation, as an emydid (= testudinid) and Estes (1964) tenta- tively assigned some shell fragments from the Lance Formation to the Emydinae. 62 PEABODY MUSEUM BULLETIN 35 Orver ?TESTUDINATA FAMILY incertae sedis Plate 9: Gand H DESCRIPTION: The distal end of a left humerus (YPM 4903) from Unit VII, locality YPM 63-28, appears to represent a fourth chelonian family, although it cannot be referred even to this order with absolute certainty. The distal end is compressed dorso- ventrally so that the breadth (24.5 mm) is more than twice the thickness (11 mm). There is no sign of a trochlear facet, the entire distal surface is broadly convex both transversely and vertically with only a slight concavity at the middle of the ventral margin to show the subequal radial and ulnar surfaces. The broad, nontrochlear form would appear to rule out the pleurosternids. The shaft appears to have been moder- ately arched and tapered to a thin cylinder (10 mm) near midlength, a condition which eliminates highly aquatic turtles. The ectepicondylar foramen has been lost, but a long, deep groove extends down the middle of the anterior shaft surface and turns sharply downward across the articular surface. Although different in several details, this fragment most closely approaches the humeral morphology of some pelomedusids, particularly that of Podocnemis. Numerous specimens of Late Cretaceous age have been referred to the Pelomedusidae, but the present specimen is totally inadequate for definite assignment, and I am not suggesting that it represents an Early Cretaceous member of that family. LOCALITY SLE 63-28. HORIZON: Unit VII, Cloverly Formation. OrpDER CROCODILIA SuBORDER MESOSUCHIA FAMILY incertae sedis Plate 10: A-D DESCRIPTION: Crocodilian remains are not very abundant in the upper three units of the Cloverly Formation. Whether this indicates that Cloverly-age crocodilians were less aquatic and more terrestrial in their adaptations, or simply less common, is not known. They do not constitute a major fraction of the known fauna. Numerous iso- lated teeth, vertebrae, dermal scutes and limb bones were collected at a large number of the Yale localities. The vertebrae all appear to be referable to the platycoelous Mesosuchia, but the teeth and scutes cited here may include representatives of the Eusuchia. None of these remains are adequate for definite assignments, so only brief comments are appropriate. Teeth. The referred teeth are of two basic types, relatively long, slender, straight or slightly curved cones and short, blunt, circular to oval “buttons”. With the excep- tion of two of the former (YPM 5440, 5448), all have moderately to strongly devel- oped ridges and grooves on all sides. REFERRED SPECIMENS: Isolated conical teeth (YPM 4884, 4890, 5343, 5345, 5346, 9348, 5353, 5354, 5358, 5361, 5362, 5363, 5364, 5372, 5381, 5438, 5439, 5443, 5444). CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 63 LOCALITIES: YPM 62-5, 62-11, 63-16, 63-18, 63-19, and 64-18. HORIZONS: Units VI and VII, Cloverly Formation. The tapered cones have two straight and rather prominent ridges, one on each side. The remaining ridges usually are most strongly developed on the concave surface and less prominent on the convex (external) surface. The two exceptions mentioned above may be variants of the more common type, but both are characterized by very pronounced, curved, anterior and posterior ridges, and an absence of other ridges. The more common, simple conical teeth range from less than 8 mm to more than 35 mm in height and up to 14 mm in basal diameter. In general, the ridges and grooves are most pronounced on the largest teeth, but not all large teeth are equally prominent in this sculpture. However, they do not differ in any significant way from the ubiqui- tous crocodilian teeth from the Morrison Formation that are commonly referred to “Gontopholis” (Plate 10: A). REFERRED SPECIMENS: Isolated teeth (YPM 5342, 5344, 5359, 5447). LOCALITY: YPM 63-19. HORIZON: Unit VII, Cloverly Formation. The blunt, buttonlike teeth, most probably posterior teeth, are represented by only eight isolated teeth from a single locality (YPM 63-19). All show faint wrinkling of the sides and all are inflated above the base. The sizes range from less than 2 mm to about 9 mm in maximum diameter. I am unable to find significant differences in these from the posterior teeth of modern Alligator (Plate 10: B). REFERRED SPECIMENS: Isolated vertebrae (YPM 4883, 5110, 5128, 5129, 5172, 5292, 5293, 5384, 5398, 5412, 5414, 5415, 5425, 5429, 5445, 5530). LOCALITIES: YPM 62-5, 63-18, 63-19, 64-3, 64-18, 64-23, 64-61, 64-63, 64-70, 64-71. HORIZONS: Units VI and VII, Cloverly Formation. Several isolated vertebrae, including three caudals (YPM 5110, 5172, 5445) and centra of a dorsal and cervical (YPM 5129, 5128), are tentatively referred to Croco- dilia. The caudals are of differing size and length and appear to represent different segments of several individuals. All are platycoelous with rather flat lateral surfaces and a shallow, broad, ventral groove on the underside of the centrum. Robust trans- verse processes occur at the level of the neural canal and anterior to centrum mid- length (Plate 10: Gand D). The dorsal and cervical centra are also platycoelous, the latter with rather robust parapophyses and a prominent ventral ridge (but not a keel) . REFERRED SPECIMENS: Limb fragments (YPM 5401, 5412; 5436; AMNH 5852). LOCALITIES: YPM 63-16, 64-18, 66-3; AMNH 03-26. HORIZONS: Units VI and VII, Cloverly Formation. From Yale locality 66-3, the proximal end of a left femur (YPM 5436) was col- lected. Although it is not possible to assign this to a particular genus, it does not differ in any significant way from femora of various sizes from the Morrison Formation that 64 PEABODY MUSEUM BULLETIN 35 e have usually been referred to Goniopholis. That genus is presently under study by Dr. Wann Langston, and any reference of material to Goniopholis at this point would be questionable. Of particular interest, though, regarding the present specimen is the fact that it is identical with the femur of Alligator mississippiensis but is clearly dis- tinct from Crocodylus. Extrapolating from Recent Alligator, the fragment is from a femur approximately 13 cm long and represents an animal about a meter and a half in length. Associated with this specimen was another fragment that appears to be the proxi- mal end of a left tibia, but it is too poorly preserved and incomplete to warrant fur- ther comment. The proximal and distal ends of a much smaller crocodilian femur (YPM 5412) were recovered from Yale locality 64-18. The original bone did not exceed 6 cm in length and represents remains of the smallest individual crocodilian found in the Cloverly Formation. A variety of crocodilian scute fragments were recovered from a number of locali- ties, particularly the quarries at Crooked Creek. All feature the deep, circular to oval, pitted type of sculpture. None were characterized by a keel. An incomplete metatarsal (YPM 5401), probably the fourth from a left pes, was also recovered at a Crooked Creek site (Locality YPM 63-16). The best crocodilian specimen, purportedly from the Cloverly Formation, is AMNH. 5852, from an unknown locality (AMNH 03-26) somewhere along Beauvais Creek on the Crow Reservation. This specimen, apparently surface scrap, consists of hundreds of chips and fragments heavily encrusted with hematite; included are two dorsal centra, a sacral centrum, most of both humeri, a right femur, part of the left femur, the right tibia, right coracoid, proximal end of the right radius, proximal end of the right scapula, the pubic peduncles of both ilia, part of the right ischium, parts of both lower jaws and dozens of scutes with numerous deep circular pits. The femur matches that described above (YPM 5436) and those referred to Gontopholis from the Morrison Formation. Femur length is about 18.5 cm. As with YPM _ 5436, it corresponds closely with the femur of Alligator, except that the shaft is slightly less robust, the fourth trochanter is less prominent, and the size and position of the insertion of the M. caudi-femoralis longus is smaller and more distally placed. The tibia is distorted, but its original length was approximately 16 cm. It also ap- pears less massive than the tibia of Alligator, but no other details can be observed due to the distortion and the encrusting hematite. Neither humerus is complete and both have suffered from crushing, but the right humerus had an original length of close to 20 cm. If correct, this means the humerus was longer than the femur, a trait that would be unique among crocodilians. Like the hind limb elements this bone was also less robust than that of Alligator. There are other differences from Alligator; specifi- cally, the radial condyle is larger than the ulnar condyle and it is bordered by a short anterior ridge at its anteroinferior margin, the proximal end is also less expanded anteroposteriorly. The remaining fragments show few other features that differ from Alligator. The anterior blade of the coracoid appears to have been thinner and longer and the pelvic elements appear to have been relatively larger, but the material is too fragmentary to be certain. The jaw fragments contain several “Goniopholis” type teeth. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 65 The vertebrae are similar to the other isolated vertebrae cited above, except that the two dorsals bear slight, midline bosses on the ventral surfaces close to the anterior margin. These may be posterior remnants of the ventral sagittal keel that is character- istic of Recent crocodilian cervicals and anterior dorsals, but, if so, there are no similar features in living crocodilians except in the cervicals, and neither of these centra are cervicals. Both are platycoelous to amphiplatyan, subcircular in end view and concave longitudinally in both ventral and lateral surfaces. As with the preceding material, this specimen cannot be assigned with certainty to any genus. OrpvEerR SAURISCHIA SuBorDER THEROPODA Famity DROMAEOSAURIDAE Matthew and Brown, 1922 Dromaeosaurinae Matthew and Brown, 1922. Dromaeosauridae Matthew and Brown, Ostrom (1969a). REVISED DIAGNOSIS: Small to moderate-sized theropods, lightly built and bipedal in posture. Fore limb not reduced. Manus long and slender with three functional digits. Digit III moderately divergent and carpus highly specialized with asymmetrical gin- glymus on radiale. Hind limb moderately long, pes of moderate length and function- ally didactyl. Digit II modified as an offensive or predatory weapon with large tren- chant claw. Digits III and IV subequal and normal, digits I and V reduced. Caudal series may be modified by extremely long prezygapophyseal and chevron processes that rendered the tail virtually inflexible throughout most of its length. KNOWN DISTRIBUTION: Late Aptian or Early Albian to Late Campanian or Early Maestrichtian, western interior of North America and central Asia. COMMENT: Matthew and Brown first used the term Dromaeosaurinae in 1922 for re- ception of their newly described theropod species, Dromaeosaurus albertensis from the Belly River Formation (Oldman) of Alberta, which they provisionally referred to the Deinodontidae (Tyrannosauridae). Gilmore (1924, 1933) and Kuhn (1966) ac- cepted this classification, but few other students have recognized the category. Most authors have in fact not accepted the deinodont assignment and have referred Dromaeosaurus to the Coeluridae, Coelurosauridae or Compsognathidae (probably because of its small size more than anything else). Discovery of the following material and its clear affinities with Dromaeosaurus has established the validity of a supra- generic category, so I have proposed (1969a) elevation of Matthew and Brown’s Dromaeosaurinae to family rank. Related species that may be included in the family (see Ostrom, 1969a and b) are Stenonychosaurus inequalis Sternberg (1932), Veloci- raptor mongoliensis Osborn (1924) and Saurornithoides mongoliensis Osborn (1924). This new rank was also adopted by Colbert and Russell (1969) in their study of Dromaeosaurus. 66 PEABODY MUSEUM BULLETIN 35 Deinonychus Ostrom Deinonychus Ostrom, 1969. TYPE SPECIES: Deinonychus antirrhopus Ostrom, 1969. TYPE LOCALITY: YPM 64-75, NE 4 Sec. 17, T.7 S., R.24 E., Carbon County, Mon- tana. (See Locality Map L.) KNOWN DISTRIBUTION: Cloverly Formation, Units V, VI and VII, northern Wyoming and southern Montana. DIAGNOSIS: Same as for the type species. Deinonychus antirrhopus Ostrom Plate 10: E-M Deinonychus antirrhopus Ostrom, 1969. TYPE SPECIMEN: YPM 5205, left pes illustrated by Ostrom, 1969a, figs. 1-3. TYPE LOCALITY: YPM 64-75, NE 4 Sec. 17, T.7 S., R.24 E., Garbon County, Mon- tana. (See Locality Map L.) REFERRED SPECIMENS: YPM 5201-5204, 5206, 5379, 5356, 5366, 5371, 5376, 5420, 5441, 5278, 5279,,5280, 5281; 4886, 4887; 5283; 5399; 52755 D287) 92887 26942 ouF 5291, 5397; AMNH 3015, 3037, uncatalogued teeth associated with AMNH 3041, and uncatalogued teeth with AMNH 3034. LOCALITIES: YPM 62-6, 62-14, 63-18, 63-19, 64-18, 64-27, 64-33, 64-41, 64-52, 64-53, 64-64, 64-65, 64-67, 64-72, 64-74, 64-75; AMNH 32-5, 32-8, 33-1. KNOWN DISTRIBUTION: Units V, VI and VII of the Cloverly Formation, north-central Wyoming and south-central Montana. DIAGNOSIS: See Ostrom, 1969a, 1969b. DISCUSSION: A detailed description of the species has been presented (Ostrom, 1969b) so additional description is not necessary here. The distribution is extended to include 16 new localities ranging from Shell Creek (Big Horn County, Wyoming) to Middle Dome (Wheatland County, Montana). Most of the materials consist of iso- lated teeth or fragmentary elements that can be referred with certainty to D. antir- rhopus on the basis of the very large collection obtained at locality YPM 64-75. The teeth are all characterized by a pronounced size discrepancy between the serrations of anterior and posterior carinae, a feature that appears to be unique to Deinonychus and related forms of later Cretaceous age. Although the majority of the localities listed produced fragmentary, isolated ele- ments, this species would seem to have been moderately abundant. It is by far the CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 67 most common theropod, and appears to have been the third most abundant element in the Cloverly megafauna. Famity ORNITHOMIMIDAE Marsh, 1890 Ornithomimus Marsh Ornithomimus Marsh, 1890. TYPE SPECIES: Ornithomimus velox Marsh, 1890. (See my Plate 11: A-E.) TYPE LocALITY: SW 4 Sec. 27, T.4 S., R.69 W., Jefferson County, Colorado. KNOWN DISTRIBUTION: ‘Denver Formation’’, Colorado. Ornithomimus sp. Plate 11: F-J REFERRED SPECIMENS: Incomplete left metatarsal II (YPM 5174) ; incomplete left metatarsal ITV (YPM 5284) ; fragment of a proximal pedal phalanx (AMNH uncata- logued) ; and a pedal ungual (YPM 5286). LOCALITIES: YPM 63-16, 63-18; AMNH 55-1 or 2 (“Beauvais Creek, Montana’) ; and YPM 64-3. KNOWN DISTRIBUTION: Unit VII, Cloverly Formation of northern Wyoming and southern Montana. DESCRIPTION: Reference of these fragmentary remains to Marsh’s genus may seem questionable, but the near identity of the two metatarsal fragments to Marsh’s type specimen of O. velox is so striking that any other action would be highly misleading. The two metatarsal fragments are from different size individuals and were collected from different quarries nearly 100 meters apart. Metatarsal II (YPM 5174) is approximately 50 percent larger than that of O. velox but otherwise is virtually indistinguishable from the latter (see Plate 11: C and H). The distal articular facet is a bulbous convexity with a broad and relatively deep in- ferior medial fossa or groove dividing two divergent condyles. However, the surface is not ginglymoid. A shallow concavity marks the inner side and a deep oval collateral ligament fossa marks the external surface. The shaft is subcircular in section with moderately well-defined, flattened surfaces internally, externally and inferiorly. These flattened shaft surfaces are somewhat less pronounced and less well defined in the Cloverly specimen than in Marsh’s type specimen. The proximal end is missing, con- sequently the length is unknown, but it almost certainly exceeded that of O. velox (YPM 542) in which the minimum length of the third metatarsal is 22.2 cm. The incomplete length of YPM 5174 is 16 cm. The fourth metatarsal (YPM 5284) is from a smaller individual approximately 15 percent larger than the type of O. velox (Plate 11: A, B, F and G). The distal facet is almost triangular in end view, as in O. velox, and strongly convex and not gingly- moid. Inferiorly, the facet is extended into a robust internal condyle and a long, thin 68 PEABODY MUSEUM BULLETIN 35 external condyle, separated by a shallow depression. The external distal surface is marked by a shallow depression, the inner surface by a well-defined oval fossa, pre- cisely as in O. velox. The midshaft is strongly flattened on the ventral and internal sur- faces. The incomplete length is 23.5 cm, compared with an incomplete length of 16.5 cm in O. velox (YPM 542). An isolated incomplete ungual (YPM 5286) of small size (3.5 cm probable maxi- mum length) is clearly distinct from those of all other Cloverly taxa. It is nearly straight, with a straight-sided narrow taper. The underside is broad and flat, the upper surface is sharply rounded. A very slight flexor tubercle is present immediately distal to the lower margin of the ridged articular facet. Although not identical to ornithomi- mid foot claws, it compares best with Ornithomimus velox and is tentatively referred to that genus (see Plate 11: I and J). DISCUSSION: Osborn (1917) proposed the name Struthiomimus “for the Belly River (Fort Pierre) stage of the Ornithomimidae” to distinguish material in the American Museum (AMNH 5339) and National Museum of Canada (NMC 930f) from the Belly River Formation of Alberta from Marsh’s specimen of possible younger age from the “Denver Formation, 12 miles from Denver, Colorado”. One of the distinctive features cited by Osborn for Struthiomimus was the retention of the fifth metatarsal, whereas Ornithomimus is distinguished “‘by the loss of metatarsal V in the pes, for which no facet remains.” Osborn further justified Struthtomimus on the grounds that it was improbable that a genus would persist from the Monoclonius—Ceratops zone (= Belly River, Judith River) into the Triceratops—Torosaurus zone (Hell Creek, Lance, Denver). I agree with Gilmore (1920) that these are inadequate bases for proposing a new genus, particularly in view of the fact that the precise age of Ornithomimus velox is debatable. Moreover, I would like to point out that the absence of the fifth metatarsal in YPM 542 is negative and inconclusive evidence. Examination of the proximal end of the type metatarsal IV reveals the presence of a distinct notch in the posterior mar- gin, the location and surface of which is highly suggestive. I suggest that a fifth meta- tarsal probably was present and occupied this notch in O. velox, and until further evidence of the distinctiveness of the various relevant materials, I prefer to use the name Ornithomimus. In the absence of distinctive characters in the few existing Clov- erly specimens, I have referred them to Marsh’s genus until more data are available. The occurrence of ornithomimid remains in the Cloverly Formation may come as a surprise, but Gilmore (1919, 1920, 1921) established the probable existence of ornithomimids in North America by Early Cretaceous times in his analysis of the collections from Arundel Formation of Maryland. He (1920) designated as co-types of Ornithomimus affinis several isolated foot bones (USNM 5703, 5704, 5453, 5684, 8456) that Marsh (1888) had designated as co-types of Allosaurus medius and that Lull (1911) transferred to the Orthopoda (= Ornithopoda) as Dryosaurus grandis. As Gilmore demonstrated (1920), these bones are not ornithopod and they do not compare closely to the corresponding elements of Allosaurus. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 69 ?Famity MEGALOSAURIDAE Huxley, 1870 Plate 10: N REFERRED SPECIMENS: Isolated teeth of medium to large size (YPM 5369, 5377, 5378, 5379) ; a single dorsal vertebra (YPM 5285) ; a metatarsal fragment (YPM 4885) ; a dorsal neural arch (YPM 5408) ; an angular (YPM 5538). LOCALITIES: YPM 62-6, 63-16, 63-18, 63-19, 64-3, 64-59. HORIZONS: Units V, VI and VII, Cloverly Formation. DESCRIPTION: Teeth. The few teeth represented in the present collections are of me- dium and large size (27, 29, 71 and 80+ mm in height). The moderate-sized teeth are significantly larger than the largest teeth of Deinonychus, but most important, none have the pronounced size discrepancy between denticles of anterior and posterior serrations. All are transversely compressed, slightly curved, narrowly tapered blades that are not significantly different from megalosaurid or tyrannosaurid teeth. The much larger teeth in all probability represent another larger species, but neither of these probable taxa can be defined on present materials. A metatarsal (YPM 4885) is represented by a fragment of the distal extremity that I tentatively refer to the Megalosauridae. The only lateral surface preserved is marked by a deep oval, collateral ligament fossa. The incomplete trochlear surface is only slightly grooved and not strongly ginglymoid. Both of these features compare closely with those of the third metatarsal of Allosaurus, but not Deinonychus or Ornithomi- mus. The fragment measures 48 mm in its greatest (incomplete) height, and the distal width probably approached 50 mm. Vertebra, A solitary dorsal vertebra (Fig. 6) collected at YPM 64-59, from the upper part of Unit V, compares reasonably well with middorsals of Allosaurus, with the exception that it is not as narrow-waisted as the latter and the neural spine is unique. The centrum is constricted laterally and ventrally, and the ends flare out broadly, as in all large theropods. The anterior centrum face is slightly concave, the posterior face is moderately concave. Both ends are nearly circular with vertical and horizontal diameters equal and only slightly less than centrum length (103 mm). These features suggest an anterior dorsal, if we can extrapolate from centrum height- length and the form of centrum faces in Allosaurus, Ceratosaurus and Acrocantho- saurus, There are no pleurocoels and in this feature YPM 5285 resembles dorsal ver- tebrae of Allosaurus and Megalosaurus and is distinct from most other large theropods, including Acrocanthosaurus, although the dorsal series is not completely preserved in the type specimen of the latter. The neural arch is distorted and the diapophyses are incomplete, but the basic form and dimensions are preserved. Most distinctive is the neural spine which is nearly complete with the summit, anterior and posterior margins intact. The low and robust bladelike neural process expands upward, the longitudinal length at the summit be- ing nearly twice that of the spine base (8 cm vs 4.5 cm). The anterior and posterior margins are heavily rugose over their entire lengths, marking the attachment of thick, strong interspinous ligaments. The spine crest is rounded transversely and nearly straight longitudinally. The summit is not expanded transversely as in all other large theropods, but the spine does expand near the anterior and posterior margins; conse- 70 PEABODY MUSEUM BULLETIN 35 FIG. 6. Reconstruction of an indeterminate theropod dorsal vertebra in lateral (A) and posterior (B) views. quently, the spine is thin near the center of the blade and thickest at the anterior and posterior edges. Maximum height of the neural spine is about 9 cm, or less than centrum length. The diapophyses appear to have been thin blades about 6 cm wide that flared out, up and back at perhaps 20° to the horizontal. The zygapophyses are small (2 cm long), close to the midline and the facets are inclined at about 45°. The arch pedicels are robust and low, extending the full length of the centrum. DISCUSSION: None of these specimens is adequate for generic assignment, but they clearly establish the presence of moderate- and large-sized theropods in the Cloverly fauna. Reference to the Megalosauridae may be debatable in view of the fragmentary nature of the remains, but bona fide tyrannosaurid remains are known only from Late Cretaceous strata. Further support of this assignment is the nonpleurocoelous condi- tion of YPM 5285, an apparently rare condition in large theropods that is known only in a few megalosaurids (Allosaurus and Megalosaurus) . The vertebra is distinct from known dorsals of Acrocanthosaurus atokensis from the Trinity Formation of Oklahoma in the absence of pleurocoels, in the circular and more concave faces of the centrum and the normal neural spines of A. atokensvs. It cannot be compared with the type of Dryptosaurus? potens (Creosaurus potens Lull, 1911) from the Arundel Formation of Maryland (see Gilmore, 1921 and page 126 of this report), an anterior caudal centrum (USNM 3049). However, the fact that the latter is not deeply constricted laterally and ventrally suggests that the dorsals may have had similar form and thus have been distinct from the present specimen. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY fil Famity COELURIDAE Marsh, 1881 Microvenator, new genus ETYMOLOGY: Mikros (Greek), small, and venator (Latin; masculine), hunter. TYPE SPECIES: Microvenator celer, new species. DIAGNOSIS: Same as that of the type and only species. Microvenator celer, new species Plate 11: L-N; Plate 12: A-P; Plate 13: A-E ETYMOLOGY: Microvenator celer, (Latin), swift, in reference to the probable rapid- running capabilities indicated by the tibia-femur ratio. TYPE SPECIMEN: AMNH 3041, a partial skeleton, lacking the skull. TYPE LOCALITY: AMNH 33-1, SW 4 Sec. 26, T.7 N., R.16 E., Wheatland County, Montana. HORIZON: Unit VII, 60 feet (18 m) below Unit VIII, Cloverly Formation. REFERRED SPECIMENS: YPM 5366?. LOCALITIES: YPM 63-19. DISTRIBUTION: Unit VII(?), Cloverly Formation, central Montana and northern Wyoming. DIAGNOSIS: Very small, delicately built coelurid with hollow thin-walled vertebrae and limb bones. Cervicals without neural spines and with double pleurocels. Dorsal neural arches low and highly sculpted, neural spines low and rectangular, postzy- gapophyses far behind posterior border of centrum. Astragalus with very high and broad ascending process. Pubis profile concave anteriorly, distal extremities only mod- erately expanded. Femur with short but prominent lesser trochanter and a depression at site of fourth trochanter. Approximately one half to two thirds the size of Ornitho- lestes or Coelurus. DESCRIPTION: Skull. A number of thin and extremely delicate fragments are all that are preserved of the skull. Most of these are not identifiable, but those that are include a right palatine, both quadrates, both postorbitals(?) and a right prearticular (?). The incomplete palatine is triangular. The anterior margin preserves the broad posterior limits of the choana between the maxillary and pterygoidal processes. The posterior por- tion is missing, but the inner margin appears to be intact and suggests the presence of a subsidiary palatal fenestra between the palatine and the pterygoid, as in Deinony- chus and Ornithosuchus. Maximum dimensions are 32.5 mm in length and 23 mm in width. The fragments identified as postorbitals are robust and moderately curved. The external surface is strongly convex, the inner slightly concave. There appears to be no qe PEABODY MUSEUM BULLETIN 35 ornamentation, sculpture or rugose texture. The extremities are missing in both frag- ments. The quadrates are not complete, the pterygoid wing being absent in both and the upper and lower extremities somewhat abraded. The lower extremity is triangular in Outline and quite robust. The anterior surface is deeply concave and bordered by sharp lateral and medial crests, the latter presumably continued as the pterygoid wing. The upper extremity is a thin blade apparently oriented in a near parasagittal plane. Contact with the squamosal appears to have been of an overlapping, squamose union. Preserved lengths of the quadrates are 22 and 23 mm, but original length was probably 30 mm or more. Axial skeleton. The vertebral count is not known. Sixteen presacral neural arches are preserved, plus 10 presacral centra or centra fragments (Pl. 11: L-N; 12: A-F).One of the latter is the axis centrum, for which no arch is present. Thus at least 17 pre- sacral segments are represented. A normal presacral count of 23 is assumed. Only three centra and four neural arches are clearly recognizable as cervicals. The remain- der appear to be dorsals. All presacral centra are pleurocoelous. The cervicals have one large lateral cavity in the anterior half and a smaller one behind at near mid- length of the centrum. The dorsals have a single, smaller pleurocoel on the lateral centrum surface at midlength. The cervicals appear to have been opisthocoelus and the centra were moderately to strongly angled as in Deinonychus, but the centra are longer relative to height and width than in Deinonychus. In this latter character they are more like cervicals of Coelurus (YPM 2010). Lengths and widths of the axis and other cervical centra are: 14 by 7.5 mm, 15 by 10 mm and 15 by 10.5 mm. The cervical neural arches are broad and low with long zygapophyses flaring out anteriorly and posteriorly in a nearly horizontal plane. The articular facets are widely separated (15 mm or more) and appear to have been inclined at 30 to 45° to the horizontal. The postzygapophyses lie far behind (6 mm) the posterior end of the centrum. None of the cervical neural arches show any indication of a significant neural spine, a very low ridge being the only evidence preserved. The dorsal vertebrae are platycoelous with moderately constricted lateral and ven- tral surfaces of the centra. Centrum length varies from about 13 mm to 16 mm, but width and height increase from about 9 mm (anteriorly?) to 15 by 10 mm (posteri- orly?). The neural arches are of moderate height, quite robust and intricately sculp- tured. The pedicels and transverse processes are constructed of various struts and ridges separated by numerous deep cavities. The transverse processes appear to have been short (total arch width is 17 to 20 mm) and extended directly lateral in a hori- zontal plane. A short, robust, rectangular neural spine rises vertically directly above the centrum. Spine height varies from 6 mm to 15 mm in the dorsal arches preserved. Articular facets lie close to the sagittal plane but are inclined at approximately 45°. The posterior facets are situated far behind the pedicels (8 mm), whereas the prezy- gapophyses are placed directly above the anterior limits of the neural arch pedicels. Several arches appear to show remnants of hyposphene—hypantrum articulations. The sacrum is represented by a broad, shallow centrum approximately 15 mm long. It appears to have been greatly distorted, although it may originally have been more compressed than the other centra. Caudal vertebrae are represented by nine cen- tra, some with arches, and three additional neural arches. All are platycoelous and are moderately constricted near midlength. None have pleurocels. Proximal caudal centra show evidence of stout transverse processes projecting out from the middle or anterior CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 73 part of the lateral surfaces. Most appear to be compressed dorsoventrally so that cen- trum width is nearly double the height, and the centra faces are thin, horizontal ovals. Centrum length varies from 12 mm to less than 9 mm in the caudal vertebrae available. Appendicular skeleton. The scapula is not known, but a nearly complete right coracoid is present. This is an extremely thin sheet of bone nearly semicircular in out- line. Proximally it expands into a stout ridge that forms the anterior limit of the glenoid. The posterior margin is thickened slightly, but otherwise shows no evidence of sutural or even solid contact with the scapula. The coracoid measures 32 mm in greatest vertical dimension and 25.5 mm in length. The fore limb is represented by the left humerus, radius and ulna, a fragment of the right ulna and six elements from the left manus (see Plate 12: G-J, and L). The humerus is slender and rather straight. The head is small and projects backward al- most at right angles to the long axis of the distal condyles. A small internal tuberosity borders the head medially and a large deltopectoral crest projects anteroexternally along the upper third of the humeral shaft. Although postmortem distortion may have contributed to the present form, the deltopectoral crest projects much more laterally and far less anteriorly than is usual in small theropods. In Coelophysis, Coelurus, Ornithomimus and Deinonychus, for example, this crest projects forward almost par- allel to the plane of flexion at the elbow. In the present specimen, it extends at ap- proximately 45° to that plane. The distal extremity is slightly crushed but the radial condyle appears to have been the larger of the two. Humerus dimensions are: length — 81.5 mm; width across deltopectoral crest 21 mm; greatest distal dimension — 13 mm; minimum shaft diameter — 6 mm. The ulna is a very slender and delicate bone; the shaft has moderate curvature convex externally, and measures 78 mm in length and 3.5 mm in minimum diameter. The proximal end is expanded anteroposteriorly (8.3 mm) and the surface is inclined medially. The distal extremity is also expanded (9.4 mm) anteroposteriorly. The ra- dius is also very delicate and slender, with a nearly straight uniform cylindrical shaft 3.5 to 4.5 mm in diameter. Neither end is intact so original length is not known, but it probably did not greatly exceed the preserved length of 75 mm. Both extremities seem to have been at least slightly expanded. The manus is represented by six elements: metacarpal I, the penultimate phalanx of digit II, the distal end of an indeterminate phalanx and three claws of different sizes, presumably representing digits I, II and III. Judging from the lengths of the complete phalanx and the claws, metacarpal I appears to have been of normal thero- pod proportions and not elongated as in ornithomimids. However, it does seem rela- tively longer (17.5 mm) and more slender (2.5 mm) in construction than do those of most theropods. The proximal end is triangular, slightly twisted relative to the distal ginglymus and has a large external appositional scar for contact with the second meta- carpal. The complete phalanx would seem to be too long (34 mm) relative to meta- carpal I to be any other phalanx except the second of digit II, but this must remain a tentative identification. The claws are thin and trenchant, and strongly curved. The largest (II?) measures 25 mm long and 3.5 mm in maximum thickness. The others measure 19 by 2 mm and 11 by 3.4 mm and probably belong to the first and third digits respectively (see Plate 12: N-P). The pelvis is represented by fragments of both ilia and ischia and nearly complete pubes (Plate 12: K and M). The left ilium consists of the anterior process, the pubic PEABODY MUSEUM BULLETIN 35 14 ayeurxoidde = & SI9JIUII| [TU UT s}UIUTOINSeIWy = ¢8 ey i = +66 0'SZ ME[D JsasIV] JO YISUIT = 06 e0'r1 sa COL O'rE o-II xueypeyd jo yysus'] = ¢8 —_ = o Sh 91 J [edivovjour jo ysus'T —_ a = — EL 0°62 JYSIoy snpesesysy = = oe =a 9 Mae YIPIM snjeseysy —s ae —= fi 81 08 JeYS JO Ig} oUILIpP Jsvo'T — = aaa: +r §°§9 63s pue [SIP JO YIPIM 6ST OS e298 -GG¢ tCE LST eIqh Jo yySUa'T = = — Tit = COI JeYs JO 1a}9WIeIp }svaT — —— —— Cr — EG YyPIm [PUIIxXOlg —= — =o +P = ¥Z puoe [eIsIp JO YIPIM L02 08h e269 +022 ss Fol INUIa} JO yISUIT ——s ed at Cc LaQe VS yyeys jo JoyoUIeIp 4yseaT — = == IT 8Ss a pua [e3stp JO YIPIM = = LHS +8/ oLI QL sniped Jo y}3us'T ee — — Sr 81 I PS yyeys jo JoyowWeirp yseoT == = == room a £82 C6 pus [eISIp JO YIPIM = O&? €8C C6 981 8L euyN jo y}3Ue'T —— — a 6 SI 9 yyeys jo JoyaWeIp }seoT — a = 92 or om pue [e3sIp JO YIPIM — — —- 02 G'St IZ ySa19 [210}99d0}[ap ssor9e YIPIM Lal OIg ers 911 Lee G18 SUA ON aT 619 HNWYV 6sSh HNNV (ZLbI WdA 48eD) 0102 WdA clos HNWV Ir0Os HNWV 1UUDULLAY $N}]D sagisuo] $1]1d:D sngoyssijuv 49199 SaJSIJOYJULE SNU1ULO1LY INLD SY snyjDusosquo,sy sninjaoc) snyrtuourag 40]DUIQOLIITPYY ‘spodo1ay} poj}de]as QUIOS pUL 40JDUaQOLIIP JO SUOISUSUIIP BAeIedWIOT) “| ATAVL CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 75 and ischiac peduncles and the acetabular border. The major part of the iliac blade and posterior process are missing. The right ilium is represented only by the pubic peduncle and part of the anterior process. The latter is relatively short and deep and extremely thin. A thin medial ridge extends dorsoanteriorly along the internal surface from the pubic peduncle. A rugose scar occurs just above the latter marking the point of contact with the first sacral rib. The peduncles are quite robust considering the mil- limeter or less thickness of the iliac blade. The upper margin of the acetabulum is thickened (7 mm or more) , reaching a maximum thickness midway between the pubic peduncle and the midpoint of the iliac acetabular margin, which suggests that the princi- pal weight-bearing axis from femur to ilium was oblique to the long axis of the ilium. The ischia are represented by the pubic peduncle of the right ischium and a mid- shaft section of the left, neither of which provides much information as to the size and form of these bones, The latter indicates a bladelike form measuring 8 mm wide and 3 mm thick. The pubes have robust proximal ends for junction with the ilia and stout, slightly curved, rodlike shafts that are transversely expanded in their distal halves. Distally, the pubes are expanded in the parasagittal dimension, both vertically and longitudinally, although they do not appear to have been expanded to the extent seen in Ornithomimus altus (AMNH 5339) or Coelurus agilis (YPM 2010). Length of the pubis is approximately 118 mm. Both femora are well preserved and undistorted (Plate 13: A and B). Both show moderate curvature and subcylindrical shafts of 10 mm minimum diameter. The head is subspherical and sharply offset from the shaft. A prominent greater trochanter ex- tends slightly above the head and is widely separated from the latter by a deep notch. A short lesser trochanter projects posterolaterally as a sharply defined crest well below the summit of the greater trochanter. The lesser trochanter is more prominent than in any other theropod with which I am familiar. The fourth trochanter is absent; in its place is a distinct, elongate, oval depression well below the head on the inner posterior aspect of the shaft. Distally the femur expands into two distinct, convex condyles of subequal size separated by a broad, deep groove. The two femora are much shorter than the tibia, measuring 124 and 122.5 mm compared with 157 mm for the left tibia. The tibia is a long, straight-shafted bone apparently oval in cross-section. The proximal end is expanded anteroposteriorly and distally it is expanded transversely. A conspicuous, thin cnemial crest projects laterally about one fourth of the way down the shaft. Only the expanded proximal end of the left fibula is preserved. The fibula may have been incomplete in life, limited to just a proximal head and tapered shaft less than one third of tibia length. This is suggested by the delicate nature of the thinly tapered incomplete extremity of the fibula fragment, plus the absence of any apposi- tional scar for the fibula along the distal external surfaces of the tibia (Plate 13: C, DandE). The astragalus extends the full width of the tibial distal extremity with only a small recess marking the site of a minute chiplike caleaneum. The calcaneum itself is missing, but any contact with the fibula appears to have been weak. The ascending astragalar process is incomplete, but that portion preserved rises more than 27 mm above the distal astragalus surface, and appears to be a relatively much longer process than is characteristic of other theropods. DISCUSSION: Mucrovenator was about the size of a small turkey, approximately twice 76 PEABODY MUSEUM BULLETIN 35 the size of Compsognathus. It is one of the smallest known theropods. The possibility exists that the remains are those of a juvenile, but the preserved bones are all well formed, and in my opinion are those of an adult individual. Many of the sutures be- tween neural arches and centra had not fused, but some in the caudal series and poste- rior dorsals appear to be closed. However, I am not convinced that open vertebral sutures have any ontogenetic significance. Microvenator is distinct from Segisaurus in its hollow limb bones and vertebrae, from hallopids in its large manus and the absence of cervical spines, and from podo- kesaurids by the long ascending astragalar process. The remains resemble most closely those of Coelurus and Ornitholestes, particularly in the hollow, thin-walled and sculp- tured construction of cervical and dorsal vertebrae. They differ from Coelurus and Ornitholestes, though, in the form of dorsal and cervical neural arches, the absence of cervical neural spines and the moderate expansion of the distal end of the pubis. Microvenator resembles Compsognathus in the femur-tibia ratio, the lack of neural cervical spines and in the form of the manus unguals, but the fore limb of Micro- venator is relatively much longer—almost equal to tibia length as in Struthtomimus altus (= Ornithomimus)—compared to the short (75% of tibia length) fore limb of Compsognathus. Microvenator may be distinguished from the dromaeosaurids in the form and greater relative lengths of cervical and dorsal vertebrae, the much smaller internal tuberosity of the humerus, the long ascending process of the astragalus, the elongated, rodlike form of the pubes and the morphology of the manus, particularly the first metacarpal and unguals. Accordingly Microvenator seems most closely allied with Compsognathus, Ornitholestes and Coelurus and is placed in the Coeluridae. Associated with the type specimen were 25 teeth of the Deinonychus type which Barnum Brown believed belonged to this specimen. There has been doubt in some minds that the teeth belong to the same individual because they are three to four times the size expected in an animal of these dimensions. Because of the extraordinarily large size of the associated teeth, this specimen has been known informally in conver- sation by the name “Megadontosaurus’”’. Without exception, the 25 associated teeth du- plicate in size and form the teeth found with the type of Deinonychus antirrhopus. The most significant character, however, is the pronounced discrepancy in the size of anterior and posterior tooth serrations, a trait that currently is known only in Deinon- ychus and Velociraptor. Conclusive evidence is not available, but on the basis of tooth form which is identical to that of another clearly distinguishable contemporary species, plus the high improbability of such relatively enormous teeth occurring in such a small animal, I here refer these teeth to Deinonychus antirrhopus. At present, however, they are still catalogued with the Microvenator remains under AMNH 3041. SUBORDER SAUROPODOMORPHA INFRAORDER SAUROPODA The present state of sauropod systematics is one of disorder and confusion—to put it mildly. ‘The reasons are rather obvious. The materials are large and difficult to handle, there are very few complete specimens and the great majority of species have been founded on incomplete and nondiagnostic fragments. A critical, modern revision is CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY ai, sorely needed, but it seems unlikely that one will be forthcoming in the near future. Recent practice has been to divide the Sauropoda into two family groups (Bothro- sauropodidae and Homalosauropodidae of von Huene [1956]; or Brachiosauridae and Titanosauridae of Romer [1956]) or simply to recognize some six or eight categories of equivalent rank as Lapparent and Lavocat (1955) did. Because most of the taxa referred to any of these categories are based on fragmentary material, few are firmly established and the suprageneric categories are rather loosely defined. Accordingly, the fragmentary Cloverly sauropod remains are only tentatively assigned. Isolated sauropod teeth, limb bones and vertebral fragments were found at a num- ber of sites, but the most important collections were made at three Yale quarries (YPM 63-16, 63-18, and 63-19) near Crooked Creek, Wyoming. YPM 63-18 pro- duced a number of limb and pelvic elements and seven vertebrae that were closely associated and these are presumed to be from a single individual (YPM 5449) and are described first. All other sauropod remains were sufficiently isolated from other sauropod elements within and between various quarries that they have been treated independently and catalogued as separate specimens. These last materials are de- scribed separately. ?Famity TITANOSAURIDAE Lydekker, 1893 Plate 13: F and G; Plate 14: A-D and F-H REFERRED SPECIMENS: YPM 4888, 5103, 5104, 5107, 5116, 5147, 5151, 5152, 5116, isolated vertebrae; YPM 5449, associated vertebrae, limb and pelvic elements; YPM 5329, 5450, 5451, 5452, isolated limb bones; YPM 5347, 5349, 5360, 5365, 5374, 5375, 5419, 5453, 5454, 5455, isolated teeth. AMNH 3042. LOCALITIES: YPM 62-10, 62-14, 63-16, 63-18, 63-19, 64-3, 64-39. AMNH 33-2. HORIZONS: Units V, VI and VII, Cloverly Formation. DESCRIPTION: YPM 5449—The items catalogued under YPM 5449 include the only closely associated sauropod material collected by Yale personnel from the Cloverly Formation and, because it includes vertebral and appendicular elements, it is the most important of the referred material and is described first. The possibility exists that these bones do not all belong to the same individual, but they were so closely associ- ated—in some instances in contact—that this seems a remote possibility. The addi- tional fact that all seven vertebrae are dorsals and were associated with two ischia and an ulna strengthens the supposition. All of the materials are distorted and incomplete; consequently, dimensions listed are only approximate and the following descriptions are based on several vertebrae. Dorsal vertebrae. Two distinctly different types of vertebrae are present in YPM 5449; these are interpreted here as anterior and posterior dorsals (Plate 13: F and G). Both are strongly opisthocoelous and neither seems to have a divided or double neural spine. The anterior dorsals are characterized by large centra that are constricted at midlength laterally and ventrally, centra width is greater than centra height or length, and the zygapophyseal facets are far apart and lack hyposphene-hypantrum. The lat- eral surfaces are marked by small, deep, oval cavities or pleurocoels. The neural spine rises vertically as a single, robust, transversely expanded blade. Although none are 78 PEABODY MUSEUM BULLETIN 35 : complete, there is no evidence that any of the neural spines were divided. The trans- verse processes or diapophyses extend laterally and slightly upward as vertically ex- panded blades. ‘The proximal parts of these are moderately excavated ventrally, poste- riorly and anteriorly. On one of these anterior dorsals the parapophyses occur on the centrum, and this presumably is one of the first three dorsals. A second anterior dorsal lacks most of the centrum and the third shows no sign of the parapophysis either on the centrum or on the arch. The four posterior dorsals, which were closely associated with the dorsals described above, are also strongly opisthocoelous and have large, oval pleurocoels high on the lateral walls of the centra. The centra are nearly circular in end view and 50 to 80 per- cent longer than the greatest diameter. A surprising feature is that the greatest diam- eters of the centra are significantly less than those of the associated anterior centra, a condition that has not been reported in any other sauropod. Although distorted and incomplete, the zygapophyseal facets are close to the midline and appear to have been oriented at about 45°. Two of the vertebrae show remnants of what I presume to be the hyposphene. None of the neural spines are well preserved, but they also appear to have been undivided and expanded longitudinally as well as transversely. Two verte- brae clearly show the neural spine inclined backward at about 30° to the vertical, but this may be the result of distortion. The neural arches are long and rather high and the pedicels are deeply excavated laterally by three complex cavities. Above the diapophysis, the base of the neural spine is similarly excavated by two deep and complex cavities. The excavations are generally similar in position and shape to those described in Camarasaurus, A patosaurus, Diplodocus and others, but differ in details. Osborn’s terminology may be applied to these excavations (infraprezygapophyseal cav- ity, infradiapophyseal cavity, and infrapostzygapophyseal cavity for those on the neu- ral arch pedicels, and supraprezygapophyseal cavity and suprapostzygapophyseal cav- ity for those on the neural spine). These cavities are separated by prominent bony struts or lamina to which Osborn applied specific terms (i.e., infradiapophyseal lam- ina). The present material does not permit close detailed comparison of neural arch structure with other described material. However, within at least some of the neural arch excavations, there are complex “sub-cavities” separated by very delicate laminae. The diapophyses are not complete in any of the present vertebrae, but they may have been shorter and more steeply inclined than those of the anterior dorsals. A soli- tary vertebra (YPM 5147) from an adjacent quarry at YPM 63-19, approximately 8 meters distant, corresponds to the last described vertebra in all respects, except that the centrum is longer relative to width or height, and the neural arch appears to be correspondingly elongated. The great length of the centrum is reminiscent of cervical vertebrae. Precise dimensions are not available due to the distorted and incomplete condition of this vertebra, and the parapophyseal region is incomplete. However, the great height of the neural arch and the close spacing of the zygapophyseal facets indi- cate this to be a posterior dorsal, rather than a cervical, but exactly which segment is not known. Although smaller than those of most well-known sauropod species, the present ver- tebrae appear to be more extensively excavated than most, and on this character alone would seem to be excluded from the Cetiosauridae. Most significant of all, however, is the solitary or undivided form of the neural spine, especially of the anterior dorsals. Double, or split, neural spines are characteristic of the cervical and anterior dorsal CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 79 TABLE 2. Approximate dimensions of sauropod dorsal vertebrae (in centimeters). YPM 5449 Vertebrae* YPM 5147 A B Cc D E F Greatest centrum width 20 Pie 1B i PAS 10+ — Greatest centrum height 13 — 14.5 14+ 16.5 10 7S Greatest centrum length 13) — 16+ 18.5 12? 19 28 Height of articular facets above centrum 10 ees 11 cg 8.5 9 28+ Tranverse separation of zygapophyseal facets 6+ 9 12 2 1+ -— 2 Greatest width of zygapophyseal facets jie = 18+ 24 9+ 13 — i183} Greatest width of diapophyses 64+ 54 60+ = — = — Minimum tranverse width of neural spine — 8.5 -- — = —- — Neural spine height above neural canal — 49+ — 34+ a - — *The exact segment number is indeterminate. Consequently, the various vertebrae have been des- ignated by letter. vertebrae of all sauropods except the Brachiosauridae and the Titanosauridae. The present vertebrae differ from both brachiosaurid and titanosaurid vertebrae in the greater diameter and length of anterior dorsal centra relative to posterior dorsal cen- tra. They also differ in the presence of a large triangular infradiapophyseal cavity in the neural arches of posterior dorsals. C. C. Young (1935) illustrated a series of poste- rior dorsal vertebrae of Euhelopus (= Helopus) from China in which there appear to be large triangular excavations beneath the diapophyses and above and between the infraprezygapophyseal and infrapostzygaphyseal cavities. Young did not identify or comment on the excavations, but this is the only sauropod material that I have been able to discover that corresponds to the Cloverly specimens in this particular character. Ischium. Closely associated with the above vertebrae were incomplete left and right ischia, both of which lack the proximal portion. The ischium is a moderate-sized bone with a broad, nearly parallel-edged blade that is expanded slightly transversely and longitudinally at the extremity. The greatest preserved length is about 74 cm with perhaps 10 or 15 cm missing from the proximal region. The narrowest part of the blade measures about 15 cm by 4.5 cm in thickness at about midlength. The distal extremity is slightly expanded to a breadth of 23 cm and a thickness of approximately 6 cm. The greatest proximal dimension is not known, nor is the nature or orientation of the iliac peduncle. The ischia are too incomplete to permit meaningful comparison with published illustrations. They differ significantly, however, from the co-ossified ischia of Alamo- saurus sanjuanensis (Gilmore, 1946), perhaps the best known North American Cre- taceous titanosaurid (Fig. 7). 80 PEABODY MUSEUM BULLETIN 35 Sternal bone. An incomplete, thin plate of bone, suboval in shape and measuring 39 by 27 cm, was found directly beneath the left ischium. It has been catalogued with the latter as YPM 5449 and referred to the previously described vertebrae. The identity of this bone is questionable, but it clearly is not part of either ischium or part of the pubis or ilium. The margins are preserved on two sides and one end, and the shape of this portion corresponds very closely to the anterior half of a right sternal bone, par- ticularly that referred to Apatosaurus excelsus (YPM 1980) by Ostrom and McIntosh (1966). It is less robust than that element and approximately four fifths as large. This bone is very different from the sternal bones of Alamosaurus which have a strongly concave external margin. Ulna. A left ulna was recovered close to the right ischium and is presumed to be- long to the same individual. Although somewhat distorted by crushing, it is almost complete and provides a reasonably close approximation to the original form. It is straight and of rather slender proportions, measuring 60 cm in length, 26.5 cm in greatest proximal width, 12 cm in distal width and 26.5 cm in minimum girth of the shaft (Plate 14: D). The ulna tapers gradually away from the proximal end, with the least diameter just below midlength. The proximal flanges are well developed and broadly rounded, the internal flange being the largest. These are separated by a rather deep radial concavity. The relatively slender proportions of the ulna are similar to those in Diplodocus or Brachiosaurus, although the ulna of the latter is much longer relative to ischium length than in the present specimen. This slenderness is in sharp contrast to the short massive proportions in Camarasaurus and A patosaurus. DISCUSSION: Definitive evidence is not available for confident assignment of these remains. The dorsal vertebrae are consistent with both titanosaurids and brachio- saurids, but the distinctive features of these two groups are in the cranial and appen- FIG. 7. Outline of sauropod ischium associated with dorsal vertebrae of Plate 12. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 81 TABLE 3. Dimensions (in centimeters) of sauropod caudal vertebrae. YPM 5147 YPM 5199 YPM 5104 YPM 5103 YPM 4888 Centrum length 21 (= 2 vertebrae) 12 10 10 10 Centrum height lie Srandel5'5 14 11 8 8+ Centrum width 25 and 21 18+ 15'S 9.5 8 Total height 29.5 and 29 — — — a dicular skeleton. The relatively thin, unexpanded ischium and the slender, but not elongated ulna suggest titanosaurid rather than brachiosaurid affinities and I have therefore tentatively referred YPM 5449 to the Titanosauridae. DESCRIPTION OF ADDITIONAL REFERRED MATERIAL: Vertebrae. A number of caudal ver- tebrae were recovered from several sites, including both proximal and distal segments. All are amphiplatyan and none possess pleurocoels. A distal caudal (YPM 5152) and a proximal caudal (YPM 5116) were collected at Yale locality 63-18, and a pair of co-ossified anterior caudals (YPM 5147) came from YPM locality 63-19. Two iso- lated anterior caudals(YPM 5199, 5104) from the latter quarry represent elements from between the fourth and tenth caudal segments, judging from the caudals of Camarasaurus. Each of these latter bones has short, low and broad centra, oval in end view, and slightly constricted in lateral and ventral surfaces. Short, robust trans- verse processes project out and backward, slightly inclined to the horizontal in the most anterior elements, and nearly horizontally in the two smaller vertebrae. The neural arch is very low and is topped by a very short, robust, and rugose neural spine. The neural arches are situated on the anterior halves of the centra and the prezy- gapophyses project well forward of the anterior face of the centrum. Distinct articular facets for the chevron are present posteriorly on the ventral surface of the two smaller vertebrae but not anteriorly. The two co-ossified caudals do not have chevron facets, indicating that these may represent the first two caudal segments. Two distal caudals (YPM 5103, 4888) are known. They show no evidence of transverse processes, but both have low neural arches rising from the anterior half of the centrum. The centrum length is greater than width or height. The centra are constricted in lateral and ventral surfaces at midlength. No pleurocoels are present and the chevron articular facets are faintly evident at the posterior centrum margin. These vertebrae differ from other sauropod caudals in several features. The am- phiplatyan, transverse oval centrum face is characteristic of Diplodocus, but the high and robust neural arch at midlength of the centrum, with the downward-directed transverse processes, exclude this genus. High neural arches and spines, circular cen- trum faces and pronounced chevron facets, anteriorly placed as well as posteriorly, distinguish caudals of Camarasaurus, Apatosaurus, Haplocanthosaurus and Brachio- saurus. Alamosaurus caudals are strongly procoelous, but the anterior position of the neural arch and the forward extension of the prezygapophyses resemble the present vertebrae. The closest resemblance I have been able to discover is a vertebra figured by Owen (1859: Pl. X) as Cetiosaurus brevis—a sauropod proximal caudal from the Wealden of Sussex, England. 82 PEABODY MUSEUM BULLETIN 35 . Questionable sauropod vertebra. When first exposed in the quarry at YPM 63-18, specimen YPM 5294 was thought to be a limb bone, but it proved to be a vertebral centrum of unusual proportions (Plate 15: A, B). The present length of 47 cm may be slightly less than the original length, but the greatest diameter (12 cm) is probably several centimeters greater than the original width. I would estimate the original max- imum width at about 9 centimeters and maximum height about the same. Although crushed the centrum appears to have been broadest at the ends and nar- row near midlength. It is a strongly opisthocoelous (or procoelous?), and has long (20 cm or more), narrow and deep pleurocoels situated near midlength. The ventral sur- face appears to have been flat, or perhaps slightly concave in the anterior(?) third. The neural arch is missing, but broad sutural tracts are preserved on both sides of the 2 to 4 cm wide neural canal. These sutures extend nearly the full length of the centrum. The inferior lateral surfaces of the anterior(?) half (if the centrum is opistho- coelous) bear thin, but long (anteroposteriorly) ridges, which extend laterally an un- known distance. The extremities of the lateral ridges are missing so the transverse dimensions are not known, nor is their original attitude preserved. These ridges would appear to be the basal or proximal portions of thin parapophyseal laminae. If so, then this centrum would appear to be a cervical vertebra. Without the distal extremities of these lateral ridges or the neural arch, no conclusion can be made, but the ridges are remarkably thin (dorsoventrally), and I am not at all certain that they bore cervi- cal ribs. Although very different in its proportions, this centrum is best referred to the Sau- ropoda on the grounds that it is apparently opisthocoelous, it bears long pleurocoels and is greatly elongated, as are many sauropod cervicals. If correctly interpreted as a cervical, it most closely resembles the midcervicals of Diplodocus or Brachiosaurus in its proportions, as the following ratios show: Posterior Maximum Diameter/Length YPM 5294 0.25 Diplodocus 0.21 Brachiosaurus OF However, the parapophyseal lamina is much more robust and not so elongated in these two genera, and the pleurocoels are of more complex construction. Despite its unusually narrow construction, this vertebra is of appropriate size for equating with the dorsal vertebrae (YPM 5449) described above from the same quarry (YPM 63-18). Because of its widely separated position in the quarry, though, and its incompleteness, I am not able to certify the relationship. Limb elements. An isolated femur, tibia, and humerus were collected at three ad- jacent Yale sites (Plate 14: A-C). These cannot be referred with certainty to the pre- vious material, but there is a distinct possibility that all the remains represent a single species. The femur (YPM 5451), a right, from Yale locality 63-18, is very large but relatively slender. It is crushed and the proximal end is missing, but original length must have been at least 1.5 meters. The preserved length is 126 cm, but the fourth trochanter which is normally at midlength is 80 cm from the distal end. The crushed, maximum proximal width is about 40 cm, approximately 40 cm above the very small fourth trochanter. The greatest transverse, distal dimension is approximately 39 cm CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 83 and the tibial or inner condyle is 20 cm in longitudinal dimension. The least breadth of the shaft is 22 cm and the circumference at that point is 52 cm. The tibia (YPM 5450), a left, from Yale locality 63-19, is also slightly crushed but otherwise intact. There is a deep external excavation proximally for the fibula, with a short, rounded cnemial crest descending for a short distance along the shaft. Both the proximal end and the two condyles distally are moderately to strongly rugose. The dimensions are as follows: Length 98.5 cm Greatest proximal width 24 cm Distal transverse width 21 cm Least shaft width 13. Cm Least circumference a2, sein The humerus (YPM 5452), a right, from Yale locality 63-16, lacks the distal end, but in general it is rather brachiosaur-like. The proximal end is greatly expanded (43 cm) compared with a midshaft diameter of 20.5 cm. The preserved length is 103 cm, but the original length may have been as great as 130 cm. This estimate is based on the position of the very prominent deltopectoral crest that extends almost 50 cm below the proximal head, and the distal limit of the deltopectoral crest in Brachiosaurus (approximately 38% of humerus length). The analogy with this genus is based on the very broad nature of the proximal end, the long and relatively slender shaft, the nearly straight external margin and the fact that the deltopectoral crest is not a continuous ridge extending from the proximal end, but is a restricted projection. The least cir- cumference of the shaft is approximately 51 cm. Teeth. A total of 13 isolated teeth were recovered from several of the Yale locali- ties. All are of one kind, which is best described as nonspatulate, Pleurocoelus or Astrodon type. Within the collection there is a considerable range in size, but very little variation in tooth form. The root is long, cylindrical and untapered and of about the same diameter as the crown; the crown is subcylindrical, being slightly flattened on one side (the inner side?) and more convex on the other. In some specimens these opposite surfaces extend straight to the bluntly tapered apex, but in others they are slightly twisted so that in crown view the entire crown appears twisted. The crown also tapers asymmetrically so the apex lies closer to one margin (the anterior?) than the other. The enamel is faintly wrinkled on unworn teeth, but there are no serrations or rugae along the two vertical ridges that separate labial and lingual surfaces of the crown. There is moderate variation in the degree of asymmetry. In some crowns the apex is near the tooth central axis and there is little or no twisting. Most teeth are nearly straight, with almost no lingual curve to the crown. A few, however, show a pronounced medial curvature of the crown. The roots are never complete, but the crown height appears to be quite constant relative to the basal crown’s least diameter, with the height almost exactly four times that diameter. The largest tooth measured 28 mm in crown height by 7 mm in least diameter. The smallest is 11 mm long by 3.8 mm basal diameter. The striking similarity of these teeth to the type of Astrodon johnstoni (YPM 798) and the numerous teeth referred to Pleurocoelus from the Arundel Formation of Maryland is evident in Plate 14. Astrodon is slightly larger (40 mm high and 10.3 mm in basal diameter) than the largest tooth from the Cloverly Formation, and the crown 84 PEABODY MUSEUM BULLETIN 35 is somewhat less convex on the lingual side and curves inward more than any of the Cloverly teeth. Otherwise the resemblances are very close. Although there seems to be a little more variation of tooth morphology in the somewhat larger Arundel sam- ple, the majority are small (under 20 mm in crown height), not strongly curved and not markedly asymmetrical—as is true of the Cloverly sample. The range of variation in the ratio of crown height to basal crown diameter is the same for both samples (0.24 to 0.29) with most teeth having a ratio of 0.25 or 0.26. The absence of large spatulate Camarasaurus-type teeth in the Cloverly is not con- clusive, but it is quite probable that the Astrodon-type teeth and the various post- cranial sauropod remains represent a single species. This is reinforced by the fact that several of these teeth were found at Yale locality 63-18, associated with postcranial remains described above. DISCUSSION: The first notice of the distinctive tooth type described above was by a Dr. Christopher Johnston (1859), who referred to a reptilian tooth from an iron ore bed (Arundel Formation) near Bladensburg, Maryland. He gave it the name Astrodon but did not describe it. Leidy (1865) described the tooth as Astrodon johnstoni, re- ferring it to the Sauropoda. Subsequently Marsh (1888) established two other Arun- del species of sauropod (Pleurocoelus nanus and Pleurocoelus altus) on isolated post- cranial elements. Hatcher (1903) synonymized Pleurocoelus nanus (a cervical centrum) with Astrodon johnstoni, and Gilmore (1921) assigned all the Arundel sauropod remains to the genus Astrodon. Lull (1911a) recognized the probable synon- ymy of Astrodon and Pleurocoelus, but rather than equating P. nanus and A. john- stont he suggested that P. altus (a tibia and partial fibula) was synonymous with A. johnstont. He concluded: “It seems preferable, however, in view of the rarity of the remains to let the matter rest in abeyance until further proof is obtained.” Further proof has not been obtained, the question is still unresolved, and I suspect it will al- ways be so. Sauropod teeth seem to be of two general types, large spatulate and small, cylin- drical, nonspatulate form. There is some variation in each, both in size and in form, even within a single individual. At present, though, there seems to be no reliable means of identifying specific or even generic taxa from isolated teeth. The large spatulate Camarasaurus-type teeth have relatively short crowns (ratio of crown height to basal crown diameter ranges from 0.30 to 0.42, with the mean approximately 0.36), and the crown is significantly broader (longitudinally) than the root. The lingual crown face is planar or moderately concave, and the unworn apex or crest is broadly rounded rather than tapered. Such features are distinct from those of an Astrodon-type tooth, but are these differences ontogenetic or taxonomic? Is the Astrodon or Pleurocoelus- type tooth merely a juvenile or immature stage in the development of the spatulate Camarasaurus tooth? The absence of any of the latter teeth in the Arundel, Cloverly or Wealden Formations, which have produced numerous examples of Astrodon or Pleurocoelus-type teeth, would seem to suggest a taxonomic distinction, but indisput- able evidence is still wanting. I am inclined to agree with Hatcher, Lull and Gilmore on the probable relation- ships of sauropod teeth and postcranial elements from the Arundel Formation. I think the same may be true of the sauropod materials from the Cloverly Formation. How- ever, in the absence of any conclusive evidence, I consider the name Astrodon john- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 85 stoni as applicable only to the type specimen and similar teeth from the Arundel For- mation, and Pleurocoelus nanus and P. altus as pertaining to certain postcranial remains from the same unit. The Cloverly sauropod remains are for the most part isolated and inadequate for the foundation of specific taxa. Vertebral and dental mor- phology indicate that these materials are best referred to Titanosauridae. In 1917, Mook described a partial skeleton (AMNH 5855) that he referred to Diplodocus. This specimen, consisting of nearly complete fore and hind limbs lack- ing the feet, had been collected by Barnum Brown in 1903 “at Horse Coulée 30 miles [48 km] east of Pryor, Montana.” No other locality or stratigraphic data are available, but the fact that these represent the most complete sauropod remains known from within the study area warrants some comment here. A specific identification is not possible, but I believe the reference to Diplodocus is correct. The limb proportions compare well with those of other Diplodocus specimens and the oblique orientation of the trans- verse scapular expansion is unique to that genus. Each limb element is significantly smaller than that in any of the Yale specimens, and the proportions do not compare closely with the latter. Photographs on file at the American Museum show the speci- men in situ, but I was unable to relocate the site from these. However, I suspect that the specimen was recovered from Unit III (Morrison Formation) and not from the Cloverly Formation. Extensive exposures of Unit III occur in the area of Horse Coulée southwest of the Yale localities (Locality Map V) and the terrain there corresponds in a general way with that shown in the American Museum photographs. OrpER ORNITHISCHIA SUBORDER ORNITHOPODA Famity IGUANODONTIDAE Marsh, 1895 Tenontosaurus, new genus ETYMOLOGY: Tenon (Greek; masculine), sinew, in reference to ossified tendons along the vertebral column, and sauros (Greek; masculine), lizard. TYPE SPECIES: Tenontosaurus tilletti, new species. DIAGNOSIS: Same as that of the type and only species. Tenontosaurus tilletti, new species Plates 16, 17, 18, 19, 20 and 21 ETYMOLOGY: Tenontosaurus tillettt; named for the Lloyd Tillett family of Lovell, Wyoming, to whom we are indebted for assistance and hospitality extended to our field parties. TYPE SPECIMEN: AMNH 3040, a partial skeleton, lacking skull and fore limbs. PARATYPES: PU 16338, a partial skeleton; YPM 5456, fine skull and partial skeleton. TYPE LOCALITY: AMNH 33-1, SW 4 Sec. 26, T.7 N., R.16 E., Wheatland County, Montana. Unit VII, 60 feet (18 m) below Unit VIII, Cloverly Formation. PARATYPE LOCALITIES: PU 48-1, T.6 N., R.15 or 16 E., Wheatland County, Montana 86 PEABODY MUSEUM BULLETIN 35 ra (exact location and stratigraphic position unknown). YPM 64-37, NW % Sec. 24, T.5S., R.28 E., Big Horn County, Montana. REFERRED SPECIMENS: Partial skeletons (YPM 5457, 5458, 5459, 5460, 5461, 5462, 5466, 5478; AMNH 3010, 3011, 3012, 3013, 3014, 3017, 3031, 3034, 3043, 3061, 3062, 3063; OU 11; PU 16514; and BB 1); skull and jaw fragments (YPM 5471, 5472; OU 8-0-52). ADDITIONAL REFERRED SPECIMENS: YPM 4882, 5117, 5195, 5299, 5410, 5411, 5413, 5416, 5417, 5421, 5422, 5424, 5426, 5427, 5428, 5463, 5464, 5465, 5467, 5468, 5469, 5470, 5473, 5474, 5475, 5476, 5477, 5479, 5480, 5481, 5482, 5483, 5523, 5533, 5534, 5535; AMNH 3020, 3044, 3045, 3050, 5854; OU 12. Locaities: AMNH 03-29, 31-3, 31-4, 31-5, 31-6, 31-7, 31-8, 31-10, 32-2, 32-5, 33-3, 33-4, 33-5, 33-8, 38-1, 38-3, 38-4; OU 40-11, 40-12; PU 49-1; YPM 62-4, 62-14, 63-18, 64-13, 64-16, 64-17, 64-18, 64-19, 64-20, 64-21, 64-23, 64-25, 64-26, 64-27, 64-28, 64-36, 64-38, 64-39, 64-41, 64-43, 64-45, 64-47, 64-49, 64-50, 64-52, 64-54, 64-57, 64-58, 64-63, 64-64, 64-67, 64-71, 64-72, 64-74, 64-75, 65-1, 66-4. DISTRIBUTION: Units V, VI and VII, Cloverly Formation, central and southern Mon- tana and northern Wyoming. DIAGNOSIS: Large, bipedal ornithopod with moderately deep, Iguanodon-like skull and extremely long tail reinforced by ossified tendons on either side of both neural spines and chevrons. Caudal series includes up to 60 vertebrae and measures twice (or more) the length of the precaudal column. Ischium long, straight; not expanded distally. Pubis with straight, shallow, parallel-sided and horizontal prepubic blade and long, straight, narrow postpubic rod. Ilium with long, narrow, sharply downturned anterior process and conspicuously concave upper margin. Pes with unreduced meta- tarsals I-IV, and splintlike V. Phalangeal formula 2-3-4-5-0. Manus very broad, with five flattened metacarpals. Phalangeal formula 2-3-3-2-2, digits IV and V lacking clawlike unguals. Vertebral count 12-16-5-59+. Skull with very large external nares, long slitlike antorbital fenestra and supplementary lateral temporal fenestra beneath the usual lateral fenestra. Orbit subrectangular; larger than either lateral fenestra. Premaxilla, which nearly encircles the nares, flares inferiorly into broad, U-shaped edentulous beak, opposed by shallow, horseshoe-shaped predentary with pseudo-tooth projections along upper margin. Mandibles bear two distinct coronoid processes and a long curved retroarticular process. Quadrate long, very narrow transversely; poste- rior margin convex rather than concave Paroccipital processes hook-shaped, and downturned at extremity. All teeth unilaterally enameled, dentary teeth with very prominent vertical keel, maxillary teeth without keels but with numerous nonparallel, subequal minor ridges. DESCRIPTION: In the following pages an attempt is made to present sufficient descrip- tion of the osteology of Tenontosaurus to define the taxon. A more detailed descrip- tion is planned for the near future. The available collections of material referable to T. tilletti are extensive, making this perhaps the most abundantly represented fossil tetrapod at the time of its proposal. Twenty-six partial or nearly complete skeletons are known, eight of which are juvenile. Most of the others are mature but not fully grown. This sample provides an ususual opportunity to do a detailed analysis of varia- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 87 tion and growth changes. The present report does not seem an appropriate place, how- ever, and I defer this to a later contribution. Skull. Several partial skulls are present in the collections of Tenontosaurus, but the best by far is the complete paratype skull YPM 5456 (Plate 16: A; Plate 17: A). In fact, this skull is probably the best skull in existence of a pre-Late Cretaceous ornitho- pod from the Western Hemisphere. The following description is based almost en- tirely on that specimen, with occasional comparisons with the sub-adult skull of YPM 5458 and several other fragmentary skulls. Some comparisons are made with skull fragments of Camptosaurus and the restorations of that genus given by Gilmore (1909), as well as with certain other ornithopods (Laosaurus, Dryosaurus, Parkso- saurus, Dysalotosaurus, Heterodontosaurus, Thescelosaurus and Iguanodon). In lateral view, the the skull is long and deep, in pronounced contrast to the low profile of Camptosaurus (Fig. 8). It has a large subrectangular orbit, a smaller oval lateral temporal fenestra and large external nares. A small oval subsidiary lateral tem- poral fenestra is situated between the jugal and quadratojugal near the lower margin of the iower temporal arch, and a long narrow slitlike antorbital fenestra descends obliquely across the maxilla from the lacrimal. The greatest skull length is approxi- mately twice the skull height. In dorsal aspect, the skull is narrowly wedge shaped with stout, rostrally rounded premaxillae and a sharply concave occipital outline. The greatest breadth is in the teinporal region. The supratemporal fenestrae are oval and of moderate size. The snout is dominated by the stout, edentulous premaxillae which flare out broadly below into a rounded, spatula-like beak. Dorsally, they extend backward as long, narrow, parallel-sided processes that interpose between the nasals for a distance of about 9 cm. This is well preserved in YPM 5456 and 5459. Similar interposition of Fic. 8. Reconstructed lateral view of the skull and mandibles of Tenontosaurus tilletti. Abbreviations: an = angular; de = dentary; f = frontal;ju = jugal; la = lacrimal; mx = max- illa; na = nasal; p = parietal; pd = predentary; pmx = premaxilla; po = postorbital; poc = paroccipital process (exoccipital &/or opisthotic) ; prf = prefrontal; qj = quadratojugal; qu = quadrate ; s = supraorbital; sq = squamosal ; sur = surangular. 88 PEABODY MUSEUM BULLETIN 35 the premaxillae exists in Hypstlophodon (Galton, personal communication) but is not characteristic of Heterodontosaurus (Crompton, personal communication), Campto- saurus, Iguanodon or apparently of Laosaurus. This region is not known in Thescelo- saurus or Parksosaurus, The premaxillary margins are moderately sharp edged with very small toothlike projections near the midline. In lateral view, the premaxilla is U-shaped with upper and lower processes projecting up and back, enclosing the ex- ternal nares. Only the upper rear margin of the narial opening is formed by the nasal. The maxilla is long and very high, accounting for the greatest fraction of snout depth. The maxilla apparently differs from that of Camptosaurus in that it extends all the way to the nasal lower margin and thus truncates the inferior premaxilla pro- cess and obstructs contact of the latter with any of the circumorbital elements. With the possible exception of Heterodontosaurus (and Iguanodon atherfieldensis?) , con- tact of the maxilla and nasal appears to be true of all primitive ornithopods for which adequate material is available. It is quite likely that Gilmore (1909) and Marsh (1896a) erred in restoring the inferior premaxilla process of Camptosaurus as extend- ing to the prefrontal and lacrimal. A long (7 cm), narrow (1.5 cm), obliquely oriented antorbital fenestra extends down and forward from the lacrimal across the maxilla. The upper wall of this fenes- tra slopes inward and inferiorly and a robust ridge, the inner maxillary lamina, defines the lower medial fenestra margin. These do not meet, however, and the fissurelike opening extends medial to the maxilla into the nasal cavity. Thus this opening is properly termed an antorbital fenestra. I have no explanation for the function of this opening, but its conformation and position seem to preclude any relationship to the pterygoideus musculature, in spite of the fact that the ventral flange of the pterygoid is unusually large for an ornithopod. The maxilla bears 13 alveoli, which are occupied by stout and unusually broad, unilaterally enameled teeth of the iguanodont type (see Plate 16: C-E). These are enameled laterally and bear five or six faint, subequal ridges, but lack a prominent keel as in Camptosaurus (Pl. 15: G) and Iguanodon. Unworn teeth are denticulate marginally; worn teeth develop internally inclined wear facets. No more than one func- tional tooth occurs in each alveolus. The tooth row length is approximately 18 cm with the anterior extremity situated exactly at the rear margin of the premaxillary beak. The maxilla articulates posteriorly with a very deep triangular jugal, which is dis- tinctive among all presently known ornithopods by its great depth. This bone is very robust dorsally where it joins the lacrimal and forms the stout lower margin of the orbit, but inferiorly the jugal is quite thin. The postorbital process is also robust and together with the descending process of the postorbital (postfrontal) forms a very massive arch between the orbit and the lateral fenestra. The jugal meets a subrec- tangular quadratojugal posteriorly, but inferiorly a posterior process extends back to the distal end of the quadrate. This process and the quadratojugal define the small auxili- ary temporal fenestra, which appears to represent a true fenestra and not just an open suture. The function of this latter opening is presumably related to the superficial external adductor muscles, in view of the fact that it is situated immediately lateral to the sum- mit of the coronoid (not dentary) process of the mandible where it would have pro- vided additional space for the bulging muscle belly. The other bones surrounding the orbit are the robust lacrimal and prefrontal ante- riorly and a narrow, wedge-shaped supraorbital, plus a lateral expansion of the frontal: CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 89 above. Small supraorbitals are preserved on both sides but these are depressed into the orbits. They appear to have been situated as restored by Gilmore (1909) for Campto- saurus, but of less robust form. The quadrate is long, narrow and nearly straight. The posterior margin is convex rather than concave, although the upper end does hook slightly backward. The quad- rate appears to have been vertical in orientation. Its dorsal extremity is rounded in lat- eral aspect, but narrow and tabular in transverse form, and fits into a shallow, rounded concavity in the squamosal. There may have been some mobility at this junction, but no other evidence of streptostyly is apparent. In YPM 5472 the proximal ends of both quadrates are in normal position with respect to the squamosals, despite considerable distortion and displacement of other skull elements, indicating a firm union of the two bones. The quadrate is extremely narrow transversely over most of its length but broadens out distally into a very robust (transversely) articular head. In anterior as- pect, the quadrate appears to have had a short (anterposterior) but high superficial flange (articulating with the quadratojugal and jugal) and a long and high pterygoid flange that extended anteromedially. Both contributed to the posterior wall of the lat- eral temporal fenestra. The dorsal aspect of the skull (Fig. 9), except for the beak, is formed by long, narrow, paired nasals, which pass between the prefrontals, the broad, very stout, paired and firmly united frontals, massive fused parietals and strongly convex, three-cornered squamosals. There is no sign of a sagittal crest across the parietals in YPM 5456 or 5472, but a slight crest occurs in OU 11 and BB 1. The greatest width of the frontals and parietals is approximately 50 to 60 percent of skull height. The occipital surface is composed of the usual elements, but the triangular supra- occipital is excluded from the foramen magnum (OU 11 appears to be a possible exception, although preservation may account for this) and the basioccipital is almost excluded. The latter forms most of the occipital condyle, with the exoccipitals con- tributing only small wedges on either side of the neural canal. Large, hook-shaped, bladelike paroccipitals extend out, back and downward from the foramen magnum, 0 5 10 ——SSE a a cm ie 4 C Yi sae oe Berean Ie Le S77 a FIG. 9. Reconstructed dorsal view of the skull of Tenontosaurus tillettt. Abbreviations: boc = basioccipital; f = frontal; ju = jugal; la = lacrimal; mx = maxilla; na = nasal; p = parietal; pmx = premaxilla; po = postorbital; poc = paroccipital process (ex- occipital &/or opisthotic) ; prf = prefrontal; qu = quadrate;s = supraorbital ; so = supraocci- pital ; sq = squamosal. 90 PEABODY MUSEUM BULLETIN 35 very similar to those of hadrosaurs. YPM 5456 and 5472 clearly show there is no dor- sal expansion of these processes as in Camptosaurus, and they appear to be composed entirely of the exoccipitals. The basicranium is greatly compressed longitudinally. The basisphenoid projects far ventrally as three massive processes. The laterally placed processes presumably represent the basisphenoid tubercles. Anterior, and slightly lateral to the latter are two very long subcylindrical basipterygoid processes that project far ventrally and slightly lateral to articulate with the broadly expanded pterygoids. The position of the brain- case itself is rather high, and the greatly deepened skull has resulted in elongation of the quadrate and the basipterygoid processes. Thus the articulation of braincase (basisphenoid) and palatal complex (pterygoid) has been maintained but depressed to a very low position close to the level of the dentition. The distal extremity of the quadrate is situated well below the dentition as in all ornithopods. The pterygoid ventral flange is a broad and deep, somewhat sinuous plate of bone. The upper portion may have provided enlarged and reinforced areas of origin for slips of the pterygoideus musculature. The broad, ventral part appears to have roofed over the posterior part of the oral cavity and formed a solid buttress between the caudal extremities of the maxillae. The ectopterygoid appears to have been reduced to a small slip of bone medial to the jugal and posterior to the maxilla, immediately behind the tooth row. The anterior portion of the palate is largely obscured, but the palatines appear to extend forward from the ventral pterygoid flange to at least midlength of the maxil- lary tooth row—the apparent position of the internal nares. Rostral to this, details can- not be recognized at present, although there is a thin lamina of bone that underlaps the ventral surface of the premaxillae. This appears to be an inferior forward exten- sion of the maxillae (which seems unlikely), but it probably is an anterior portion of the vomer. The skull of Tenontosaurus resembles the skull of Heterodontosaurus, Hypsi- lophodon, Laosaurus and Dryosaurus in its deep, narrow form and the elongated and nearly vertical quadrate. Camptosaurus, on the other hand, has a very low, long and relatively broad skull, with a short, forwardly inclined quadrate. Heterodontosaurus and Hypsilophodon are distinct in having premaxillary teeth, as well very large or- bits and small external nares. Both have moderate- to large-sized antorbital fenestrae, but of distinctive form. Similar openings apparently were present in Laosaurus and Dryosaurus where, like Heterodontosaurus, they were entirely within the maxilla. In Hypsilophodon this fenestra is bordered by the maxilla and the lacrimal, as it is in Tenontosaurus. Hypsilophodon appears to be the only other ornithopod known in which a second- ary or subsidiary lateral temporal fenestra occurs. In the British genus, however, it is situated within the quadratojugal, whereas in Tenontosaurus fenestration appears to have taken place along the quadratojugal—jugal suture. Of special interest, however, is the fact that in all other adequately known hypsilophodonts and iguanodonts (Iguanodon and possibly Dryosaurus excepted), there is a distinct to very prominent, ventroposteriorly directed bony process or boss on the inferior margin of the jugal arch. A narrow to broad notch or recess occurs between this and the lower part of the quadrate. It seems likely that the jugal fenestra (subsidiary lateral fenestra) may have been enclosed by extension of this jugal flange back to the quadrate. Dryosaurus(?) CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 91 and Parksosaurus lack both the jugal flange and the recess behind it. However, the Parksosaurus skull is incomplete in the upper temporal region, and it is conceivable that two lateral fenestra were present. There is no evidence for this, however. The fact that the jugal of Tenontosaurus articulates with the quadrate below and behind this secondary fenestra, and not with the quadratojugal, is strong evidence that this is a secondary and perhaps specialized adaptation, conceivably to further buttress the quadrate close to the jaw articulation. This would suggest that the subsidiary fenestra is not due to a failure of the jugal-quadratojugal suture to close. Mandible. The lower jaw of Tenontosaurus is of moderate length and robustness (Plate 16: B; Plate 17: B)). In lateral view it is straight, with parallel upper and lower margins, and of uniform depth anterior to the coronoid process. The two mandi- bles are closely appressed together in YPM 5456 so that very little of the medial aspect is visible. For this reason, the details of the postdentary and medial elements are not completely known. The symphysis is capped by a median, horseshoe-shaped predentary of shallow depth that is remarkably similar to that of [guanodon (Casier, 1960, Fig. 13). The two lateral rami rest in dorsally facing grooves along the upper anterior margins of the dentaries. These grooves appear to terminate immediately in front of the first tooth so that the tooth row is continuous with the upper margin of the predentary. This up- per predentary margin is sharp crested and is decorated by small (posterior) to large (anterior) conical projections, like the predentary of I[guanodon. These projections may have served to unite firmly the predentary and a covering horny bill, or they may have served to reinforce similar projections along the margins of the horny beaks. A broad ventral process extends ventrally in the midline and overlaps the symphyseal region of the dentaries anteriorly. The symphysis itself is not sutured and appears to have been rather flexible, re- stricted in mobility by the capping predentary and ligaments. The dentary is moder- ately massive and bears a long straight tooth row (17 cm) of 12 and 13 teeth. Poste- riorly, the dentary expands upward into a short and relatively lightly constructed coronoid process, which is separated by a shallow notch from the lower, and broader bladelike ‘“‘coronoid process” formed by the surangular. Although the exact size and form is not known, the surangular appears to form most of the external surface of the mandible below and behind the coronoid process. In addition to the dorsal blade, it extends backward to the glenoid region and perhaps beyond. No suture has been recognized between it and the articular, so exactly what portions of the glenoid and retroarticular process are constructed of the surangular are not known. A large surangular foramen is present immediately anterior to the glenoid. Part of the left angular is present, although displaced, but its exact relation to the surangular is indeterminate. A long splenial is partially visible along the inferior medial aspect of the right dentary, but its form and length are not known. The glenoid and retroarticular process are presumed to be composed chiefly of articular. The retroar- ticular process is quite long and bladelike, narrow transversely and broad vertically. It curves sharply upward behind the glenoid. The latter occurs as a broad, transverse concavity at the base of the surangular “coronoid process”. In both rami, it is signifi- cantly narrower in its transverse dimension than is the distal head of the quadrate. This could mean that the medial portion of the glenoid has been displaced and the articular, or prearticular, is not preserved. Several bone fragments partly exposed be- 92 PEABODY MUSEUM BULLETIN 35 tween the two jaws could be parts of the prearticular, and I have so interpreted them. The articular, I believe, was fused with the surangular. The mandibular teeth are of the iguanodont type, enameled on the medial side only (Plate 17: C, D and E). Most are large and oval in crown shape, with denticu- late margins. The enameled surface bears a very prominent vertical ridge (unlike Camptosaurus mandibular teeth, Plate 15: F), on either side of which are several faint, subparallel ridges. ‘Tooth-wear facets are inclined labially. Associated with the jaws (and the right quadrate) are a number of subcylindrical bones, approximately 1 centimeter in maximum diameter, that are presumed to rep- resent hyoid elements. These are too incomplete and poorly preserved to be identified further. A very small cylinder of bone is also preserved medial to the upper end of the right quadrate. This may represent part of the right stapes. Vertebral column. The presacral vertebral count is 28, including 16 dorsals and 12 cervicals. The count is based on several specimens (OU 11, YPM 5459 and 5456, BB 1, and AMNH 3031). The sacrum consists of 5 segments, which may be aug- mented by a dorsosacral and/or a caudosacral. Where either of these is coalesced with the sacrum, they are counted here as dorsal or caudal vertebrae. The caudal series is extremely long, including 59 or 60 segments, and total tail length measures two or two and a half times the length of the sacrals and presacrals. Camptosaurus, with which the present species can most adequately be compared, has 9 cervicals, 16 or 17 dorsals, 4 or 5 sacrals and approximately 44 caudals. There was some question about the vertebral formula in Camptosaurus, according to Gil- more (1909), but the articulated series of C. medius (CM 11,337) described by Gil- more (1925) established the presacral count at 9 cervicals and 17 dorsals. Gilmore recognized 5 sacral vertebrae in this specimen, but as he noted (1909, p. 235), the sac- rum of C. dispar consists of only 4 vertebrae. Whatever the sacral count, Camptosaurus apparently had 26 presacrals compared with 28 in Tenontosaurus. A complete caudal series is not known for Camptosaurus, but Gilmore (1909) es- timated the caudal count at 44, on the basis of two nearly complete series of 33 and 34 segments (USNM 4282 and 2210). Including the 11 missing distal caudals and sev- eral missing presacrals in USNM 4282, the tail length of Camptosaurus browni would have been only slightly longer than the precaudal column. The cervicals of Tenontosaurus (see Plate 18: A-D) are distinct in the low neural spine, low arch, and in the position of the parapophysis on the centrum. They compare closely with those of Camptosaurus, except in number. In general, the cervical centra are relatively shorter and slightly broader and deeper than those of Camptosaurus. They also tend to be amphiplatyan rather than opisthocoelous. All except the atlas and axis are moderately keeled ventrally and bear broad, low neural arches. In con- trast to Camptosaurus where only faint ridges mark the cervical neural spines, the cervicals of Tenontosaurus bear short but well-developed neural spines on all seg- ments. These are well preserved in YPM 5456. Also, contrary to the condition in Cam ptosaurus, the atlas centrum is significantly shorter than succeeding centra, but it carries a Camptosaurus-like arch bearing a high wedge-shaped neural spine with a broad, concave posterior surface. The atlas intercentrum, odontoid and axis intercen- trum are represented in several specimens, and are similar to those of Camptosaurus. In OU 11, both the odontoid and axis intercentrum are fused to the axis centrum. In YPM 5456, which is the largest specimen presently known, the odontoid is not fused CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 93 to the axis, but the axis intercentrum is. In BB 1, both elements are free and not co- ossified with the axis centrum. Despite Gilmore’s statement to the contrary (1909, p. 225), the odontoid is coalesced with the axis in at least one specimen (YPM 1877) of Camptosaurus. The axis intercentrum apparently always is fused with the axis cen- trum in Camptosaurus. The dorsal vertebrae (Plate 17: E-H) are well preserved in the type of Tenonto- saurus (AMNH 3040) and the paratype (PU 16338). Again these vertebrae are rather similar to those of Camptosaurus, but differ in having relatively shorter centra with much shorter and narrower neural spines and transverse processes. Also, the neural spines are more rounded or less rectangular in profile. All centra are amphi- platyan and subcircular in anterior or posterior view. The neural arches are firmly sutured to the centra in sub-adult specimens, but the sutures apparently remained open even in the largest individuals, as is evidenced by several separated centra and the arches in YPM 5456. The neural arches are low and robust and the zygapophyses quite short with facets inclined at about 45° throughout the series. The parapophysis and diapophysis are widely separated on the first 12 dorsals but are closely spaced on the thirteenth. The last three dorsals have a common articular facet for the capitulum and tuberculum at the extremity of the transverse process, and in at least some in- stances the single-headed rib is fused to that process. The sixteenth dorsal, with the transverse process and rib contacting the anterior blade of the ilium, also supports the anterior part of the first sacral rib borne on the following sacral. The sacral count is dependent on distinguishing between true sacrals and coalesced dorsosacrals or caudo- sacrals. I have defined the first sacral as the first vertebra bearing a lateral process (transverse process) that is not borne entirely on the neural arch. The last sacral ver- tebra is the most posterior segment bearing distally expanded lateral projections (sac- ral ribs) for extensive sutural contact with the ilium. By this definition, there are five sacral segments in AMNH 3040, OU 11, PU 16338, and YPM 5462. In AMNH 3040, the last dorsal is coalesced with the first sacral, but the last two sacrals are not fused. This condition appears to be true also of YPM 5462, and OU 11. The sacral neural arches are incompletely preserved in PU 16338, but there is no fusion of any sacral centra. This may be an ontogenetic condition, although the neuro- central sutures are firmly united (if not fused) in all dorsals and caudals. The sacral vertebrae of Tenontosaurus are a little less robust than the posterior dorsals. They resemble those of Camptosaurus in the deep and broad neural canal and the faint development of the “peg and notch”-like junction of adjacent sacral centra, as described in Camptosaurus by Marsh (1894) and Gilmore (1909). The present sacrals differ from those of Camptosaurus in lacking even a slight longitudinal groove along the inferior surfaces of the centra; Tenontosaurus sacrals show a broadly rounded ventral aspect. The caudals of Tenontosaurus (Plate 18: I-N; Plate 19: A and B) constitute two thirds or more of the vertebral column, based on estimates from PU 16338 and AMNH 3040. The anterior caudal centra are short, deep and broad, with nearly flat lateral surfaces, strongly concave ventral surfaces and subcircular ends. The anterior neural spines are moderate in length, narrow, and curve back and upward—the ante- rior margin being concave rather than convex as in Camptosaurus. The neural spines of the anterior caudals also are relatively shorter and narrower than those of Campto- saurus. Moderate- to small-sized transverse processes occur on the first eight caudals, 94 PEABODY MUSEUM BULLETIN 35 compared with the first 12 in Camptosaurus. The midcaudals are more elongate (length exceeds height and width), and the lateral surface is marked by an increas- ingly prominent longitudinal ridge, which produces a distinctly hexagonal outline to the ends of the centra. The neural spines are of moderate but decreasing height, straight, narrow, vertical and slightly expanded near the summits. The spine is re- duced to a posteriorly placed, low, triangular blade near midtail, and gradually di- minishes to nothing at the extremity. The first chevron is situated between the first and second caudals. None of the present specimens permits a positive conclusion, but several indicate that the last 20 or so segments may have been free of chevrons. The type and the Princeton paratype show an absence of recognizable facets for chevrons, and in YPM 5466, a sequence of 33 medial and distal caudals has chevrons preserved with the first 10, but not the rest. Ossified tendons are preserved in most of the specimens, closely associated with the neural spines and the chevrons (see Plate 19). The tendons along the dorsal series appear to have extended without interruption from the fourth or fifth dorsal back close to the tail extremity. The hypaxial tendons begin at about the fifth or sixth chevron and presumably extended to the caudal extremity. To the best of my knowledge, ossified hypaxial tendons have not been found in any other ornithopod except Thescelosaurus neglectus (Gilmore, 1915) and Parksosaurus warreni Parks, 1926. Sternberg (1940), in describing a second species of Thescelosaurus (edmontonensis) , noted that no ten- dons were present along the underside of the tail in that specimen and suggested that this might be a youthful condition. Such may be the case in Thescelosaurus edmon- tonensis, but it apparently was not true in Tenontosaurus. Among the specimens in the Yale collections is a small juvenile (YPM 5478), less than one third the size of the largest specimen. Ossified tendons are well developed in this specimen, both above and below the caudals. (This is in a region of the tail that I would judge to be close to the 40th segment inasmuch as the centra have lost the hexagonal outline and measure 15 by 8 by 13 mm in length, height and width, respectively). There is no record of hypaxial tendons in Camptosaurus, although ossified epaxial tendons are preserved in several specimens. Appendicular skeleton. The pectoral girdle of Tenontosaurus consists of scapulae, coracoids and sternals. The scapula and coracoid are virtually identical to those of Cam ptosaurus, except that the coracoid is more hook shaped anteriorly and the cora- coid foramen is complete even in juveniles, whereas in Camptosaurus it is a notch open to the coracoid-scapula suture. Of particular interest is the presence of well- ossified sternal plates in every Tenontosaurus specimen in which the shoulder region is preserved. Although subsequent discoveries may alter this, at the present time sternal plates are unknown in Camptosaurus. They are not present in any of the several artic- ulated skeletons, and the presumption is that they were not ossified. Sternal bones have been reported in Iguanodon, Parksosaurus (Thescelosaurus warrent Parks, 1926) and Laosaurus (Gilmore, 1925b), as well as in hadrosaurs. The Tenontosaurus ster- nals resemble those of Parksosaurus, with the exception that the posterior external margin curves forward more strongly. They are rather thin, but the anterior, medial and posterior margins are thickened for cartilaginous contact with the coracoid, the opposite sternal and sternal ribs. The humerus appears to be less massive than in Camptosaurus, at least the shaft circumference to length ratio is less, but the deltopectoral crest and internal tuberosity CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 95 are much more pronounced in Tenontosaurus. The radius and ulna also are somewhat less massive than in Camptosaurus. The carpus apparently consists of three elements, presumably the radiale, ulnare and intermedium. Other carpals may have been present, but they are not preserved in place in any of the present specimens. Gilmore (1909) described eight carpals in Cam ptosaurus, the three mentioned above and five small distal carpals. A small lozenge- shaped element is present beneath the fourth metacarpal in BB 1, and this may repre- sent a fourth or fifth carpal. The manus (Plate 21: A) is distinct, being broader and flatter than that of Camp- tosaurus. The metacarpals particularly are broad and flat and somewhat longer than those of Camptosaurus. The phalangeal formula of Tenontosaurus is 2-3-3-2-2 (based on OU 11, BB 1, AMNH 3031 and YPM 5459), that of Camptosaurus is 2-3-3-3-2. The unguals of I, II and III are long and narrowly tapered compared to the broad, almost hooflike unguals of Camptosaurus. As in the Morrison species, the terminal phalanges of IV and V are small, nubbinlike elements. The pelvic girdle (Plate 20: A, B and C) is perhaps the most distinctive post- cranial structure and different from that of other ornithopods. The ilium is long, low and robust. It is distinctive in the very long and narrow anterior process that is bent sharply downward. Distally this process is parallel to the narrow, ventroanteriorly directed pubic peduncle. The ilium is also distinctive in the concave form of its upper margin. There is no evidence of an antitrochanter. The pubis differs from that of Cam ptosaurus in the short, straight and narrow form and horizontal projection of the prepubic blade and the straight and narrowly tapered form of the postpubic rod. The obturator foramen apparently is never closed off from the pubic-ischiac suture. The ischium differs from Camptosaurus in the straight, parallel-sided shaft that is not ex- panded distally. It resembles that of Thescelosaurus, except that the shaft is some- what broader and the obturator process is more proximally placed in Tenontosaurus. The limb, tarsus and pes are of normal iguanidontid construction. The limb ele- ments, particularly the femur (Plate 20: D and E) and tibia, are appreciably less massive than those of Camptosaurus. The fourth trochanter is slightly less prominent and is more proximal in position in Tenontosaurus. The astragalus lacks an anterior ascending process, and neither the astragalus or calcaneum are ever fused to the tibia or fibula. In addition to the astragalus and calcaneum, the tarsus appears to consist of only two distal tarsals; at least that is all that is preserved in the numerous complete or nearly complete feet in present collections. Presumably these represent tarsals II-III and IV in that they articulate with metatarsals II, III and IV. A splintlike fifth metatarsal is preserved in two specimens (BB 1 and AMNH 3031). However, there is no scar or notch in metatarsal IV to indicate the presence of a fifth metatarsal, as there usually is when the latter occurs as a vestigial splint-line bone. The phalangeal formula is the normal 2-3-4-5-0, but the pes (Plate 21: B) of Tenontosaurus is dis- tinct from Camptosaurus in the shorter length of the metatarsals relative to digit length, and in the unreduced form of metatarsal I, which has a fully developed prox- imal end and participates in the tarso-metarsal joint. In this, and in general propor- tions, the pes and metatarsus of Tenontosaurus are more like Thescelosaurus neglectus (USNM 7757) than anything else. DISCUSSION: Tenontosaurus may be distinguished from Camptosaurus in the higher PEABODY MUSEUM BULLETIN 35 96 8's 6€ VE 9° CoO+trVe IPE | WYysIIY > UWINIJUID [VOTAIIO YC yysuot | uin.1ju99 JO YIPIM 4so} e018 ‘sIxy winsju99 JO 1YSlay 389} e915 “sIxy uInsju99 JO YSUN] so} vaIs ‘sIxy UINI}UIDII}UT SeIIe pue plojuopo jo yysu0'T suorjisod y300} Arejuaq suorjisod y300} Are][Ixe yy YSU] MOI Y}00} Ie[NqipueyW yisug] aqipury yi suZ]| JYSIOY VASIUI] [V19}e'T WYysIOY yisuay qIO YyySug] MOI Y}00} Are] [Ixepy (jeqorsed 03 ie) 6 RA ayeIpenb) 7YysIey (uinuiTxeur) YIPIM [[NYAS (a]Apuoo jeqdr990 0} *xeuroid) y3suU2a] [[NYS ew WysTy 1 ad 21 weary PT 0r0s HNNV 8'¢ 6'F 09 oF Gs LY ortss SUOTSUJUIT( [e4qQ29 A ral §I = rll ral — OLT 081 = +092 19 oF +l +12 WSIY yet WSIY Tela | WSIY yoT 8SS9I Nd Il no 6S4S WdA SUOISUIUTIG] [VIULIT) 19]9]]1] Snanvsojuoua J JO syusUIsINseaw [edioulig “fp ATAVL GG g'¢ €'¢ GG GG og + 9'¢ gI rat IT II c6l S61 Och *0'8F 6S = vs 8'¢ 89 c9 64 0°8 81 0°02 SCs 0°94 MEI Ea bog gobs WdA o7 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY BP 9°¢ i o'8< BP 0G 0'V 0G ov Ov cv Vv ov oS 8S 0S Ov G9 69 BP OL ES 0's 319 0:9 qc GIT 09 09 0's G6 0S Gs 0G G6 LY 0G cP Tv a CTr OL 09 09 06 G9 09 GGT *0°6 Gol -0'S Gole GLé £9¢ €°9é (PEM | 1ySI0Y wind}UI9 [epNed YIG Yi Sus] WYySstoY aurds [einau [epneo 3s] UINIJUID [VPNL 4ST ie 1YSsI9Y UINIZUID [BIIVS YIG Tipe WY sIoy UINI}UID [VINES 4ST yj sue] WYsIOY ouids [eineau [essiop y3G | IPI | JY soy UINI}UI9 [eSIOP YIGT yisugy | WYysIOY ouids [vinau [esiop YI] yypim | 14 S10Y UINIJUI9 [esIOP YI0] yj sue] \ WsIoY aurds [einou [esiop YIG yapIm |] Jy sI0y UINI}UII [esIOp YIG yisue] \ ieee JYySIOY > WINI}UID [VOIAIIO YIOT y3sue| \ Gs ¢ éé pin LG 0¢ 9Gé qYySIay > = uINIyUIO [epNed yIGE LG ov 0'Sé yy 3ue] 8° 8G GE se vs Go G &é WYSZIey > = uINI}UV0 [epnes YyIg¢E G9 oF CGé yy) 3ue] YysIOY S'S == auids [vinou [epned YICZ cv Ae 3 yypIm ral SF as qystIay > = winsIjUVd [epNed YIGZ z 8°9 6+ | = YysIOY cs 06 +0'8 auids [einau [epnes yI0Z 5 Lv cs pin ~Q Ly gE 7YSI0Y WInd}UI9 [epNed YI0Z 2 CL oS ysu2] =) oa 1yS19yY 5 se OvT 0'OT auids [einou [epned YIGT a VP SF Lg upprm a Osc 0S Vv WYySIey > = =uINI}ZUVO [epNed YICT e) 8G GL GG yySue] < WYsIOY ie OvT G02 Grr auids feinau [epned yIQ] Lv 8b L'¢ yapim | sy GG ov WySIey > wINI}UId [epned YIOT LG G9 BP y}3ue] \ YSIOY GrT oLT Gst auids [einau [epned yIG wysry PT WwsTY WY = e'T WysTY 1 da 0v0 HNWV 8SE9T Nd IT NO 6S¢S WdA 96> WdA S ( penutjuo)) 99 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY cv Vet c OT Gol LG VV? LY ja! L°0 Go ol 8'0 Go om ol o§& eT eT co Ve Lek 8's c‘9 O'sT 66 GOr LI Gol GG LI 9b 08 OL €& G9 IT VE 8°cT Ge ie a bP G&G cI GG GLI GY Cvs v9 && SUOISUIUIC] QUII'T 210,J pue I[PATy [e10}99g qIPIM [eIstp YpPIM [eurxoid snipey yisuo] UP IAS TE rstp YIpIM jeurxoid euly) y} Sus] IOUIIIFUINIATN YeYS SNIOUIN FT YySUyI s9tO [e10}99d 0} 9q RASH REED YIpIM jeurxoid yi sue] y3sug] [eusaig WYSTOY 1? pe=10 6) 0} Co}: Col@) snsouin Fy YPM wnuwrxeul yysug] epndvog “pr IYsIOY yrsu9] ep yy SOY yi su] UINIJUI9 [epNned 4IQG uInsJjUI9 [epNed YIGG ya sua] ee WYsIOY yysuz] Hep ee WYsIOY ysu2] wWINni}Us9 [epned YG eee WYystoy > wmsyUed [epNned YIQG | wINIJUID [ePNed YIOF PEABODY MUSEUM BULLETIN 35 100 +O FI 202 = O'+I O'+I Conrad 0'S2 — == C92 = 9°81 281 LOE 0'6¢< — COr On. = OTT LO1 OSI ¢9I Gl = cst a= C6 C6 OCI = — a 0'8r = ccs qcs 0°8¢ OLS Clr i=. — = C9I< a == as an EG 9% LY GY CES = oem a 7 Sl 0'8I OLI == OL = o'¢ og OL ¢9 C62 0'9F “= ccg OFS ccc ¢’°9¢ GL 06 L8 G9 OL OTT = 26 0'tr OCF C82 0°82 O'1S = as SuUOISUSUIG] QUIT] pu] pu 2[pITy OIAleg ae o's FOS 07% s3 Cr 9°¢ =. 86 +09 06 = = 0°8 08 PSs = g'¢ rang 8h ol [igf VL 99 == +6 CL 29 66 26 9°¢ = 29 Lg Gs i WSIy 2 lg | WSTYy IyeT WSTYy Yeo'T WSTYy eT WSry iol I ag 0r0S HNWV 8SS9I Nd II nO 6ShS WdA way eT 9Gb¢ WdA vIUVIOFUINIITD WINUITUTUL INU Ja} Ue YIN YIP OF peoy INUI9; WOdJ vue YSIG Y}PIM [PISIp | Yi pIM [eurxoid INUI3 J Yy3sus] usUIeIO} 10}e1N}qGo puryeq yisueg] pos s1qndjsog WysIOY y1suz] epeyq o1qndoig TEP Se astp Yisus] UINTYOsT uwin[nqeya08 je jy Say yysue] uN] A HIP AI 3181p III #!5!p I] 3151p [ #181p A [edivorqayy AJ [edieorppy II] [edreoejaypy II [edieseiayy J [edivovjayy ySusT _————————————————————— —ooOooooooooeoOo————s—ssSsoOaOowswxwmawaowOwnhaaanMMWM@sSsaOomOololeqeoqoooeeeoeoeoeoO=$qao ee ewe=xx eee (pe nul}uod) ‘p ATAV], 101 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY OST *8'PI cst *G'6 Cll OVI Gol G8 ov se) o& 8's 69 8'CE OTT 0Or Ges O'ST crt Gol G6 elt L’st col 9°8 VY 6S ce VG 89 L1& £01 CO! O'GE c6l GI¢ 081 OrI< 081 Ge cst OFT O'sT G6! ‘ayeurxoidde ATuo st JUIUIoINSvaUI Sa}eOIpUL += ‘[NJIqQnop SI JoqUINU JUSUIZ—as SayVOIpUT ¢ *S19}9UITJUIO UI S}USUIOINSeIUL [[V AI 8G III 3!3!q Il u51d yisusy [ WsIq AI [esrb 219, III [eS8223 "19 [I [eszey eB yisug] J [esivzeJI/[ Y}pPIM wUNnsaueogyjer) YPM Y} Sug] sniesesjsy YIPI™ [easIp yapim yeurtxord emnqry yysug] YIP [esp yi pmM yewrxoid eIqLh yj} su9]| 102 PEABODY MUSEUM BULLETIN 35 presacral count (28), much longer tail, ossified hypaxial caudal tendons, distinctive form of ilium, ischium and pubis, lesser robustness of all limb bones, the presence of sternals, the manus phalangeal formula of 2-3-3-2-2, the form of the metatarsus and tarsus, and a whole suite of cranial characters, including the presence of a subsidiary lateral temporal fenestra, a fissurelike antorbital fenestra, narrow and straight quad- rate, compressed basicranium, tooth morphology, ‘“‘double” coronoid process and the very deep, narrow form of the skull. Some of the same features also distinguish Ten- ontosaurus from Thescelosaurus: the higher caudal count, the form of the pelvic elements, the presence of sternals, and the manus formula. In addition, the morphol- ogy of the caudal vertebrae, the higher position of the fourth trochanter and the shapes of the scapula and humerus are distinct from Thescelosaurus neglectus, and dental and mandibular morphology, and sacral count distinguish it from Thes- celosaurus edmontonensis. Parksosaurus differs from the present species in dental mor- phology, the slender jugal and deep, lateral temporal fenestra, orientation of the antorbital fenestra, six sacrals, shorter tail, the shapes of pelvic elements, the lower position of the fourth trochanter and the reduced first metatarsal. Laosaurus differs in the shape of the humerus, the higher position of the fourth trochanter and the rela- tively longer and more slender metatarsals and phalanges of the pes. Laosaurus also appears to have a robust supraorbital bar and a supraorbital fenestra, rather than the slender tapered supraorbital of Tenontosaurus. Dryosaurus is separate from Tenonto- saurus in the shape and position of the antorbital fenestra, the shape of the lateral temporal fenestra, the presence of a supraorbital fenestra and the relative proportions of the skull. It differs also in having six sacrals, a very long, low ilium with a convex upper margin, and a slender and elongated metatarsus. [guanodon resembles the present species in general form of the skull, but differs in having a lower snout, a shal- low jugal arch, a smaller orbit but larger lateral fenestra, lack of a subsidiary lateral fenestra, the closer spacing of teeth, the vertebral count, the form and formula of the manus and the shapes of ilium, ischium and pubis. Laosaurus and Camptosaurus are clearly distinct. Dryosaurus may be synonymous with Laosaurus, but further preparation and study of the types of Laosaurus gracilis (YPM 1875) and Dryosaurus altus (YPM 1876), and the two Carnegie Museum skulls (CM 11340 and 3392) referred to these last two genera is necessary before the matter can be resolved. Until such time as that is accomplished, or new and more complete material is discovered, it is impossible to draw any firm conclusions about the affinities of Tenontosaurus with either Laosaurus or Dryosaurus. The skull of Camptosaurus is not well known despite the restorations given by Gilmore (1909). Consequently it is difficult to make adequate comparisons with the present material. The differences in postcranial osteology between Camptosaurus and Tenontosaurus do not preclude an ancestral-descendant relationship. The reduced manus, the complete first metatarsal, the increased vertebral count, the pelvic and pectoral girdle features could all have been derived from the Camptosaurus condition. Thus, the cranial evidence is critical, and the inadequate nature of the Camptosaurus skull material makes final judgment difficult. Examination of all known cranial material has led me to conclude that Gilmore’s reconstruction of the skull of Camptosaurus is correct in most details. Those points that I have reservations about (the long length of the lower premaxillary lobe, the very short upper premaxillary process, the position and shape of the quadratojugal, CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 103 and the form of the paroccipital process) do not alter the most significant aspects of Gilmore’s reconstruction, which is of a long and very low and broad skull. Virtually all adequately known ornithopods are characterized by deep and relatively narrow skulls with long, nearly straight and vertical quadrates, deep pterygoids and long, ven- trally directed basipterygoid processes. These conditions are true of the few known Triassic forms (Heterodontosaurus, Fabrosaurus) and apparently were true for other Jurassic ornithopods (Laosaurus, Dryosaurus? and Dysalotasaurus) and many Cre- taceous species (Hypsilophodon, Iguanodon and nearly all hadrosaurs). It may have been true of Thescelosaurus, but it appears not to have been characteristic of Parkso- saurus. Camptosaurus would thus seem to be an exception with its long and low, broad skull, short and curved quadrates, and short and ventrolaterally directed basipterygoid processes. These suggest that Camptosaurus may have been an aberrant line and not ancestral to Tenontosaurus or any of the other well-known Cretaceous ornithopods. Gilmore (1909) proposed a new species of Camptosaurus (C. depressus) for a very fragmentary specimen (USNM 4753), from what has been called “Lakota sand- stone”’, of possible Early Cretaceous age, at Calico Canyon near Buffalo Gap, South Dakota. The precise stratigraphic level and age have not been determined. The possi- ble Early Cretaceous age of this specimen invites comparison with Tenontosaurus. The specimen, which consists of portions of both ilia, one pubis(?), an incomplete sacrum, a sacro-dorsal, 12 caudals and a few rib fragments, is at best a doubtful type specimen. Comparison with other Camptosaurus materials suggests that it may repre- sent a distinct species, but it is also possible that the diagnostic features noted by Gil- more are due to individual variation. Whether or not C. depressus is a valid species, there can be no doubt about its dis- tinction from Tenontosaurus. The ilia of C. depressus lack the concave upper margin, and the long anterior process of the ilium is straight and projects forward and only slightly downward, whereas that of Tenontosaurus turns very sharply downward. Also, this anterior process is very robust and triangular in section in C. depressus. In Tenontosaurus it is very thin transversely and bladelike. The caudal vertebrae are in- complete, but at least one anterior caudal bears a rodlike neural spine that is inclined backward at approximately 45°, instead of being bladelike and nearly vertical. The distal caudals also appear to have had short neural arches instead of the nearly full- length arches characteristic of Tenontosaurus. Inadequate as the type of C. depressus is, I see no evidence to equate it with Ten- ontosaurus, but there appears to be good evidence for considering the two as distinct. SuBorDER ANKYLOSAURIA Famity ACANTHOPHOLIDAE Romer, 1927 Sauropelta, new genus ETYMOLOGY: Sauros (Greek; masculine), lizard, and pelta (Greek; feminine), small shield, in reference to dermal armor. TYPE SPECIES: Sauropelta edwardst, new species. DIAGNOSIS: Same as that of the type and only species. 104 PEABODY MUSEUM BULLETIN 35 Sauropelta edwardsi, new species Plates 22-27 ETYMOLOGY: Sauropelta edwards; named for Nell and Tom Edwards of Bridger, Montana, in appreciation of the hospitality and assistance they gave to Yale field crews. TYPE SPECIMEN: AMNH 3032, a partial skeleton, lacking the skull. TYPE LocALITy: AMNH 32-3, NE % Sec. 20, T.5 S., R.28 E., Big Horn County, Montana. Unit V, VI or VII (precise stratigraphic level unknown) of the Cloverly Formation. REFERRED SPECIMENS: Partial skeletons (AMNH 3016, 3033, 3035, 3036, 5833, 5853) ; isolated elements® (YPM 4896, 5069, 5072, 5074, 5086, 5094, 5095, 5098, 5101, 510255105; 5106,.5108% 5109; 5111-5115); 5118-5122,, 51245125. 51275051 S50 emia 5133, 5134, 5136, 5137, 5139-5146, 5148-5150;,.5154-5159, 5161, 5163-51695 a073; 5179-5179» 5181-5189, 5191; 5192; 5194, 5196, 51985 5200) 5295-5298, 530025509. 5307; 5309-5315),5317;,5320-5327, 5333-5341,..5350-5352) 5367, 5368;)53895 520i 5393, 5402, 5405, 5408, 5409, 5442, 5448, 5486-5503, 5505-5513, 5516, 5517, 5520- 592215925-59295 55a DOS2)is ADDITIONAL REFERRED SPECIMENS: AMNH 3064; YPM 4892, 4897, 4905, 5076- 5078; 5085, 51125, 5136, 51405-5150, 5190, 5193, 5306; 9308; 5316, 5518s a5 ty aoce 5330-5332, 5390, 5394, 5395, 5406, 5485, 5504, 5515, 5536. LOCALITIES: AMNH 03-28, 04-9, 31-9, 32-4, 32-6, 32-7, 38-2; YPM 62-11, 63-16, 63-17, 63-18, 63-19, 63-20, 63-22, 64-20, 64-23, 64-24, 64-29, 64-31, 64-47, 64-67. DISTRIBUTION: Units V, VI and VII, Cloverly Formation, southern Montana and northern Wyoming. piAGNosis: Medium-sized acanthopholid ankylosaur with extensive dorsal and flank armor consisting of a mosaic of large flat and keeled dermal plates interspersed with small plates and irregular ossicles. Flank armor consists of large hollow-based plates projecting lateroposteriorly as long triangular spines. Skull inadequately known, but apparently relatively long and deep, and perhaps narrower than in other ankylosaurs. Lateral temporal fenestra present, but upper fenestra closed by dermal ossifications. Mandible long, with low coronoid process, and co-ossified with a superficial dermal plate. The latter does not extend onto inferior medial surface. Mandibular tooth row long, extending almost to symphysis. Mandible tooth count 25 to 27. Teeth of ankylo- saurid type with laterally compressed crowns triangular in lateral aspect and denti- culate along anterior and posterior edges. External and internal surfaces usually not striated or ridged, but crown base irregularly and variably inflated to produce a bul- bous labial cingulum and a narrow lingual cingulum. Either or both cingula may be absent. Cervical vertebrae short, massive and wide. Width of centrum exceeds length and height, and centra faces oval and amphiplatyan. Neural canal very large. Neural 5 Disarticulated and scattered scutes, vertebrae, ribs, limb bones and skull and jaw fragments of at least five individuals were collected in the six closely spaced Yale sites (YPM 63-16, 63-17, 63-18, 63-19, 63-20 and 63-22). There being no way to establish true associations of most ele- ments, the majority have been catalogued as individual entries. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 105 arch low, diapophyses short, massive and projecting laterally, neural spines low, robust and triangular. Inferior surface of centra with a broad, shallow longitudinal groove bordered laterally by thin, ventrolaterally projecting laminae. Dorsal centra long, constricted laterally and ventrally at midlength, terminal faces circular and amphiplatyan. Neural arches high, with high oval neural canal. Diapophyses stout, short, and extend up and outward at 50 to 60° to horizontal. Both diapophyses and short bladelike neural spines expanded distally, the latter both transversely and longitudinally. Postzygapophyses overhang well behind the centrum posterior surface. Ribs not co-ossified to vertebrae. Proximal caudal centra short, but very deep and wide, nearly circular in end view and amphiplatyan. Transverse processes project out and downward proximally, but become horizontal posteriorly. Neural spines stout, short and greatly expanded distally. Distal caudals elongate, hexagonal in end view and with a narrow, deep midline groove ventrally (haemal canal). Large, pro- jectant chevron facets at posterior inferior margins of centra, but little or no facet anteriorly. Chevrons infrequently fused to centra. Fore limb short and massive with very heavy humerus and short, stout radius and ulna. Manus phalangeal formula un- known. Scapula-coracoid fused, very massive, short and downcurved both anteriorly and posteriorly. Sacrum consists of seven or eight segments. Ilia greatly expanded into near horizontal plates overhanging far lateral to acetabulae and with long narrow anterior blades. Ischium a simple rod, strongly downcurved distally, but without any distal expansion. Pubis greatly reduced to small hook-shaped element. Hind limb long, with stout and long femur and moderately elongated tibia and fibula. Tarsus un- known, but pes phalangeal formula 2-3-4-5?-0. All digits terminate in flat, hooflike unguals. DESCRIPTION: Ankylosaur remains are rather common in fossil vertebrate collections from the Cloverly Formation and appear to be second only to Tenontosaurus in abun- dance. No complete skeletons are known, however; in fact, other than numerous iso- lated elements, only four partial skeletons exist in addition to the type specimen. It is quite possible that more than one species® is represented among the items here re- ferred to Sauropelta, but no concrete evidence to that effect is available at present. Accordingly the following description and the preceding diagnosis are based on the type specimen (AMNH 3032) where possible, but other specimens in the American Museum and Peabody Museum collections have been used for characterization of those elements not preserved in the type. In particular, I call attention to the Yale Crooked Creek quarries of northern Wyoming (YPM localities 63-16, 63-17, 63-18, 63-19 and 63-20) that produced large numbers of ankylosaur scutes and postcranial bones. At these sites, ankylosaur remains were the most abundant materials by far, but nearly all were disarticulated and occurred as isolated elements. At least five individ- uals are involved here and nearly every skeletal part is represented. Comparable ele- ments are indistinguishable from those of the type, and it is concluded that the type 6 The most suggestive evidence of a second species lies in the “unique” armor preserved in AMNH 3036 which seemingly lacks any hollow-based spikes or strongly keeled plates, both of which are abundantly represented in the other partial skeletons known and in the isolated ankylo- saur remains. (See Plate 27: G to L for the keeled and hollow-based scutes and compare with Plate 75, Colbert, 1961 for the dermal armor of AMNH 3036.) 106 PEABODY MUSEUM BULLETIN 35 ; specimen and all Crooked Creek ankylosaur remains are of a single species. Thus the Crooked Creek materials have been used extensively in this description. Skull. The skull is missing in the type specimen, but a partial skull is present in AMNH 3035 and several skull fragments were recovered from Yale locality YPM 63-19 (YPM 5528, 5529, 5499). Although poorly preserved and lacking much of the preorbital region, the skull of AMNH 3035 appears to have been significantly higher than most nodosaur skulls. The skull roof, which is veneered with thick dermal ossi- fications, lies approximately 12 cm above the ventral margin of the foramen magnum, equal to half the skull width at the orbits (25 cm). This compares with 8 and 30 cm in Edmontonia rugosidens (USNM 11868) and 8 and 28 cm in E. rugosidens (ROM 1215). A low or depressed skull also appears to be characteristic of Panoplosaurus miris (NMC 2759) and Silvisaurus condray: (UKM 10296). The skull roof of Sauro- pelta appears to have been flat and completely covered with dermal bone concealing all dorsal and lateral bones and sutures. Greatest skull width is just behind the orbits and equals about 35 cm. The orbits are small and appear to have been oval with a maximum diameter (length) of about 6 cm. Although portions of the circumorbital area and maxilla are present in the type, no sutures are recognizable and little can be said about precise relationships. The right and left circumorbital regions are also known from fragments collected at Yale site YPM 63-19. In both, the skull bones are covered by small- to moderate-sized, knobby or flat dermal ossifications. Several prom- inent sulci are preserved, particularly one extending from the rear margin of the orbit across the supraorbital rim and medially across the lateral part of the skull roof. Thus the dermal scutes overlying the orbital region might be described as preorbital and postorbital scutes. This same pattern occurs in Edmontonta rugosidens (USNM 11868 and ROM 1215) and, contrary to Gilmore’s statement (1930, p. 3), there does appear to be some uniformity of sulci and scute patterns. The lateral temporal fenestra is not recognizable in this specimen, but an isolated left quadrate (YPM 5529), with a complete anterior margin, shows that at least a small lateral fenestra was present. The quadrate flares out slightly ventrally and ap- pears to have sloped forward and slightly outward as in most ankylosaurs, at approxi- mately 60° to the vertical. As a consequence of this forward inclination of the quad- rate, the broad distal extremities of the quadrates are situated lateral to the anterior end of the basicranium, and the stout pterygoid flanges extend directly medial. Mod- erate-sized posttemporal fenestra are present on either side of the braincase between the exoccipital and the pterygoid flange of the quadrate. The occipital surface is broad and low and, although no sutures are discernible, appears to be constructed entirely of the exoccipitals and supraoccipital. The small subspherical condyle (4.5 cm) 1s formed exclusively of the basioccipital. This structure points down and back at a sharp angle to the tooth row, but I agree with Lambe (1919) and Russell (1940) that the ankylosaur skull in life was probably held at an inclined angle of perhaps as much as 60° to the horizontal. Thus in the normal position the quadrates are nearly vertical and the occipital condyle projects back horizontally. This position appears to be veri- fied by the attitude of the floor of the endocranial cavity and what appears to be part of the semicircular canal cavity preserved in an isolated fragmentary braincase (YPM 5929): The braincase is very massive and short. The basioccipital-basisphenoid junction is greatly inflated ventrally and marked by two irregular lateral projections (basisphe- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 107 noid tubercles) and a broad midline swelling. A large foramen, presumably for the internal carotid artery, pierces each side of the basiphenoid well below the endocranial cavity and passes into the pituitary fossa. Immediately anterior to this, the basicra- nium narrows abruptly and passes forward as a thin sagittal blade (parasphenoid) above the fused pterygoids. The inflated basisphenoid butts closely against the poste- rior surfaces of the broad pterygoids. In normal articulation the basipterygoid proces- ses are concealed, but the isolated basicranium (YPM 5529) shows a very short knob- like projection on the left side that appears to be a vestige of that process. Never- theless, there appears to have been complete immobility between endocranium and palatoquadrate. Mandible. Portions of the right mandible are preserved in AMNH 3035, but again no teeth are visible. Its length is approximately 35 cm from the center of the glenoid to the symphyseal region and it bears a low triangular coronoid that rises approxi- mately 13 cm above the ventral margin of the mandible. The tooth row is long and curved, but no count of alveoli can be made. The right mandible is imperfectly pre- served in the type. It compares exactly with the above mandible and a Yale specimen (described below) and includes a long tooth row (23 cm) with 27 alveoli that extends very close to the symphysis. Several isolated mandibles were collected at various Yale sites, among them one excellent jaw (YPM 5502) illustrated in Plate 22: A, B and C that provides the fol- lowing details. It is of moderately massive construction but tapers to a narrow sym- physis. The length is 37 cm and the height at the coronoid process is 11.3 cm. The most distinctive feature is the long, curved tooth row (20 cm minimum length, 22 cm along the curve) with 25 alveoli. A second jaw (YPM 5391) also has 25 alveoli. This compares with 18 alveoli and a straight length of 14.5 cm in a mandible 35.2 cm long for Edmontonia rugosidens (USNM 11868). The long tooth row reaches to within 3.5 cm of the symphysis and extends farther forward than in any nodosaur except Silvisaurus. Eaton (1960) reported “about 27” mandibular alveoli extending to within 25 mm of the symphysis and measuring (in a straight line) 170 mm back from the symphysis. Silvisaurus is the only nodosaur(?) in which premaxillary teeth are known (and for this reason it should perhaps be referred to the Acanthopholidae), but the long mandibular tooth row in the present material certainly indicates their probable existence in Sauropelta. The tooth row curves markedly over its length, concave externally. It also curves in the vertical plane with anterior and posterior teeth situated at a much lower level than those near midlength. The external mandibular surface is marked by a long and broad rugose or sculp- tured region—a dermal ossification that has fused to the mandible. This dermal plate does not reach either to the symphysis or over the short retroarticular process. The “exposed” posterior portion of the mandible behind the dermal plate marks the posi- tions of the pterygoideus muscles that probably inserted on the external surface be- hind this scute and wrapped around beneath the mandible and passed forward to the greatly expanded pterygoids. The upper limit of the dermal ossification is well below (approximately 3 cm) the tooth row and parallels it to the base of the coronoid pro- cess. Eight large foramina pierce the dentary in this region between the tooth row and the dermal scute and two more occur close to the symphysis. Unlike most nodosaurs, this superficial dermal ossification has a sharply defined ventral margin along the infe- 108 PEABODY MUSEUM BULLETIN 35 rior margin of the mandible and does not extend up onto the inner surface of the jaw. The internal aspect of the mandible is smooth and gently concave. A row of prom- inent round foramina lies just below the alveolar margin. They correspond one for one with the alveoli and presumably functioned as passages for germ teeth from the dental lamina as suggested by Edmund (1957). Four other large foramina appear to penetrate the inner wall of the mandible to the Meckelian canal, one each at the ante- rior and posterior ends of the splenial and one at the top and one at the center of the splenial. This last bone overlaps the dentary as a thin sheet of bone, is triangular and extends over the middle third of the jaw. Posteriorly it unites by a firm digitate suture with the angular. Dorsally it contacts the coronoid and ventrally, over part of its length, it joins the external dermal ossification. Near the rear extremity of the tooth row the splenial height is slightly less than the dentary height. In Edmontonza it appears to be comparable, although Russell (1940) shows it as a thin sliver of bone along the lower internal surface. The coronoid is a narrow L-shaped bone, the anterior process of which loosely overlaps the last six dental foramina, immediately lingual to the tooth row. The pos- terior or dorsal process laps over the anterior edge of the coronoid process (dentary?) and fuses solidly with that structure. The, angular is solidly united with the other postdentary bones and all sutures are obliterated. Presumably, the mandible medial, ventral and posterior to the Meckelian canal, is composed of the angular, surangular, articular and prearticular, but none are recognizable. The surangular presumably forms the posterior part of the coronoid process and the external surfaces of the region behind. A small foramen (the suran- gular foramen?) penetrates this area at the posterior edge of the dermal ossification and opens into the rear of the mandibular fossa 2 cm anteriorly. The glenoid region is separated from the floor of the mandibular fossa by a prominent transverse ridge. The articular area itself is broad transversely and consists of two large, shallow concavities in an oblique trend, the larger one situated lateral and slightly behind the other. These extend almost to the end of the short, but robust retroarticular process. The symphysis is moderately wide (from front to back) but surprisingly shallow. In fact, the symphyseal region is the shallowest part of the mandible except for the retroarticular process. The symphyseal surface is marked by broad, shallow depres- sions, and the upper superficial region just lateral and anterior to the symphysis bears numerous deep pits and bosses or tubercles. These features suggest a cartilaginous or ligamentous union of the mandibles that may have been somewhat mobile. There is no clearcut scar for a predentary that is identifiable as such. Teeth. Ten functional and replacement teeth are preserved in mandible YPM 5502. An additional seven replacement teeth are visible in the second mandible, YPM 5391. Two teeth are preserved in place in a maxilla fragment (YPM 5368) and 20 isolated teeth were recovered from several sites (see Plate 22: D, E and F). There seem to be no consistent differences between maxillary and dentary teeth. All are laterally compressed, triangular blades with denticulate anterior and posterior mar- gins. The number of denticles varies from three to five on one edge and five to seven on the other, exclusive of the apical denticle. The higher denticle count appears to be always on the anterior edge, but this cannot be confirmed with the present limited sample. There is moderate variation in crown height, with some being relatively low CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 109 and broadly triangular, others high and more narrowly tapered, as shown in Plate 22: D, E and F. The basal part of the crown is inflated to variable degrees and usually is developed into an irregular cingulum. This structure is most prominent on the external side of lower teeth but may be present on either or both sides. However, a cingulum appar- ently is not universally present, as several teeth in the Yale collections (YPM 5525, 5502) show (PI. 22: E). Below the crown, the cylindrical root is constricted and then expands slightly before tapering to its extremity. All teeth appear to have had open roots. The only apparent difference between the present material and teeth of nodosaurs is the absence of even faint vertical rugae across the inner and outer crown faces. Such rugae are prominent features in Ankylosaurus magniventris (AMNH 5895) , Edmon- tonia longiceps (NMC 8531), Edmontonia rugosidens (USNM 11868) , Panoplosaurus miris (NMC 2759) and all species of Palacoscincus. Only Silvisaurus condray: (UKM 10296) similarly lacks these rugae, further evidence for allying these species. Vertebral column. The vertebral count is not known for $ auropelta, but represen- tative vertebrae are available for all parts of the column. No cervical vertebrae are preserved in the type specimen, but six cervicals are present, either completely or in part, in AMNH 3035. Among those represented are the atlas and axis. In contrast to all nodosaurs, only the odontoid is fused to the axis. The remainder of the atlas is missing, but it is quite evident that the altas intercentrum and arch were not co- ossified with the axis (see Plate 22: G). This condition is found in primitive acan- thopholid ankylosaurs (i.e. Struthiosaurus transsylvanicus, Nopcsa, 1929), but not, as far as I know, in any nodosaur. The odontoid is moderately long, tapers anteriorly, both in lateral and dorsal views. The upper surface is concave from side to side, but the ventral surface is narrowly con- vex, almost “keeled”, so that in anterior aspect the odontoid is almost triangular. The axis centrum is long and low, oval in end view and moderately concave in its posterior surface. The underside of the centrum is broad and nearly flat, with a thin, sheetlike lamina of bone projecting back from the anterior edge. This may represent a greatly flattened and backward-directed hypopophysis. The lateral centra surfaces are marked by a large but short parapophysis at midheight and close to the anterior margin. The neural pedicels are high, enclosing a very large, vertically ovate neural canal. Short, stubby transverse processes project directly laterally from the pedicels at midheight of the neural canal. The postzygapophyses are large, projecting backward beyond the posterior face of the centrum. In contrast to nodosaurids, particularly Edmontonia rugosidens (USNM 11868), the neural spine is a very low triangular knob overlying the postzygapophyses. The other cervicals, presumably the third through fifth (Plate 22: I and J), are shorter in centrum length but have the same low oval outline in axial view. These centra are amphiplatyan and slightly angled, reflecting a slight arch to the neck. The ventral surface is broad with a shallow sagittal groove and low but distinct lateral ridges. The neural arch is high and broad, with short, horizontal diapophyses and short, robust and sub-bladelike neural spines. Thirteen dorsals are present in the type specimen, but few are complete, and the number of missing segments is not known. Unfortunately, all information about the relationships of these segments is lost, so none can be identified as to position with 110 PEABODY MUSEUM BULLETIN 35 absolute certainty. Dimensions are similar enough and preservation capricious enough to frustrate establishment of sequences based on length, height or width of the centra (see Plate 22: K; and Plate 23: A). All dorsals are amphiplatyan, but many show a faint central convexity 2 to 3 cm in diameter on both anterior and posterior centra surfaces. Both ends are nearly circular with height slightly greater than width. The sides and under surfaces are smooth and strongly concave longitudinally. No pleurocoels are present. The neural arch pedicels are very high and narrow, enclosing a high, elliptical canal. The parapophyses are high on the pedicels, well above the level of the neural canal, and project only slightly outward. Pre- and postzygapophyses are very close to the midline and are joined. The postzygapophyses project well behind the centrum and directly above the neural canal. Whereas the zygapophyseal facets of the cervicals are inclined at a low angle of 20 to 30° to the horizontal, those of the dorsals are steeply inclined at 60° or more. The transverse processes are long and project up and out (not backward) at a very steep angle of close to 60°. None are complete but these are quite stout and apparently were expanded distally. They appear to have terminated at the level of the neural spine summit. The neural spine is a stout blade with an upright and very backward orien- tation. It is rectangular, thin transversely, and the summit is swollen both transversely and longitudinally. A complete sacral series is not known for Sauropelta. The type includes seven fused segments of which the last four probably are true sacrals and the first three (and pos- sible additional segments) are fused posterior dorsals. The posterior elements are mod- erately broad ventrally, the remainder are narrow and strongly rounded transversely. Sacral ribs are evident in only four of the segments. YPM 5102 is the major part of a sacrum, including the neural arch pedicels and massive sacral ribs. Five segments are present, all solidly fused. The most anterior segment may be a dorsosacral, but the remaining four are true sacrals. The transverse widths of the centra increase markedly from front to back, as does the diameter of the neural canal. The maximum diameter of the latter occurs at the last sacral. Silvisaurus is characterized by six sacrals and six additional segments fused into a presacral rod. Gilmore (1930) described three sacrals, four presacrals and two sacro- caudals coalesced into a “‘synsacrum”. This number corresponds with Nodosaurus textilis as described by Lull (1921) but is three more than reported in Panoplosaurus miris by Sternberg (1921) who recognized four sacrals, one dorsosacral and one sacro- caudal. Obviously, there is considerable variation in sacral count (or interpretation) within the Nodosauridae, and the incomplete remains of Sauropelta presently prevent establishment of sacral count in this genus. Thirty-nine caudal vertebrae (Plate 23: B-E) are preserved in the type specimen, but the series is incomplete with an unknown number of segments missing from the extremity and within the series. Unfortunately, field data again are not available and the original sequence of these vertebrae is unknown. Seventeen bear prominent to very long transverse processes; the remainder lack this structure and are clearly distal seg- ments. All caudal centra are amphiplatyan with the anterior face slightly concave. Proximal caudal centra are short but high and broad, the breadth being slightly greater than the height. Centra faces are nearly circular. Long, stout, rodlike trans- verse processes project out and downward from the most proximal caudals. These become nearly horizontal in succeeding segments. The neural arch is low and robust CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY tel and bears a short, massive neural spine that is inclined up and backward (the anterior margin being concave) and terminates in a prominent knob. Both pre- and postzy- gapophyses overhang the centra faces and the anticular facets are inclined (45°) and separated at the midline. Distal caudals are much longer than they are wide or high, and centra are distinctly hexagonal in end view. The lateral surfaces are often marked by several slight, longi- tudinal ridges, and the ventral surfaces consist of a deep, narrow midline groove bor- dered by prominent lateral ridges extending between anterior and posterior chevron facets. The neural arch is low and extends over one half to two thirds of centrum length. Neural spines are thin and diminish from short bladelike structures to low, caudally projecting triangles. In anterior caudals, the articular facets for the chevrons occur as prominent ventral projections only at the rear margins of the centra. In pos- terior caudals, chevron facets occur at both anterior and posterior margins but the latter are most prominent. The chevrons are short, massive blades that occasionally fuse to the centrum an- terior to it. Ossified tendons are preserved in contact with several dorsals and caudals in the Yale collections, but in each instance they are fragmentary and nothing can be said about their frequency, arrangement or distribution along the vertebral column. The best evidence of tendons is preserved on both sides of the neural arches of the sacrum YPM 5102, but again the evidence is fragmentary. These are rodlike ossifications, probably of the epaxial musculature, and presumably they extended along the vertebral column from the anterior or middorsals to at least midtail. Ribs. The dorsal ribs are well represented in the type specimen, as well as in the Yale collections from localities YPM 63-18 and 63-19. None of these are fused to the dorsal vertebrae, contrary to the usual condition in nodosaurs. All appear to have been massive and T- or L-shaped in cross-section, and all are double-headed. Cervical ribs are short and Y-shaped. Shoulder girdle. The shoulder girdle elements (Plate 24: A and B) are damaged and incomplete in the type specimen, but the right side is preserved in AMNH 3035 and several scapulo-coracoids are represented in the Yale collections. The shoulder girdle appears to have consisted only of a very massive, fused scapulo-coracoid, as no evidence of either sternals or clavicles (see Russell, 1940) has been recognized. The scapulo-coracoid consists of a short, strongly curved, thick scapula and a very large, crescentic coracoid. Both elements are very massive but particularly so at the glenoid. For example, in AMNH 3035 the transverse thickness of the scapula at the glenoid is approximately 12 cm and the least width of the scapular blade is 10 cm (maximum width is 16 cm at the extremity). A robust, knoblike acromion process projects for- ward and laterally from the upper proximal external surface of the scapula, directly above the rear margin of the glenoid. The scapular blade thins slightly distally and curves strongly downward. Internally its surface is strongly concave. The coracoid is firmly fused to the scapula with all signs of the suture obliterated. The margins are moderately thick, but maximum thickness of 11 cm is attained ad- jacent to the glenoid. The coracoid foramen is large and oval and extends inward and backward from the external surface. In general form, the scapulo-coracoid is nearly identical to those of most nodosaurs and particularly that illustrated by Sternberg (1921) of Panoplosaurus. 112 PEABODY MUSEUM BULLETIN 35 * Fore limb. As in all nodosaurs, the humerus of Sauropelta is a short and very mas- sive bone (Plate 24: C and D). Both humeri are present in the type; the left is also present in AMNH 3035, and numerous others are represented in the Yale and Ameri- can Museum collections. In addition to its massive form, the most distinctive feature of the humerus is its short length relative to that of the femur. In the type specimen, the humerus is approximately three quarters the length of the femur (0.72 to 0.77). The shaft is nearly straight and is marked by a very long, stout deltopectoral crest along its proximal half that apparently extends forward nearly perpendicular to the long axis of the distal extremity. The head is robust and subspherical, projecting back well behind the shaft in a direction perpendicular to the long axis of the distal ex- tremity. The distal condyles are large, the external condyle being the larger. The two condyles are separated by a broad, shallow groove distally and anteriorly and there is a moderate ectepicondyle that projects approximately 5 cm beyond the lateral con- dyle. Aside from the massive proportions, the most important feature of the humerus is the fact that the distal extremity is not twisted with respect to the proximal end. The plane of the external and internal condyles, which must be perpendicular to the plane of elbow flexion, is also perpendicular to the axis of the humeral head. This means that the humerus could not have been held in a horizontal attitude, as main- tained by Nopcsa (1928b) for Scolosaurus and by Russell (1940) for Edmontonia. It is quite obvious that the plane of flexion and extension of the elbow is very nearly co- incident with the plane of extension and retraction of the humerus in the glenoid. Hence the fore limb could not have functioned in the sprawling manner of a lizard or salamander but must have been maintained in a near vertical or upright position beneath the glenoid. Both ulnae are preserved in the type specimen, also in AMNH 3035, and in numer- ous other American Museum and Yale specimens. The ulna (Plate 24: E and F) is very robust proximally with a massive olecranon projecting well above the humeral articular facet. Distally, however, the shaft tapers abruptly and the distal end is rather narrow transversely and of only moderate (10 to 11 cm) longitudinal diameter. Both radii of the type specimen and that of AMNH 3035, together with several in the Yale collections, reveal this bone as a short, massive and cylindrical bone with broadly expanded, flaring extremities (see Plate 24: G). The shaft is straight and robust. The proximal end flares out abruptly in all directions and terminates in a broad, oval, slightly concave surface. The distal end flares out gradually to a broad, convex articular condyle. The carpus is not known, but the left manus is represented by five metacarpals, seven phalanges and three poorly preserved hooflike unguals. Data regarding the re- lationships of these elements are not preserved, and no phalangeal formula can be given. The metacarpals tentatively are identified from shortest to longest as follows: I, II, III, V and IV. Attempts to identify the phalanges on the basis of articular fits suggest that the proximal phalanges of all five digits are present, plus the second phalanges of III and IV. The unguals appear to be those of II, III and IV. If these identifications are correct the phalangeal formula would seem to be 2-3-4-3-2 or 3. The metacarpals are quite massive, except for the first and fifth, but are considerably less massive than the metatarsals. The phalanges are broad but short—sometimes very short. The unguals are broad, flat and bluntly rounded. Pelvic girdle. The type specimen includes most of both ischia (Plate 25: A, B and CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 113 C) and ilia, but the pubes are not preserved. A solitary right pubis (Plate 25: D, E and F) is known (YPM 5141) from Yale locality YPM 63-16, as well as several in- complete ischia (YPM 5101 and 5141 from localities YPM 63-19 and 63-16, and YPM 5513 from YPM 63-20). The ilia are greatly expanded plates of bone that extended far laterally from the sacrum in a nearly horizontal plane, as in Nodosaurus, Polacanthus and presumably all nodosaurs. In the type specimen neither ilium is complete and both are distorted, but the general form corresponds approximately to that figured for Dyoplosaurus by Parks (1924). It is best described as a massive, broad, triangular bone, oriented close to the horizontal. It has a short, massive posterior blade and a very long, narrow and thin anterior blade that extends forward, and slightly out and downward. This ante- rior process apparently conformed to the external body profile (as presumably did the nearly horizontal proximal region of the ilium) , because toward the extremity it curves from the horizontal to an inclined plane 30 to 40° from the horizontal. No evidence to this effect is preserved, but presumably this anterior process was contacted by one or more transverse processes of the several dorsosacral vertebrae that fused to the sacrum. The acetabulum, which is closed, consists of a large, massive, ventrally directed cuplike socket on the underside of the ilium. It is nearly completely surrounded by stout, ventrally projecting walls of bone. The ilia are fused to the sacral vertebrae by four massive sacral ribs that attach in the region of the acetabulum. The region be- tween the acetabulum and the sacral vertebrae is open above (i.e. there is no medial expansion of the ilium) but presumably was covered with dermal scutes. The incom- plete left pubis (the posterior blade is missing) measures 87 cm anterior to the center of the acetabulum and approximately 40 cm in width lateral to the center of the acetabulum. The external edge of the left ilium, lateral to the acetabulum, was more than 70 cm from the sagittal plane. The right ilium appears to have had comparable dimensions, the distance between the external margin and the center of the acetabu- lum is 45 cm, and the length anterior to that center is 90 cm. The length of the right ilium is 129 cm. The ischium is a relatively stout and long bone, broad and massive proximally and thin and tapered distally. Its precise relationship to the ilium is not known but it ap- parently articulated with the ventral edge of the massive posterior-internal wall of the acetabulum. The iliac peduncle is very stout and the pubic peduncle is moderately so. Between these peduncles the ischium is deeply concave externally, and a thin bony lamina extends between them. The maximum proximal dimension (longitudinal) is in excess of 25 cm for the right ischium of the type, and more than 23 cm in YPM 5141. The shaft tapers distally to about midlength, at which point the maximum lon- gitudinal dimension is 8.5 cm in the type. Just below midlength the ischium shaft bends strongly downward at approximately 35 to 45° to the proximal shaft and tapers further to 5 cm, just above the very slightly inflated distal extremity. The external surface at midlength is marked by a long flat scar that probably is the origin site of part of the M. pudo-ischio-femoralis. The ischium closely resembles that of Edmon- tonia rugosidens (USNM 11868) figured (as Palaeoscincus) by Gilmore (1930) with the exception that the distal third is less tapered and more ventrally deflected in the present species. In longitudinal-profile the distal part of the shaft curves inward at about 30° to the proximal part of the shaft, thereby placing the extremity in or near 114 PEABODY MUSEUM BULLETIN 35 the sagittal plane. Rugose areas on the extremity indicate that the ischia were probably joined by cartilage. The pubis is known only from a nearly complete right pubis (YPM 5141) that was found closely associated with a right ischium. As in all nodosaurs, the pubis is greatly reduced to a very small triradiate, hook-shaped bone, measuring only 13.5 cm in the present instance. The hooked or downcurved portion is quite massive and rugose and represents the remnant anterior or prepubic blade. Posteriorly a stout, triangular-in- section, rugose articular surface is the ischiac articulation. In the present specimen (YPM 5141) this surface fits the pubic peduncle of the associated ischium almost per- fectly (see Plate 25: G). A thin, narrow blade projects dorsomedially and backward from the medial surface of the “prepubic process”. This process, which represents the postpubic process, expands into a broad blade distally and extends at least 10 cm caudally. Dorsally a broad rugose area, at right angles to and adjoining the ischiac articular surface, is the articular surface for the ilium. The internal surface, with the exception of the postpubic process, is smooth. The external surface, however, is very irregular and rugose, as are the adjacent surfaces of the ischium. These presumably mark cartilaginous and ligamentous attachments along the inner wall of the acetabu- lum. Quite obviously the pubes did not meet in the midline, in view of the widely spaced positions of the acetabulae. Aside from the dorsal rugosity mentioned above, there is no clear evidence in presently known Sauropelta material as to the nature of the pubis-ilium union, but I suspect that the entire upper margin of the pubis articu- lated with the ventral edge of the anteromedial wall of the acetabular cup, as seems to have been the situation in Polacanthus (BMNH R175), although both the pubis and ischium are of quite different form in Polacanthus. The Yale specimen compares al- most exactly with that of Edmontonta rugosidens (Palaeoscincus) illustrated by Gil- more (1930). Eaton (1960) figured and described a small bladelike bone as the left pubis of Silvisaurus on the grounds (in part) that it resembled the pubis of some other or- nithischians—if the postpubic process were removed (italics mine). This bone resem- bles much more closely the sternal bone of some ornithopods, particularly that of hadrosaurs (see Lull and Wright, 1942). Russell (1940) described a pair of nearly identical bones in Edmontonta rugosidens as clavicles (clavicles have been reported by Brown and Schlaikjer [1940] in Protoceratops) , although he was unable to show how they articulated. I am inclined to disagree with both identifications because of the resemblance of these bones to ornithopod sternals, plus the fact that Eaton’s bone does not resemble in the slightest way any known ankylosaurian pubes. Eaton apparently was misled by Gilmore’s figure (1930, fig. 16) of what he interpreted as the right pubis of “Palaeoscincus’ (= Edmontonia), that illustrates the internal side—not the exter- nal side as stated in the caption. The error in the caption apparently led Eaton to conclude that “Gilmore’s bone can hardly be a pubis” because the figure shows a large lateral process that Gilmore labeled as a “postpubic process’. The supposed lateral position of this bladelike process would have placed it projecting across the acetabu- lum—an impossible situation. Gilmore’s text, however, clearly states that the post- pubic process branches off the internal surface and extends backward and downward (medial to the acetabulum). As noted above, Gilmore’s specimen is very similar to the pubis described here that was found closely associated with and articulates perfectly with a right ischium. Thus CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 115 the present material would seem to clear up any question that may have existed re- garding the validity of Gilmore’s identification. It also suggests that the element de- scribed by Eaton as the pubis of Szluzsaurus probably is not that bone. Hind limb. Most of the hind limb and pes elements (Plate 26) are known in the type specimen and from isolated elements in the Yale collections. Only the astragalus and calcaneum, a single ungual and the tarsals (if present) are not represented. The femora of the type are long (76 to 77 cm) and quite robust (31.32 cm in minimum shaft circumference) (see Plate 26: A and B). A stout, ellipitical head projects medi- ally from a massive greater trochanter. There is little indication of a distinct lesser trochanter. The fourth trochanter is represented by an elongated, irregular swelling slightly above midlength of the shaft. The most distinctive feature is the very robust form of the distal end of the femur, with large, well-rounded internal condyles. These project far backward and are separated both distally and posteriorly by a deep inter- condylar groove. The tibia (Plate 26: C and D) is similarly robust and long, measuring 57.5 cm (left) in length and more than 26 cm in minimum circumference. The proximal end is greatly expanded in correspondence with the femur (minimum circumference is 67 cm) and the distal end is transversely expanded. The cnemial crest is short and not very prominent. A broad external concavity proximally and a faint flattened surface distally mark the areas of fibula apposition. The fibula is a slender, slightly curved, compressed cylinder. Neither end is well pre- served in the two fibulae of the type but both extremities were expanded. The length of the type right fibula is 55 cm, only slightly shorter than the tibia (57.5 cm) (PI. 27: A). As noted previously, the tarsus is not known, but the pes is known from the nearly complete right foot of the type. With the exception of the reduced splintlike fifth metatarsal, the metatarsals are very robust. The third is the longest and the second, fourth and first are progressively shorter in that order. No records are available of the original arrangement of the 12 phalanges preserved, but the arrangement illustrated in Plate 26, as determined by the best articular fit of the various bones, is a reasonable pattern. It indicates a phalangeal formula of 2-3-4-4 or 5-0. The proximal(?) pha- langes are the longest and most massive on each digit, with successive phalanges being progressively shorter or more compressed, The unguals are broad, flat, only slightly curved longitudinally and are rounded bones with rugose and irregularly sculptured surfaces. The foot as a unit was short, broad and quite massive, but almost certainly was not plantigrade. The left foot is also present in the type specimen but very poorly preserved. It con- sists of five metatarsals, eight phalanges and four unguals. This would seem to confirm a phalangeal formula of 2-3-4-4-0, but it does not eliminate the possibility of five phalanges in the fourth digit. AMNH 3016, which includes parts of both hind feet, suggests that the formula may have been 2-3-4-5-0. The left pes includes five meta- tarsals, ten phalanges and four unguals, the right pes includes five metatarsals, nine phalanges and three unguals. If none of these are from the manus (and again no quarry data are available to show preserved relationships) , then the fourth pedal digit clearly must have had five phalanges. Because no field data exist, this formula must re- main as unconfirmed although probable for Sauro pelta. Dermal armor. A wide variety of dermal plates, spines, spikes and irregular ossi- fications are preserved in the type specimen and also in AMNH 3035, 3016, 3033 and PEABODY MUSEUM BULLETIN 35 116 = yyStIoy outds [enau [eotAr99 YAITT 6 yIpIm | ¢c9 74 S104 UINIJUID [VOTAIID YT 08 y3uet | Gav yYySIoy outds [einau [eotAsa9 YANO 06 y}pIM OL WYStay > UINIYZUID [eTAIVO YANO GL y13u2] COI y8tay surds [ernau [eoIAIao party J, 8 ypIm S°9 WYSIoy > UINIQUVD [BIIAIVO pary T, 08 y1su9] £8 74 Stay ourds [einou sixy C8 a G9 WYSIey > winNsQuao sIxy C Or y38uay J SUOISUBUIIG] [e1qo}19 A, OCT OTT om — ssad0id prouos09 3e yYSId}y 92 Ge é9¢ Le suorjisod OT% 8°61 0'%2 02 YISus] MOI 4300} AepNqipueyy 0'9E L98 ce< GS BE< = Haus] S14 IP UE suorjtsod 4300} Y3SUI] MOL Y}00} Ale] IXe yy FGE qapim FYSIOY ¢ [INAS yi sus] | SUOISUIUIIG] Je[Nqrpueyy pue [eruesy way «PT way | e'T way ET wysye'T wysYy eT ItIG WdA 16S WdA Z0SS WdA ¢sos HNWV 760 HNWV ‘ISpsvMpa DI] ag OLNDG Jo SyUsWIINseoUI [edioullg ‘CG ATAVL Wi? CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY WYySI0Y api yisua] eon yypIm ers WYySI9Yy sales yysuey, uinsjUe0 | f,, yystoy ourds [einou | f,, yypim ils WYySIoY eels; yi sue] célss yypIm a2 WYSI9Y eels yi sua] reais. yapIm ess WYyS1I04 Pes yisue] obs: yapIm alae WSI0Y ends ysua] adias yyprim cri 1ySI0Y price yy Sue] reals yypIm ass WYST9Y ads yasus] as yapim ois WYSIOY Oss yy3u2] HON yypim ess WS19Y aes yy3u9] aes qIpIm Nas WysI9Y4 NA yU3us] UINIQUI0 [BOIAII9 YIXIS evi LEO [BOTAI99 YUSAVS PEABODY MUSEUM BULLETIN 35 118 Gst OO! 06 OL O'cT cor 06 OL 0°91 O wry = PT way PT way = eT wey | yPT IvIS WdA Toss WdA c0SS WdA cco’ HNNV (penuuo0s) ‘¢ aTdVL 119 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY ae O'GTé sos =a GIlé ae; ie (OP ke ay ae 8°6¢ ae ap = OCT a3 = cst a = FO'GE 001 06 OTT o 81 06T 061 0'6F G'8r OEP = O'F< OTe = GEG Oral | = G'9¢ 06S SUOISUSUIIC QUIT] 210, pue a[psty [e10}00g A Al III II yysugl | [edivorjaypy YIPIM [eIsIp | YPM [eurxoid snIpey YI su9] UF PIM [esstp 3 PrIM [eurxoid eu, yi sue] QOUIIIFUINIITID VINUITUTUT sntouIn Fy Yy} Bug] jsa19 [es10j99d039q CAP SES y}sua] [eurxoid + snsournzy yy sug] YSIOY Y}8UZ] plooes0+ YPM [eurxoid YIPIM [eIsIp > eNdeog yj} sus] URE «II, IYsIOY «lII,, yisu9] «II, Whe ees «(d,, ELEN «dd, yj8u2g] wnjus0 ..qq,, yystoy ourds [einou =x, PEABODY MUSEUM BULLETIN 35 120 ‘ayeurxoiddy = = ‘UIe}IIOUN SI }UIWEII Jo AUIPyY = | (‘peist] yuewsas YY AtaAq) “193397 Aq poyeUsSisop oie s[epned pur sjessop |e sousy “UMOUYUN Ize sIaquINU jUSWIZas T2°U x “SI9}IUIT}ZUID UI S}UIWIIINSvIUI ITV ef a A GGTé a AI G8l¢ a III GOTé = II FCTé — yyBug] [ [esieyeoWy a = Y}PIM [eIsIp = aa WPM [eurxoid - — epnqry = = yj} 3U2] ove GSEs YiPIM [e3sIp 0°9¢ 0S? yIpIM [ewrxoid PIL, O'cS ccs ysu9] 0'¢ £°SS YIPIM [eIsSIp GL?e O'L?e Y3pIM [eultxoid Inula J 0°92 OLL yisue] Cor qySI9y O'sT yisua] siqng ee re Sy Meee RELL 07< — GiGé Y)pIM [ewurxoid } umnTYosy OrS< — 06S (qsaj10ys) Yy}Su2] = FOE1 06ST yySuay wn] suoIsUSUNIC] QUIT] pur] pure e[psIy o1Ajog way PT WySIY IeT WSIY IyeT WSsTYy IyeT qysIy oT WSTYy oT I ad 00s HNWV 8SS9I Nd 11 no 6StS WdA 9646 WdA (penutju0d) ‘¢ aTaVL CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY as 5853, as well as numerous isolated elements from a large number of Yale sites (see Plate 27). These vary from small, circular to oval, flat or slightly curved plates to larger, oval, keeled plates, to triangular and strongly bladed or spined, or long thin, sharp-crested blades with narrow elliptical bases. A few solid, oval to round-in-section spikes—perhaps caudal spikes—are also known. All except the latter spikes show some degree of external rugosities or irregular sculpture, as though they had been covered in life by horny scutes. With the exception of the smallest oval, flat plates, all have distinctly concave to deeply hollowed inferior surfaces. This is most pronounced in the high and narrow, sharp-crested blades. The arrangement of the various dermal ossifications is not entirely known, but it is preserved in part in AMNH 3035 and 3036. These specimens show that at least por- tions of the shoulders, back and flanks were veneered with a mosaic of scutes, plates, spines and ossicles. The main plates and spines seem to have been arranged in trans- verse rows, with flat- or low-keeled plates near the midline and progressively more strongly keeled and spined plates situated laterally. Some fusion of adjacent plates is known, but the interspaces between major plates or spines appear to have been oc- cupied by medium (4 to 5 cm) to small (1 cm) plates and irregular ossicles. The arrangement of the long shoulder spines in AMNH 3035 is in contrast to that shown by Brown (1908) for Ankylosaurus (= Palaeoscincus). In the latter, Brown recon- structed several shoulder spikes as pointing forward and outward. In AMNH 3035, comparable spikes point out, or backward and out—but none point forward. (The same is true of the shoulder spines of Phrynosoma, Zonurus and Moloch illustrated for comparison with Palaeoscincus by Matthew, 1922.) I suspect that the pattern of AMNH 3035 is correct. Forward-directed shoulder spikes surely would have snagged on brush and tree trunks and therefore would seem an improbable arrangement. In most details the various dermal plates of Sauropelta resemble those of Nodo- saurus, Edmontonta, Ankylosaurus, Hierosaurus, Stegopelta and Hoplitosaurus, as well as those of Polacanthus. However, the present materials are less massive and con- siderably more concave or hollowed in the basal surfaces than are those preserved in these genera. DISCUSSION: The present state of our knowledge of the Ankylosauria is very poor, and a modern systematic study is sorely needed. A large number of species have been pro- posed, most on very incomplete (and probably inadequate) material. In the follow- ing discussion comparisons are made with several of these taxa, but with the exception of Hoplitosaurus I have made no judgment as to their validity; ankylosaurian system- atics is outside the scope of this paper. It is obvious that the suborder as a whole was extremely conservative. The dermal armor, the morphology of the pelvic and pectoral elements, the form of cervical, dor- sal and caudal vertebrae and the general design of the skull, jaws and dentition are very similar in all forms. The most aberrant species, perhaps, is Silvisaurus condrayi. This conservatism, together with the rarity of complete specimens, will make any analysis of ankylosaurian systematics very difficult. Among North American ankylosaurs, Silvisaurus (Dakota), Hoplitosaurus (Da- kota?) Stegopelta landerensis (Thermopolis) and Sauropelta (Cloverly) are the ear- liest known representatives. Nodosaurus textilis may also be of Early Cretaceous age, from either the “Dakota” Sandstone or the Thermopolis or Mowry Shales east of 122 PEABODY MUSEUM BULLETIN 35 Como Bluff, Wyoming, but the precise location and stratigraphic level have been lost. Polacanthus, Hylaeosaurus and Polacanthoides of the Wealdon are the earliest known European ankylosaurs. All other ankylosaurs apparently are of Late Cretaceous age. Stlvisaurus is clearly distinct from all nodosaurs in its small form, tapered skull, pre- maxillary teeth, long mandibular tooth row, depressed position of the orbits, covered lateral temporal fenestra, the form of dermal scutes and spines, and the unfused ribs and dorsal vertebrae. The type (and only known) specimen of Hoplitosaurus, from an uncorrelatable stratigraphic horizon of restricted exposure in Calico Canyon near Buffalo Gap, South Dakota (the same site that produced Camptosaurus depressus, USNM 4753, men- tioned on page 00), in my opinion is completely inadequate and not diagnostic in any way. However, there are some differences that set Hoplitosaurus apart from Sauro- pelta. The femur of Sauropelta is at least one third longer than that of Hoplitosaurus, yet is less massive. The greater trochanter extends to a level even with the proximal level of the head in Sauropelta, and the lesser trochanter is represented by a low crest rather than a distinct process as in Hoplitosaurus. Also, the distal condyles are much larger and project further backward in the present material. The distal end of the humerus of Hoplitosaurus is not well preserved, but it appears to be far less robust than that of Sauropelta and the condyles far less rounded. The solitary anterior caudal vertebra present in the Hoplitosaurus type does not correspond to any of those of the Sauropelta type (AMNH 3032). Centrum height is greater than width, it differs markedly in end view outline, the neural arch is relatively lower and the neural spine curves up and back (anterior margin is convex). The dermal scutes and spines are generally similar to those of Sauropelta, except that all appear to be more massive and only three show even moderately concave inferior surfaces. None show the strongly hollowed bases characteristic of most Sauropelta scutes. These differences may not be great, but in view of the extremely fragmentary na- ture of the type specimen of Hoplitosaurus, it is impossible to define this genus. In my opinion Hoplitosaurus marshi is a nomen dubium, Until a thorough systematic analysis of the Ankylosauria is available, assignment of Sauropelta must be considered as tentative. Present classifications generally agree on a dual subdivision of the suborder into the primitive Acanthopholidae and the more advanced Nodosauridae (= Ankylosauridae of Brown, 1908). Some of the char- acters usually cited for the Acanthopholidae are: Skull small and high, lateral temporal opening present but reduced, no preorbital fenestra, occipital condyle deflected slightly downward, dermal covering thin, snout tends to be narrow, no predentary, mandibular tooth row long, upper tooth row with premaxillary teeth. Neck moderately long, atlas and axis unfused, dorsal ribs not fused to vertebrae, caudal series unarmored, and chevrons not fused to centra. Ilium with long preacetabular process, pubis somewhat reduced, acetabulum usually open and femur slender. Body tends to be high and narrow and dermal armor thin, not coa- lesced, and rarely fused with ilium, ribs and vertebrae. With a few exceptions, these characters are true of Sauropelta. The most impor- tant features would seem to be the very long mandibular tooth row (which we have seen in Silvisaurus is matched by premaxillary teeth above), the unfused atlas-axis, the failure of ribs and vertebrae to fuse, the long form of the femur, and the thin, unfused nature of the dermal armor. Accordingly, Sauropelta has been referred to the Acan- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 123 thopholidae. For the same reasons, I believe that Silvzsaurus should also be referred to this family. Eaton (1960) noted that “Szlvisaurus may be little changed anatomically from the Old World acanthopholids . . .”, but he preferred to assign his new genus to the more universally distributed Nodosauridae. I prefer to extend the range of the Acanthopholidae to the New World and to refer to it both Silvisaurus condrayi and Sauropelta edwardst. 5. FAUNAL COMPARISONS There are relatively few terrestrial vertebrates known from the Lower Cretaceous of North America. Prior to this study, published reports were available on fragmentary vertebrate fossils from the Arundel Formation of Maryland, the Trinity Formation of Oklahoma and Texas, the Lakota(?) of South Dakota, the Dakota of Kansas and the Kootenai of Montana. The Arundel and Trinity Formations have produced more than one or two taxa and will be considered in some detail here. The other three for- mations require only a few remarks as only one or two vertebrate specimens have been reported to date. Eaton (1960) described a partial skeleton of a primitive ankylosaur from the Terra Cotta Clay Member of the Dakota Formation of central Kansas. This specimen (UKM 10296), Silvisaurus condrayt, differs from Sauropelta in size, vertebral, mandi- bular and dental morphology and in the dermal armor. While I consider them distinct, both Silvisaurus and Sauropelta are primitive and probably are closely related. The fact that Silvisaurus has a longer tooth row than Sauropelta, extending almost to the symphysis, suggests that it is more primitive but not necessarily of greater age than Sauro pelta. Olson (1960) reported a pair of incomplete mandibles from the Kootenai of south- western Montana (Toxolophosaurus cloudi) which he identified as a trilophosaurid protorosaur. Nothing comparable to this has been recovered so far from the Cloverly Formation. The only other vertebrate remains that I am aware of from the Kootenai is a partial skeleton of an ankylosaur collected by Barnum Brown near Great Falls, Montana. This specimen (AMNH 3075) has not been described, but personal exam- ination has led me to conclude that it is quite inadequate and cannot be positively referred to any presently known ankylosaur. It may be another specimen of Sauropelta, but there is no dependable anatomical evidence. Consequently there is no reliable vertebrate evidence to support equation of the Cloverly of northern Wyoming and the Kootenai of central Montana. They may, at least in part, be equivalent, but more data are required. Two very fragmentary specimens were reported (Lucas, 1901, 1902; Gilmore, 1909) from a single locality in Calico Canyon, near Buffalo Gap, South Dakota. The horizon has been considered of questionable Dakota age. One specimen (Hopflito- saurus marsht, USNM 4752) has been described by Gilmore (1914) as a scelidosaurid (Stegosauria) , but Romer (1956, 1966), Huene (1956) and Lapparent and Lavocat (1955) consider it a nodosaurid (Ankylosauria). There can be little doubt that it is of ankylosaurian rather than stegosaurian affinity. However, the specimen is quite in- adequate as a type specimen and could be referred to almost any ankylosaurian genus. hee CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 125 It appears to be distinct from Sauropelta, but I nevertheless consider Hoplitosaurus a nomen dubium. The second specimen’ from Calico Canyon (Camptosaurus depressus, USNM 4753) is also very fragmentary. As I have commented elsewhere in this report, C. depressus may be a valid taxon. It clearly is distinct from Tenontosaurus tillettt and may well be distinct from Morrison species of Camptosaurus. With such fragmentary specimens it is impossible to make meaningful assessments as to affinities with Cloverly taxa. Certainly there is no reliable evidence here for equating the Calico Canyon stratum with the Cloverly Formation to the west. These reports constitute the published record of Early Cretaceous vertebrate re- mains from the western interior with which the Cloverly fauna might be compared. ARUNDEL FORMATION, MARYLAND The first published records of fossil vertebrate remains from the Arundel Formation were those of Johnston (1859) and Leidy (1865). They were followed by studies by Marsh (1888, 1896b), Hay (1908), Lull (1911la, 1911b) and Gilmore (1920, 1921). Although the Arundel collections included more than 100 specimens, they consist entirely of isolated teeth, bones or fragments. Hatcher reported that “no two bones or fragments of all that material collected from the Potomac beds [Arundel Formation] in Maryland were found in such relation to one another as to demonstrate that they belonged to the same individual. .. . the scattered and disarticulated state in which [they were] found, must be constantly borne in mind.” (Quoted by Gilmore [1921, p. 582].) The fragmentary nature of the Arundel specimens has been a major source of difficulty in interpreting this fauna and is the principal reason why the Arundel and Cloverly faunas cannot be positively equated. The lists given below illustrate the diverse interpretations of Marsh, Lull and Gilmore of the Arundel vertebrate fauna. It is not appropriate to review here the details of these interpretations or the collections on which they are based. They have been amply expressed by Lull (1911la, 1911b) and Gilmore (1920, 1921). Although I am inclined to disagree with some of the synonymies adopted by Gilmore (ie, Pleuwrocoelus = Astrodon) on the basis that there is insufficient evidence, I will use the faunal list given by Gilmore (1921) in the remarks that follow. SAUROPODA: With the exception of several small (10 cm long) pleurocoelus verte- brae, the limited postcranial sauropod remains recovered from the Cloverly Formation do not compare closely with the few comparable elements from the Arundel Forma- tion. The Cloverly material is clearly from a much larger animal than any represented in the Arundel collections. For example, the type tibia of Astrodon altus (USNM 4971), the larger of the two species established by Marsh (1888) in the Arundel, is one third shorter than the tibia (YPM 5450) that we collected at Crooked Creek (63.5 cm vs 98.5 cm), (compare Plate 14: B with Plate XVIII, fig. 3 of Lull, 1911b). The dorsal vertebrae collected by us are considerably larger than any from the Arun- 126 PEABODY MUSEUM BULLETIN 35 VERTEBRATE FAUNA OF THE ARUNDEL FORMATION Listed by Marsh, 1888 SAUROPODA Pleurocoelus nanus Pleurocoelus altus THEROPODA Allosaurus medius Coelurus gracilis ? Priconodon crassus CROCODILIA TESTUDINATA Listed by Lull, 1911 SAUROPODA Pleurocoelus nanus Pleurocoelus altus Astrodon johnstoni THEROPODA Allosaurus medius Coelurus gracilis Creosaurus potens ORTHOPODA Priconodon crassus Dryosaurus grandis CROCODILIA Goniopholis affinis TESTUDINATA Glyptops caelatus Listed by Gilmore, 1921. SAUROPODA Astrodon nanus Astrodon altus Astrodon johnstoni THEROPODA Dryptosaurus? medius Coelurus gracilis Dryptosaurus? potens Ornithomimus affinis ORTHOPODA Priconodon crassus CROCODILIA Goniopholis affinis TESTUDINATA Glyptops caelatus del; the latter, which consist only of centra, are also too incomplete to be compared adequately with the Cloverly specimens. In contrast to the postcranial material, sauropod teeth from the Cloverly Forma- tion compare very closely with teeth from the Arundel Formation. Both formations have yielded only nonspatulate, simple cylindrical cones slightly compressed, curved and twisted—the so-called Astrodon-type of tooth. Most of the small sauropod teeth from the Arundel have been referred to “Pleurocoelus” (Astrodon nanus in Gilmore’s list) because they are smaller than the very similar type specimen of Astrodon johns- tont. No teeth are represented among the type materials of Astrodon nanus, but it is obvious that the size differences could be ontogenetic. Compare the type of Astrodon johnston in Plate 14: E with a typical “Pleurocoelus’ (= Astrodon nanus) tooth shown in Plate 14: F. Collections from the Cloverly include both large and small teeth that are remarkably similar to the type of Astrodon johnstoni and to the smaller teeth referred to “Pleurocoelus” or Astrodon nanus. It would appear from the dental evidence that one or more rather closely related species of sauropod existed during Arundel and Cloverly times. The postcranial ma- terial does not contradict this, but the available material simply is not comparable. THEROPODA: Gilmore recognized four theropod species in the Arundel fauna. All four are based on extremely fragmentary remains that are impossible to compare ade- CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 127 quately with our Cloverly collections. Dryptosaurus? medius is based on a single tooth (USNM 4972), Dryptosaurus? potens on a single dorsal centrum (USNM 3049), Coelurus gracilis on an ungual phalanx (USNM 4973) and Ornithomimus affinis on an astragalus, fragments of metatarsals II and III and five phalanges (USNM 5652, 5704, 5684, 5453, 6108, 5703, 8456 and 6107). The latter cotypes had been used by Marsh (1888) in founding Allosaurus medius and subsequently were referred by Lull (1911b) to his ornithopod species Dryosaurus grandis (leaving only the tooth, USNM 4972, as the type of A. medius). Gilmore (1920) established the ornithomimid affinities of these foot bones. In summary, the Arundel Formation contains one and perhaps two species of large theropod, one small theropod species and one ornithomimid. The Cloverly Formation contains at least one large theropod species (undefinable), one small thero- pod (Deinonychus) , one very small theropod (Microvenator) and an undefinable or- nithomimid. Coelurus gracilis would appear to have been intermediate in size between Microvenator and Deinonychus. The ungual morphology is quite similar to that of the manual unguals of the latter (compare Plate 110, fig. 1 of Gilmore, 1921 with Plate 10: M of this report). On the basis of the metatarsal fragments, Ornithomimus affinis was slightly larger than the Cloverly ornithomimid (see Plate 11: F, G and H com- pared with Gilmore’s Plate 113, fig. 3 and Plate 114, fig. 1). ANKYLOSAURIA: A number of ankylosaur teeth, including a worn tooth that is the type of Priconodon crassus (USNM 2135), have been found in the Arundel. The number is small and most are stream abraded. Lull and Gilmore agreed that these closely resembled the teeth of Palaeoscinus. These teeth do not differ significantly from those of Sauropelta edwardsi of the Cloverly Formation. However, the similarity does not necessarily indicate close af- finities, for dental morphology in the Ankylosauria appears to have been quite con- servative. It does, however, establish the presence of this group in both faunas (see Plate 22: D, E and F here and Plate XX, fig. 5 of Lull, 1911b). crocopILiA: Lull (1911b) established a new species of crocodile, Gontopholis affinis, designating a single tooth (USNM 8452) as the type specimen after comparison with teeth from the Morrison Formation that were then referred to Goniopholis felix. Gil- more doubted the generic assignment of such meager materials. The conical crocodilian teeth from the Cloverly Formation have the same ridged and grooved enamel that is characteristic of those from the Arundel and that appear to be characteristic of all “goniopholids”. Beyond indicating the presence of what could be similar crocodilians in both faunus, these remains have no real significance. CHELONIA: Turtle remains from the Arundel Formation consist of two fragmentary specimens, including the type (USNM 1930) of Glyptops caelatus. Perhaps the most significant fact about this specimen is the absence of Naomichelys type of pustulose ornamentation. DISCUSSION: Although it cannot be established that there are any species or genera that are common to the Arundel and Cloverly faunas, it is evident, even from these fragmentary remains, that there is striking similarity between the two. Perhaps the 128 PEABODY MUSEUM BULLETIN 35 most important similarities are in the “Astrodon’’-toothed sauropods, the ornitho- mimids, and the ankylosaurs. These similarities may be more apparent than real, but this is the hazard of working with such limited evidence. The faunal similarities may also be more ecologic than chronologic, except for the fact that the most common element of the Cloverly fauna is not represented in the Arundel collections. Not a single scrap is known of an ornithopod in the Arundel collections—now that Gilmore has shown Lull’s Dryosaurus grandis to be an ornithomimid. Tenontosaurus is such an important element of the Cloverly fauna that absence of all ornithopods from the Arundel must have particular significance if the faunal similarities cited above are real. TRINITY FORMATION, TEXAS AND OKLAHOMA Work is currently under way by B. H. Slaughter of Southern Methodist University on the terrestrial fauna, particularly the microvertebrate fauna, of the Trinity For- mation. The following remarks do not include data from Slaughter’s studies, most of which are not yet published. My comments are restricted to the few published records and to two undescribed ‘specimens, one in the collections of the J. Willis Stovall Museum of Science at the University of Oklahoma and the other at the Field Museum in Chicago. Unfortunately, the published data have little or no relevance to the Cloverly fauna as it is presently known. S. W. Williston (im Larkin, 1910) described a right coracoid of an unidentifiable sauropod from near Caddo, Oklahoma and Stovall and Langston (1950) described two partial skeletons of a large theropod, Acrocanthosaurus atoken- sts from Atoka County, Oklahoma. The sauropod coracoid is not comparable to sauropod remains from the Cloverly. On the other hand, at least one large theropod is present in the Cloverly fauna, as shown by the large tooth (YPM 5377) illustrated in Plate 20: N, and the unusual dorsal vertebra (YPM 5285) reconstructed in Figure 6. The vertebral series of Acrocanthosaurus is not fully known, but the greatly elongated neural spines of the known dorsals of the Trinity species are totally unlike the short, wedge-shaped neural spine of YPM 5285. Thus we may safely conclude that the two are quite distinct. The only other Trinity vertebrates reported to date are mammals and, in view of the fact that mammals are not yet known from the Cloverly, of little value in faunal comparisons. The only reason for comparing the Trinity fauna with that of the Cloverly is the existence of the two undescribed specimens mentioned earlier. The first is a nearly complete and uncrushed skull of a medium-sized ornithopod that appears to be refer- able to Tenontosaurus tilletti. This specimen (OU 8-0-S2) is presently being studied by Dr. Wann Langston. The second specimen is a remarkably complete turtle that appears to be referable to Naomichelys. This specimen is in the Field Museum col- lections (FMNH PR-273). I have examined both specimens, and there is little doubt in my mind that both are very close to, if not conspecific with, the Cloverly specimens. Final assessment, however, must wait for detailed studies of these two specimens. Despite that fact that the Trinity fauna is presently known from fewer taxa than the Arundel fauna, there is significant unpublished evidence that the Trinity and Cloverly faunas may be contemporaneous. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 129 WEALDEN BEDS, EUROPE A thorough analysis of the vertebrate fauna of the Wealden of western Europe is beyond the scope of this report. Consequently, the following comparison of the Wealden and Cloverly faunas must be considered with certain facts in mind. First, with the exception of the multiple, articulated skeletons recovered at Bernissart, most of the Wealden taxa have been proposed on the basis of very fragmentary remains (even solitary bones and teeth). Second, a considerable bibliography has developed over the last century relating just to questions of taxonomy and synonymy regarding these classic Wealden fragments. Third, although most fossil vertebrate remains from the Wealden have been recovered from relatively few locales (on both sides of the English Channel), the stratigraphic relationships of these sites have not been estab- lished. For example: the stratigraphic relationships between the classic British local- ities on the Isle of Wight (that produced Hypsilophodon among other things) and the Iguanodon coal mines at Bernissart, Belgium, are quite unknown. In view of the fact that so many of the Wealden taxa are based on such fragmentary specimens, and considering the unresolved problems of synonymy, I am restricting my comparison with Cloverly taxa to very general observations. It is appropriate to make these comparisons in spite of the difficulties because the Wealden and the Cloverly are the two most productive terrestrial formations of Early Cretaceous age. The following lists include the major elements of the Wealden vertebrate fauna. They are not exhaustive lists, and no doubt a number of species have been omitted. Time simply did not permit further search. Because we found no mammals or amphib- ians in the Cloverly Formation, those groups will not be discussed further. sAuRopopA: The following species have been proposed for presumed sauropod remains from the Wealden: Cetiosaurus brevis Owen, 1842 Cetiosaurus conybeart Melville, 1849 Pelorosaurus conybeari Mantell, 1850 Pelorosaurus becklesti Mantell, 1852 Ornithopsis hulkei Seeley, 1870 Bothriospondylus elongatus Owen, 1875 Bothriospondylus magnus Owen, 1875 Chondrosteosaurus gigas Owen, 1876 Ornitho psis eucamerotus Hulke, 1882a Pleurocoelus valdensis Lydekker, 1890 Titanosaurus valdensis Huene, 1929a Cetiosaurus brevis was originally based on three dorsal and caudal vertebrae. These clearly are not sauropod but Iguanodon, probably I. bernissartensis, Four referred caudals (BMNH 2544-2550), which are sauropod, were made the new type of C. brevis—a procedure that I consider impossible. Melville (1849) subsequently desig- nated the same four caudals as the type of C. conybeari. In the following year, Mantell (1850) referred these vertebrae to his Pelorosaurus conybeari which he had based on 130 PEABODY MUSEUM BULLETIN 35 a large humerus (BMNH 28626). In 1852, Mantell proposed a new species, Pelo- rosaurus becklesit, on the basis of a short, stout sauropod humerus (BMNH R-1868). The distinct differences between the long, slender humerus of P. conybeari and the short, stout humerus of P. becklesu clearly establish the presence of two sauropod species in the Wealden. The former may be a brachiosaurid, the latter appears to be a titanosaurid. An interesting, and complicating, fact is that Mantell (1850) indicated that the type caudals of C. conybeart (BMNH 2544-2550) came from the same quarry in the Tilgate Forest, at Cuckfield, Sussex as the type humerus of P. conybeart. The type of Ornithopsis hulkei, a dorsal vertebra (BMNH 28632), appears to be brachiosaurid and may belong to the same species as the slender type humerus of P. conybeari. Bothriospondylus elongatus is based on a single, long, pleurocoelous dorsal centrum (BMNH 2239) which is not diagnostic. Bothriospondylus magnus is based on the type vertebra of Ornithopsts hulket (BMNH 28632) and, as noted above, is perhaps referable to Pelorosaurus and appears to have brachiosaurid affinities. The two type cervicals of Chondrosteosaurus gigas (BMNH 46869, 46870), which may not belong to the same individual, are poorly preserved but appear closer to titano- saurids than to brachiosaurids. The type pubis and ischium (BMNH R97) of Ornithopsis eucamerotus may belong to one of the previously described Wealden species, but this cannot be demonstrated with present material. The pubis is similar to that of Titanosaurus, but the ischium is unique. It is a deep blade with a very sharp, caudally directed curve at about midlength. This curve along the posterior margin approximates 70° and is greater than in any other sauropod ischium that I am aware of. Pleurocoelus valdenstis is based on a single tooth that is remarkably similar to those from the Arundel and Cloverly Formations, but little can be said about its true affin- ities. Titanosaurus valdensis is based on a single, very procoelous caudal vertebra (BMNH R151) that strongly suggests titanosaurid affinities. For the most part these type sauropod specimens from the Wealden do not com- pare closely with any of the Cloverly specimens. For example, the type humerus of Pelorosaurus conybeari is of much more slender construction than that of the Cloverly sauropod (YPM 5452, see Plate 14: C), and that of Pelorosaurus becklesw is much too small. The ischium of Ornithopsis eucamerotus is not comparable to the Cloverly ischia (YPM 5449). Lydekker’s “neotype” caudals of Cetiosaurus brevis (= Cetto- saurus conybeart, BMNH 2544-2550) are similar to two anterior caudals (YPM 5199, 5104) collected at Crooked Creek (Locality YPM 63-19) in Wyoming, but are slightly more procoelous. Only the numerous “Pleurocoelus” or Astrodon-like teeth from the Wealden compare closely with any sauropod remains from the Cloverly Formation. Some are indistinguishable from Cloverly specimens. Unfortunately, this evidence can not be assessed in terms of systematic relationships at the present time. It appears that only the “Pleurocoelus” or Astrodon kind of sauropod teeth are known from Creta- ceous strata; Camarasaurus or A patosaurus teeth are unknown. THEROPODA: The following species of Theropoda have been proposed, based on various specimens, from the Wealden of the British Isles: Calamospondylus owent Fox, 1866 Potkilopleuron pusillus Owen, 1876 Thecospondylus horneri Seeley, 1882 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 131 Megalosaurus dunkert Dames, 1884 Aristosuchus pusillus (Owen), Seeley, 1887 Thecospondylus daviest Seeley, 1888 Calamospondylus foxu Lydekker, 1889g Megalosaurus oweni Lydekker, 1889b Calamospondylus oweni and Potkilopleuron pusillus were based on the same specimen, five sacral vertebrae and part of the pelvis (BMNH R178). In 1887 Seeley made Poikilopleuron pusillus the type of his new genus Aristosuchus. Thecospondylus hor- neri is based on the natural cast of a sacral vertebra (BMNH R291) and is of inde- terminate nature. Thecospondylus daviesi was established for two cervical vertebrae (BMNH R181). These vertebrae have been referred to Coelurus but subsequently were made the type of a new genus, Thecocoelurus, by Huene (1923). Calamospon- dylus foxit is based on two other very similar cervical vertebrae (BMNH R901). Lydekker later (1891) proposed the name Calamosaurus when he discovered that Calamospondylus was preoccupied. Thecocoelurus daviest and Calamosaurus foxu may very well be synonyms, in view of the very similar form and size of the type cervicals of each. The fact that the two type specimens do not include a common segment makes formal action to this effect unwise. It is also my opinion that Aristo- suchus pusillus (= Poikilopleuron pusillus = Calamospondylus owent) probably be- longs to the same species. Thus, it is quite possible that only a single species of small theropod is represented among all the fossil vertebrate remains presently known from the Wealden Beds. These do not compare closely with any of the small theropods from the Cloverly Formation (i.e., Deinonychus or Microvenator). The pubis of Aristo- suchus pusillus (BMNH R178) appears to be the same size as that of Coelurus fragilis (YPM 2010), but differs from that species in the nearly straight inferior margin of the expanded distal pubic foot, compared with the strongly curved inferior pubic margin in Coelurus. The vertebrae also compare closely in both form and size to those of Coelurus fragilis (YPM 2010) from the Morrison Formation of southern Wyoming. Two species of large theropods have been proposed for Buckland’s (1824) genus Megalosaurus (which is from the Stonesfield Slates rather than the Wealden). Mega- losaurus dunkeri was based on a single tooth and M. owent on three metatarsals (BMNH 2559). The latter was originally figured by Owen (1872) as Hylaeosaurus, but Hulke (1881) noted its distinctive form and Lydekker (1889b) assigned it to Megalosaurus. These remains, plus additional referred materials, show the presence of at least one species of large theropod in the Wealdon. These remains have been referred to Altispinax by Huene (1923), which he characterized by very high-spined dorsal vertebrae. If correctly referred to Altispinax, then the Wealden species do not compare at all with the solitary low-spined vertebra (YPM 5285, see Fig. 6) from the Cloverly Formation. ORNITHOPODA: Ornithopods seem to be the best represented and most studied ele- ments of the Wealden fauna. The following list summarizes the various ornithopod species that have been proposed for Wealden specimens: Iguanodon anglicum Holl, 1829 Iguanodon mantelli Meyer, 1832 132 PEABODY MUSEUM BULLETIN 35 Streptospondylus major Owen, 1842 Cetiosaurus brevis Owen, 1842 Cetiosaurus brachyurus Owen, 1842 Streptospondylus recentior Owen, 1851 Stenopelix valdensis Meyer, 1859 Hypsilophodon fox Huxley, 1870a Vectisaurus valdensis Hulke, 1879 Iguanodon bernissartensis Boulenger, 1881 Iguanodon seeleyi Hulke, 1882b Sphenospondylus gracilis Lydekker, 1888a Iguanodon dawsoni Lydekker, 1888a Cam ptosaurus valdensis Lydekker, 1889d Iguanodon fittont Lydekker, 1889c Iguanodon hollingtoniensis Lydekker, 1889c Iguanodon atherfieldensis Hooley, 1925 With the exception of Stenopelix valdensis, I have seen the type specimens of all of these species as well as numerous other referred specimens. I have also studied the wax impression molds of parts of the type specimen of Stenopelix valdensis that are currently housed in the collections of the Humboldt Museum in East Berlin. Al- though the 17 species were purportedly collected from the “Wealden” Beds, not all were recovered from the same stratigraphic level. Nevertheless it is extremely improb- able that such a large number of ornithopod species existed in western Europe during Wealden time. The nomenclature of Wealden ornithopods is in a chaotic state to say the very least, yet materials do exist for resolving at least part of the present chaos by means of modern multivariate analyses. The numerous specimens that have been referred to various species of [guanodon, or to some other relatively large ornithopod species, indicate that the Wealden fauna included at least one, and possibly two species of Iguanodon. One was large and robust and is typified by most of the specimens re- covered from the Bernissart coal mine and now on exhibit in the Royal Institute of Natural Science in Brussels. For the moment we may label this animal as Iguanodon bernissartensis, as proposed by Boulenger in 1881. A second species, of smaller and more slender stature, may best be represented by the solitary skeleton (IRSNB 1551), currently referred to I. mantelli, or the slightly larger type skeleton of I. atherfieldensis (BMNH R5764). One or both of these latter two specimens may represent female specimens of J. bernissartensis, but a thorough biometric analysis is required before this can be evaluated. If such studies were to show that the morphologic differences between I. atherfieldensis (BMNH R5764) or J. mantelli (IRSNB 1551) and I. bernissartensis were probably sexual differences, [guanodon mantelli would have priority. However, the name Iguanodon is based on the teeth described by Mantell (1825) and Mantell failed to supply a species name. Meyer’s (1832) species “J. man- telli” was preceded by a brief description of Mantell’s “type” teeth (BMNH 2392) by Holl (1829), in which he proposed the name Iguanodon anglicum. Thus, if it were to be established that only a single species of [guanodon was represented in the Wealden, according to the rules of priority, Iguanodon anglicum would be the valid name. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 133 At this point, it is important to note that no less than 13 of the 17 “species” listed above could belong to just a single species of Iguanodon. After careful examination of the type specimens (all of which are in the British Museum, with the exception of I. bernissartensis), I believe the type specimens of I. anglicum, Streptospondylus major, “Cetiosaurus” brevis (BMNH 2544-2550) , Streptospondylus recentior, Iguan- odon bernissartensis and Iguanodon atherfieldensis probably represent remains of a single species. This conclusion has been reached with full awareness of the taxonomic problems raised (for example, Streptospondylus major and Streptospondylus recentior are both based on the same solitary cervical vertebra [BMNH 2116]). I have chosen not to try to resolve such matters here. A possible second species of Iguanodon may be represented by the fragmentary remains from the lower Wealden Wadhurst Clay, presently recognized in the type specimens of Iguanodon dawsont (two dorsal and one caudal vertebrae; BMNH R798), J. fittoni (a left ilium; BMNH R1635) and J. hollingtoniensis (a right femur; BMNH R1148). Sphenospondylus gracilis (BMNH 142a,b,c,d), “Cetiosaurus” brachyurus (BMNH 2109, 2151) and Iguanodon mantellt (as represented by the skeleton in Brussels, IRSNB 1551) may represent a third species of Iguanodon. I. seeleyi may be a valid junior synonym of J. bernissartensis since the latter was proposed without description or diagnosis. Thus there may have been one, two or conceivably three species of Iguanodon during Wealden times. The remaining four ornithopod species that have been proposed for Wealden specimens appear to represent no more than three species. Hypsilophodon foxu has been thoroughly analyzed by Galton (in press). Camptosaurus valdensis, an isolated left femur (BMNH R167), is considered a large individual of Hypsilophodon fox by Galton (personal communication). Vectisaurus valdensis, based on a partial right ilium (BMNH R2497), a caudal centrum (BMNH R2496), three dorsal vertebrae (BMNH R2494, R2495) and two incomplete dorsal neural arches (BMNH R2498, R2499), all from the Wealden of Brixton, Isle of Wight, appears to be distinct from both Hypsilophodon and Iguanodon, but additional material is required before this can be certified. Stenopelix valdensis is comparable in size to the type specimen (BMNH R196) of Hypsilophodon foxti. However, the wax impression of the right ilium in the Humboldt Museum collections reveals a somewhat shallower posterior blade and a distinctive downward-directed distal hook on the extremity of the anterior iliac blade. Neither condition is present in the known Hypsilophodon specimens, but it must be emphasized here that these features were observed on a wax impression of the type specimen. According to the labels in the Humboldt Museum, the original specimen is preserved in the “Gymnasium in Bucheburg”, but I was not able to locate it. The original type specimen consisted of both ilia and ischia, three or four posterior dorsals, four or five sacrals and four caudal vertebrae, plus parts of the right tibia, fibula and the right pes. Purportedly it was collected from the Hastings sand of the Wealden Beds. In the absence of the original specimen, my observations and conclusions regarding this specimen can be only speculative. Stenopelix has been considered a hypsilopho- dontid by Nopcsa (1928a) , Rozhdestvensky and Tatarinov (1964) and Romer (1966), but Huene (1956), Romer (1956) and Colbert (1961) placed it in the Psittacosau- ridae. The former alignment seems rather unlikely in that the ilium is very shallow from top to bottom in both the anterior and the posterior processes. In contrast, the latter process seems to have been quite deep in Hypsilophodon. Also, both ischia (as 134 PEABODY MUSEUM BULLETIN 35 figured by Meyer [1859]) seem to show the strong downward curvature characteristic of ceratopsian (but not Psittacosaurus) ischia. Finally, the four metatarsals of the right foot appear to have been subequal in length and robusticity—features that are not typical of most ornithopods. The evidence is aggravatingly inadequate, yet the sum total seems to favor psit- tacosaurian rather than hypsilophodont affinities. Relocation of the type specimen is critical for further evaluation of Stenopelix. In summary, an ultraconservative roster of Wealden ornithopod species might include the following as morphologic—if not valid taxonomic—entities: A robust I[guanodon (= I. bernissartensis? ) A slender Iguanodon (= I. mantelli?) A Wadhurst Clay Iguanodon (= I. dawsont?) Hypsilophodon fox Vectisaurus valdensis Stenopelix valdensis The last species may well be of psittacosaurian, if not ceratopsian, affinity rather than ornithopod relationships. One of the obvious similarities between the Wealden and Cloverly faunas is the dominance of ornithopods and, specifically, the abundance of moderately large orni- thopods. Although there are numerous similarities in the osteology of [guanodon and Tenontosaurus, there are also very significant differences in skull, dental, manus, pes, pelvic, pectoral and vertebral morphology. These creatures were not closely related, although at the present time they are perhaps best assigned to the same family. The Cloverly Formation has not yet produced evidence of anything comparable to Hypsilophodon, Stenopelix, or Vectisaurus. Despite the dominance of ornithopods in both faunas, there is no evidence of very close phyletic relationship. One or more species of large Iguanodon during Wealden times and a solitary species of Tenon- tosaurus in the Cloverly appear to be little more than ecologic equivalents. ANKYLOSAURIA: Perhaps most important after ornithopod remains are those of anky- losaurians in the Wealden fauna. To date, seven species have been proposed. These are listed below. Hylaeosaurus armatus Mantell, 1833 Hylaeosaurus oweni Mantell, 1844 Regnosaurus northamptoni Mantell, 1848 Iguanodon phillipsi Seeley, 1869 Priodontognathus phillipsi Seeley, 1875 Polacanthus foxti Hulke, 1881 Polacanthus becklesi Hennig, 1925 Polacanthoides ponderosa Nopcsa, 1929 As with the preceding categories, there are taxonomic and other errors within this roster. First of all, Hylaeosaurus oweni is a junior synonym of Hylaeosaurus armatus, as they are based on the same specimen (BMNH 3775), and as far as I know the name armatus has not been invalidated. The type specimen of Regnosaurus northamp- toni consists of a midlength fragment of a dentary (BMNH 2422) lacking teeth CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 135 crowns. Although commonly referred to the Ankylosauria, apparently because of the near-circular sections of teeth roots, the subquadrangular cross-section of the man- dible, the very large Meckelian canal, the straight tooth row and the absence of super- ficial dermal ossifications seem to rule out this suborder. The alveoli are subequal in size and many contain cylindrical, hollow roots. The tooth row appears to have been nearly straight and aleveoli are closely spaced (1.0 to 1.5 mm apart). The cylindrical roots, close spacing and straight tooth row could be typical of an Astrodon or “Pleuro- coelus”’ type of sauropod. Thus sauropod, rather than ankylosaurian, affinities are possible, but the present specimen simply is not adequate for ordinal placement given our current knowledge. A maxilla fragment (SM B53408) originally described by Seeley (1869) and named Iguanodon phillipsi, and later (1875) assigned by him to a new genus Priodon- tognathus, is equally difficult to place. Moreover, the specimen is from an unknown horizon, although presumed to be from the Wealden. The fragment shows no dermal sculpturing and contains no functional or fully erupted teeth in the 18 circular alveoli preserved. Several unerupted replacement teeth have been exposed and these have an acutely tapered, bladelike crown with the anterior and posterior margins strongly serrated. The denticles vary in size but there is no indication of corresponding ridges descending across the crown face. No cingula were observed. This specimen might be referred to either Stegosauria or Ankylosauria but, unfortunately, it is of little value in comparing the Wealden and Cloverly faunas. Polacanthus foxii is based on a major portion of the posterior part of a skeleton (BMNH R175), including ilia, ischia and pubes, five sacrals co-ossified with five dorsosacrals, five incomplete dorsal vertebrae, both femora, the right fibula, several tarsals and metatarsals, 18 caudal vertebrae and numerous dermal plates and spines. Unfortunately, the specimen cannot be compared with the type specimen of Hylaeo- saurus armatus (= Hylaeosaurus oweni) (BMNH 3775), which consists of the an- terior part of a skeleton but no skull (right scapulocoracoid, ribs, three posterior cervicals, three dorsal vertebrae and numerous dermal spines and plates). Although they are from different localities (Barnes Chine, Isle of Wight and Cuckfield, Sussex) of undetermined stratigraphic relationships, I strongly suspect that the two specimens belong to a single species. The type material of Polacanthoides ponderosus, a left tibia, left humerus and left scapula (BMNH 1107, 1106 and 2584), may also belong to the same species, although there is some evidence to the contrary. The tibia compares very closely to that of Polacanthus foxii, but the scapula is distinct from that of Hylaeo- saurus. The latter bears a prominent, robust, thumblike acromion process, whereas the scapula of Polacanthoides has a massive flangelike acromion expansion. If these three elements are from the same individual, then Polacanthoides would appear to be distinct from Hylaeosaurus. As before, the fragmentary nature of most specimens that are the bases of Wealden ankylosaurian species permits only the most qualified comparison with Sauropelta from the Cloverly Formation. There are differences in the dermal armor of Hylaeo- saurus and Polacanthus foxii from that of Sauropelta, and the scapula of Polacan- thoides differs from that of the Cloverly species. Nevertheless, the two most complete specimens from the Wealden (Hylaeosaurus armatus, BMNH 3775 and Polacanthus foxiit, BMNH R175) appear to be primitive—as is Sauropelta. However, without additional material, particularly cranial material, the true affinities of the Wealden ankylosaurs remain in doubt. 136 PEABODY MUSEUM BULLETIN 35 STEGOSAURIA: This suborder is very doubtfully represented among the fossil verte- brate collections obtained from the Wealden Beds. Seeley (1874) established a new species, Craterosaurus pottonensis, on a solitary dorsal neural arch that is presently housed in the Sedgewick Museum at Cambridge, England. The specimen does re- semble the tall, narrow arches of Stegosaurus, particularly in the height of the pedi- cels. However, this same condition is present in many ankylosaurs (such as Sauropelta edwardsi and Polacanthus foxti), and it is quite probable that the fragmentary neural arch that is the sole basis for recognizing the Stegosauria among Wealden vertebrates (or among Cretaceous vertebrates for that matter) most probably is referable to the Ankylosauria. crocopILIA: Currently, four species of crocodilians are known from the Wealden, Crocodilus cultridens Owen, 1842 (based on a tooth), Gontopholis crassidens Owen, 1842 (a tooth), Goniopholis simus Owen, 1842 and Bernissartia fagesi Dollo, 1883. The type specimen of the last (IRSNB 1538, the major part of a fine skeleton) and a nearly complete specimen referred to Goniopholis srmus (IRSNB 1537) were recov- ered from the Iguanodon level in the Bernissart coal mine and presently are displayed in the Royal Institute in Brussels. Crocodilian teeth, the majority of which are of the narrowly tapered cone shape with fluted or grooved and ridged enamel, as in so-called Goniopholis teeth, are known from many other Wealden sites. These are of no systematic significance, though. Numerous indeterminate crocodilian scutes are also present. The very fragmentary nature of most crocodilian remains from both the Wealden Beds and the Cloverly Formation, together with the very unsatisfactory state of “gonio- pholid” systematics, make any meaningful comparison of Cloverly and Wealden crocodilians impossible. All that can be said at this time is that both faunas include possibly similar crocodilian elements. CHELONIA: Thirteen chelonian species have been proposed for fossil turtle remains recovered from the Wealden Beds. These are as follows: Trionyx bakewellt Mantell, 1833 Tretosternon bakewelli Mantell, 1833 Platemys mantelli Owen, 1842 Tretosternon punctatum Owen, 1842 Chelone costata Owen, 1853 Platemys dixoni Owen, 1853 Plestochelys bullocki Rutimeyer, 1873 Tropidemys valanginiensis Rutimeyer, 1873 Chitracephalus dumoni Dollo, 1884 Peltochelys duchasteli Dollo, 1884 Hylaeochelys koeneni Lydekker, 1889e Desmemys bertelsmanni Wegner, 1911 Brodtechelys brodet Nopcsa, 1928b Helochelydra Nopcsa, 1928b Only Peltochelys and Chitracephalus are based on reasonably complete specimens. The other species are based on isolated fragments and are of doubtful affinities. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 137 Chelonian remains from the Cloverly are even less adequate than those of the Wealden. Consequently, no significant comparisons can be made. One surprising coin- cidence, however, is the nearly identical pustulose ornamentation of both the carapace and plastra of Naomichelys speciosa from the Cloverly and Tretosternon punctatum and Tretosternon bakewelli from the Wealden. It is unlikely that this is more than coin- cidence but with the existing fragments no other interpretation is possible. VERTEBRATE FAUNAS OF THE WEALDEN AND CLOVERLY FORMATIONS (From Casier, 1960; Clemens, 1963; C. Patterson, 1966; and others) WEALDEN CLOVERLY Class Chondrichthyes Order Selachii Suborder Hybodontoidea Family Hybodontidae Hybodus basanus Hybodus ensis Hybodus parvidens Hybodus brevicostatus Lonchidion breve Lonchidion striatum Lonchidion rhizion Lonchidion heterodon Family Ptychodontidae Hylaeobatis ornata Class Osteichthyes Order Palaeonisciformes Suborder Palaeoniscoidei Family Coccolepidae Coccolepis macropterus Order Semionotiformes Suborder Semionotoidei Family Semionotidae Lepidotus mantelli Lepidotus bernissartensis Lepidotus brevifulcratus Lepidotus arcuatus Order Pycnodontiformes Family Pycnodontidae Coelodus mantelli Mesodon bernissartensis Order Amiiformes Suborder Amioidei Cloverly amioid Family Caturidae Callopterus insignis Caturus tenuidens 138 PEABODY MUSEUM BULLETIN 35 Family Amiidae Amiopsis dolloi Amiopsis lata Family Macrosemiidae Notagogus parvus Order Pholidophoriformes Family Pholidophoridae Pholidophorus obesus Family Pleuropholidae Pleuropholus sp. Order Leptolepiformes Family Leptolepidae Clupavus sp. Order Clupeiformes Suborder Clupeoidei Family Chirocentridae Pachythrissops sp. Order Dipnoi Family Ceratodontidae Class Amphibia Order Urodela Family Proteidae Hylaeobatrachus croyi Class Reptilia Order Testudinata Suborder Amphichelydia Family Pleurosternidae Desmemys bertelsmanni Plesiochelys bullocki Family Plesiochelyidae Brodiechelys brodet Hyaelochelys koeneni Family Thalassemyidae Tropidemys valanginiensis Family Apartotemporalidae Chitracephalus dumoni Suborder Cryptodira Family Glyptopsidae Family Dermatemydidae Tretosternon punctatum Tretosternon bakewelli Peltochelys duchasteli Family Chelydridae Helochelydra sp. Ceratodus frazieri Naomichelys speciosa Glyptops pervicax CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 139 Platemys mantelli Platemys dixont Chelone costatus Gontopholis simus Bernissartia fagest Cetiosaurus conybeari Pelorosaurus becklesiu Ornithopsis hulkei Bothriospondylus elongatus Bothriospondylus magnus Chondrosteosaurus gigas Ornithopsis eucamerotus Pleurocoelus valdensis Titanosaurus valdensis Aristosuchus pussillus Thecospondylus horneri Thecocoelurus daviesi Calamosaurus foxti Megalosaurus oweni Megalosaurus dunkeri Hypsilophodon foxii Iguanodon bernissartensis Iguanodon mantelli Iguanodon dawsoni Vectisaurus valdensis Steno pelix valdensis Family Testudinidae Cloverly testudinid ? Family Cheloniidae Order Crocodilia Suborder Mesosuchia Family Goniopholidae Cloverly crocodilian Suborder Eusuchia Family Hylaeochampsidae Order Saurischia Suborder Sauropodomorpha Family Brachiosauridae Family Titanosauridae Cloverly titanosaurid Family incertae sedis Suborder Theropoda Family Coeluridae Microvenator celer Family Dromaeosauridae Deinonychus antirrhopus Family Megalosauridae Cloverly carnosaur Family Ornithomimidae Cloverly ornithomimid Order Ornithischia Suborder Ornithopoda Family Hypsilophodontidae Family Iguanodontidae Tenontosaurus tilletti Family Psittacosauridae? 140 PEABODY MUSEUM BULLETIN 35 Suborder Ankylosauria Family Acanthopholidae Hylaeosaurus armatus Sauropelta edwardsi Regnosaurus northamptont Priodontognathus phillipsi Polacanthus foxti Polacanthoides ponderosus Suborder Stegosauria? Family Stegosauridae? Craterosaurus pottonensis Class Mammalia Order Multituberculata Family Plagiaulacidae Loxaulax valdensis Order Pantotheria Family Dryolestidae Melanodon goodrichi Order Symmetrodonta Family Spalacotheriidae Spalacotherium tricuspidens DISCUSSION One major difficulty in comparing the Wealden and Cloverly faunas is the great discrepancy in the numbers of taxa that have been described from each. Sixty or more species (excluding fish) have been proposed for the vertebrate remains from the Wealden Beds, whereas only six are listed here from the Cloverly Formation. (Evidence of perhaps seven or eight additional Cloverly species was deemed inade- quate for founding formal binomials.) This discrepancy is easily explained: more than a century of collecting from the Wealden Beds compared with slightly less than 40 years for the Cloverly, and the early tendency (obsolete but not entirely abandoned even now) to propose formal binomials for even the most fragmentary remains. When the Wealden list is considered carefully, with the object of eliminating all possible synonyms, a greatly shortened faunal list results. The sauropod remains, for example, include only one basic type of tooth, but there are two distinctly different humeri (Pelorosaurus conybeari, BMNH 28626 and Pelorosaurus becklesii, BMNH R1868). Similarly there appear to be two types of dorsal vertebrae (Ornithopsis hulket, BMNH 28632 and Bothriospondylus elongatus, BMNH 2239). All other sauropod remains could conceivably belong to one of these two kinds. Thus there may have been as few as two species of sauropods in the Wealden. There is evidence for only one certain species in the Cloverly. The sauropod postcranial remains of these two formations are not comparable, but the dental evidence is and indicates that the Wealden and Cloverly sauropods may have been closely related. The absolute minimum number of theropod species represented in the Wealden evidence could be two—one small species (Calamospondylus oweni?) and one large species (Megalosaurus dunkeri?) The Cloverly contains a minimum of four species: one large species (undefinable), one ornithomimid, one small species (Deinonychus CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 141 antirrhopus), and one very small species (Muicrovenator celer). The relationships between New and Old World theropods cannot be established. The number of Wealden ornithopod species could be as low as four: Iguanodon anglicum, Vectisaurus valdensis, Hypsilophodon foxti and Stenopeltx valdensis. From the Cloverly, there is evidence of only one ornithopod species, Tenontosaurus tilletti, unless some of the fragmentary remains of small individuals have been incorrectly interpreted as juveniles. Tenontosaurus does not appear to be especially close to any of the Wealden forms unless it be Vectisaurus (which conceivably could be either an immature Iguanodon or a more Camptosaurus-like form). All that can be said here is that both faunas included a moderate- or large-sized ornithopod, which appears to be dominant in both. The Wealden ankylosaur fauna is reducible to a minimum of two species on the basis of the distinctly different scapulo-coracoids of Hylaeosaurus armatus and Pola- canthoides ponderosus. Evidence of only one ankylosaurian species, Sauropelta ed- wards, is known from the Cloverly. All ankylosaurian remains from both units appear to be primitive and are perhaps best referred to the Acanthopholidae. The overall similarity in the general compositions of the Wealden, Cloverly and Arundel faunas strongly suggests similar ages. These faunal similarities also reflect similar ecologic factors, but the latter appear to be of secondary importance. No pre- cise tally of numbers of individuals can be given, but even it if could, without precise stratigraphic data it would have little meaning. However, having examined nearly all of the specimens collected from these three formations, I have clear impressions of the relative abundances of the tetrapod elements of the three faunas. Qualitative though they are, the following summary suggests distinctive ecologies for all three: CLOVERLY ARUNDEL WEALDEN Ornithopoda Sauropoda Ornithopoda Decreasing Ankylosauria Theropoda Sauropoda Abundance Sauropoda Ankylosauria Ankylosauria | Theropoda Crocodilia Theropoda Crocodilia Chelonia Chelonia Chelonia Crocodilia In all three faunas, I estimate the most common group to be approximately five times more abundant than the second most common group. In the Cloverly fauna, orni- thopods outnumber all other elements combined and I suspect the same would be true of the Wealden fauna. The total absence of ornithopods in the Arundel fauna, al- though negative evidence, takes on added significance in this light. 6. AGE OF THE CLOVERLY FORMATION The discontinuous fossil record of terrestrial vertebrates and the rarity of Early Cretaceous vertebrate remains in particular preclude precise dating of the Cloverly Formation on the basis of its vertebrate fauna alone. Other evidence must be con- sidered. Peck and Craig (1962) reported that the “Lower Cretaceous” nonmarine sediments of Wyoming and adjacent states (Kootenai, Cloverly, Burro Canyon, Peter- son, and Lakota Formations) contain ostracods and charophytes (Cyprideinae and Clavatoraceae) that elsewhere (western interior, Gulf Coast region, Europe, Asia and Africa) are of Aptian age. Unfortunately, no samples were available to them from the Cloverly Formation within the Bighorn Basin, Cloverly samples that were analyzed by them were collected from the Wind River Basin, the northwest flank of the Wind River Mountains, the Jackson Hole area, the Rawlins uplift and the north flank of the Uinta Mountains. Kootenai samples were obtained from southwest and western Montana (Beaverhead and Powell Counties). Thus their samples that are most relevant to this study were collected well outside of our study area. Consequently, until similar analyses are made of the microfauna of the Cloverly Formation within the Bighorn Basin area, we must consider Aptian as only a probable maximum age for these strata. Whether the entire Cloverly sequence, from Unit IV to Unit VII, is of Aptian age is not known. It is of particular interest, however, that Peck and Craig note that collections from the Cloverly “are mostly from calcareous clays associated with the limestones of the middle variegated clay unit’. This description seems to correspond to our Unit V, rather than VII, so it is conceivable that the upper part of the Cloverly Formation is Lower Albian. The occurrence within our study area of Inoceramus comancheanus and Haplophragmoides gigas (Eicher, 1962) in the upper 25 feet (7.6 m) of the Thermopolis Shale (as that unit was redefined by Eicher in 1960) establishes a minimum age limit of Middle Albian for the underlying Sykes Mountain and Cloverly Formations. As I noted above, two undescribed specimens from the Glen Rose Formation of the Trinity Group of northern Texas appear to be conspecific with specimens from the Cloverly Formation. One is a skull (OU 8-0-S2) that seems referable to Tenonto- saurus tilletti. The other is a complete turtle skeleton (FMNH PR-273) referable to Naomichelys speciosa. Unfortunately, precise stratigraphic data are not available for these specimens, but both are recorded as from the Glen Rose Formation. Stanton (1947), on the basis of numerous collections of pelecypods and gastropods from the Trinity Group, has judged the Glen Rose Formation to be basal Middle Albian in age. Thus the Glen Rose appears to be slightly older than the Thermopolis Shale and younger than the ostracod-charophyte faunas of middle or lower(?) Cloverly. Both of the above specimens require careful study to ascertain whether in fact they are conspecific with Cloverly specimens. 142 CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 143 Stanton’s age for the Glen Rose corresponds with the Trinity placement given by Stephenson et al. (1942) and is consistent with Wieland’s (1931) belief that the Trinity cycadeoids compare most closely with those of the lower Lakota. Thus, with all due respect for our present lack of precise stratigraphic control of paleontologic sites in both formations, it is probable that parts of the Glen Rose and Cloverly Formations are temporal equivalents. The latter most probably is late Aptian (Unit V?) to Early Albian (Unit VII?). Our present state of knowledge about Mesozoic tetrapod ecology and phyletic re- lationships makes it difficult to explain the differences between the Morrison and Cloverly faunas. Moberly (1960) has presented important lithologic evidence indicat- ing a significant change in the physical environment from Morrison to Cloverly time. Thus, the Morrison to Cloverly faunal change could well be an ecologic, rather than a simple evolutionary transition. The fact that few, if any, of the Cloverly taxa are clearly derivable from Morrison species, together with the fact that the Cloverly fauna is more closely allied with Late Cretaceous vertebrates than with those of the Morrison (or Jurassic) (in Brown’s opinion [194la] and mine) indicates either im- migration of a new fauna or a major temporal hiatus between the Morrison and Cloverly faunas. If the Kimmeridgian age generally assigned to the Morrison fauna is correct, a hiatus equal to most or all of Portlandian and Neocomian time exists— an interval of perhaps 18 to 20 million years. Marsh (1888) correlated the Arundel fauna with that of the Atlantosaurus beds (Morrison Formation), as did Lull (191la). This interpretation was based largely on the presence of sauropod remains, which at that time were not known to occur above the Jurassic in North America. Hatcher (1903) provided additional, but doubtful, evidence for the correlation when he referred two pleurocoelous centra from the “Atlantosaurus beds” on Sheep Creek, Albany County, Wyoming to Astrodon (Pleurocoelus). Ample evidence now exists showing that sauropods survived to Late Cretaceous times, and Hatcher’s vertebrae are suspect and not positively referable to any genus. Berry (1911), on the basis of the flora contained in the Patuxent Formation (immediately beneath the Arundel Formation) , concluded that these Maryland strata were of Early Cretaceous age and equated the Patuxent with the Kootenai Formation of Montana. In the same paper, he concluded that the Patuxent-Arundel flora and fauna span all but the earliest part (Berriasian) of the Neocomian. Stephenson et al. (1942) accepted this placement. Allen (1955) and Hughes (1958) have concluded that the Wealden Beds range from Berriasian at the base (Fairlight Clay) to Barremian or Lower Aptian at the top (Upper Wealden Clay), encompassing the entire Neocomian of North American terminology. This conclusion is based primarily on plant microspores and mega- spores. Clemens (1963) found no evidence in the mammalian remains to challenge this post-Tithonian pre-Aptian age for the Wealden Beds. The mammal remains are from the Ashdown Beds (lower Wealden) and the Grinstead Clay (mid-Wealden). Thus, the Wealden vertebrate fauna, which is chiefly from the Wadhurst Clay immedi- ately overlying the Ashdown Beds and from the Wealden Clay, appears to be distinctly older than the Cloverly fauna. The probable ages of the Cloverly, Trinity, Arundel and Wealden strata are summarized below. 144 ” 3 F 8 8 M4 Oo o z a Aptian Barremian | Hoaterivian Valanginian Berriasian PEABODY MUSEUM BULLETIN 35 Wyoming and Texas and Montana Oklahoma Maryland Cloverly Formation Patuxent REFERENCES CITED Agassiz, Louis. 1837, [First published notice of Ceratodus latissimus]. In Egerton, P. de M. G. Catalogue of fossil fish. 3: 129. Allen, P. 1955. Age of the Wealden in North-Western Europe. Geol. Mag. 92: 265-281. Andrews, C. A., W. G. Pierce, and D. H. Eargle. 1947. Geologic map of the Bighorn Basin, Wyo- ming and Montana, showing terrace deposits and physiographic features. U.S. Geol. Surv., Oil and Gas Invest., Prelim. Map. 71. Baker, A. A., C. H. Dane, and J. B. Reeside, Jr. 1936. Correlation of the Jurassic formations of parts of Utah, Arizona, New Mexico and Colorado. U.S. Geol. Surv. Prof. Paper 183: 1-66. Bauer, C. M., and E. G. Robinson. 1923. Comparative stratigraphy in Montana. Bull. Amer. Assoc. Petrol. Geol. 7: 159-178. Berry, Edward W. 1911. Correlation of the Potomac Formations. Jn Lower Cretaceous Volume, Maryland Geol. Surv. p. 153-172. Boulenger, George A. 1881. Sur l’arc pelvien chez les dinosauriens de Bernissart. Bull. Acad. Sci. Belgique. (3) 1: 600-608. Bowen, C. F. 1919. Anticlines in a part of the Musselshell Valley: Musselshell, Meagher and Sweetgrass Counties, Montana. U.S. Geol. Surv. Bull. 691F: 185-209. Brown, Barnum. 1908. The Ankylosauridae, a new family of armored dinosaurs from the Upper Cretaceous. Bull. Amer. Mus. Nat. Hist. 24: 187-201. 1933. Stratigraphy and fauna of the Fuson-Cloverly Formation in Montana, Wyoming and South Dakota (Abstract). Bull. Geol. Soc. Amer. 44: 74. 1935. Sinclair Dinosaur Expedition, 1934. Nat. Hist. 36: 2-15. 1941a. The age of sauropod dinosaurs. Science. 93: 594-595. 1941b. The last dinosaurs. Nat. Hist. 48: 290-295. Brown, Barnum and Erich Schlaikjer. 1940. The structure and relationships of Protoceratops. Ann. New York Acad. Sci. 40: 133-266. Brown, Roland W., 1936. A fossil shelf fungus from North Dakota. Jour. Washington Acad. Sci. 26: 460-462. 1938. Two fossils misidentified as shelf fungi. Jour. Washington Acad. Sci. 28: 130-131. 1946. Fossil plants and the Jurassic-Cretaceous boundary in Montana and Alberta. Bull. Amer. Assoc. Petrol. Geol. 30: 238-248. Buckland, William. 1824. Notice on the Megalosaurus or great fossil lizard of Stonesfield. Trans. Geol. Soc. London. 21: 390-397. Burke, C. A. 1957. Stratigraphic summary of the nonmarine Upper Jurassic and Lower Cretaceous strata of Wyoming. Guidebook, Wyoming Geol. Assoc. 12th Ann. Field Conf. p. 55-62. Calvert, W. R. 1909. Geology of the Lewiston coal field, Montana. U.S. Geol. Surv. Bull. 390: 3-83. Case, E. C. 1921. A new species of Ceratodus from the Upper Triassic of western Texas. Occas. Papers Mus. Zool. Univ. Mich. 101: 1-2. Casier, Edgard. 1960. Les Iguanodons de Bernissart. Edit. Patrimoine, Inst. Roy. Sci. Nat. Belgique. Brussels. 134 p. Clemens, William A. 1963. Wealden mammalian fossils. Paleontology. 6: 55-69. Cobban, William A., and J. B. Reeside, Jr. 1952. Correlation of the Cretaceous formations of the western interior of the United States. Bull. Geol. Soc. Amer. 63: 1011-1044. Colbert, Edwin H. 1961. Dinosaurs: their discovery and their world. E. P. Dutton and Co., New York. 300 p. 145 146 PEABODY MUSEUM BULLETIN 35 Colbert, Edwin H. and Dale A. Russell. 1969. The small Cretaceous dinosaur Dromaeosaurus. Amer. Mus. Nat. Hist. Novitates no, 2380: 49 p. Cope, Edward D. 1868. On the origin of genera. Proc. Acad. Nat. Sci. Philadelphia 20: 242-300. 1876. Descriptions of some vertebrate remains from the Fort Union beds of Montana. Proc. Acad. Nat. Sci. Philadelphia. 28: 248-261. 1877. On reptilian remains from the Dakota beds of Colorado. Proc. Amer. Phil. Soc. 17: 193-196. Craig, L. C., et al. 1955. Stratigraphy of Morrison and related formations, Colorado Plateau re- gion, a preliminary report. U.S. Geol. Surv. Bull. LOOQE: 125-168. Curry, William H. III. 1962. Depositional environments in central Wyoming during the Early Cretaceous. Guidebook, Wyoming Geol. Assoc. 17th Ann. Field Conf. p. 118-123. Dames, Wilhelm. 1884. Vorlegung eines Zahnes von Megalosaurus aus dem Wealden des Deisters. Sitz.-Ber. Ges. naturforsch. Fr. Berlin. p. 186-188. Darton, N. H. 1904. Comparison of the stratigraphy of the Black Hills, Bighorn Mountains, and Rocky Mountain Front Range. Bull. Geol. Soc. Amer. 15: 379-448. 1906. Geology of the Bighorn Mountains. U.S. Geol. Surv. Prof. Paper 51: 1-129. Dollo, Louis. 1883. Premiére note sur les crocodiliens de Bernissart. Bull. Mus. Roy. Hist. nat. Belgique. 2: 309-340. 1884. Premiére note sur les cheloniens de Bernissart. Bull. Mus. Roy. Hist. nat. Belgique. 3: 63-84. Dorr, John A., Jr. 1966. Wind-polished stones: two similar sites. Papers Michigan Acad. Sci., Arts, Letters. 51: 265-273. Downs, G. R. 1947. Mesozoic stratigraphy of the Bighorn Basin area. Guidebook, Univ. Wyoming, Geol. Assoc. and Yellowstone-Bighorn Research Assoc. 1947 Field Conf. p. 131-141. 1952. Summary of the Mesozoic stratigraphy, Bighorn Basin, Wyoming. Guidebook, Wyoming Geol. Assoc. 7th Ann. Field Conf. p. 26-31. Dunbar, Carl O., and John Rodgers. 1957. Principles of stratigraphy. John Wiley and Sons, New York. 356 p. Eaton, Theodore H., Jr. 1960. A new armored dinosaur from the Cretaceous of Kansas. Paleont. Contrib. Univ. Kansas, Vertebrata, Art. 8: 1-24. Edmund, A. Gordon. 1957. On the special foramina in the jaws of many ornithischian dinosaurs. Contrib. Roy. Ont. Mus., Zool. Paleont. 48: 3-14. Eicher, Don. L. 1960. Stratigraphy and micropaleontology of the Thermopolis Shale. Bull. Pea- body Mus. Nat. Hist., Yale Univ. 15: 126 p. 1962. Biostratigraphy of the Thermopolis, Muddy, and Shell Creek Formations. Guide- book, Wyoming Geol. Assoc. 17th Ann. Field Conf., p. 72-93. Estes, Richard. 1964. Fossil vertebrates from the Late Cretaceous Lance Formation, Eastern Wyo- ming. Univ. Calif. Pub. Geol. Sci. 49: 1-180. Fisher, C. A. 1906. Geology and water resources of the Bighorn Basin, Wyoming. U.S. Geol. Surv. Prof. Paper 53: 1-72. 1908. Southern extension of the Kootenai and Montana coal-bearing formations in north- ern Montana. Econ. Geol. 3: 77-99. 1909. Geology of the Great Falls coal field, Montana. U.S. Geol. Surv. Bull. 356: 3-85. Fisher, Donald W. 1956. Intricacy of applied stratigraphic nomenclature. Jour. Geol. 64: 617-627. Fox, W. 1866. Another new Wealden reptile. Geol. Mag. 3: 383. Gaffney, Eugene. 1969. The North American Baenoidea and the Cryptodira-Pleurodira dichot- omy. Unpublished dissertation, Columbia University, New York. Galton, Peter. (In press). The ornithischian dinosaur Hypsilophodon from the Wealden of the Isle of Wight. Bull. British Mus. (Nat. Hist. ). Gardner, L. S., T. A. Hendricks, H. D. Hadley, and C. P. Rogers, Jr. 1945. Columnar sections of Mesozoic and Paleozoic rocks in the mountains of south-central Montana. U.S. Geol. Surv. Oil and Gas Invest., Prelim. Chart 18. 1946. Stratigraphic sections of Upper Paleozoic and Mesozoic rocks in south-central Montana. Mem. Montana Bur. Mines. 24: 1-100. Gill, Theodore. 1872. Arrangement of the families of fishes, or classes Pisces, Marsipobranchi, and Leptocardii. Smithson. Misc. Coll. no. 247. 49 p. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 147 Gilmore, Charles W. 1909. Osteology of the Jurassic reptile Camptosaurus, with a review of the species and genus, and descriptions of two new species. Proc. U.S. Nat. Mus. 36: 197-332. 1914. Osteology of the armored Dinosauria in the United States National Museum, with special reference to the genus Stegosaurus. Bull. U.S. Nat. Mus. 89: 1-136. 1915. Osteology of Thescelosaurus, an ornithopodous dinosaur from the Lance Formation of Wyoming. Proc. U.S. Nat. Mus. 49: 591-616. 1919. An ornithopod dinosaur in the Potomac of Maryland. Science (n.s.) 50: 394-395. 1920. Osteology of the carnivorous Dinosauria in the United States National Museum, with special reference to the genera Antrodemus (Allosaurus) and Ceratosaurus. Bull. U.S. Nat. Mus. 110: 1-154. 1921. The fauna of the Arundel Formation of Maryland. Proc. U.S. Nat. Mus. 59: 581-594. 1922. A new sauropod dinosaur from the Ojo Alamo Formation of New Mexico. Smith- son. Misc. Coll. 72:(4): 1-9. 1924. A new coelurid dinosaur from the Belly River Cretaceous of Alberta. Bull. Canadian Geol. Surv., Dept. of Mines. 38: 1-12. 1925a. Osteology of ornithopodous dinosaurs from the Dinosaur National Monument, Utah. Part I: On a skeleton of Camptosaurus medius Marsh. Mem. Carnegie Mus. 10: 385-393. 1925b. Osteology of ornithopodous dinosaurs from the Dinosaur National Monument, Utah. Part III: Ona skeleton of Laosaurus gracilis Marsh. Mem. Carnegie Mus. 10: 403-409. 1930. On dinosaurian reptiles from the Two Medicine Formation of Montana. Proc. U.S. Nat. Mus. 77: No. 16: 1-39. 1933. On the dinosaurian fauna of the Iren Dabasu Formation. Bull. Amer. Mus. Nat. Hist. 67: 23-78. 1946. Reptilian fauna of the North Horn Formation of central Utah. U.S. Geol. Surv. Prof. Paper 210C: 29-53. Gray, John E. 1825. A synopsis of the genera of reptiles and Amphibia with a description of some new species. Ann. Philos. (London). 26: 193-217. Hares, C. J. 1917. Gastroliths in the Cloverly Formation. Proc. Geol. Soc. Washington, in Jour. Washington Acad. Sci. 7: 429. Hatcher, John B. 1903. Discovery of remains of Astrodon (Pleurocoelus) in the Atlantosaurus beds of Wyoming. Ann. Carnegie Mus. 2: 9-14. Haun, J. D. and J. A. Barlow. 1962. Lower Cretaceous stratigraphy of Wyoming. Guidebook, Wyoming Geol. Assoc. 17th Ann. Field Conf. p. 15-22. Hay, O. P. 1908. The fossil turtles of North America. Pub. Carnegie Inst. Washington. 75: 1-568. Hennig, Edwin. 1925. Kentrosaurus aethiopicus Die Stegosaurier-funde vom Tendaguru, Deutsch Ostafrika. Paleont. Suppl. 7: 101-253. Hewett, D. F. 1914. The Shoshone River section, Wyoming. U.S. Geol. Surv. Bull. 541: 89-113. Hewett, D. F. and C. T. Lupton. 1917. Anticlines in the southern part of the Big Horn Basin, Wyoming. U.S. Geol. Surv. Bull. 656: 3-192. Hintze, F. F. Jr. 1915. The Basin and Greybull oil and gas fields, Bighorn County, Wyoming. Bull. Wyoming Geol. Surv. 10: 2-62. Holl, Friedrich. 1829. Handbuch der Petrefactenkund. p. 84. Hooley, Reginald W. 1925. On the skeleton of Iguanodon atherfieldensis sp. nov. Quart. Jour. Geol. Soc. London. 81: 1-60. Hose, R. K. 1955. Geology of the Crazy Woman Creek area, Johnson County, Wyoming. U.S. Geol. Surv. Bull. 1027: 33-118. Huene, Friedrich von. 1923. Carnivorous Saurischia in Europe since the Triassic. Bull. Geol. Soc. Amer. 34: 449-457. 1929a. Die Besonderheit der Titanosaurier. Centralbl. Min. Geol. Palaeont. B. 10: 493- 499. 1929b. Los Saurisquios y Ornithisquios de Cretaceo Argentino. Ann. Museo de La Plata. III, 2: 1-196. 1956. Palaontologie und Phylogenie der Niederen Tetrapoden. Gustav Fischer Verlag; Jena. 716 p. Hughes, N. F. 1958. Palaeontologic evidence for the age of the English Wealden. Geol. Mag. 95: 41-49. 148 PEABODY MUSEUM BULLETIN 35 Hulke, J. W. 1879. Vectisaurus valdensis, a new Wealden dinosaur. Quart. Jour. Geol. Soc. Lon- don. 35: 421-424. 1881. Polacanthus foxii, a large undescribed dinosaur from the Wealden formation in the Isle of Wight. Proc. Roy. Soc. London. 31: 336. 1882a. Note on the os pubis and ischium of Ornithopsis eucamerotus. Quart. Jour. Geol. Soc. London. 38: 372-376. 1882b. Description of some J guanodon remains indicating a new species, J. seelyi. Quart. Jour. Geol. Soc. London. 38: 135-144. Huxley, Thomas H. 1870a. On Hypsilophodon foxii, a new dinosaurian from the Wealden of the Isle of Wight. Quart. Jour. Geol. Soc. London. 26: 3-16. 1870b. The classification and affinities of the Dinosauria. Quart. Jour. Geol. Soc. London. 26: 32-51. Imlay, R. W. 1952. Correlation of the Jurassic formations of North America, exclusive of Canada. Bull. Geol. Soc. Amer. 63: 953-992. Johnson, G. D. 1934. Geology of the mountain uplift transected by the Shoshone Canyon, Wyo- ming. Jour. Geol. 42: 809-838. Johnston, Christopher, 1859. [Comments on Astrodon]. Amer. Jour. Dental Sci. 9: 341. Knappen, R. S. and G. F. Moulton. 1930. Geology and mineral resources of parts of Carbon, Big Horn, Yellowstone, and Stillwater Counties, Montana. U.S. Geol. Surv. Bull. 822A: 1-70. Knight, W. C. 1898. Some new Jurassic vertebrates from Wyoming. Amer. Jour. Sci. (4)5: 186. Kuhn, Oskar. 1966. Die Reptilien. Krailling, Munich. 154 p. Lambe, Laurence M. 1919. Description of a new genus and species (Panoplosaurus miris) of an armored dinosaur from the Belly River beds of Alberta. Trans Roy. Soc. Canada. (3)13: 39-50. Lammers, E. C. 1939. The origin and correlation of the Cloverly Conglomerate. Jour. Geol. 47: 113-132. Lapparent, Albert F., and René Lavocat. 1955. Dinosaurien, p. 785-962. In Jean Piveteau et al. (ed.). Traité de Paleontologie. V. Masson et C'* Paris. Larkin, Pierce. 1910. The occurrence of a sauropod dinosaur in the Trinity Cretaceous of Okla- homa. Jour. Geol. 18: 93-98. Lee, W. T. 1927. Correlation of the geologic formations between eastcentral Colorado, central Wyoming and southern Montana. U.S. Geol. Surv. Prof. Paper 149: 1-57. Leidy, Joseph. 1865. Memoir on the extinct reptiles of the Cretaceous formations of the United States. Smithson. Contrib. Knowledge 14: 135 p. Love, J. D. et al. 1945. Stratigraphic sections and thickness maps of Lower Cretaceous and non- marine Jurassic rocks of central Wyoming. U.S. Geol. Surv., Oil and Gas Invest., Prelim. Chart 13. Love, J. D., J. L. Weitz, and R. K. Hose. 1955. Geologic map of Wyoming. U.S. Geol. Surv. Lucas, Frederick A. 1901. A new dinosaur, Stegosaurus marshi from the Lower Cretaceous of South Dakota. Proc. U.S. Nat. Mus. 23: 591-592. 1902. A new generic name for Stegosaurus marshi. Science (n.s.). 16: 435. Lull, Richard S. 1911la. The reptilian fauna of the Arundel formation. Jn Lower Cretaceous Vol- ume, Maryland Geol. Surv. p. 173-178. 1911b. Systematic paleontology of the Lower Cretaceous deposits of Maryland: Vertebrata. In Lower Cretaceous Volume, Maryland Geol. Surv. p. 183-210. 1921. The Cretaceous armored dinosaur Nodosaurus textilis Marsh. Amer. Jour. Sci. (5) 1: 97-126. Lull, Richard S. and Nelda E. Wright. 1942. Hadrosaurian dinosaurs of North America. Spec. Paper Geol. Soc. Amer. 40: 1-242. Lupton, C. T. 1916. Oil and gas near Basin, Big Horn County, Wyoming. U.S. Geol. Surv. Bull. 621L: 156-190. Lydekker, Richard. 1888a. Note on a new Wealden iguanodont and other dinosaurs. Quart. Jour. Geol. Soc. London. 44: 46-61. 1888b. Catalogue of the fossil Reptilia and Amphibia in the British Museum. I, Contain- ing the orders Ornithosauria, Crocodilia, Dinosauria, Rhynchocephalia, and Proterosauria. London. 309 p. 1889c. Notes on new and other dinosaurian remains. Geol. Mag. (3)6: 352-356. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY 149 1889d. On the remains and affinities of five genera of Mesozoic reptiles. Quart. Jour. Geol. Soc. London. 45: 41-59. 1889e. On certain chelonian remains from the Wealden and Purbeck. Quart. Jour. Geol. Soc. London. 45: 511-518. 1889f. Catalogue of the fossil Reptilia and Amphibia in the British Museum. III. Con- taining the order Chelonia. London. 239 p. 1889g. On a coelurid dinosaur from the Wealden. Geol. Mag. (3) 6: 119-121. 1890. On the remains of small sauropodous dinosaurs from the Wealden. Quart. Jour. Geol. Soc. London. 46: 182-184. 1891. On certain ornithosaurian and dinosaurian remains. Quart. Jour. Geol. Soc. London. 47: 41-44. 1893. Contributions to a knowledge of the fossil vertebrates of Argentina. I. The dinosaurs of Patagonia. Ann. Museo de la Plata. 2: 1-91. MacClintock, Copeland. 1957. Upper part of the Morrison Formation and Cloverly Formation, southeastern Bighorn Mountains, Wyoming. Univ. Wyoming, Unpubl. dissertation. 142 p. MacKenzie, Frederick T. and J. Donald Ryan. 1962. Cloverly-Lakota and Fall River Paleocur- rents in the Wyoming Rockies. Guidebook, Wyoming Geol. Assoc. 17th Ann. Field Conf. p. 44-61. Mantell, Gideon. 1825. Notice on the Iguanodon, a newly discovered fossil reptile, from the sand- stone of Tilgate Forest in Sussex. Philos. Trans. Roy. Soc. London. 115: 179-186. 1833. The geology of the south-east of England. Longman, Rees, Orme, Brown, Green and Longman, London. 415 p. 1833. Observations on the remains of the Iguanodon, and other fossil reptiles, of the strata of Tilgate Forest in Sussex. Proc. Geol. Soc. London. 1: 410-411. 1844. The medals of creation. 2 vols. Henry Bohn, London. 1016 p. 1848. A brief notice of organic remains recently discovered in the Wealden Formation. Quart. Jour. Geol. Soc. London. 5: 37-43. 1850. On the Pelorosaurus; an undescribed gigantic terrestrial reptile, whose remains are associated with those of Iguanodon and other saurians in the strata of Tilgate Forest, in Sussex. Philos. Trans. Roy. Soc. London. 140: 379-390. 1852. On the structure of the [guanodon, and on the fauna and flora of the Wealden For- mation. Proc. Roy. Inst. Great Britain 1: 141-146. Marsh, Othniel C. 1878. New species of Ceratodus from the Jurassic. Amer. Jour. Sci. (3) 15: 76. 1881. New order of extinct Jurassic reptiles (Coeluria). Amer. Jour. Sci. (3)21: 339-340. 1888. Notice of a new genus of Sauropoda and other new dinosaurs from the Potomac formation. Amer. Jour. Sci. (3) 35: 85-94. 1889. Notice of gigantic horned Dinosauria from the Cretaceous. Amer. Jour. Sci. (3)38: 173-175. 1890a. Description of new dinosaurian reptiles. Amer. Jour. Sci. (3)39: 81-86. 1890b. Additional characters of the Ceratopsidae, with notice of new Cretaceous dino- saurs. Amer. Jour. Sci. (3)39: 418-426. 1890c. Notice of some extinct Testudinata. Amer. Jour. Sci. (3) 40: 177-179. 1894. Restoration of Camptosaurus. Amer. Jour. Sci. (3)47: 245-246. 1895. On the affinities and classification of the dinosaurian reptiles. Amer. Jour. Sci. (3)50: 483-498. 1896a. The dinosaurs of North America. 16th Ann. Rept. U.S. Geol. Surv. p. 133-414. 1896b. The Jurassic formation on the Atlantic coast. Amer. Jour. Sci. (4)2: 433-447. Matthew, William D. 1922. A superdreadnaught of the animal world. Nat. Hist. 22: 333-342. Matthew, William D., and Barnum Brown. 1922. The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta. Bull. Amer. Mus. Nat. Hist. 46: 367-385. Melville, A. G. 1849. Notes on the vertebral column of the Jguanodon. Philos. Trans. Roy. Soc. London. 139: 285-305. Meyer, Hermann von. 1832. Die Abtheilung der Mineralien und fossilen Knochen im Museum der Senckenbergischen naturforschenden Gesellschaft zu Frankfurt a M. Neues Jahrb. Min. Geo. Geog. Geol. 268-279. 1857. Beitrage zur naheren Kenntniss fossilier Reptilien. Neues Jahrb. Min. Geog. Geol. 532-543. 150 PEABODY MUSEUM BULLETIN 35 1859. Stenopelix valdensis aus der Wealden-Formation Deutschland’s. Palaeéntographica. 7: 25-34. Mirsky, Arthur. 1962a. Stratigraphic sections of Upper Jurassic and Lower Cretaceous rocks in the southern Bighorn Mountains, Wyoming. Wyoming Geol. Surv. Rept. Invest. 8: 1-33. 1962b. Stratigraphy of nonmarine Upper Jurassic and Lower Cretaceous rocks, southern Bighorn Mountains, Wyoming. Bull. Amer. Assoc. Petrol. Geol. 46: 1653-1680. Moberly, Ralph, Jr. 1960. Morrison, Cloverly, and Sykes Mountain formations, northern Bighorn Basin, Wyoming and Montana. Bull. Geol. Soc. Amer. 71: 1137-1176. 1962. Lower Cretaceous history of the Bighorn Basin, Wyoming. Guidebook, Wyoming Geol. Assoc. 17th Ann. Field Conf. p. 94-101. Mook, Charles C. 1916. Study of the Morrison formation. Ann. New York Acad. Sci. 27: 39-191. 1917. The fore and hind limbs of Diplodocus. Bull. Amer. Mus. Nat. Hist. 31: 815-819. Nopcsa, Baron Franz. 1928a. The genera of reptiles. Palaeobiology 1: 163-188. 1928b. Palaeontological notes on reptiles. Geol. Hungarica. Ser. Pal. 1, 1: 1-84. 1929. Dinosaurierreste aus Siebenburgen. V. Geol. Hungarica. Ser. Pal. 1, 4: 1-76. Olson, E. C. 1960. A trilophosaurid reptile from the Kootenai Formation (Lower Cretaceous). Jour. Paleo. 34: 551-555. Osborn, Henry Fairfield. 1917. Skeletal adaptations of Ornitholestes, Struthiomimus and Tyran- nosaurus. Bull. Amer. Mus. Nat. Hist. 43: 733-771. 1924. Three new Theropoda, Protoceratops zone, central Mongolia. Amer. Mus. Nat. Hist. Novitates 144: 1-12. Ostrom, John H. 1969a. A new theropod dinosaur from the Lower Cretaceous of Montana. Pos- tilla (Peabody Mus. Nat. Hist.) 128: 17 p. 1969b. Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cre- taceous of Montana. Bull. Peabody Mus. Nat. Hist. 30: 165 p. Ostrom, John H., and John S. McIntosh. 1966. Marsh’s dinosaurs: The collections from Como Bluff. Yale Univ. Press, New Haven. 388 p. Owen, Richard. 1842. Report on British fossil reptiles, Part II. Report. British Assoc. Adv. Sci. 11th Mtg., p. 60-204. 1851. Monograph on the fossil Reptilia of the Cretaceous formations. Palaeontogr. Soc. Mon. 5: 1-118. 1853. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Part I, Chelonia. Palaeontogr. Soc. Mon. 7: 1-12. 1859. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supple- ment 2. Crocodilia. Palaeontogr. Soc. Mon. 11: 20-44. 1872. Monograph on the fossil Reptilia of the Wealden formation. Supplement 4. Dino- sauria. Palaeontogr. Soc. Mon. 25: 1-15. 1875. Monograph of the fossil Reptilia of the Mesozoic formations. Part 2. Palaeontogr. Soc. Mon. 29: 15-93. 1876. Monograph on the fossil Reptilia of the Wealden and Purbeck formations. Supple- ment 7. Crocodilia, Dinosauria. Palaeontogr. Soc. Mon. 30: 1-7. Parks, William A. 1924. Dyoplosaurus acutosquameus, a new genus and species of armoured dinosaur; and notes on a skeleton of Prosaurolophus maximus. Univ. Toronto Studies. Geol. Ser. 18: 1-35. 1926. Thescelosaurus warreni, a new species of orthopodous dinosaur from the Edmonton Formation of Alberta. Univ. Toronto Studies, Geol. Ser. 21: 1-42. Patterson, Brian. 1951. Early Cretaceous mammals from northern Texas. Amer. Jour. Sci. 249: 31-46. 1955. A symmetrodont from the Early Cretaceous of northern Texas. Chicago Nat. Hist. Mus. Fieldiana, Zool. 37: 689-693. 1956. Early Cretaceous mammals and evolution of mammalian molar teeth. Chicago Nat. Hist. Mus. Fieldiana, Geol. 13: 1-105. Patterson, Colin. 1966. British Wealden sharks. Bull. British Mus. (Nat. Hist.), Geol. 11: 283- 350. Peck, R. E. 1941. Lower Cretaceous Rocky Mountain nonmarine microfossils. Jour. Paleo. 15: 285-304. CLOVERLY FORMATION, STRATIGRAPHY AND PALEONTOLOGY ibe 1951. Nonmarine ostracodes — the Sub-Family Cyprideinae in the Rocky Mountain area. Jour. Paleo. 25: 307-320. Peck, R. E., and W. W. Craig. 1962. Lower Cretaceous nonmarine ostracods and charophytes of Wyoming and adjacent areas. Guidebook, Wyoming Geol. Assoc. 17th Ann. Field Conf. p. 33-43. Peck, R. E. and C. C. Recker. 1948. The Morrison and Cloverly Formations. Guidebook, Wyoming Geol. Assoc. 3rd Ann. Field Conf. p. 125-139. Pierce, W. G. 1948. Geologic and structure contour map of the Basin-Greybull area, Big Horn County, Wyoming. U.S. Geol. Surv. Oil and Gas Invest. Prelim. Map 77. Pierce, W. G., and D. A. Andrews. 1940. Geology and oil and coal resources of the region south of Cody, Park County, Wyoming. U.S. Geol. Surv. Bull. 921B: 99-180. Richards, P.W. 1955. Geology of the Bighorn Canyon-Hardin area, Montana and Wyoming. U.S. Geol. Surv. Bull. 1026: 1-93. Rogers, C. P. et al. 1948. Geology of the Worland-Hyattville area, Big Horn and Washakie Coun- ties, Wyoming. U.S. Geol. Surv. Oil and Gas Invest., Prelim. Map 84. Romer, Alfred S. 1927. The pelvic musculature of ornithischian dinosaurs. Acta Zool. 8: 225-275. 1956. Osteology of the reptiles. Univ. Chicago Press, Chicago. 772 p. 1966. Vertebrate paleontology, 3rd ed. Univ. Chicago Press, Chicago. 468 p. Ross, C. P., D. A. Andrews, and I. J. Witkind. 1955. Geologic map of Montana. U.S. Geol. Surv. Rozhdestvensky, A. K, and L P. Tatarinov. 1964. Order Ornithischia, p. 552-588. In J. A. Orlov (ed). Osnovy Paleontologu (Fundamentals of Paleontology), vol. 12. Moscow. Russell, Loris. 1940. Edmontonia rugosidens (Gilmore), an armoured dinosaur from the Belly River series of Alberta. Univ. Toronto Studies, Geol. Ser. 43: 1-28. Rutimeyer, L. 1873. Die fossilen Schildkroten von Solothurn und ubrigen Jura formation. Mit Beitragen zur Kenntniss von Bau und Geoschichte der Schildkroten im Allgemeinen. Neue Denkschr. schweizer. Gesellsch. Naturwiss. 25: Art 2: 1-185. Seeley, Harry G. 1869. Index to the fossil remains of Aves, Ornithosauria and Reptilia, from the secondary system of strata arranged in the Woodwardian Museum of the University of Cam- bridge. Cambridge. 143 p. 1870. On Ornithopsis, a gigantic animal of the pterodactyle kind from the Wealden. Ann. Mag. Nat. Hist. (4)5: 279-283. 1874. On the base of a large lacertilian cranium from the Polton sands, presumably dino- saurian. Quart. Jour. Geol. Soc. London. 30: 690-692. 1875. On the maxillary bone of a new dinosaur (Priodontognathus phillipsi), contained in the Woodwardian Museum of the University of Cambridge. Quart Jour. Geol. Soc. London. 31: 439-443. 1882. On Thecospondylus horneri, a new dinosaur from the Hastings sand, indicated by the sacrum and neural canal of the sacral region. Quart. Jour. Geol. Soc. London. 38: 457-460. 1887. On Aristosuchus pusillus (Owen), being further notes on the fossils described by Sir R. Owen as Poitkilopleuron pusillus, Owen. Quart. Jour. Geol. Soc. London. 43: 221-228. 1888. On Thecospondylus daviesi (Seeley), with some remarks on the classification of the Dinosauria. Quart. Jour. Geol. Soc. London. 44: 79-87. Simpson, George Gaylord. 1926. The age of the Morrison Formation. Amer. Jour. Sci. (5) 12: 198-216. Slaughter, Robert. 1965. A therian from the Lower Cretaceous (Albian) of Texas. Postilla (Pea- body Mus. Nat. Hist.) 93: 18 p. Stanton, T. W. 1947. Studies of some Comanche pelecypods and gastropods. U.S. Geol. Surv. Prof. Paper 211: 1-116. Stephenson, Lloyd W., P. B. King, W. H. Monroe, and R. W. Imlay. 1942. Correlation of the outcropping Cretaceous formations of the Atlantic and Gulf coastal plain and Trans-Pecos, Texas. Bull. Geol. Soc. Amer. 53: 435-448. Sternberg, Charles M. 1921. A supplementary study of Panoplosaurus miris. Trans. Roy. Soc. Canada. (3) 15: 93-102. 1928. A new armored dinosaur from the Edmonton Formation of Alberta. Trans. Roy. Soc. Canada. (3)22: 93-106. 152 PEABODY MUSEUM BULLETIN 35 1932. Two new theropod dinosaurs from the Belly River Formation of Alberta. Canadian Field Nat. 46: 99-105. 1940. Thescelosaurus edmontonensis, N. sp., and classification of the Hypsilophodontidae. Jour. Paleo. 14: 481-494. Stokes, William L. 1942. Some field observations bearing on the origin of the Morrison “gastro- liths”’. Science. 95: 18-19. 1944. Morrison and related deposits in and adjacent to the Colorado Plateau. Bull. Geol. Soc. Amer. 55: 951-992. 1952. Lower Cretaceous in Colorado Plateau. Bull. Amer. Assoc. Petrol. Geol. 36: 1766-1776. 1955. Nonmarine Late Jurassic and Early Cretaceous formations. Guidebook, Wyoming Geol. Assoc. 10th Ann. Field Conf. p. 80-84. Stovall, J. W. and Wann Langston. 1950. Acrocanthosaurus atokensis, a new genus and species of Lower Cretaceous Theropoda from Oklahoma. Amer. Midl. Nat. 43: 696-728. Thom, W. T., Jr., G. M. Hall, C. H. Wegemann, and G. F. Moulton. 1935. Geology of Big Horn County and the Crow Indian Reservation, Montana. U.S. Geol. Surv. Bull. 856: 1-200. Thomas, H. D. 1962. Some problems of the earlier Cretaceous rocks of Wyoming. Guidebook, Wyoming Geol. Assoc. 17th Ann. Field Conf. p. 28-32. Waage, Karl M. 1955. Dakota Group in northern Front Range foothills, Colorado. U.S. Geol. Surv. Prof. Paper 274B: 15-51. 1958. Regional aspects of Inyan Kara stratigraphy. Guidebook, Wyoming Geol. Assoc. 13th Ann. Field Conf. p. 71-76. 1959a. Stratigraphy of the Inyan Kara Group in the Black Hills. U.S. Geol. Surv. Bull. 1081: 11-90. 1959b. Dakota stratigraphy along the Colorado Front Range. Guidebook, Rocky Moun- tain Assoc. Geologists 11th Field Conf. p. 115-123. Warthin, Alfred S. 1928. Fossil fishes from the Triassic of Texas. Contrib. Mus. Paleont. Univ. Michigan. 3: 15-18. Washburne, C. W. 1908. Gas fields of the Bighorn Basin, Wyoming. U.S. Geol. Surv. Bull. 339: 348-363. 1909. Coal fields of the northeast side of the Bighorn Basin, Wyoming, and of Bridger, Montana. U.S. Geol. Surv. Bull. 341: 165-199. Wegner, Th. 1911. Desmemys bertelsmanni, n.g. n. sp. Ein Beitrage zur Kenntnis der Thalassemy- didae Rutimeyer. Palaeontographica. 58: 105-132. Weller, J. Marvin. 1960. Stratigraphic principles and practice. Harper and Bros., New York. 725 p. Wieland, G. R. 1931. Landtypes of the Trinity beds. Science 74: 393-395. 1934. A silicified shelf fungus from the Lower Cretaceous of Montana. Amer. Mus. Nat. Hist. Novitates 725: 1-13. Williams, Ernest E. 1950. Variation and selection in the cervical central articulations of living turtles. Bull. Amer. Mus. Nat. Hist. 94: 505-562. Williston, Samuel S. 1910. (comments on a sauropod coracoid) In Pierce Larkin, The occurrence of a sauropod dinosaur in the Trinity Cretaceous of Oklahoma. Jour. Geol. 18: 93-98. Wilson, C. W., Jr. 1936. Geology of Nye-Bowler Lineament, Stillwater and Carbon Counties, Montana. Bull. Amer. Assoc. Petrol. Geol. 20: 1161-1188. Young, C. C. 1935. Dinosaurian remains from Mengyin, Shantung. Bull. Geol. Soc. China. 14: 519-533. Ziegler, Victor. 1917. The Byron oil and gas field, Big Horn County. Bull. Wyoming Geol. Surv. 14: 181-207. 153 APPENDIX A MEASURED SECTIONS Multiplicity of definitions and inconsistent use of theterms "Cloverly" and "Morrison" by both past and current workers make it necessary to provide careful comparisons of these applications and those used in this report. The section on stratigraphy discusses this matter at length, based on extensive field observations, and is supplemented by Charts I through VII. In addition, the following 28 measured sections (Fig. 4) are presented. Each of the following measured sections is preceded by a brief statement giving the location and other pertinent comments. Wherever possible, parts of a section are equated with formal units proposed by other workers. Many, but not all, of these sections were measured at or in the vicinity of fossil vertebrate sites, the levels of these sites are indicated. I measured all sections, most with a Brunton compass, others with a steel tape. All sections were measured at sites where the strata were dipping gently or flat-lying. In all sections Unit VIII was used as the uppermost datum and only the lower massive sandstone was measured. DEG TION Sf =| CODY! WYOMING Measured in the southwest-facing exposures 1.3 miles (2 km) south of Cody on the east limb of Horse Center Anticline. NE 1/4, Sec. 11, T. oz N., R.102 W., Park County, Wyoming. Thickness SYKES MOUNTAIN FORMATION: (ft) (m) ll. Massive and thin-bedded quartz sandstone, inter- bedded with occasional, thin beds of dark-gray, fissile shale. Sandstone, medium- to fine-grained, tan to buff on fresh surfaces, weathers to rusty brown. Ironstone nodules and hematite staining abundant, ripple marks and fucoid impressions com- mon. Overlain by black fissile shale of Thermopolis Formation (= Greybull sandstone?; Sykes Mountain Formation in. part; Unit VII of this report). ss... Stay ead 154 Thickness CLOVERLY FORMATION: (ft) (m) 10. Variegated claystone , reddish-brown to purple in lower 60 feet (18.3 m), grading to rusty red near top. Silty throughout. Occasional discontinuous 6 to 10 inch (15 to 25 cm) sandstone lenses. Claystone, non-stratified, mottled gray-green and purple on fresh surfaces. Some polished pebbles or so-called "gastroliths", and satin spar. Chal- cedony, barite and calcareous concretions absent. (=Himes Member of Cloverly Formation in part?; Unit. VElsobothi Sore DONE) bvcnsescaa-noteeoten-e a case yet chur: chen aie ORME 9. Sandstone, fine- to medium-grained, massive, parallel stratification. Iron-oxide pellets through- out, quartz and some feldspar. Buff to tanon fresh surfaces, weathers tan to light brown. (=Darton's basal sandstone?; Unit VI of thisreport) 8 2.4 8. Claystone, variegated, purple to dark-gray in upper half, pastel to light-gray below. Massive, to poorly stratified. Weathers to "popcorn" sur- face; bentonitic, abundant chalcedony concretions, white to orange satin spar, some selenite crystals. Occasional, discontinuous 6to15 inch (15 to 38 cm) sandy zones and strata. Polished pebbles lacking. (= Little Sheep Mudstone Member, Cloverly Forma- tions. Winity Vion tiniSere pont) ise rier aieiaeopi ees ostatordie WG Oamorues 7. Sandstone, quartz, coarse-grained, massive, yel- low on fresh surface, weathers to yellow brown. Forms prominent ledge here, but is less conspicu- ous at exposures 1 to 2 miles (1.6 to 3.2 km) to 6. Claystone, variegated, gray to pinkish-gray, un- stratified, gray on fresh surfaces. Some chalced- Ony concretions and at least one sandy zone..... 49 14.9 MORRISON FORMATION: 5. Sandstone, white to buff, medium- to coarse- grained, quartz, clay pellets and occasional 0.25 to 0.50 inch (0.6 to 1.2 cm) pebbles. Massive and strongly cross-laminated, some strata 8 to 12 feet (2.4 to 4.1 m) thick. Some levels friable, but generally well indurated. Iron staining and 155 Thickness (ft) (m) frequent ironstone concretions in upper 3 to 6 feet (0.9 to 1.8m). (Equated by Lee, 1927, with "lower" Cloverly sandstone"; designated Unit II here.).... 86 26.2 4. Claystone, calcareous, variegated-pink, reddish- brown, gray-green and light-gray with occasional thin, tan, medium-grained sandstone strata. Chalcedony, and gypsum conspicuous by their ab- sence. Claystone poorly to unstratified and silty throughout. (= Morrison Formation; part of Unit I OF MMS EDO) cciace-ah ale alecs tela to: slle ve! 6) ave; ole tscetayet a srale ts eter CLO 9 Ser 3. Sandstone, massive and thin-bedded, interbedded with massive claystone and thin-bedded fissile shale. Sandstone fine-grained, quartz, white to very light-gray. Shale and claystone light-gray to gray-green. Entire sequence variable laterally.... 37 11.3 2. Concealed. Apparently nonresistant claystone.... 25- 7.6- AQ. «L252 SUNDANCE FORMATION: 1. Sandstones and shales, interbedded, glauconitic, containing abundant marine invertebrates, Gryphaea, and belemnites. (= Upper Sundance Formation).... Not measured Concealed 5S b@ TAO 2 eee NUARIO AE es Cr sbiEK Measured in the prominent, north-facing exposures, 1.5 miles (2.4 km) south of the Hill ranch, 0.5 mile (0.8 km) east of Marquette Creek. SE 174 Secu Zand. SW / 4, SeCs12 27... 0. LAN eRe LOS Ve bark County, Wyoming. SYKES MOUNTAIN FORMATION: 8. Sandstone, thinly laminated to massive, interbedded with thin layers of fissile black shale. Sandstone fine- to medium-grained, tan fresh, weathering to brown. Ripple marks common. Ironstone concretions present in overlying shale and sands. (= Greybull sandstone ?; Sykes Mountain Formation in part; Umie Vil Oe ERMUS me PONE) sare sce Sie, etsre, 3 p,epeun a ecoiel tensions ZO 118 156 Thickness (ft) CLOVERLY FORMATION: 7. Claystone, variegated, maroon to red-brown, be- coming rusty toward top. Fresh surfaces purple- gray with green mottling. Generally sandy. Mas- sive to poorly stratified. Polished pebbles or "gastroliths" frequent. (= Himes Member, Cloverly Formation in part; Unit VII of this report)......... 48 6. Sandstone, olive-yellow, weathering yellow brown, massive, variably indurated, some cross-lamina- tion, medium-grained, quartz, feldspar and white chert. (= Darton's basal sandstone ?; Unit VI of tHiS GEDOGE) sca sac = seus 2 5 Case, os Si scar ereeare rede tenes 5. Claystone, variegated, gray to purplish, dark- to light-gray on fresh surface. Unstratified, breaks into irregular, "greasy'"-surfaced chips, bentonitic, weathering to "popcorn"-covered slopes. Chalced- ony concretions and pink to orange satin spar com- mon. (= Little Sheep Mudstone Member, Cloverly Formation; Unit V of this report)....... gfecat aterehe ened 86 4. Chalcedony zone, irregular concretionary masses of purple, blue, white and yellow chalcedony and barite in light-gray claystone. Forms prominent ledge or caps small knolls. (= Unit V in part of Chiise TS PONt) iy sate lets oes sv eeeaenctions Sh ad he aRe tae Paneeee ney opens 2- MORRISON FORMATION: 3. Claystone, variegated dark to light-gray, purplish zones locally and conspicuous orange to rust- yellow zone near top. Fresh surfaces dark-to light- gray, nonfissile and unstratified. Highly benton- itic. (="Unit lll?’ tf this-repoert) aes sere eee 84 Ze CONCEAL enc cere: conte etere eae ba veraha nttel Ole Tenet eietenerete 48- 1. Sandstone, massive, cross-laminated, medium- to coarse-grained, quartz and white chert, with few pebbles. White to buff, weathers white to yellow- ish. Baseconcealed. (= Unit II? of this report).... 42 Concealed. 26 29. 14. 1G. ee (m) = 6 e 2 po LLOSN. J2= OL THe PORKIOOAL DRAW lar Measured in the east-facing exposures at the west end of Thermopolis Anticline, 1.5 miles (2.4 km) west of South Fork of Coal Draw, 11 miles (17.6 km) northwest of Thermopolis, Wyoming. SW 1/4 Sec. 27 and SE 1/4 Sec. 28, T.44N., R.96 W., Hot Springs County, Wyoming. ESE Thickness SYKES MOUNTAIN FORMATION: (ft) Sandstone, tan to light-brown, with hematite stain- ing and ironstone concretions near top. Massive to thin-bedded, abundant ripple marks, and fucoids. Fine- to medium-grained, chiefly quartz grains. Overlain by fissile black shales and thin sandstone strata. (= Greybull sandstone?; Sykes Mountain (m) Formation in part; Unit VIII of this report)........ DAs do Gels CLOVERLY FORMATION: ze Pie uO; Claystone, variegated, weathers maroon, purple, rose and gray; gray to pink or purple-gray with green mottling on fresh surfaces. Massive to poorly stratified. Silty throughout, some polished pebbles. (= part of Himes Member, Cloverly Formation; Unit WEE ‘of thls Tepisey tern cseree ele stesso a tae ee ee 22 Limestone, massive, light-gray weathers white, Pnely Cry Stalline. we we saa te ate ete oreo) © -eceiee "a, eleven eer aus l- Claystone, variegated, weathering to maroon and red brown, unstratified, forming steep, fluted slopes. Polished stones or "gastroliths" present, but not abundant. Locality YPM 66-2 is located near the middle of this claystone. (= part of Himes Member, Cloverly Formation; Unit VII of thd TE MOGE) rio auebarcveterererae io ee ona elas eee ays enc ateneit pee Claystone, variegated, weathers red to red brown in lower half and purple, rose and nearly white in upper part; generally medium-gray to yellow-gray on fresh surfaces. Thin (6tol0inch [15 to25cm]), discontinuous, brown and white limestone strata present locally. Chalcedony, barite and calcerous concretions abundant throughout. Bentonitic, wea- thers to "popcorn" surfaces. (= Little Sheep Mud- stone Member, Cloverly Formation; Unit V of this FO DOLE) Yorteiccd’s ec teieale tonne eee Beater inte tte tok aie eral ete et oo Ie eS 158 Sandstone, massive, weathers brown; pale- green to light-gray on fresh surfaces, fine- to medium-grained, quartz, white chert and some black chert grains. Occasional coarse grains but not conglomeratic, parallel stratification and occasional cross-lamination. (= Unit IV? of CHES ITE POrt)". oro Rees ciate. aliele euchalutelte seine de taneimeanenatamememarats MORRISON FORMATION: Claystone, medium- to light-gray, with numerous thin tan sandstone strata, and thin white limestone layers. Conspicuous limestone concretion zone at base. Claystone grades into fissile dark shale interbeds at top. (= part of Unit III of this report). Claystone, green to yellow-gray, massive or un- stratified. Fresh surfaces gray. Calcareous, dis- continuous sandy zone near base. (= part of Unit TWIP Of Enis report) uetwec's « Gecko cctets oto crorae coone tener onan Sandstone, weathers yellow brown, soft, friable, poorly cemented. Quartz grains, medium-grained.. Claystone, sandy, greenish-yellow, massive, un- stratified; forms partly concealed slopes..... oerens Sandstone, massive, weathers tan or white; white and sparkly on fresh surface. Weathers into rounded knobs and blocks. Quartz and white chert, medium-grained. Not conglomeratic. Individual beds up to 10 and 15 feet (3 and 4.5 m) thick. (="Unit lof this report): «cies sits ote 56 66 ae ae el Concealed. eo feracta w cxovetcrencueere. one di ahah erovedes alee tete,oieie SUNDANCE FORMATION: re Sandstone and shale, interbedded, glauconitic. Occasional mollusc shells and belemnites....... Concealed. Thickness (ft) (m) L2e5 .oe 18 5.5 64.5 1936 2 026 Le Sse) 48 14.6 SU so Not measured 159 SEGRIOWN 40> MUD CREEK Section measured in west-facing exposures 1.5 miles (2.4 km) south- east of Mud Creek, just west of the head of Rattlesnake Gulch, 7 miles (11.2 km) due west of Thermopolis. NE 1/4 Sec. 35, T.43 N., R.96W., Hot Springs County, Wyoming. Thickness SYKES MOUNTAIN FORMATION: (Et) (m) 12. Sandstone, yellow to tan, medium- to fine-grained, weathering "rusty" to brown, thin-bedded and mas- sive with ripple marks and fucoidal markings. Over- lain by dark-gray to black fissile shale and iron- stone lamina interbedded with thin, brown sandstone strata. (= Greybull sandstone?; Sykes Mountain Formation in part; Unit: VILL of this report). ..6. <=. « SS KOn 3 11. Claystone and shale, medium-gray to black, mas- sive below, becoming thin-bedded and fissile near the top. Silty throughout. Weathers to "rusty" color. (= Himes Member, Cloverly Formation in DALE? - Pabt OL Unit VilllMOrsthi sereioOrk)! say TRE RMO POM is WYOMING This section was measured on the west side of U.S. 20,3 miles (4. 8 km) north of Thermopolis in the exposures of the road cut and along the ridge to the west on the north limb of the Thermopolis Anticline. N 1/2, Sec. 24, T.43 N., R.94 W. , Hot Springs County, Wyoming. SYKES MOUNTAIN FORMATION: 10. Sandstone, tan to brown on weathered surfaces, buff to light-gray on fresh surfaces, massive, becoming thin-bedded toward top. Ripple marked. Fine- to medium-grained, chiefly quartz. Hema- tite staining and ironstone concretions in upper levels. Overlain by interbedded black fissile shale and thin brown sandstone beds. (= Greybull sandstone; Sykes Mountain Formation in part; Unit Villofthis feperteve ss. ees BOOST PRE. s CLOVERLY FORMATION: Si Claystone, variegated, light-gray to pink-gray on fresh surfaces with small patches of red-brown mottling, weathers to pale maroon. Unstratified. One foot (0.3 m) thick pink-gray siltstone near middle of unit. (= part of Himes Member, Cloverly Formation; part of Unit VII of this report). Sandstone, massive, medium-grained rounded quartz. Conspicuous parallel stratification. Weathers light brown, tan on fresh surface...... Claystone, variegated, lavender, maroon to red- brown with green mottling on fresh surfaces, tan to gray near top. Silty in lower 8 to 10 feet (2.4 to 3.0 m). Sandy zone about 15 feet (4.5m) below top. Massive throughout. Polished peb- bles or "gastroliths" moderately abundant. (= Himes Member, Cloverly Formation; Unit VII Ol EMIS PE DOC) sats) eleearere ewe leer a fereiclca caste cra ARE ee te Sandstone, conglomeratic in lower half. White to tan, massive, medium- to coarse-grained quartz, quartzite and white chert. Conglomeratic wedges increasingly abundant toward base with pebbles of quartzite and white chert up to 0. Sinch (1.2 cm) in diameter. Some feldspar. (= Darton's lower sandstone, Cloverly Formation; Otter Creek sandstone’: Unit Vi of this re pont)... sce. cacbabe ao Conglomeratic sandstone, massive, dark-gray or brown. Appears to grade abruptly into overlying unit. Pebbles chiefly of black and brown chert, some quartz, up to 0.5 and 1 inch (1.2 and 2.5cm) in diameter. (= Pryor Conglomerate ?; Unit IV? of Eh TE OE) nw ore ane euaeetereeRereceke mien = cane a seen hae nererciG 161 Thickness (ft) (m) 9 Died i7/ 52.2 5 IEE) Aso) lin 8) 35 105 6 LS 4.5 162 Thickness MORRISON FORMATION: (ft) (m) 4. Claystone, sandy, greenish-tan and gray. Nonre- sistant and partly covered. Occasional indurated sand strata 1 to 2 feet (0.3 to 0.6 m) thick, all apparently discontinuous. Claystone unstratified. (=AUmit Il of this report)... <<< avin + eielel oketele ohenaretar AS) eam a7 3. Sandstone, brilliant white to yellow, quartz and white chert in medium-sized grains. Chalky- white grains of chert conspicuous. Entire unit is massive, with cross-laminations throughout. Generally somewhat friable, weathering into smooth, rounded, sloping surfaces and isolated pedestals and knobs. No conglomeratic zones noted. (= Unit LIMOENEHTS TEMOLE i raisc ce ores cllet oral ovm: oo cuietens uel oe eirem noes USA ae a ere 2. Concealed, thickness undetermined but in excess Of NOvVieeta(S 30 ma)eoniee SU Rares. caieteterciereretereter oe eens SUNDANCE FORMATION: 1, Sandstone, glauconitic, weathering from pale green to lightbrown. Marine invertebrate remains common 20 feet (6.0 m) below top ....c.cccmcces seco nes +) Olmedounee Concealed bi.@ LO NT 6 = EE RM OE Omi aGler WYOMING This section was measured on the east side of the Bighorn River directly across from Section 5, onthe north limb of the Thermopolis Anticline. SE 1/4, Sec. 19, T.43 N., R.94 W. , Hot Springs County, Wyoming. The section is included here because it contains a sequence signifi- cantly different from that described in Section 5 slightly over a mile (1.6 km) away, a sequence that I believe provides the best evidence for correlation of sections on all sides of the Bighorn Basin. SYKES MOUNTAIN FORMATION: 9. Sandstone, buff to gray on fresh surfaces, weathering tan to rusty brown. Massive and thin bedded, fine- to medium-grained, predomi- nantly quartz in well-rounded grains. Ripple marks and fucoids common at various levels. Some hematite lamina and staining near top and in overlying black shales and thin sandstone. (= Greybull sandstone; Sykes Mountain Formation iMmepart=” Unity lh orsthiiswre pork) Mes 6 Paes aese CLOVERLY FORMATION: 8. Claystone, variegated, maroon, red-brown, laven- der to gray, green mottling on fresh surfaces. Sandy in upper half and near base. Massive or un- stratified. Polished pebbles infrequent. (= Himes Member, Cloverly Formation; Unit VII of this report) 7. Sandstone, white to light-gray or tan, massive with cross-laminations. Medium- to coarse-grained, corm glomeratic in lower half. Chiefly quartz, white quartzite and white chert and some feldspar. Almost no dark grains or pebbles. Well-cemented, forms large blocks on lower slopes. (= Otter Creek Sand- SEGne, ec Umit Vii Of tlceremOur) cise «ssn sss eneershensnsuche 6. Shales, dark-gray to gray-green and brown, thin seams of coal and lignite shales, highly fissile. (= spartvol Unit aVie vor Enlssne pork) yvs.suebe beets cets, One are 5. Conglomerate, massive, dark-brown, both on fresh and weathered surfaces. Cross-laminations common. Consists of moderately well-rounded grains and peb- bles up to 0.5 and I inch (1.2 and 2.5 cm) in dia— meter, of dark-gray to black chert, dark quartzite, yellow-brown and white quartzite. Less than 10% of material is light-colored. Overall appearance and composition very similar to those of the Pryor Conglomerate. (= Pryor Conglomerate ?; Unit IV of EUS” FO DOLE) ‘one uaeMereh eee tek eee REGia k) GREE ee ; MORRISON FORMATION: 4. Claystone, greenish to light-gray, silty through- out with occasional thin sandstone strata. Clay- stone poorly stratified. Concretions lacking. Fresh rock dark gray-green, breaking into irregular chips.) Galeareous: (= Unit IN-of this: report) sas. 163 Thickness (ft) (m) 8 DOA 528 ALLS E68 58 Wo 7/ ie 33.46 28 8.9 0) ea 164 Thickness 3. Sandstone, brilliant white to pale-yellow or buff. (Et) (m) Medium-grained quartz and white chert. Chalky- white grains of chert a prominent feature giving a white "spattered" appearance to fresh surfaces. Dark grains extremely rare. Weathers into smooth massive, rounded surfaces and isolated knobs. (= Unit Il om thistreport) ...i esses sae ye once oe te eee 2. Concealed interval, apparently of nonresistant lithology. Equalstat least) 10‘feeti(S*m)s Fonde.ns SakO 25 SUNDANCE FORMATION: 1. Sandstone thin-bedded and glauconitic. Marine invertebrate shells common in sands and shales He Neath se Sieric SANE oie S whatbvere wv een abelian Miata el aoe! oh ometle aan ICN ERHING cite Rect! Concealed SE.C PLON 2 =ssNO WO @ DNGIVE Es Section measured at limited exposures near ridge top 1 mile (1.6 km) west of Nowood Creek and "Orchard Ranch", Sec. 4 (?), T.42 N., R.88 W., Washakie County, Wyoming. SYKES MOUNTAIN FORMATION: 3. Sandstone, light-gray, weathering tan to yellow, fine- to medium-grained, sparkly, massive strata cross-laminated, ironstone nodules abundant in upper part, overlain by thinly laminate fissile black shale. (= Greybull sandstone: Sykes Mountain Formation in part: Unit VIII of this report)... . cme. 5, As5 CLOVERLY FORMATION: 2. Claystone, variegated red-brown to maroon-gray, un- stratified, sandy. Polished pebbles or "gastroliths" infrequent. (= Himes Member, Cloverly Formation; Unit VII of this report). «,.,.¢. we NSE ee Measured across the nearly vertical section 1 mile (1.6 km) due westof Tensleep on the west side of Nowood Creek, north of U.S. 16,SW1/4 Sec. 24, T.47 N., R.88 W. , Washakie County, Wyoming. SYKES MOUNTAIN FORMATION: 9. Sandstone, thin-bedded, light-gray, weathering brown. Some cross-laminations, ripple marks 167 Thickness and fucoidal markings common, fine- to medium- (ft) (m) grained, chiefly quartz. Iron-stained. Grades into dark-gray and black shale and thin-bedded sandstone lamina. (= Greybull sandstone; Sykes Mountain Formation in part, ?; Unit VIII of this FE POLE). ofc.n.0 « eget ere gore oie aevehe Coie” ars. eta tenad erate ose in iaitons CLOVERLY FORMATION: 8. Claystone, dark-gray, weathers light gray, silty, unstratified. Some carbonized plant re- mains and occasional polished pebbles (= part of Himes Member, Cloverly Formation ?; middle clay member of Darton's Cloverly Formation; part Ob Unil Vilbofthisire port) seers tw ce iake Sate eee 21 6.4 Sandstone, light-gray to yellow, weathers brown or tan, fine-grained, siliceous. Massive bedding. (=*part*Of Unit VIPOL this Tepore)).,'s:.1.-ekree. Sees 2 0.6 Claystone, variegated, gray, green, lavender, red- brown, unstratified, silty throughout. Polished pebbles moderately abundant. (= part of Unit VII Of tHPSHFS POTE) ea I eE ot 9.4 Sandstone, fine to coarse-grained, conglomeratic locally, particularly in lower third. Brilliant white, sparkly, to light-gray. Quartz and white chert abundant, some feldspar. Massive bedding, fre- quent cross-laminations, well-indurated. Promi- nent ridge-former. (= lower sandstone of Darton's Cloverly Formation; Otter Creek Sandstone; Unit VI Of this report) sec: ees Oe RPL ere hPa Gi Ol S.6 MORRISON FORMATION? 4. Claystone, variegated, greenish to yellow-tan in upper part, orange to pale-red in lower part. Un- stratified, nonfissile. Several 3 to 8 inch (7.5 to 20 cm) sandstone and siltstone lenses, yellow or tan in color. No chalcedony or barite concretions evident. (= Unit III? of this report)..... sa ttee ee 7S “22.8 Sandstone, yellow to white, medium-grained, chiefly quartz and white chert. Some cross-laminations, mas- sive bedding. Friable. (= Unit II? ofthis report)... 12 326 168 Thickness Claystone, yellow to greenish-gray, silty or sandy (ft) (m) throughout. Occasional thin yellow or buff sand- stone lenses. Claystone unstratified, calcareous. No chalcedony or limestone concretions. Partly eoncealeds "(= Unit f? of this report)ztne aeees ee el oe pcoee SUNDANCE FORMATION: i Shale, greenish-gray, fissile, with thin sand lamina. Marine invertebrates abundant......... . Notmeasured Dp ECiLO Nie Oi SRY ATE dle NOUV NEG This section was measured on the east limb of the Hyattville Anticline, at the north end of the prominent ridge 0.75 mile (1. 2 km) southwest of Hyattville. N1/2 Sec. 12, T.49 N., R.90 W., Big Horn County, Wyo- ming. SYKES MOUNTAIN FORMATION: a Sandstone, yellow-brown or "rusty", thin-bedded with thin interbeds of dark fissile shale. Medium- grained, quartz, with abundant ripple marks and fucoids. Hematite-staining and ironstone lamina. A ledge-former. Overlain by black shale. (= Grey- bull sandstone; Sykes Mountain Formation in part; Unit) VIDOE ‘thisire poms) sab ss. eae Bete Gieiene weaves "4 all CLOVERLY FORMATION: 6. Claystone, variegated, maroon to red-brown, purple- gray in lower part. Unstratified, sandy in part. Polished pebbles common. Chalcedony and barite concretions lacking. Locality YPM 66-3 is located in the lower third of this claystone. (= Himes Mem- ber, Cloverly Formation?; middle shale member of Darton's Cloverly Formation; Unit VII of this report). 39 11.9 Sandstone, white to light-gray, massive, medium- grained, chiefly quartz with some feldspar, mica and dark chert. (= Otter Creek Sandstone ?; Unit VI? OF THIS TEpOrt) sis) dune aceyelebaveryehs) Sevetetanduens eikete eyaae erect Cne nnn aman 169 Thickness 4, Claystone, variegated, brightly colored, red, (Et) (m) deep-maroon, red-brown and gray. Upper 20 feet (6 m) chiefly pastel or light-gray weather- ing to "popcorn" surface. Sandy in places, bentonitic in upper half. Chalcedony and barite concretions frequent in upper 35 to 40 feet (10.5 to 12.2 m), but appear to be absent below. (= Little Sheep Mudstone Member, Cloverly Formation?; Units V and perhaps ?III of this PEORIA Sel a Seas Peet ees cee. AOS Ae PB2ES MORRISON FORMATION: 3. Sandstone, white to light-gray, massive, fine- to medium-grained. Chiefly quartz with some white chert and feldspar. No conglomeratic or pebbly zones found. Well-cemented, a promi- nent ridge-former (= Unit II of this report)..... ie Sil 9.4 2. Concealed beneath valley alluvium. Thickness ; + + appromimate. eeceeervreere eee ee ee eceecoecoveveevevee eee ee ee 68- Zor 7- SUNDANCE FORMATION ? 1. Sandstone, glauconitic, coarse-grained and highly calcareous. Thin-bedded. Poorly ex- posed. No marine invertebrates found in situ, but fragments of Gryphaea and belemnites are SCattered On SURFACE. sashes wrdes DGale steele cierole ae Not measured SE ClO N Vieni tee Lee Wey OM NE This section was measured in the badlands 2 miles (3.2 km) southwest of Shell, Wyoming. N 1/2 Sec. 4, T.52 N., R.91 W., Big Horn County, Wyoming. SYKES MOUNTAIN FORMATION: 12. Sandstone, massive, 1 to 2 foot (0.3 to 0.6 m) beds, tanto yellow-brown, considerable hematite staining and some ironstone concretions and thin lamina at top. Medium- to fine-grained, quartz. Ripple marks com- mon, some fucoidal markings. Weathers intorectangu- larblocks. (= Greybull sandstone; Sykes Mountain 10- Formation in part: Unit VIM Of this ve port)... ese. 6 4 12 Ww Ww 170 tales 10. Thickness CLOVERLY FORMATION: (£t) Claystone, variegated, orange, red-brown and maroon, yellow near top. Gray to purple-gray on fresh surfaces with some green mottling. Sandy throughout. Polished stones or "gastroliths" com- mon. Unstratified. Two localities (YPM 62-4 and 62-5) are located in the lower part of this claystone. (= middle shale member of Darton's Cloverly For- mation: Himes Member, Cloverly Formation; Unit VII Of this Trepont)).. < s.sic sieeve 0 Snclioue ie) oer NOMI Penne none e Wil BE. Sandstone, very thin or absent. Five to 6 feet (1.5 to 1.8 m) thick at nearby exposures 300 yards (270 m) to north and west. Massive, cross-laminated, gen- erally friable, but well-cemented at some localities. Medium- to coarse-grained, chiefly quartz and feld- spar, some dark minerals and white chert. (= lower sandstone of Darton's Cloverly Formation; Unit VI of thAS EpORE)iacpsheysvee «is sewNeene tae eek late eet ea ee Claystone, variegated, dark-gray, pale-purple to nearly white at top. Dark-gray on fresh surfaces. Massive, breaks into irregular chips. Bentonitic, weathers to "popcorn" surface. Limestone and chalcedony concretions abundant. Thin, white, discontinuous limestone lenses common, especially to the north of section site. Locality YPM 62-6 is situated near the base of this unit. (= part of Little Sheep Member, Cloverly Formation; part of Unit V Of TAUSHFE DONE) A eirels cisieteiere ee ake eI ae eee 36) al Fragmental tuff, white, fine-grained with infrequent 1 to 3 mm fragments. Massive, weathers to irregu- lar, bright-white, knobby masses. Forms distinct ledge ree eS oS RR Gs eee ersceeee 3 0. Claystone, variegated, rose to Indian-red, dark red-brown and dark-gray. Massive and silty throughout. Occasional thin, white limestone lenses. Chalcedony and barite concretions and selenite crystals abundant. (= part of Little Sheep Mudstone Member, Cloverly Formation; part of Unit V. of ‘this rep ont) Sync eeveecsayerekereteme ete etoienete tel eect le (m) s) g 171 Thickness MORRISON FORMATION: (ft) (m) 6. Sandstone, yellow to orange-brown, white on fresh surfaces, massive. Medium to coarse- grained with prominent cross-laminations. Well- cemented at most exposures, but tends to be fri- able at some sites. Quartz and white chert con- stitute 99% of grains. Weathers to smooth, rounded surfaces, little jointing. (= Unit II? of ERTS ET OME atin ey tree Coca CAC uate rehe aca Gitomer ate aetna om loess 25 hes 9. Claystone, light-gray to blue-gray, dark-gray on fresh surface. Massive and nonresistant. Cal- careous in part. Chalcedony and gypsum rare or lacking: (= part of Unit’? of! this report). 3 U.% 2. S35 10.2 4. Sandstone, massive, and strongly cross-laminated. White or light-gray. Almost complete lack of joint- ing, weathering into large rounded masseSs....... bt Sa 3. Claystone, pale-greenish-gray to yellow-gray. Poorly exposed but appears to be unstratified and not fissile. Color reminiscent of Sundance shales, but no marine fossils noted. Tentatively placed in Morrison, (= Uniti? of his report) weaned: -2eeeneee n= 2. Concealed, presumed to be similar to #3 above... 20- 6. es SUNDANCE FORMATION: 1. Sandstone and shale, interbedded. Sands coarse and rich in quartz, glauconite and calcite. Shale, greenish, thinly stratified and fissile. Some levels (nearly icoquinoidh i. icsiackicsuss. fe ee on ao eon mCcasurcad Concealed. pi CuRL@ Ne G2 sao En SC REE mOuNilE Measured in "Devils Kitchen", 0.25 mile (0.4 km) north of Shell Creek, 6 miles (9.6 km) northeast of Greybull, Wyoming. NE 1/4 Sec. 31, T.9o3 N., R: 92 W. , Big Horn County, Wyoming. 172 SYKES MOUNTAIN FORMATION: 4. Thickness Sandstone, buff, weathering yellow or tan, mas- sive bedding, well-indurated, medium-grained, becoming thin-bedded upward with increasing rusty to red-brown, overlain by ironstone-bearing sandstones interbedded with black fissile shale. (= Greybull sandstone, Sykes Mountain Forma- tion in part UnitsVIN Of :thistre porta. oceania ee 5 CLOVERLY FORMATION: 3. Claystone, variegated, gray, weathers tan in upper 20 feet (6.0 m), lower 40 feet (12 m) mottled gray- green and maroon, weathering red brown, speckled red, silty, polished pebbles abundant, nonbedded to poorly stratified, forms steep-rilled slopes. (= Himes Member in part, Cloverly Formation; Uaitt VIof this Feport)es ees ote eee to Sandstone, yellow, olive, to green, weathering to green, locally brown. Coarse-grained somewhat friable quartz, feldspar in subangular grains, weathers into rounded knobs or pinnacles. Cross- laminated. Locality YPM 62-10 is situated in the upper few feet of this sandstone. (= Himes Mem- ber in part, Cloverly Formation; Unit VI of this re- POLE) Fe ect fora eia reece s cichare Prone ae ener ene one ae 15 Claystone, dark-gray, weathering nearly white, bentonitic, abundant chalcedony concretions, poorly stratified, breaks into irregular chips. Largely concealed. (= Little Sheep Mudstone (ft) (m) UES) 18 Member, Cloverly Formation; Unit V of thisreport). > 9 > 2.7 Concealed. SECTION, lien = CLOVE RLY ee Elis Erkan Measured at prominent bluffs along west side of Orville Leavett's reservoir onFenton Draw, NW 1/4 Sec. 24, T.54N., R.92 W., Big HornCounty, Wyoming. There canbe nodoubtthat these exposures are those which Dar- ton measured and used as the basis for proposing the Cloverly Formation (Darton, 1906: p. 52). The Cloverly Post Office, upon which the name was based, was situated approximately 0.75 mile (1.2 km) tothe east. 173 Thickness SYKES MOUNTAIN FORMATION: (ft) (m) Sandstone, gray and yellow-brown, weathering buff to brown, fine- to medium-grained, silty, massive bedding, becoming thinly bedded at top and interbedded with fissile black shale. Ripple marks common. Fucoids. (= Greybull sand- stone; Sykes Mountain Formation in part; Unit VIII OE WIVES IGE DOLE era castaaye eaeteve epaanie wierele sik se creheimee mines V2 326 CLOVERLY FORMATION: 6. Claystone, variegated, gray, tan, chocolate- brown, maroon to purple and rusty-yellow. Gen- erally light- to medium-gray on fresh surfaces with green-gray mottling. Silty throughout with oc- casional sand lenses. Massive or unstratified, except for some fissile, dark shale lenses 2 to 4 inches (5 to 10 cm) thick in lower 15 feet (4.5 m). Lower 30 feet (9 m) forms steep, fluted slopes. "Gastroliths" or polished stones dispersed through- out, but most abundant in middle 20 feet (6 m), (= middle shale member of Darton's Cloverly Forma- tion; Himes Member, Cloverly Formation; Unit VII OP EMS VS OOPE) ei ona tenauercs toptaalicuc! @'% e>u, «carey anette enceatere game 48° BAS Sandstone, maroon, medium-grained, chiefly hematite-stained quartz grains. Weathers to chocolate brown. Massive. (= part of Unit VI of EHIS. TODOEE) ae cueue GA eopieceie a Musue wis) & CARRIER E erent ore ee ee Sandstone, yellow to olive-green, weathers to yellow-brown ormaroon brown near top. Coarse- grained, angular grains of quartz, feldspar and some dark minerals, pebbly in places. Has dis- tinctive "salt and pepper" appearance. Massive and strongly cross-laminated. Isolated dinosaur bone fragments occur infrequently throughout the upper 10 to 15 feet (3 to 4.5 m) of this sandstone. (=lower sandstone of Darton's Cloverly Formation; Unit. VI Of this report). 0... « 2 igs ariejih cats ia seaside tol eee 39: ALES Claystone, dark- to medium-gray, weathers to light gray or nearly white. Bentonitic, weathers into low- rounded, vegetation-free mounds with "popcorn" sur- faces. Chalcedony, barite and calcareous concre- tions very abundant, selenite crystals and satin spar 174 Thickness common. (= Little Sheep Mudstone Member, (£t) (m) Cloverly Formation, in part; Unit V of this report + + LY DETE)/ Meo tants ee eae ae eee Ne oS Se Pa s8 35- 10.6- 2. Fragmental tuff, light-gray, weathers brilliant white and forms low-rounded mounds or benches. Unstratified and very fine-grained with rare 2 to 3 mm fragments. Very conspicuous white chalky- looking band below vivid Cloverly bluffs. (= Little Sheep Mudstone Member, Cloverly Formation in part. Unit V OF this report: impart)... seis sateen S 0.9 1. Claystone, dark- to medium-gray, weathers to dark gray green. Unstratified, bentonitic, weathers to low angle "popcorn" slopes. Chalcedony and barite concretions present, but not common. Base concealed. (= Little Sheep Mudstone Member, Cloverly Formation in part; Unit V of this report in Danke om eee Debt Shy Sarl aie ona ile io Beha teeth sie RRO e. SLES, 7 5 Sandstone, tan to gray, weathers to buff brown, gray streak near top, massive, medium-grained, chiefly well-rounded quartz. Some cross-lamina- INO Dartee ERIE ORG eee eoeeee#eese’e eeeoeeer#ee#ee eoeeeeee#e#ee#ee#eese 5 Claystone, light-gray, weathers to buff with maroon mottling. Colors subdued compared with other lo- calities. Polished pebbles common. (= Himes Member Cloverly Formation; Unit VII of this report). 28.5 Sandstone, white, weathers white to very light tan, massive, strongly cross-laminated, medium-grained, sparkly, very high quartz content....... eee iere ) Sandstone, yellow to brown, weathers to gray, some brown and maroon mottling, coarse-grained withclay, becoming finer-grained at top, massive, occasional cross-laminations. Base concealed. (= Unit VI of ENdS TepOnt) sa elaa-es See Set oss sR oe Boe 37- Claystone, variegated, light- to dark-gray, grading downward to pale and deep purple and maroon. Bentonitic , forms extensive soft "popcorn" sur- faces. Chalcedony and barite concretions very abundant, some satin spar. (= Little Sheep Mud- stone Member, Cloverly Formation; Unit V of this FEPODE ee ce oe. SASS A aeNe al hare oa a gues oeee a cee Dae 38- Concealed. 5S hGyETONG O17. |SihvE ik PY MO.) NEPA Ue (m) Measured across the east-facing exposures on the west limb of Sheep Mountain Anticline, 1. 25 miles (2 km) westof the bentonite plant at the west entrance to Bighorn Canyon. SE 1/4 Sec. 3,T.53 N.,R.94W., Big Horn County, Wyoming. 180 SYKES MOUNTAIN FORMATION: gi: Sandstone, yellow to rusty-brown, buff on fresh surfaces. Massive bedding, cross-laminations, few ripple marks. Medium-grained, well-rounded quartz. Hematite staining. Overlain by thin dark- brown sandstone strata, interbedded with fissile black shale, weathering rusty color. (= Greybull sandstone; Sykes Mountain Formation in part; Unit Villvoithis)meport) ssi ene aha se yenilene paler eee Mes CLOVERLY FORMATION: Claystone, variegated, red, maroon, purple and bluish-gray. Massive or unstratified, weathering to steep fluted slopes. Occasional discontinuous sand lenses, usually friable. Polished stones or "gastroliths" common. Localities YPM 62-11, 62- 12, and 62-13 are situated near the top of this unit. (= middle shale member of Darton's Cloverly For- mation; Himes Member, Cloverly Formation; Unit VII Of this KEPOLE) es «creak adtmarmmdas ai opiates aay Sandstone, white on fresh surface, weathering to light brown. Massive to thin-bedded, generally well-cemented. Fine- to medium-grained subangu- lar quartz, feldspar, some white chert and dark minerals. (= Unit Vi? of, this; repont)ie. 9. 5 seteaee Claystone, variegated, yellow, rose, rose-gray to light-gray or white. Unstratified, bentonitic, weathering to low angle slopes with "popcorn" sur- faces, soft and collapsible. Chalcedony and barite concretions very abundant, selenite and pink and orange satin spar common. Occasional discontinu- ous, thin sandstone lenses. (= Little Sheep Mud- stone Member, Cloverly Formation; Unit V of this GE DOLE) oes cic terae oe Geelote Sue eee “EEN Nes 5 Sandstone, tanto gray, gray on fresh surface. Massive parallel stratification. Cross-lamina- tions conspicuous. Coarse-grained, quartz with some light-gray and yellow chert. Pebbles ex- tremely rare. (= Unit IV? of this report)......... Thickness (ft) (m) 4- .2- 6 76 32 957 2 0.6 KOs “S104 8 2.4 181 Thickness MORRISON FORMATION: (ft) (m) 4. Claystone, variegated, yellow-gray, dark-gray, to rose-pink. Thin, discontinuous, tan sand- stone lenses just above middle of sequence. Chalcedony and barite concretions abundant in lower half, but gypsum apparently absent. Mas- sive or poorly stratified, weathers into low, sandy slopes. (Presence of chalcedony suggests assignment to Unit V, but on the basis of a very similar lower claystone bearing similar concretions which underlies a dark conglomerate believed to be the Pryor Conglomerate in Section 14 at Cedar Creek, I have tentatively referred this to UnitIII).. 109 33.2 3. Sandstone, brown, light-brown on fresh surface. Massive, parallel stratification. Fine-grained 2- 0O.6- GQUaTEDs sc5 Wiens w wreh ein shave loretet aetela ef eles al eceter el oveateee a 4 1.2 2. Claystone, partly concealed, predominantly yellow- gray to light-gray and sandy. Nonresistant and cal- careous. Occasional 2 to 3 inch (5 to 7.5 cm) sand- stone layers. (Presumed to equal part of Unit I of Ee i this report). 72% 42 She eter ememre rs PASEO DRIER oc 45- 13.7- SUNDANCE FORMATION: l. Sandstone, gray-green, coarse, glauconitic and containing shell fragments. Surface littered with Gryphaea fragments less than 10 feet (3 m) below the Contact (witha tZ.. wid ett ehele estate 2 atiwthe ed rhehana tokens Not measured SEC BION eb38 k= SLi TiS DEE PeMeuU NibA DN Measured across the hogbacks on the west limb of Little Sheep Moun- tain Anticline, 1.5 miles (2.4 km) south of U.S. 14 Alternate, 4 miles (6.4 km) east of Lovell, Wyoming. NE 1/4 Sec. 21, T.56 N., R.95 W., Big Horn County, Wyoming. SYKES MOUNTAIN FORMATION: 6. Sandstone, orange-brown, with much dark iron staining. Massive, parallel and cross-stratifica- tion, and frequent ripple marks. Medium- to fine- 182 Thickness grained, chiefly well-rounded quartz. Ironstone (ft) (m) concretions common at top and in overlying dark- gray fissile shales and sandstone. (= Sykes Mountain Formation in part; Greybull sandstone; Unit VIL of thisire port)... eS eae eee 6 1.8 CLOVERLY FORMATION: 5. Claystone, variegated, maroon to red-brown, be- coming yellow-brown near top. Gray-green with purple and red mottling on fresh surfaces. Un- stratified, sandy throughout. Polished pebbles rare. (= part of middle shale member of Darton's Cloverly Formation; Himes Member, Cloverly Formation; Unit VIMO this repout) tlm ees cea ee te eS eee rai tc ais Nbr LS 4a5 4. Sandstone, gray, weathers tan. Coarse-grained, chiefly quartz with some feldspar as subangular grains. Massive and resistant........ Sis) ete tes lotions 3 0.9 3. Claystone, gray, weathers tan to red brown and maroon, unstratified and sandy throughout. Several massive 3 to 8 inch (7.5 to 20 cm) sandstone lenses. Polished pebbles present, but not abun- dant. Forms bright-colored, steep, fluted slopes. Base concealed. (= part of middle shale member of Darton's Cloverly Formation: Himes Member, Cloverly Formation; Unit VII of this report)....... 43. Seat 2. CGoncealled interval sm ....s secece oot eeh at ee ats a feb ane tere 34- 10. 32 (Approximately 0.25 mile (0.4 km) to the south of this site, a 4 to 8 foot (1.2 to 2.4 m) massive sandstone crops out at what appears to correspond to this concealed interval #2) in this Section. Ex- posures here are poor, though, so adjacent units could not be established. The general character of this sandstone [yellow-brown to almost olive color, medium-grained, rich in subangular quartz, feldspar with some dark grains] is comparable to that of Unit VI in the vicinity of the Cloverly Post Office site. ) 1. Claystone, dark-gray, weathers light gray to pale pur- ple. Massive. Bentonitic, weathering into soft, low- angle slopes with "popcorn"-like surface. Chalced- ony concretions abundant, some selenite crystals and white satinspar. Baseconcealed. (= part of Little Sheep Member, Cloverly Formation?; Unit V of this re- DOLE) acne tapers craters Ss el ojwiehoh ala raiciteledelereleletchier Velierecen ea meee >Z4 S753 Concealed. 183 vee LOW wo = Ss VRES MOUNTAT N Composite section measured on the southwest flank and in exposures in the prominent gorge through the southwest flank of Sykes Mountain, ap- proximately 2.5 miles (4 km) southeast of State secondary highway #0208 to the Big Horn Recreation Area at Horseshoe Bend. S 1/2 Sec. 11,T.57 N., &.95 W., Big Horn County, Wyoming. Thickness SYKES MOUNTAIN FORMATION: (ft) (m) Ta Sandstone, rusty-brown to dark-brown, tan on fresh surfaces. Massive to thin-bedded, ripple marks abundant. Medium- to fine-grained quartz in rounded grains. Six inches (15 cm) to several feet of dark fissile shale beneath lowest sandstone and thin shell interbeds with predominantly sand- stone facies. Overlain by dark fissile shales and 0.5 to 2 inch (1.2 to 5 cm) sandstone layers with frequent ironstone concretions. (= Greybull sand- stone; Sykes Mountain Formation in part; Unit VIII Oftndis *re DOE)s wien eres nie echo levee ¢ A Polatane Ri saet ater sim 320 CLOVERLY FORMATION: UO Claystone, variegated, red-brown, maroon, purple- gray, becomes rusty near top. Occasional, white to light-gray, discontinuous zones 2 to 5 feet (0.6 to 1.5 m) thick. Massive or poorly stratified, generally light-purple-gray on fresh surfaces, breaks into irregular, slickensided blocks. Some dark-green mottling on fresh surfaces. Sandy throughout. Polished pebbles abundant. (= middle shale member of Darton's Cloverly Formation; Himes Member, Cloverly Formation; UnitVIlofthisreport). 53 16.1 Sandstone, white to tan or light-brown, becoming "fire'""-red in upper part locally. Generally buff to yellow-tan on fresh surfaces. Medium- to coarse- grained, chiefly angular to subangular grains of quartz, feldspar and white chert. Massive, paral- lel- and cross-laminations. Not conglomeratic. Forms smooth, high, resistant cliffs. (= Unit VI Of thissreport)s acs NN ev cele aah a oisaee alec. ore iele aaener tars Bl 2A Fe Claystone, variegated, purplish-red or maroon in lower two thirds, gray in upper third. Bentonitic, calcareous and sandy, several discontinuous sand 184 lenses up to 10 inches (25 cm) thick. Chalcedony and barite concretions very abundant, gypsum ap- parently absent. Unstratified and nonresistant. (= Little Sheep Mudstone Member, Cloverly Forma- tion: Unit WV OL this TeDOLL) », «0 «crs svcuaienwre aie cianeuereds Conglomerate, sandy with abundant pebbles up to l inch (2.5 cm) in diameter. Gray, weathering to dark-gray and gray-brown. Black and dark-brown chert predominate, some yellow chertand light- colored quartzite. Grains and pebbles wellrounded. Parallel and cross-laminations. (=Pryor conglom- erate: Uinit IV. Of tis: report). .s.s,s 4.eusremeseane slo MORRISON FORMATION: Sandstone, tan to light-brown, fine- to medium- grained. Pebbles rare. Chiefly well-rounded grains of quartz and light-colored chert. Cross- laminations common, massive bedding. (This unit clearly separable on lithic character and by a con- Spicuous irregular break from overlying conglom- erate. Tentatively equated with Unit II in this re- DOLE) esciche, seca MPsadstieneue cs Meovaweioke, haces reaeuanc nein Re cuseenmnenees Claystone, greenish-gray, bentonitic, unstratified and nonresistant, often concealed beneath fallen blocks and talus of overlying sandstone and con- glomerate that litter most lower slopes. (= part of Unit 1? (of this report) ac em ecsicrss cueke tere ae reece Sandstone and shale interbedded. Sandstones tan to yellow, from 6 inches to 2 feet (15 to 60 cm) thick, apparently rather persistent. Shales, thinly bedded and fissile, gray on fresh surfaces, weath- ering tan. (=part of Unit I? of this report)...... Claystone, yellow to gray-green, fresh surfaces pale-green — almost olive in color. Massive or unbedded. Sandy at some levels. Chalcedony and gypsum absent. Calcareous throughout. ( Unit I OF this WEpor et}... sxa.s:s. ¢.sueoajie ‘ausloleeenelaneeetenen eee ence nee Sandstone, tan, massive, resistant and conspicu- ous ledge-former. Medium-grained quartz well- cemented with Calcite... one. siac,teve wise enete C6560 60d 05 Thickness (ft) (m) Us QB 45 Wo 7/ 62 18.9 Ti “ees 16 Ae 34 HORS 3 0.9 185 Thickness 1. Claystone, yellow to pale-green, weathering (ft) (m) predominantly yellow. Forms low-angle, soft slopes. No concretions or gypsum. Calcareous locally. Base concealed. (= part of Unit I of Et See DUOFEM... Lhe te mate etch alae Gekerne ela ciate oe Oe > 24: JS TES Concealed. HEC DION MAOSeNCROOKEDUGREERK Section measured across series of cuestas and ridges between Crooked Creek on the west and the Dryhead road on the east, approximately 1.5 miles (2.4 km) south of the Montana State line. W1/2 Sec. 27 and N 1/2 Sec. 28, T.58 N., R.95 W., Big Horn County, Wyoming. The upper part of the sequence is in the immediate vicinity of Yale Localities YPM 63-20 and 22. SYKES MOUNTAIN FORMATION: Zi Sandstone, light-gray, weathers tan to light orange, massive, well-indurated, medium-grained, strongly cross-laminated, thin-bedded and fine-grained at base. (= Greybull sandstone; Sykes Mountain For- matiornnin parts UnibiiMohithismeport)2 re rk eitts.eie8 2.4 CLOVERLY FORMATION: FAVE LES) 1Lt3},- Claystone, gray, yellow-brown and brown; weath- ers light yellow brown (rusty), large to small iron- stone concretions, poorly stratified to massive, silty throughout. (= Himes Member in part? of Cloverly Formation; part of Unit VII of this report). 11.5 3.5 Siltstone, olive, weathering tan, thin-bedded, well-cemented, becoming more massive and coarser grained at the base, brick-red and brown mottling, gypsum (satin spar) seam at base. (= Himes Mem- ber in part of Cloverly Formation; part of Unit VIIof thisreport) ics eee betes Scots yevtsrrteuiss cas 5. aa a7 Claystone, variegated yellow to olive, weathering gray maroon and red, mottled, silty in lower third. (= part of Himes Member, Cloverly Formation; Unit VIE Giithisirenonh): Sak tlneeeceings aside he mwas eee old 3 186 Zhe fis 15. 14. 13s iene Sandstone, white, medium-grained, rounded quartz grains, friable, cross-laminated, massive bedding. (= Himes Member, in part, of Cloverly Formation; part of Unit VIl of thisinepont).t:@icesisiie. Sees sete Claystone, variegated dark to light-gray, with green and red-brown mottling; weathers brown, red brown, maroon, massive, silty becoming sandy at base. Forms steep, irregularly fluted slopes. Fresh material breaks into irregular slickensided blocks. Fossil bone at base. Localities YPM 63-17, 63-18, 63-19 and 63-20 produced bone from the lower part of this claystone. Polished pebbles common, but not abundant and not closely associated with fossil bone. (= part of Himes Member, Cloverly Forma- tionsnUMit: VIW Of hESIEe PORE e «cure oe cucu cia eer Sandstone, light-gray to green, coarse- to medium- grained, massive, cross-laminations. YPM localities 63-17, 63-18, 63-19 and 63-20 produced bone from nearly all levels in this sandstone. (= part of Himes Member, Cloverly Formation; part of UNndteVill of ithiis report) Si sslas coke 2 ie eevatel cians. oan Claystone, variegated dark-brick-red with green and yellow mottling, weathers brown, silty, moder- ate stratification. Some polished pebbles, but not closely associated with fossil bone. Localities YPM 63-18, 63-19, 63-27, and 63-28 produced fossil bone from several levels within this clay- stone. (= Himes Member in part, Cloverly Forma- tion spart of Minit VITOb thisepepor)reict., sec seue rien: Sandstone, gray to yellow-tan, weathers tan; ir- regular green and reddish clay seams, coarse- grained, quartz, feldspar and minor ferric minerals. Massive, resistant, strongly cross-laminated; pebbles and clay balls at base. Localities YPM 63-16 and 63-32 are situated near the top of this unit. (= Unit! VIF thitswre pert) asters epee ee oe Claystone, dark-gray to gray-green, weathers to light gray and pale purple. Fresh material breaks into irregular chips, bentonitic, satin spar; cal- careous concretions rare. Chalcedony and barite concretions also rare. Forms low, rounded, vege- tation-free slopes, surfaces softand "popcorn"-like. Thickness (ft) (m) 4 Les Ali a2 WAS 4 ka 4 1.2 hh Ss hoes 187 Thickness Discontinuous 6 inch (15 cm) sandstone lenses, (Et) (m) usually white or tan. Some fossil bone in upper 25 to 30 feet (7.5 to 9 m). Also petrified wood. Localities YPM 62-14, 63-22 and PU 49-1 occur in the upper third of this claystone. (= Little Sheep Mudstone Member, Cloverly Formation; Unit V of this TEpOrt)i~ .« « Suns Sinan See ee Miata ets eae aeiatte vane Fae OG sat SO ll. Sandstone, brown, coarse-grained, well-rounded, sparkly quartz grains, well-cemented. Massive with some cross-laminations. Resistant, forms prominent, persistent ledge. sto a4 oid westeremave axe ovens 10. Claystone, variegated, rose-pink to light-purple. Breaks into irregular chips, poorly laminated. Cal- careous. No chalcedony observed. (= part of Uris Vig @ike thts: OT OE) S creaeycacney ic Ste lale Gio spevexclove-cuartwodane 27 Baz 9. Sandstone, conglomeratic in upper 15 to 18 feet (4.5 to 5.5 m). Medium-gray on fresh exposures, weathers dark gray to brown. Consists of coarse quartz and dark chert grains. Pebbles up to 0.75 inch (1.6 cm), chiefly dark chert and yellow or brown quartzite. Strongly cross-laminated. Mas- sive beds, very resistant. Forms cap-rock of ir- regular, knobby and pedestal-marked surfaces, capping ridge west of Dryhead road. No distinct break between conglomerate and sandstone: grada- tional textural change. (= Pryor Conglomerate; Unit IY Of this TepORe) seme cis ahs er hean ties Ry ee nie 28 8.5 MORRISON FORMATION: 8. Claystone, weathers gray and pale green. Fresh surfaces medium-gray but with greenish cast. Generally sandy, but unstratified. Several 1 to 6 inch (2.5 to 15 cm) discontinuous sand lenses, especially in lower half. No chalcedony or gypsum observed: (=Unit Il of, this report) mice eure se > 2G Bi - L585 7. Sandstone, yellow-brown fresh and weathered. Mas- sive, forming prominent cap-rock. Weathers into thick, smoothly rounded blocks. Medium- to fine- grained, quartz and light to nearly white chert. Cross-laminations throughout. (= Unit II? of this VEWOLE) sis daisies Ste eis te Soe Oe eho o aame ane ela eee Sines Se eer ey Diez 188 Thickness 6. Claystone, gray, weathers tan, poorly stratified, (ft) (m) non-resistant. Forms low-angle slopes where not protected by overlying sandstone. Calcareous and silty, but no chalcedony, or limestone concretions, or gypsum observed. (= part of Unit I of this re- DOVE) Pe Ps SEER ES Ie 5 PE ere ale ee ener e seme een 8.2 5. Sandstone, light-tan both fresh and weathered. Medium-grained, rounded quartz. Massive, paral- lel and cross-stratification. Resistant, weathers to smooth, rounded blocks and cliff surfaces. Very similar in appearance to # 7 above except white chert is rare or lacking. (= part of Unit I of this FSport)s Gk Ses A SO Oe OP oe ee ee 6.4 4. Claystone, gray, weathers pale yellow. Silty and calcareous. Rare selenite crystals observed, but not found in situ. Forms deeply weathered, low- angle slopes. (= part of Unit 1 of this report)..... 19 one 3. Sandstone, weathers brown, tan on fresh surfaces. Blocky and massive in lower half, thin-bedded in upper part. Medium-grained, rounded quartz with calcareous and limonitic cement. (= part of Unit I Of this TEeporey ees ae TT ow ees Sere ears Le a ees 4.2 2. Claystone, gray-green on fresh surfaces, weathers green to greenish tan. Partly concealed, but at least locally shows thin parallel-stratification. Not fissile. (Tentatively referred to Unit I, but may be upper part of Sundance Formation)......... a Sie’ SUNDANCE FORMATION: 1. Sandstone, brown, alternating massive and paper-thin parallel-stratification. '"Paper- parting" of weathered exposures characteristic. Medium-grained quartz, some glauconite and calcareous throughout. No marine invertebrate remains found in situ, but surfaces near by are strewn with belemnites and Gryphaea....... Not measured SCE TO Ny Sele ES U MiG 2K 189 Section measured across east limb of Gypsum Creek Anticline, just north of the Warren road. Horn County, Wyoming. SYKES MOUNTAIN FORMATION: Nes Sandstone, brown to orange, with dark, fissile shale interbeds. Fine-grained quartz. Abundant ripple marks and fucoidal impressions. Forms re- sistant ridge. Overlain by thin sandstone layers and dark fissile shale. (= Greybull sandstone?; Sykes Mountain Formation in part; Unit VIII of this ROport)é apes Meher, SSRIS. een. sale Me CLOVERLY FORMATION: 10% Claystone, maroon to red-brown, some blue-gray, maroon and purple mottling on fresh surfaces. Un- Stratified. Sandy near base. Polished pebbles common throughout. Occasional gypsum (satin spar) seams. (= Himes Member, Cloverly Forma- Lion: (UnstiVllpof thishrepores Scie « sce sheiane Sas Sandstone, weathers buff to orange tan, yellow locally. Tanon fresh surfaces. Medium- to coarse-grained. Not conglomeratic. Chiefly quartz, some chert and feldspar. Cross-lamina- tions pronounced. Massive and resistant, forms very prominent ridge. (= Unit VI of this report)... Claystone, weathers to pastel rose and purple, purplish dark gray on fresh surfaces. Unstratified, breaks into irregular, waxy chips. Bentonitic and weathers to soft "popcorn" surfaces,generally free of vegetation. Chalcedony and barite concretions very abundant, satin spar and selenite crystals are also common. Occasional buff to white sandstone wedges up to 6 inches (15 cm) thick. (= Little Sheep Mudstone Member, Cloverly Formation; Unit V of thissre pone) ht.iack Sys saevee skate axes Ape Oke Sandstone, gray to light-brown, gray on fresh sur- faces. Coarse-grained,angular to sub-rounded quartz, dark and light chert, and yellow quartzite?. Massive and very resistant—a ridge-former. Not SE 1/4-Seex 22 )-Ti58 IN. #Ra96; Way Big Thickness (ft) (m) 7 a 21 6.4 58: «veer eae Saad 190 Thickness conglomeratic at the site of this section, but (£t) (m) several conglomeratic wedges occur in exposures to the north. Cross-laminations common and well- developed throughout full thickness. (Tentatively equated with Unit VI;= Pryor Conglomerate)....... 46 14 MORRISON FORMATION: 6. Claystone, variegated, pale-green and gray in upper 80 feet (24 m), gray, rose and orange in lower 60 feet (18 m). Medium- to light-gray on fresh surfaces. Sandy or silty throughout, promi- nent light-tan sandstone wedges and strata scat- tered throughout section, including a persistent 2 foot (0.6 m) massive sandstone at 58 feet (17.7 m) above base. Calcareous but lacks calcite, barite and chalcedony concretions. Gypsumalso lacking. (=) Unie sill? 208 tthisine pore) iene eee Sap el a ate tates 145) HAAN 5. Sandstone, white to light-tan, white and sparkly on fresh surfaces. Chiefly rounded quartz with some white and dark chert in medium-sized grains. Cross- laminations frequent. Persistent, massive bedding. Moderately well-indurated, but surfaces friable. (= Unit Il ofthis report) ee. i.e t BESS a 19 5.8 4. Claystone, neutral-gray, medium to dark, poorly stratified and nonfissile. Chalcedony and calcite concretions apparently absent. (= part of Unit I Of this neport) i. cee sora cs chee rene ME ws BR AS Big) lon 3. Sandstone, yellow to gray, buff on fresh surfaces. Thin-bedded with ripple marks on upper bedding planes. Medium- to fine-grained. Concealed locally. (= part Of Unit of this! report)is a... es 5 eS 2. Claystone, yellow to greenish-gray, medium-gray on fresh surfaces. Poorly exposed, but thinly stra- tified locally. Very sandy at base, and grades into green, glauconitic, thin-bedded sandstone beneath. May represent upper part of Sundance Formation. (Unitslsof this reportjiacc. dias uae Mots Gaee ces Dich Pere ee 3.6 SUNDANCE FORMATION: 1. Sandstone, greenish-gray, glauconite and quartz highly calcareous. Thin-bedded with occasional interbeds of fissile, sandy shale. Fragments of Gryphaea abundant 15 to 30 feet (4.5 to 9 m) down section, but infrequently noted in situ in these Strata. << > srw smn Suto ooo chaos Not measured SEG eE LOM 22) = RED) DOME 191 Composite section measured in discontinuous hogbacks on south side of Red Dome, immediately north and south of the Bridger-Pryor road. S 1/2 Sec. 20,2): 71S), Ru22 Es, Carbon Gounty? Montana. Ne Thickness SYKES MOUNTAIN FORMATION: (ft) Sandstone, dark, rusty-brown on weathered sur- faces, light-brown on fresh surfaces. Thin and massive bedding, with some shale interbeds. Fine- grained, chiefly quartz with occasional dark grains. Ironstone concretions at top, upper strata with dark ironstone staining. Fewripple marks. (= Greybull sandstone ?; Sykes Mountain Formation in part; (m) Unit Vill of thisre pert): < 22: NaHS. iss EP ie Be Mas MOS) Bee CLOVERLY FORMATION: 1g 10. Claystone, variegated, red-brown, maroon, purple- gray and gray, some rusty-yellow in upper 4 to 8 feet (1.2 to 2.4m). Fresh surfaces green-gray with green and red-brown mottling. Sandy in lower half, massive throughout. Fresh rock breaks into irregular blocks with shiny slickensided surfaces. Polished stones or "gastroliths" common. Locality YPM 64-52 is situated near the middle of this unit. (= Himes Member, Cloverly Formation; Unit VII of EHS Fe port) see). ee A aan Sete. se 265 Sandstone, yellow-brown, medium-grained, sub- angular quartz, feldspar and light-colored chert. Friable and poorly cemented. Massive with occa- sional cross-beds. (= Unit VI? of this report).... 3 Claystone, light-gray and blue-gray, generally medium-gray on fresh surfaces. Unstratified, breaks into irregular, "greasy" chips. Bentonitic, weathers to soft "popcorn" surfaces. Chalcedony concretions common, occasional seams of satin spar and selenite crystals. Infrequent, discontinu- ous sandstone lenses. (= Little Sheep Mudstone Member, Cloverly Formation; Unit V of this report). 64 Conglomerate, dark-gray and brown, fresh surfaces also dark-gray and brown. Coarse sand grains and subrounded pebbles up to 1 inch (2.5 cm) of quartz, GS) 8 O29 Se 5 192 Thickness yellow to brown quartzite, black and brown chert. (ft) (m) Massive bedding with frequent large cross-beds. Very resistant, forms massive vertical cliffs and prominent ridges, a cap-rock. (= Pryor Conglom- erate: Unit IV of this.seport)..4,.uctmmeeniades oh os | be aloe MORRISON FORMATION: Claystone, variegated, red-brown, green, yellow- gray, fresh surfaces predominantly gray-green. Un- stratified, sandy and calcareous throughout. Sev- eral 3 to 6 inch (7.5 to 15 cm) sandstone lenses, well-indurated and resistant. Claystone, nonresis- tant, forms deep-weathered, silty-sandy slopes. Chalcedony and barite concretions apparently lack- ing. \(SjUnit Iof, this,ceport) ..ctseeteeeereneei Bee Sandstone, light-yellow to light- gray or white, nearly white on fresh surfaces. Some 6 to 1Sinch (15 to 37.5 cm) strata but most of the unit is very thin-bedded — some of it extremely thin-bedded, weathering into "paper-thin" sheets. Medium- sized grains of quartz with some white chert. Oc- casional cross-beds, but no ripple marks. (Ten- tatively equated with Unit Il in this report)........ 17 Claystone, greenish-gray, fresh surfaces darker gray. Conspicuous light-gray and pink zone near the middle. Unstratified. Silty and calcareous throughout. Several discontinuous sandstone wedges just below the pink zone. Nochalcedony. (= part of Unitsivofithismeapont)= sevrserieiae nalaerevetel LI CS Sandstone, yellow to light-tan, buff on fresh sur- faces. Massive bedding, medium-grained, well- rounded quartz grains, firmly cemented with cal- cite... Sparkly on:fresh sumfacesia. 2 ciciclere oh eteeeete 6 Claystone, like unit #5 above, greenish-gray to yel- low onweathered surfaces. Fresh surfaces dark to medium gray. Unstratified, and nonresistant, weath- ers to low-angle slopes. Silty and calcareous through- out. (= part, of, Unit 1 jo this, report). secre coke eee Concealed interval sg,..ic.scend cpanel cxeveusnsitecncleheueneneeenane 15- 26. Se 22 Le 4. 8 2 8 5- 193 Thickness SUNDANCE FORMATION: (ft) (m) 1. Thin-bedded, sandstone and shale. Medium- grained and calcareous. Shell fragments, some levels coquinoid. Glauconitic........ biases Net Sie Not measured Concealed. ob © LO Ns t23n02SIM Dine) FOR Ks BIRT DG, E RS Gukbe K This section was measured on the south-facing scarp directly across from the prominent pyramid-like butte, 0.5 mile (0.8 km) north of Middle Fork of Bridger Creek. NE 1/4 Sec. 17, T.7S., R.24E., CarbonCounty, Montana. Five Yale localities (YPM 64-57, 58, 74, 75 and 65-1) are within 200 yards (183 m) of this section site and three others, (YPM 64- 53, 54 and 56) and probably one American Museum locality (AM 33-8) are 0.5 to 0.75 mile (0.8 to 1.2 km) distant. SYKES MOUNTAIN FORMATION: 10. Sandstone, buff, weathering tan to yellow, "rust- stained’, fine-grained to medium-grained, massive, ripple-marked, overlain by gray, fissile shale. Ironstone concretions near top and common in over- lying shale (= Greybull sandstone; Sykes Mountain Formation in part; Unit VIII of this report)......2.. 12 3.6 CLOVERLY FORMATION: 9. Claystone, variegated gray, yellow, rust-brown, weathers yellow buff to gray, massive to poorly bedded, some ironstone concretions (= part of Himes Member, Cloverly Formation; part of Unit VEO this FE DORE) acts o asiewe usta al < tavet Shei ousvenntes ceanete ile Bars 8. Sandstone, buff to light-gray, weathers to dark rust, yellow, fine-grained, well-indurated, mas- SIVG)s 0:0 ‘ein aie avlepeboimieeetetete ls voctuala vet's alelisoeies ake ioweLotes saake 1 0.3 7. Claystone, gray with yellow to rust staining, weathers gray at base, variegatedred browninmid- section, and variegated yellow, brown and buff in upper half. Massive non-bedded, forms steep, fluted slopes. Occasional polished pebbles. 194: Thickness Fossil bone level 12 feet (3.6 m) above base (ft) (m) (YPM 64-53). (= part of Himes Member, Cloverly Formation: Unit Villvofthis report) taste see eerie eee 28 gag 6. Claystone, variegated red and gray, weathers brick red to purple with yellow limonite staining, silty, poor stratification, fissile in part. Polished pebbles common throughout, but not closely asso- ciated with fossil bone. Bone, at 3 feet (0.9 m) below top (YPM 64-61, 65-1) and 2 feet (0.6 m) above base (YPM 64-65). (= part of Himes Member, Cloverly Formation; Unit VII of this report)....... 18 S)a6) 5. Siltstone, gray, weathers brown, well-indurated, usually not exposed..... e igvaveteitatietaverareyiereetene Serotcene 1 OFS 4. Claystone, gray, becoming darker near top, to variegated green and red, weathers red brown, yellow to gray, non-bedded, silty. Bone-bearing in lower 4 feet (1.2 m) (YPM 64-57, 64-58, 64-74, 64=75). (= part of Unit’ Vilbofthisirepost) eee o. ) Dixit 3. Siltstone, dull-gray to red, weathers brown to red- dish, poorly stratified, ledge-former............ 25 SU kOe 2. Sandstone, gray to buff, weathers to tan or brown, fine- to medium-grained, well-indurated, massive 0.3 (= "Unite Vi? of this report) ies uh chet ene TR Pe eae one 1. Claystone, dark-gray weathering to light-gray. Unstratified, bentonitic, weathering to soft "pop- corn" surfaces littered with chalcedony and barite concretions. Fossil bone at several levels in section exposed (YPM 64-54). Base concealed. (= part of Little Sheep Mudstone Member, Cloverly Formation; partiof Unit’ Veol this report) an areas i RESUZ S164 Concealed. DEG TLIO N24) =) Bal EWA ERs Gon BiEK Composite section measured in the exposures south and north of North Fork Bluewater Creek in the immediate vicinity of the point where the Fish Hatchery road crosses Bluewater Creek. The lower part of the sec- tion was measured north of this crossing in SE 1/4 Sec. 5 and the upper part of the section was measured southwest of the crossing in NW 1/4 pec. 8, T.6 S., R. 24 E. , Carbon County, Montana: SYKES MOUNTAIN FORMATION: 13. Sandstone, orange and rusty-brown, light-brown and sparkly on fresh surfaces. Thin-bedded and interbedded with black, fissile shale. Fine- grained quartz, well-cemented with limonite and hematite. Some ripple marks. Overlain by fissile, dark shale with thin strata of dark sandstone. (= Greybull sandstone; Sykes Mountain Formation im part: Unit VINVoOk thig reports. Gi... 6 Show CLOVERLY FORMATION: 16 We HO! Claystone, variegated, predominantly red, red- brown, maroon, purple and violet-gray. Unstrati- fied, breaks into irregular violet-gray and maroon- mottled blocks with some slickensides. Sandy throughout. Few sand lenses. One 6 foot (1.8 m) sandstone wedge 200 yds (183 m) to the south, 20 feet (6.1 m) belowtop. Polished pebbles or "gastroliths" present, but not abundant. Localities YPM 64-71 and 64-72 are situated near the base of this claystone. (= Himes Member, Cloverly For- mations UnitVil of this mepork) a iiteies a's eetenees Sandstone, tan, yellow to tan on fresh surfaces. Medium-grained, subrounded quartz with some feldspar. Thin-bedded, but with prominent cross- beds. General appearance is very similar to #13 above, but lighter in color and lacking shale inter- beds. + «(= Unit VLobthis report) aio aera Claystone, variegated, predominantly dark-gray, light-gray to white, pink. Fresh surfaces gener- ally drab medium- to dark-gray. Unstratified, breaks into small irregular dark-gray chips. Ben- tonitic in upper part, weathering to light-gray, soft, "popcorn"-covered gentle slopes. Chalced- ony and barite concretions abundant, except in upper 15 feet (4.5 m). Calcareous concretions common in lower half. Several 1 to 3 inch (2.5 to 7.5 cm), white limestone strata at the 40 and 48 foot (12 and 14.5 m) levels. A persistent dark- brown, 8 to 12 inch (20 to 30 cm) limestone, dark- gray on fresh surface, at the 78 foot (24 m) level. Irregular dark-brown fragments of this limestone lit- terallslopes beneath. (= Little Sheep Mudstone Mem- ber, Cloverly Formation; Unit V of this report)...... 195 Thickness (ft) (m) 7 5.2 og oy eas 3 0.9 96. 22:952 196 Thickness Conglomerate, dark-gray and brown, very conspicu- (ft) ous massive "rim rock" capping many dip slopes and mesas in the area. Coarse sand and pebbles up to 2 and 3 inches (5 and 7.5 cm), composed chiefly of black, gray, dark-brown and yellow chert, some yellow quartzite and white quartz. Sand lenses have peppery appearance. All fragments well- to subrounded. Large scale cross-beds in sandstone and fine conglomerate facies. (= Pryor Conglom- erate? Unit 1V ofthis report) save ke sieveees beekeeeerene ome re) MORRISON FORMATION: 8. Claystone, blue-gray and light-gray, calcareous and silty. Unstratified and nonresistant. Poorly exposed, often covered by large blocks fallen from overlying unit. No chalcedony or barite concre- tions observed. Some thin (6 to 10 inch [15 to25 cm] ) sandstone strata noted, all appear to be dis- continuous over short distances, but exposures do not permit verification. (= part of Unit III of this FE DONE); cwidsvand whaees oteneiaiie be eavenegd o Seine 2 ae ee eS Sandstone, tan, light-gray on fresh surfaces. Medium-grained, but some pebbly lamina locally. Weathers into smooth, rounded, massive blocks. Bedding massive, cross-laminations rare. Promi- nent ledge-former locally, but not as prominent as unit # 9 above. Grains almost entirely quartz, some light-gray chert. (Tentatively equated with Unit IM omMthisyreport)i perenne ae Reel oe Sa ole Claystone, variegated, rose-colored in lower half, tan or gray in upper half. Silty and calcareous throughout. Nonresistant and partially concealed. Infrequent satin spar seams, but no chalcedony, barite or calcareous concretions. (=part of Unit I of: this: report)'s’.< aadare cud ere eedlerei tery eee eS Sandstone, light-tan both weathered and fresh. Fine-grained, almost a siltstone. Massive bedding, a resistant ledge-former. (Probably equals part of Unit: L.of this:irepont) . cane, archers se nee 3 Claystone, greenish-gray to very pale-green. Fresh surfaces medium-gray. Unstratified. (= part of Unit, ok this report) easter cameo ete ahanecale aime yeaa tees Zh Ls. Zo ile 26. 0. (m) 7 8 9 17 Thickness Sandstone, light-tan or buff, fresh surfaces nearly (ft) (m) white. Fine-grained, massive and well-indurated, forming prominent, light-colored bluffs........... 17 Sry Claystone, greenish-yellow, sandy and calcareous. Nonresistant and largely concealed. ( May repre- Sent Upper part Of Sundance: F OrmMation. )..«.< s.015 >4.5 Concealed interval ...... Gh chiatio a anememete oe taetee lene phere 35 =" 08 eae Conglomerate , dark-gray and brown. Lower 25 feet (7.6 m) coarse gray sandstone, massive and strongly cross-laminated, with occasional 0.25 to 0.5 inch (0.6 to 1.2 cm) pebbles of dark chert. Upper 30 feet (9 m), conglomeratic with well- rounded pebbles up to 2 inches (5 cm) of black, gray and brown chert, and yellow and gray quart- zite. Massive, well-cemented and resistant. (= Pryor Conglomerate; Unit IV of this report) .... 55; Ges MORRISON FORMATION: Concealed: tntervialins ence oe oro ce eee cre eee ie aot 42~ Toeee Sandstone, buff to light-brown, fresh surfaces buff and nearly white. Medium- to coarse-grained quartz with some white or light-gray chert of well- rounded grains. Massive with some cross-strati- fication. (= Uniti? of this report) The only information available now places this site at 25 miles (40 km) eastof Pryor, Montana, which suggests the Cashen ranch area (similar descriptions were given for other sites discovered later that have been pinpointed in the Cashen ranch area), probably along Beauvais Creek. 207 Soon AM 3I- _ (P‘AM32-10: e” (PiAM324§ feet) ssn 1000 2000 N 300 _ 600 ; meters ; LOCALITY MAP U See regional map (Fig.2) in pocket for location AM 31-9 SE 1/4 Sec. 16, T.4S., R.26 E., 3.5 miles (5.6 km) north of Pryor, Yellowstone County, Montana. See Locality Map P. Horizon: Unit V? Specimen collected: Sauropelta edwardsi (AMNH 3016). AM 31-10 SW 1/4 Sec. 16, T.4 S., R.26 E., 0.25 mile (0.4 km) west of AM31-9, Yellowstone County, Montana. See Locality Map P. Horizon: Unit VII. Specimen collected: Tenontosaurus tilletti (AMNH 3017). 6 Sites AM 31-9 and 31-10 were relocated with the help of Mr. Roy Marsh of Pryor, Mon- tana, who worked for Barnum Brown at these excavations. 208 LOCALITY MAP P AM 32-2 SW 1/4 Sec. 8, T.5 S., R.30 E., 6 miles (9.6 km) SE of Cashen ranch house, on Mott Creek, Big Horn County, Montana. See Locality Map X. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (AMNH 3031). Uae Brown described the location of sites 32-2, 4, and5 as"9miles (14.4km) east of Cashen's ranch on Mott Creek". However, there are no exposures of the Cloverly For mation more than 2 miles to the east of Cashen's ranch. From Horse Coulée the outcrop trends southeasterly and is crossed by Mott Creek 6 miles (9.6 km) southeast of Cashen's ranch. No where else along the course of Mott Creek does the Cloverly Formation crop out. Therefore, I have provisionally placed localities AM 32-2, 32-4, and 32-5 within a 2000 foot (610 m) radius of this crossing. 209 NE 1/4 Sec. 20, T.5 S., R.28 E. , Approximately 1.5 miles (2.4 km) west of Thor K. Lande ranch, on Push Creek, Big Horn County, Montana. See Locality Map Q. Horizon: Unit V, Vi or VII. Specimens collected: Sauropelta edwardsi (AMNH 3032). SW 1/4 Sec. 8, T.5 S., R.30 E., 6 miles (9.6 km) SE of Cashen ranch house, on Mott Creek, Big Horn County, Montana. See Locality Map X. Horizon: unknown. Specimen collected: Sauropelta edwardsi (AMNH 3033). SW 1/4 Sec. 8, T.5 S., R.30 E., 6 miles (9.6 km) SE of Cashen ranch house, on Mott Creek, Big Horn County, Montana. See Locality Map X. Horizon: unknown. Specimens collected: Deinonychus antirrhopus (AMNH uncatalogued); Tenontosaurus tilletti (AMNH 3034). feet 1000 2000 —-—————} Sy 300 600...” meters one LOCALITY MAP X eTrownts field records describe this locality simply as "10 miles (16 km)SWof Cashen's ranch, Montana", but a field photograph places the "nodosaur" (AMNH 3232) and "camp- tosaur" (AMNH 3062?) in the region specified here and in Locality Map Q. 210 AM 32-6 SEM 40Seces2) Le40S eRe 200 bee ler2 Semillen(Zakimn) sSS\Waota@ashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit VI, 3 feet (0.9 m) below Unit VII. Specimen collected: Sauropelta edwardsi (AMNH 3035). AM 32-7 SE 1/4 Sec. 32, T. 4S., R.29.E., 1.25 mile (2 km) SSW of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit VI, 8 feet (2.4m) below Unit VII. Specimen collected: Sauropelta edwardsi (AMNH 3036). AM 32-8 NE 1/4 Sec. 32, T.4 S., R.29 E., 0.75 mile (1.2 km) SSW of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit V, 5 to 15 feet (1.5 to 4.5 m) below Unit VI. Specimen collected: Deinonychus antirrhopus (AMNH 3037). AM 32-10? These sites have been placed on Locality Map U, on information re- AM 32-11? corded by Barnum Brownon an oblique areal photograph (see Plate 6:B). It is not known what, if anything, was collected at these sites. All known specimens collected by Brown in the Crow Indian Reservation are accounted for and known to have come from other sites. These sites appear to be in Unit V. AM eeeie SW 1/4 Sec. 26, T.7 N., R.16 E., Wheatland County, Montana. Horizon: Unit VII? , approximately 60 feet (18 m) below base of Unit VIII. Specimens collected: Tenontosaurus tilletti (AMNH 3040); Deinonychus antirrhopus (teeth associated with AMNH 3041); Microvenator celer (AMNH 3041). AM 33-2 Sec. 26, 27, 34, or 35, T.7 N., R.16 E., Wheatland County, Montana. Horizon: Unit VII? Specimen collected: Sauropoda (AMNH 3042). AM 33-3 Sec. 26, 27, 34 or 35, T.7 N., R.16 E., Wheatland County, Montana. Horizon: Unit VII?. Specimen collected: Tenontosaurus tilletti (AMNH 3043). 1 AM 33-4 g Sec. 34, T.7 N.?, R.16 E. , Wheatland County, Montana. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (AMNH 3044). AM CO-50" Sec. 34, T.7 N. ?, R.16 E., Wheatland County, Montana. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (AMNH 3045). opeounes field records place the following six localities at Middle Dome, 12 miles (19.2 km) southeast of Harlowton, Montana. Except for Locality 33-1, no record ofthe precise location exists. A photograph (Plate 7:B) from Barnum Brown's files pinpoints Locality AM 33-1 on the north rim of Middle Dome approximately 0.5 mile (0.8km) from the north entrance into the Middle Dome basin. Inquiry and exploration of the Middle Dome exposures failed to determine other locations. UTnese two localities were placed by Barnum Brown in Sec. 34, T.4 N., R.16 E. There are no Cloverly exposures within 15 miles (24 km) of this location anditis probable that Brown's notation was intended to read T.7 N. instead of T.4 N., where Cloverly exposures crop out along the south flank of Middle Dome. ail AM 33-6 Sec. 26; 27, 34 or 35, T.7 N., R.16 E. , Wheatland County, Montana. Horizon: unknown. Specimen collected: Sauropelta? (AMNH 3046). AM 33-811 25eCGumle OG lla ioe Ra24 Ey sormilesi (926 km)! SEiof Bridger: Carbon County, Montana. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (AMNH 3050). AM pees ?NE 1/4 Sec. 20, T.5 S., R.28 E. , approximately 8 miles (12.8 km) SW of Cashen ranch house and 1.5 mile (2. 4 km) west of Thor K. Lande ranch on Push Creek, Big Horn County, Montana. See Locality Map Q. Horizon: Unit V, VI or VII. Specimen collected: Tenontosaurus tilletti (AMNH 3062). AM 38-2 NW 1/4 Sec. 28, T.4S., R. 29 E., 0.5 mile (0.8 km) north of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: unknown. Specimen collected: Sauropelta? (AMNH 3064). AM 38-3/° T.4 8S. , R.29 E. , Big Horn County, Montana. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (AMNH 3061). AM 33-414 T.7 N. , R.16 E. , Wheatland County, Montana. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (AMNH 3063). tone precise location of this site isnotknown. Barnum Brown placed it "11 miles (17. 6 km) east of Bridger, Montana, near Red Dome.“ No Cloverly exposures could be found in the area 11 miles east of Bridger, but extensive exposures do occur approximately 6 miles (9.6 km) SE of Bridger and in the immediate vicinity of Red Dome. Consequently, it is presumed that locality AM 33-8 was in this area, probably close to localities YPM 64-54, 64-57, 64-58, 64-74, 64-75. See Locality Map L. a6 precise location can be given for this site because R. T. Bird recorded its location simply as 10 miles (16 km) SW of Cashen's ranch. However, the Cloverly formation is completely covered west of the ridge end 1.5 miles (2.4 km) west of Push Creek, making it unlikely that the site was situated further to the west. Moreover, a handwritten nota- tion by Brown on the back of a photograph indicates that this locality was at the western end of the outcrop in the area cited here and shown in Locality Map Q, inthe vicinity of AM 32-3. No detailed field records are available to establish this, though. 3a precise location cannot be given for this locality. R.T. Bird described it as"2 miles (3.2 km) East of Cashen's ranch", which would place it somewhere along the east side of Horse Coulée near YPM 64-23 if distances and bearings were recorded accurately. Serie ld records of R. T. Bird indicate this locality was in Middle Dome, 12 miles(19. 2 km) southeast of Harlowton, Montana. This would place it somewhere in the southern part of T.7 N., R.16 E., Wheatland County, Montana. 212 15 ’ AM. 55=1)? T.4 S.,R.29 E. , Big Horn County, Montana. Horizon: unknown. : Specimen collected: ?Ornithomimus sp. (AMNH uncatalogued). AM 55-22>° T.4 S., R.29 E. , Big Horn County, Montana. Horizon: unknown. Specimen collected: ?Ornithomimus sp. (AMNH uncatalogued). UNIVERSITY OF OKLAHOMA LOCALITIES OU AO-U1 © SE 1/4 Sec. 32, T.4 S., R.29 E., 1.25 miles (2 km) SSW of Cashen ranch house, 400 yards (366 m) west of road, Big Horn County, Montana. See Locality Map U. Horizon: Unit V. Specimen collected: Tenontosaurus tilletti (OU 11). OU 40-12'° SE 1/4 Sec. 32, T.4 S., R.29 E., 1.25 miles (2 km) SSW of Cashen ranch house near OU 40-11, Big Horn County, Montana. See Locality Map U. Horizon: Unit V. Specimen collected: Tenontosaurus tilletti (OU 12). PRINCETON UNIVERSITY LOCALITIES PU moe! T.6 N., R.15 E., or T.6 N., R.16 E. , Wheatland County, Montana. Horizon: unknown. Specimen collected: Tenontosaurus tilletti (PU 16338). PU Boni NW 1/4 Sec. 34, T.58 N., R.95 W., 1.75 miles (2.8 km) SW of Tillett Fish Hatchery, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit V, 35 to 40 feet (10.6 to 12. 2 m) below Unit VI. Specimens collected: Ceratodus frazieri (VPM 5276); Tenontosaurus tilletti (PU 16514). No precise location can be given forthese sites. Brown simply recorded it as "Beauvais Creek", which, on the basis of known distribution of Cloverly exposures, would place them somewhere between the junctions of Buster Creek and Horse Coulée with Beauvais Creek in the general vicinity of the Cashen ranch. 6 Iam indebted to Dr. Wann Langston of the Texas Memorial Museum for providing the location of these sites. Ue precise location can be given for this specimen (Pu 16338). Al Silberling indicated it was collected from the Cloverly Formation southeast of Harlowton, Montana. The only extensive exposures known to the author in that area are in Middle Dome, T.7 N., R.16 E., Wheatland County, Montana. aaa Lloyd Tillett of Lovell, Wyoming directed me to the site at which Al Silberling col- lected the Princeton specimen from Crooked Creek in 1950. 213 PEABODY MUSEUM, YALE UNIVERSITY, LOCALITIES YPM 62-4 NW 1/4 Sec. 12, 1.52 N., R.92 W., 4 miles (6.4 km) WSW of Shell, Big Horn County, Wyoming. See Locality Map D. Horizon: Unit VII, 7 feet (2.1 m) above Unit VI. Specimen collected: Tenontosaurus? (YPM 4882). feet 1000 2000 LOCALITY MAP D SE 1/4 Sec. 3, T.52 N., R.92 W., 5.5 miles (8.8 km) WSW of Shell, Big Horn County, Wyoming. See Locality Map E. Horizon: Unit VII, 15 feet (4.5 m) above Unit VI. Specimens collected: Crocodilia? (YPM 4883, 4884). YPM) 625 214 1000 2000 300 600 meters LOCALITY MAP E YPM 62-6 SW 1/4 Sec. 3, T.52 N., R.92 W., 6 miles (9.6 km) WSW of Shell, Big Horn County, Wyoming. See Locality Map E. Horizon: Unit V, 30 feet (9 m) below Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 4886, 4887; Theropoda, Megalosauridae (YPM 4885). YPM 62-10 SE 1/4 Sec. 26, T.53 N. , R.93 W., Big Horn County, Wyoming, 0.8 mile (1.2 km) WNW of junction of Bentonite Company road and road to Kane, 4 miles (6.4 km) NE of Greybull, Wyoming. See Locality Map F. Horizon: Unit VII, 5 to 8 feet (1.5 to 2.4 m) above Unit VI. Specimens collected: Sauropelta edwardsi (YPM 5511, 5512, 5513). YPM YPM YPM GZ 62-12 62-13 7115) t 1000 2000 : 300 600 * meters LOCALITY MAP F NE 1/4 Sec. 1, T.54 N., R.95 W., 2.5 miles (4 km) WSW of Himes, Big Horn County, Wyoming. See Locality Map G. Horizon: Unit VII, 2 to 3 feet (0.6 to 0.9 m) below Unit VIII. Specimens collected: Glyptops ? pervicax (YPM 4889, 4891); Crocodilian tooth (YPM 4890); Sauropelta? (YPM 4892). NE 1/4 Sec. 1, T.54 N., R.95 W., 2.5 miles (4 km) WSW of Himes, Big Horn County, Wyoming. See Locality Map G. Horizon: Unit VII, 2 to 3 feet (0.6 to 0.9 m) below Unit VIII. Specimen collected: Glyptops? (YPM 4893). NE 1/4 Sec. 1, 1.54 N., R.95 W., 2.5 miles (4 km) WSW of Himes, Big Horn County, Wyoming. See Locality Map G. Horizon: Unit VII, 2 to 3 feet (0.6 to 0.9 m) below Unit VIII. Specimens collected: Glyptops pervicax? (YPM 4894, 5282); Crocodilia (YPM 4895). 216 YPM 62-14 YPM: 63= 6 YPM 63-17 1000 2000° 300 600 meters LOCALITY MAP G NW 1/4 SE 1/4 Sec. 28, T.58 N., R.95 W., 1.75 miles (3 km) WSW of Tillett Fish Hatchery, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit V, 20 feet (6 m) below Unit VI. Specimens collected: Sauropoda (YPM 5455); Deinonychus antirrhopus (YPM 5275); Tenontosaurus tilletti (BB #1). NW 1/4 Sec. 28, T.58 N., R.95 W., 20 yards (18 m) SE of YPM 63-17, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VI, 1 to 3 feet (0.3 to 0.9 m) below Unit VII. Specimens collected: Crocodilia (YPM 5444, 5401); Ornithomimus sp. YPM 5284); Theropoda (YPM 5369); Sauropoda (YPM 5452); Sauropelta edwardsi (YPM 5296, 5297, 5298, 5402, 5405, 5408, 5409); Sauropelta? (YPM 5406). NW 1/4 Sec. 28, T.58 N., R.95 W., 20 yards (18 m) NW of YPM 63-16, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VII, 5 to 8 feet (1.5 to 2.4 m) above Unit VI. Specimens collected: Sauropelta edwardsi (YPM 4896, 4905). YPM 63-18 YPM “63-19 217 feet 1000 2000 —_—————— 10) 300 600 meters LOCALITY MAP H NW 1/4 Sec. 28, T.58 N., R.95 W., 20 yards (18 m) NW of YPM 63- 17, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VII, 2 to 8 feet (0.6 to 2.4 m) above Unit VI. Specimens collected: Crocodilia (YPM 5343, 5345, 5346, 5348, 5357, 5358, 5439, 5172, 5128, 5129); Deinonychus antirrhopus (YPM 5379, 5371); Ornithomimus sp. (YPM 5174); Theropoda (YPM 5378); Sauropoda (YPM 5449, 5451, 5347, 5375, 5419, 5152, 5116); Sauropoda? (YPM 5294); Sauropelta edwardsi (YPM 5111-5115, SHS =S122)) S124 S27, SLOOP Sse, SUS Ist) eolopeol cer SA Slo S54 —5il59), ss ole Sili6s ol 69), Siler oly o-old 9 ole 5183 75192 ,5200, 5295, 5301=5305, 5307, 5309-53 15),-o317, 5320-5327, 5333-5341, 5391, 5393, 5486-5498, 5528); Sauropelta? (PIM S125, Sis, S140), 5150, S93, Ssi0b 5308), Seley, 008i, 5319, 5328, 5330-5332, 5390, 5394, 5395, 5485, 5515). NW 1/4 Sec. 28, T.58 N., R.95 W., 30 yards (27 m) NW of YPM 63- 18, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VII, 0 to 8 feet (0 to 2.4 m) above Unit VI. Specimens collected: Naomichelys speciosa (YPM 5385, 5432, 5433, 5434); Deinonychus (YPM 5271, 5441, 5274, 5356, 5376); Crocodilia (VPM 5344) 5353, 53954, S355, 5359, 5e61, 53162, 5363, 218 YPM YPM YPM YPM YPM YPM YPM YPM YPM 63-20 63-22 63=27 63-28 63-32 64-3 64-13 64-16 64-17 5364, 5372, 5381, 5342, 5440, 5447, 5445, 5110, 5384): Thero- poda (YPM 5377, 5408, 5538); Microvenator celer? (YPM 5366); Sauropoda (YPM 5103, 5104, 5107, 5147, 5151, 5450, 5349, 5360, 5365, 5374); Tenontosaurus tilletti (YPM 5099); Sauropelta edwardsi (YPM 5069-5072, 5074, 5075, 5079-5084, 5086, 5094, 5095, 5098, SOM S02 S05, Sl06 SOS SOS bll42—Si4 oe ol4aee Slaor ol B4—Hili8i9, SLOT) Si94 S96, S98 Soo0—5o'02 Dolo mo C oor 5389, 5442, 5448, 5499-5503, 5505-5510, 5516, 5525-5527, 5529); Sauropelta? (YPM 5076-5078, 5085, 5150, 5190, 5504). NW 1/4 Sec. 28, T.58 N., R.95 W., 75 yards (69 m) NW of YPM 63- 19, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VII, 5 to 8 feet (1.5 to 2.4 m) above Unit VI. Specimens collected: Sauropelta edwardsi (YPM 5511, 5512, 5513). NW 1/4 Sec. 28, T.58 N., R.95 W., 210 yards (192 m) NW of YPM 63-20, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit V, 2 feet (0.6 m) below Unit VI. Specimen collected: Sauropelta? (YPM 4897). NW 1/4 Sec. 28, T.58 N., R.95 W., 225 yards (199 m) NW of YPM 63-22, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VII, 3 feet (0.9 m) above Unit VI. Specimen collected: Testudinidae? (YPM 4900). NW 1/4 Sec. 28, T.58 N., R.95 W., 15 yards (13.7 m) NW of YPM 63-27, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VII, 1 foot (0.3 m) above Unit VI. Specimen collected: Testudinata, family incertae sedis (YPM 4903). NE 1/4 Sec. 29, T.58 N., R.95 W., 500 yards (455 m) due west — "over the scarp" —of YPM 63-28, Big Horn County, Wyoming. See Locality Map H. Horizon: Unit VI, 1 to 3 feet (0.3 to 0.9 m) below Unit VII. Specimen collected: Tenontosaurus tilletti (YPM 4904). SE 1/4 Sec. 28, 1:4 S. ; R-29) E., 0. 75 mile (1. 2 km)eastio® Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit VII, 4 to 6 feet (1.2 to 1.8 m) above Unit VI. Specimens collected: Theropoda (YPM 5397); Ornithomimus? (YPM 5286); Sauropoda (YPM 5453); Crocodilia (YPM 5398). NE 1/4 Sec. 32, T.4 S., R.29 E., 0.6 mile (0.9 km) WSW of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit V, 18 feet (5.5 m) below Unit VI. Specimen collected: Tenontosaurus sp. (YPM 5410). SE 1/4 Sec. 32, T.4 S., R.29 E., 1.25 mile (2 km) SSW of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit VII, 4 feet (1.2 m) above Unit VI. Specimen collected: Tenontosaurus? (YPM 5299). SW 1/4 Sec. 33, T.4 S., R.29 E., 1.25 mile (2 km) SSW of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit VII, 11 feet (3.3 m) above Unit VI. Specimen collected: Tenontosaurus tilletti (YPM 5535). YPM 64-18 YPM 64-19 YPM 64-20 feet (9) 41000 0 y 300 \ meters 219 SW 1/4 Sec. 33, T.4 S., R.29 E., 350 yards (320 m) east of YPM 64-17, 1 mile (1.6 km) south of Cashen ranch house, Big Horn County, Montana. See Localty Map U. Horizon: Unit VII, 45 to 50 feet (13. 7 to 15 m) below Unit VIII. Specimens collected: Naomichelys speciosa (YPM 5437); Crocodilia (YPM 5412, 5438, 5443, 5414, 5415); Deinonychus antirrhopus (YPM 5420); Sauropoda (YPM 5449); Tenontosaurus sp. (YPM 5411, SAIS 5416): SW 1/4 Sec. 33), 0.4 Se, R29 E., 150) yards (137 m)) east of YPM 64-18, 1 mile (1.6 km) south of Cashen ranch house, Big Horn County, Montana. See Locality Map U. Horizon: Unit VII, 45 to 50 feet (13. 7 to 15 m) below Unit VIII. Specimens collected: Tenontosaurus 'sp. (YPM 5421, 5424). SW 1/4 Sec. 36, T.4 S., R.29 E., 3 miles (4.8 km) ESE of Cashen ranch house, 700 yards (640m) NW of Point Creek, Big Horn County, Montana. See Locality Map W. Horizon: Unit VII, 7 feet (2.1 m) above Unit VI. Specimens collected: Tenontosaurus sp. (YPM 5422,5426);: Sauro- pelta edwardsi (YPM 5511, 5512, 5513). 164 20COn ae 600 - nr LOCALITY MAP W 220 YPM 64-23 SW 1/4 Sec. 26, T.4 S., R.29 E., 2 miles (3.2 km) east of Cashen ranch house on Horse Coulée, Big Horn County, Montana. See Locality Map V. Horizon: Unit VI, 2 feet (0.6 m) below Unit VII. Specimens collected: Crocodilia (YPM 5425); Tenontosaurus sp. YPM 5428); Sauropelta edwardsi (YPM 5300, 5522). YPM 64-24 NW 1/4 Sec. 35, T.4 S., R.29 E. , 300 yards (274 m) south of YPM 64-23, 2 miles (3.2 km) east of Cashen ranch house, Big Horn County, Montana. See Locality Map V. Horizon: Unit VII, 8 feet (2.4 m) above Unit VI. Specimen collected: Sauropelta ? (YPM 5536). feet 1000 2000 300 600 ...., meters Y.P.M. 64-24, YPM. 64-25 * Y.P.M. 64-26 3 LOCALITY MAP V YPM 64-25 NW 1/4 Sec. 35, T.4 S., R.29 E. , 200 yards (183 m) south of YPM 64-24, Big Horn County, Montana. See Locality Map V. Horizon: Unit VII, approximately 17 feet (5 m) above Unit VI. Specimen collected: Tenontosaurus? (YPM 5534). YPM 64-26 NW 1/4 Sec. 35, T.4 S., R.29 E. , 160 yards (146 m) SE of YPM 64- 25, Big Horn County, Montana. See Locality Map V. Horizon: Unit VII, approximately 28 feet (8.5 m) above Unit VI. Specimen collected: Tenontosaurus tilletti (YPM 5459). YPM 64-27 YPM 64-28 YPM 64-29 YPM 64-31 Horizon: 221 SE 1/4 Sec. 35, T.4 S., R.29 E., 300 yards (275 m) SE of YPM 64-26, Big Horn County, Montana. See Locality Map V. Horizon: Unit VII, 10 feet (3 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5283); Tenontosaurus tilletti (VPM 5195, 5417). NE 1/4 Sec. 1, T.5 S., R.29 E., 500 yards (457 m) SE of Point Creek, 3.75 miles (6 km) SE of Cashen ranch house, Big Horn County, Montana. See Locality Map W. Horizon: Unit VII. Specimen collected: Tenontosaurus? (YPM 5533). NE 1/4 Sec. 1, T.5 S., R.29 E., 300 yards (274 m) SE of YPM 64-28, Big Horn County, Montana. See Locality Map W. Horizon: Unit VII. Specimen collected: Sauropelta edwardsi (YPM 5517). oom Lee \ a 3 * oo° aes feet N 0 1000 2000 ee O 300 600 meters LOCALITY MAP T NE 1/4 Sec. 6, 1.5 S., R.29 E., 2.25 miles (3.6 km) SW of Cashen ranch house, Big Horn County, Montana. See Locality Map T. Unit VII, approximately 42 feet (12.8 m) above Unit VI. Specimens collected: Sauropelta edwardsi (YPM 5531); Dipnoi? (YPM 5537). 222 YPM 64-33 YPM 64-36 WPNip 64377 SE 1/4 Sec. 6, T.5 S., R.29 E., 300 yards (275 m) SW of YPM 64-31, Big Horn County, Montana. See Locality Map T. Horizon: Unit VII, 40 to 45 feet (12 to 13.5 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5281, 5288). Sig IA See, 12, Wo Sa, ROA Ho, So AS watllas (6 vam) SW OF Casinen ranch house, 400 yards (366 m) NW of the junction of West Buster and Middle Buster Creeks, Big Horn County, Montana. See Locality Map T. Horizon: Unit VII, 1 foot (0.3 m) above Unit VI. Specimen collected: Tenontosaurus tilletti (YPM 5460). NW 1/4 Sec. 24, T.5 S., R.28 E., 5.5 miles (8.8 km) SW of Cashen ranch house, 600 yards (550 m) west of West Buster Creek, Big Horn County, Montana. See Locality Map S. Horizon: Unit VII, 14 feet (4.2 m) above Unit VI. Specimens collected: Tenontosaurus tilletti (YPM 5456, 5457, 5483). 1000 2000 300 600 meters LOCALITY MAP S YPM 64-38 YPM 64-39 YPM 64-40 223 SE 1/4 Sec. 14, T.5 S., R.28 E., 1100 yards (0.9 km) NW of YPM 64-37 on opposite side of mesa, Big Horn County, Montana. See Locality Map S. Horizon: Unit V? Specimen collected: Tenontosaurus tilletti (YPM 5476). NE 1/4 Sec. 22, T.5 S., R.28 E., 700 yards (640m) east of Thor Lande ranch, on Push Creek, Big Horn County, Montana. See Locality Map R. Horizon: Unit VII, 16 feet (4.8 m) above Unit VI. Specimens collected: Sauropoda (YPM 5454); Tenontosaurus sp. (YPM 5482); Naomichelys speciosa (YPM 5518). nee cade ae 2 >-- ¥.P.M 64 - 40._-- SS feet 1000 2000 300 600 meters LOCALITY MAP R NW 1/4 Sec. 22, 7.5 S., R.28 E., 500 yards (450 m) east of Thor Lande ranch on Push Creek, Big Horn County, Montana. See Locality Map R. Horizon: Unit VII, 12 feet (3.6 m) above Unit VI. Specimen collected: Osteichthyes (Amioidei?) (YPM 5519). 224 YPM 64-41 NW 1/4 Sec. 21, 1.5 S., R.28 E., 1 mile (1.6 km) west of Thor Lande ranch on Push Creek, Big Horn County, Montana. See Locality Map Q. Horizon: Unit VII, 8 feet (2.4 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5272, 5273); Tenontosaurus tilletti (YPM 5458). / / o&, + APO ; \:. ers A>, PM:64-4 3; Ox, Ue ras fone canny 1000 2000 LOCALITY MAP Q YPM 64-43 NE 1/4 Sec. 20, T.5 S., R.28 E., 650 yards (595 m) west of YPM 64-41, Big Horn County, Montana. See Locality Map Q. Horizon: Unit VII, 3 feet (0.9 m) above Unit VI. Specimens collected: Tenontosaurus tilletti (YPM 5464, 5477). YPM 64-47 NE) 1/4 Sec. 19), T.8 S.-AR.25 Bo, 5.5 miles’ (8.8! km) NNWiok Warren, Carbon County, Montana. See Locality MapIl. Horizon: Unit VII, 52 feet (15.8 m) below Unit VIII. Specimens collected: Tenontosaurus tilletti (YPM 5463); Sauropelta edwardsi (YPM 5521). 225 QBs . . : z ee eas feet 1000 2000 300 600 meters LOCALITY MAP I YPM 64-49 SE 1/4 Sec. 12, T.8 S., R.24 E., 7 miles (11.2 km) NNW of Warren, Carbon County, Montana. See Locality Map J. Horizon: Unit VII. Specimen collected: Tenontosaurus tilletti (YPM 5465). 226 YPM 64-52 YPM 64-53 LOCALITY MAPJ SE 1/4 Sec. 29, T.7 S., R.24 E., 2.5 miles (4 km) SSE of Tom Edwards ranch house, Carbon County, Montana. See Locality Map Kk. Horizon: Unit VII, 35 feet (10.5 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5287); Tenontosaurus tilletti (YPM 5467). NW U/40Sec Seli7 le See Ree 4) Eee lemiles (ds 6ykm) eNEF or lom Edwards ranch house, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 27 feet (8.2 m) below Unit VIII. Specimen collected: Deinonychus sp (YPM 5397). YPM 64-54 YPM 64-56 1000 2000 300 600 meters LOCALITY MAP K NW 1/4 Sec. lV tie7 Se, Rez4Ee mile (6) km)INE of tom Edwards ranch and 60 yards (55 m) east of YPM 64-53, Carbon County, Montana. See Locality Map L. Horizon: Unit V, 8 feet (2.4 m) below Unit VI. Specimen collected: Tenontosaurus tilletti (YPM 5469). NEV 425 SECn a7 Ula 7eSae Re2 be le Semillesm(2e4 km) Nie Of lon Edwards ranch, 260 yards (238 m) west of YPM 64-54, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 12 feet (3.6 m) above Unit VI. Specimen collected: Naomichelys speciosa (YPM 5431). 228 YPM YPM YPM YPM 64-57 64-58 64-59 64-61 co A 7 *, " me. * i é Edwards 3. on ¢ 40, Y.PM 64-6! ee sn. ne oF IS. YPM 64-53 L Sey = S 1000 2000 300 | Ranch LOCALITY MAP L NE 1/4 Sec. 17, 1.7 S. , R.24 E., 1.5 miles (2.4 km)! NE of Lom Edwards ranch, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 4 feet (1.2 m) above Unit VI. Specimen collected: Tenontosaurus tilletti (YPM 5470). NEW/4 See. 17), Lal San Rez Bap loSemiles (274m) NE of our Edwards ranch, on NW side of knob, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 4 feet (1.2 m) above Unit VI. Specimens collected: Tenontosaurus tilletti (YPM 5471, 5472). NE 1/4 Sec. 17, T.7 Sw »R«24 Ea, 1.5 miles (2.4 km) NE of Tom Edwards ranch on east side of knob, Carbon County, Montana. See Locality Map L. Horizon: Unit V, 12 feet (3.6 m) below Unit VI. Specimen collected: Theropoda (Megalosauridae) (YPM 5285). SE 1/4 Sec. 5, 1.7 S., R24 E., 2.25 miles (3.6 km) NE of Tom Edwards ranch, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 25 feet (7.5 m) above Unit VI. Specimen collected: Crocodilia? (YPM 5530). YPM 64-63 YPM 64-64 YPM 64-65 229 SE 1/4 Sec. 29, T.6 S., R.24 E. , 220 yards (200 m) north of YPM 64-64, Carbon County, Montana. See Locality Map M. Horizon: Unit VI, 7 feet (2.1 m) below Unit VII. Specimens collected: Tenontosaurus tilletti (YPM 5468, 5480); Crocodilia (YPM 5293). feet - i000 +2000 N LOCALITY MAP M SE 1/4) Secs 29), i. 61S.) R224 E. 74.25 miles (6.8 km)! NINE) or tom Edwards ranch, 3.75 miles (6 km) ESE of Bridger railroad station, Carbon County, Montana. See Locality Map M. Horizon: Unit VII, 18 feet (5.5 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5279); Tenontosaurus tilletti (VPM 5461, 5523). SW 1/4 Sec. 34, T.5 S., R.24 E., 2.5 miles (4 km) NE of Bluewater Creek Fish Hatchery, Carbon County, Montana. See Locality Map O. Horizon: Unit VII, 25 feet (7.6 m) above Unit VI. Specimen collected: Deinonychus antirrhopus (YPM 5278). 230 ® = c S arr ~ . ® % > 1000 2000 ; 300 meters LOCALITY MAP O YPM 64-67 SE 1/4 Sec. 31, 1.5 S., R24 E: , 5 miles (@ km) NE of Bridger railroad station, Carbon County, Montana. See Locality Map N. Horizon: Unit VII. Specimens collected: Deinonychus? (YPM 5289); Tenontosaurus tilletti (YPM 5473); Sauropelta edwardsi (YPM 5520). YPM 64-70 NE 1/4 Sec. 5, T.6°S., R.24 E., 1.25 miles (2 km) NNW of Blue- water Creek Fish Hatchery and 650 yards (600 m) NE of YPM 64- 71, Carbon County, Montana. See Locality Map N. Horizon: Unit VII. Specimen collected: Crocodilia (YPM 5292). YPM 64-71 NW 1/4 Sec. 5, T.6 S., R.24.E., 4.5 miles (7.2 km) NE of Bridger railroad station,0.5 mile (0.8 km) north of Bluewater Creek, Carbon County, Montana. See Locality Map N. Horizon: Unit VII, 9 feet (2.7 m) above Unit VI. Specimens collected: Tenontosaurus tilletti (YPM 5475, 5481); Crocodilia (YPM 5429). Zon YPM 64-72 SWaal/4e Secs 5) elcon oe, Reed thee OnZo anilen(O24eikim) "sourhiot YPM 64-71, Carbon County, Montana. See Locality Map N. Horizon: Unit VII, 5 feet (1.5 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5280); Tenontosaurus tilletti (YPM 5474). yee Ss . : "YPM. 64-709 1000 2000 300 600 LOCALITY MAP N YPM 64-74 NE /45Secn 7) a7 Sep Re2ee lem eich (2-140 kim) Nibpoteton Edwards ranch, on north side of knob, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 14 feet (4.2 m) above Unit VI. Specimens collected: Deinonychus? (YPM 5291); Tenontosaurus tilletti (YPM 5478). YPM 64-75 Nie I/4! Sexo, 17, Way Sop ROPE 1B A oS ales (2. 4! ein) INE) © Wosen Edwards ranch on north side of knob, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 14 to 17 feet (4.2 to 5.1 m) above Unit VI. Specimens collected: Deinonychus antirrhopus (YPM 5201-5271); Tenontosaurus tilletti (YPM 5466). 232 YPM 65-1 YPM 66-2 YPM 66-3 SE a4: Sect 8), Lay) St) R24 E. el. 75 miles) (2.8 km) NEsofelom Edwards ranch, 200 yards (183 m) north of knob, Carbon County, Montana. See Locality Map L. Horizon: Unit VII, 25 feet (7.6 m) above Unit VI. Specimen collected: Tenontosaurus tilletti (YPM 5462). NW 1/4 Sec. 36, T.44 N., R.96 W., 2.5 miles (4 km) NE of junc- tion of State Highway 120 with Hamilton Dome road, Hot Springs County, Wyoming. See Locality Map A. Horizon: Unit VII, 52 feet (15.8 m) below Unit VIII. Specimen collected: Crocodilia (YPM 5436). 1000 2000 300 600 meters LOCALITY MAP A NW 1/4 Sec. 17, T.49 N., R.89 W., 2 miles (3.2 km) SE of Hyatt- ville, Big Horn County, Wyoming. See Locality Map B. Horizon: Unit VII, at least 30 feet (9 m) below Unit VIII. Specimens collected: Glyptops pervicax? (YPM 5435); Deinonychus ? (YPM 5290). 233 feet 1000 2000 300 600 meters LOCALITY MAP B YPM 66-4 NW 1/4 Sec. 29, T.49 N., R.90 W., 1 mile (1.6 km) SE of bridge over Paint Rock Creek, Big Horn County, Wyoming. See Locality Map C. Horizon: Unit VII. Specimen collected: Tenontosaurus? (YPM 5484). 234 feet % 1990 _2000 | 300 600~ 5 meters oa : % = Qa a] a © = n” ° 3 LOCALITY MAP C PLATES PLATE 1A Exposures of the upper part of the Morrison-Cloverly section (Units V, VI and VII) plus the lower sands (Unit VII) of the Sykes Mountain Formation (“rusty beds”) approximately 0.5 mile (0.8 km) north of the type Cloverly section, west of Beaver Creek, Big Horn County, Wyoming. Units VI and VII equal Darton’s original Clo- verly Formation, Unit V the top of his Morrison Formation. The light-colored stratum just beyond the distant figure is the fragmental tuff. PLATE 1B Cloverly, Sykes Mountain and Thermopolis Formations exposed 4 miles (6.4 km) north of the type section of the Cloverly Formation. The hill is situated immediately west of the North Fork of Beaver Creek in Big Horn County, Wyoming. The Sykes Mountain Formation extends from the base of Unit VIII to the dark gray zone above. The base of the Cloverly Formation as defined in this report is concealed here, but probably lies slightly above the level of the automobile in the left foreground. The light-colored fragmental tuff is prominent just below Unit VI. ec eae ee Ae PLATE 2A Exposures of the upper part (Units V, VI and VII) of the Morrison-Cloverly section approximately 3 miles (4.8 km) north of the Cloverly type section, near the head- waters of East Branch of Bear Creek, Big Horn County, Wyoming. The thickness of Units VI and VII (Darton’s Cloverly) is about 115 feet (35 m) here. The white tuff is exposed in the foreground. PLATE 2B Upper part of the Morrison-Cloverly section at outcrops 5 miles (8 km) north of the Cloverly type section on East Branch of Bear Creek, Big Horn County, Wyoming. Notice the local variation in thickness of the channel sand (Unit VI) and the dis- cordance between the base and the stratification of Unit VII. The relief of the contact between VI and VII resulted from scouring and removal of material prior to deposi- tion of the clay and silt of Unit VII. an «0,80 Pa, ta a se PLATE 14 A) Right humerus (YPM 5452) of indeterminate sauropod in anterior view; B) left tibia (YPM 5450) of indeterminate sauropod in posterior view; C) right femur (YPM 5451) of indeterminate sauropod in posterior view; D) left ulna (YPM 5449) of indeterminate sauropod in medial view; E) type tooth of Astrodon johnstont (YPM 798) in longitudinal (left) and internal (right) views; F) tooth referred to Pleuro- coelus nanus (USNM 6105) from the Arundel Formation, Md., in longitudinal (left) and medial (right) views; G) Pleurocoelus-like tooth (YPM 5375) from the Cloverly Formation in longitudinal (left) and medial (right) views; H) Astrodon-like tooth (YPM 5374) from the Cloverly Formation in longitudinal (left) and medial (right) views. Scales indicate cm. PLATE 15 A and B) Probable sauropod cervical centrum (YPM 5294) in lateral and dorsal views; C, D and E) indeterminate amioid dentary (left) (YPM 5519) in dorsal, me- dial and lateral views; F) Camptosaurus dispar dentary tooth (YPM 1877, type) in medial view; G) Camptosaurus dispar maxillary tooth (YPM 1877, type) in lateral view. Scales indicate cm. PLATE 16 A) Skull of Tenontosaurus tilletti (YPM 5456) in left lateral view; B) left mandible of Tenontosaurus tilletti (YPM 5456); C and D) maxillary teeth of Tenontosaurus tilletti (YPM 5456) in lateral view; E) right maxillary tooth of Tenontosaurus tilletti (YPM 5456) in anterior view. Scales indicate cm. PLATE 17 Skull (A) of Tenontosaurus tilletti (YPM 5456) in right lateral view; B) right mandi- ble of Tenontosaurus tilletti (YPM 5456); C) right dentary tooth of Tenontosaurus tilletti (YPM 5456) in anterior view; D and E) worn and unworn dentary teeth of Tenontosaurus tilletti (YPM 5456) , in medial view. Scales indicate cm. PLATE 18 A) Axis and odontoid of Tenontosaurus tillettt (YPM 5456) in lateral view; B) same in posterior view; C) cervical vertebra of Tenontosaurus tilletti (YPM 5456) in lateral view; D) same in posterior view; E) 5th dorsal vertebra of Tenontosaurus tilletti (AMNH 3040) in lateral view; F) same in posterior view; G) 14th dorsal vertebra of Tenontosaurus tilletti (AMNH 3040) in lateral view; H) same in poste- rior view; 1) 5th caudal vertebra of Tenontosaurus tillettt (AMNH 3040) in lateral view; J) same in posterior view; K) 12th caudal vertebra of Tenontosaurus tilletti (AMNH 3040) in lateral view; L) same in posterior view; M) 32nd caudal vertebra of Tenontosaurus tilletti (AMNH 3040) in lateral view; N) same in posterior view. Scale indicate cm. PLATE 19 A) Partial caudal series (Nos. 20 to 42) of Tenontosaurus tilletti (AMNH 3034) with ossified hypaxial and epaxial tendons in place; B) proximal half of same, enlarged to show details of ossified tendons. (Photographs courtesy of American Museum of Natu- ral History.) Scales indicate cm. PLATE 20 A) Left pubis of Tenontosaurus tilletti (AMNH 3040) in lateral view; B) left ilium of Tenontosaurus tilletti (AMNH 3040) in lateral view; C) right ischium of Tenonto- saurus tillettit (AMNH 3040) in lateral view; D and E) right femur of Tenontosaurus tilletti (PU 16338) in posterior and internal views. Scale indicates cm. A) Left manus of Tenontosaurus tilletti (OU aw in Tenontosaurus tilletti (PU 16338) in dorsal vi Cae saurus tillett (AMNH 3034). Sanaa ca . wl oil oe oat Pet PLATE 22 A) Right mandible of Sauropelta edwardsi (YPM 5502) in external view; B) same in medial view; C) same in dorsal view; D, E, and F) isolated teeth of Sauropelta edwardsi (YPM 5526, 5525 and 5350) in transverse (labial or lingual?) above, and longitudinal (anterior or posterior?) below; G) axis and odontoid of Sauropelta edwardsi (AMNH 3035) in lateral view; H) same in posterior view; I) posterior cer- vical of Sauropelta edwardsi (AMNH 3035) in lateral view; J) same in anterior view; K) a posterior dorsal vertebra (12th?) of Sauropelta edwardsi (AMNH 3032, type) in lateral view. Scales indicate cm. PLATE 23 A) Posterior dorsal vertebra (12th?) of Sauropelta edwardsi (AMNH 3032, type) in posterior view (same as Plate 22K); B) anterior caudal vertebra of Sauropelta edwardsi (AMNH 3032, type) in lateral view; C) same in anterior view; D) distal caudal vertebra of Sauropelta edwardsi (AMNH 3032, type) in lateral view; E) same in posterior view. Scales indicate cm. PLATE 24 A) Left scapulocoracoid of Sauropelta edwardst (YPM 5179) in medial view; B) same in lateral view; C and D) right humerus of Sauropelta edwardsi (AMNH 3032, type) in posterior and anterior views; E and F) left ulna of Sauropelta edwards (AMNH 3032, type) in posterior and internal views; G) left radius of Sauropelta edwardst (AMNH 3032, type) in internal view. Scales indicate cm. PLATE 25 A) Left ischium of Sauropelta edwardsi (AMNH 3032, type) in medial view; B) same in external view; C) same in dorsal view; D) right pubis of Sauropelta edwards (YPM 5141) in medial view; E) same in external view; F) same in dorsal view; G) right ischium and pubis of Sauropelta edwardsi (YPM 5141) in articulation. Scales indicate cm. PLATE 26 A and B) Right femur of Sauropelta edwardsi (AMNH 3032, type) in posterior and medial views; C and D) left tibia of Sauropelta edwardsi (AMNH 3032, type) in lateral and posterior views; E) right pes of Sauropelta edwardsi (AMNH 3032, type) in dorsal view. Scales indicate cm. PLATE 27 A) Proximal half of left fibula(?) of Sauropelta edwards. (AMNH 3032, type) in medial(?) view; B through L) various types of dermal plates of Sauropelta edwardst, ranging from flat or slightly convex (B, C and D), slightly peaked (E, dorsal and F ventral views), moderately peaked (G), narrow blades (H), moderately keeled or ridged (I and J), to sharply ridged (K, dorsal view and L, longitudinal view) ; M) a long cylindrical spine, presumably from the shoulder region. B, C, and D) = (AMNH 3035) ; E and F) = (YPM 5072); Gand H) = (AMNH 3032, type) ; * and J) = (AMNH 3032, type) ; K and L) = (YPM 5082) ; M) = AMNH 3032, type). Scales indicate cm. a 7 I-A ALKALI CREEK* CLOVERLY POST OFFICE** Darton, 1906 and Fisher, 1906 Red and tan sandy clay. Deep maroon sandy clay. Deep maroon & purple Deep maroon sandy clay. Pale-green massive shale. Pale-green massive shale. Variegated massive shale. 10’ Light buff sandstone. 10° ‘Tan sandstone. 4’ ~~ Maroon clay. 10’ 10’ Drab sandy clay. 20’ Su Hard tan sandstone. PDs variegated clay. - By Maroon sandstone 20’ 1s 50’ 15’ Gray sandstone. Oy 10’ Blue-black shale. 10’ Maroon massive shale. 45’ 6’ ‘Thin-bedded gray sandstone. 65’ 6’ Pale-green to white sandstone. 85’ shale. 45’ Pale-green massive sandstone. 40’ Red sandy shale. Variegated massive shale. Pale-green and maroon This Report Vill III This Darton, 1906 Report 15’ Massive brown sandstone. VIII By oH a es 2 > <= = m 20’ Soft gray sandstone © (sandy clay). VII 20’ Soft deep brown sandstone me (sandy clay). a4 e) |p ae eee ees ee! okie Nee 2. 2 one ee ie) 15’ Olive-green sandstone. VI MORRISON FORMATION (Not described ) V IV 3 Vee 5 So sS 55 SSS Sasa o2 ¢ e <= = fad eo) es III Z e) 4 a4 a4 e) Pi eee ee ome POD platy A II I I-B SHELL CREEK DOME < SHELL ( Hewett and } 25’ “Greybu 75’ = Variegai Sandsto: Variega L sands ’ ‘ EEK: '- ALKALI ar OFFICE** = This This ’ . 1906 and Fisher, 1906 _Report Darton, 1906 Report 1 Sean ene: VIL 15’ Massive brown sandstone. VIII {0 Tansandstone. ee === oo 5 --------------- +--+ ——= = eC Maroon clay. ] 0’ Redand tan sandy clay. s i’ Drabsandy clay. % 20’ Soft gray sandstone 2) Deep maroon sandy clay. VIL (e) (sandy clay). VIL ey Hard tan sandstone. % 20’ Soft deep brown sandstone We tread | (sandy clay). Maroon sandstone m 2) Deep maroon sandy clay. 3 eee a ee weceeeeen-a== 1S) 1!’ Olive-green sandstone. VI 15’ Olive-green sandstone. VI MORRISON FORMATION Vv (Not described) 10 Maroon massive shale. Wy Variegated massive shale. IV IV to —— , ---------------------- ig) , & | 6 Thin-bedded gray $ v Chea “z ‘ariegated massive shale. | & Pale-green to white Ill 2 Ill y nas Zz ‘green and maroon ° shale, D 4 4 (e) ti es eee on eS eo Il I <> SHELL CREEK DOME SHELL CREEK DOME CLOVERLY POST OFFICE This This Hewett and Lupton, 1917 Report Lee, 1927 Report 25’ “Greybull sandstone”. VIII 25’ “‘Greybull sandstone”. Vill 28—e2 =... eee ie ee ee ° 7 B < z : 45’ Variegated clay. 75’ Variegated shale. VII 2 10’ Saudiene y Vil > 50’ Variegated clay. Q [4 } me le) Eee 3S (eS eels ae ee eee. 2) anditaié. VI 35’ — Light-colored pebbly VI sandstone, ee Variegated shale and sandstone, Vv 2’ Dark shale Vv tl » IV IV ee — a ee g = < = 6 {I ? Ill ee ” (?) Ill Zz ie} 2 [4 24 ° cee ee Sa od ere eels,

+ 4 100’ — Sandstone. VIII 75’ Sandstone. VIII B WW ee ee eee iS) z 95’ Highly colored clay. VII _ Red shale. VII (e} J & Zz 3 g [4 & (0): 6 ee eee Ge See ee eee oe Se : : oe) | VI 4 VI a > > 4 O ---------------------------- M% ---------------------------- i ii o > ° — 2) 70' Gypsum. 118’ Variegated clay. Vv 150’ uw) Vv 20’ Nodular chert. 4 } & < EEE a ee oe ee = 4 IV 50’ Sandstone, coarse-grained, Iv iS) cross-bedded, massive. - Se eo. | ——— eG 8 % 4 fe) = zx 1 Variegated shale. Ill 7 Variegated shale, 1 2 es Zz $ g % a is shee eee nee B 2) a P Il & II _ Z 8) eo eca teens. Ola Sk a a ee are ee e) 4 (4 2 4 C a 240’ ” I 290° » (?) I Sec. 3 & 10, T.51 N., R.91 W. WYOMING This This Pierce, 1948 Report Moberly, 1960 Report 72' (Rusty Beds) + as , 42’ —Interbedded gray, yellow VU Re . = or red shale and yellow, % a sruelitone, siltstone and VIII & i wee shale. pink or gray thin na bedded. fine-grained ss. 2 * 4° Sandy mudstone. 43' — Silty, clayey shale, palely 13’ Gray and brown claystone. variegated gray, red vil 15’ Channel sandstone VI and purplish, — 6' —-Yellow-gray claystone (See Unit VI below) 4’ Green-gray sandstone 14° Sandstone, gray and red. 2' Sandstone, dark red. z Seo Seco Sse moreatt & ase Ot aa aaa a ene eee ee nen By a8 2’ =2-foot bed of fine gray ss. VI < 6' — Soft, yellow sandstone VI at base. = 28 Sandstone, greenish- 5 yellow. Hose He eso ee Soe Se Se Pa i ali le pose So ob cae 19’ Bentonitic(?) gray clay. 4 36’ Gray mudstone. Lower part is black and fe 1’ Siliceous mudstone waxy. > 84 Dark gray mudstone. 5’ Gray fine-grained, tuffa- © 40’ Mudstone, green and ceous(?) sandstone A red-brown. weathers to sharp Vv ) 2’ — Siliceous mudstone Vv angular pieces. 8’ Mudstone, green and 47’ Variegated gray, red and red-brown, purplish shale: lower 35’ Sandstone, white. part contains 12’ Mudstone, green and chalcedony. red-brown. 8’ Gray and yellow sand- stone, locally coarse- Iv 18’ Sandstone, quartz and IV grained and ledge black chert. forming. —_—.s 79’ Gray, yellow and green bentonitic shale. 6’ — Soft, clayey sandstone. ll 15° Maudstone, dark I 76' Variegated red, gray and red-brown, greenish-gray shale with thin sandstone. z ie) & < Sap ee ee eee ---+---- SJ -------------- — Variegated reddish-brow: 4 and gray shale and ll © Il yellow or light gray sandstone. Zz SSeS ee eee Se Ox ee 4 4 -4 ° = I I SUNDANCE FORMATION CHART I PUBLISHED SECTIONS: CLOVERLY — SHELL CREEK AREA (See Figure 2 for locations.) Lc <0) SHEEP MOUNT XREEK DOME CLOVERLY POST OFFICE 8 Miles NW of G This This upton, 1917 Report Lee, 1927 Report ll sandstone”. Vill 25’ “Greybull sandstone”. VIII Sandstone. Variegated clay. CLOVERLY FORMATION — a ed shale. Vil 10° = Sandstone. VII y 95’ Highly colored cla 50’ Variegated clay. re) = < 2 fa 4 — SE a «eee eee ae ee pe (oo eee ee ye oe 35’ Light-colored pebbl cc sandstone. rs > —————— a ey se — Oo ted shale and 70° Gypsum. tone. Vv ?’ ~Dark shale Vv 118’ Variegated clay. Nodular chert. IV IV 2 =e Steg item lala oa laa la ca ss ee © < = 5 III fa am (?) III y J Variegated shale. a ‘e) 9 E: 2 < wf _ z Z ° ) sai a, ae Sop Sar Oe kes pe os ean ae el a set en Fd as ace os erm a oe v4 Il I 3 x se eee ew eee eee ew ees aac we we ee ew wees ew ee eee eww ew ewe ee ee eS Se ~ ~———<_—<— = = = eo) a NORTH BIG TRAILS, WYOMING This SENS Report Mirsky, 1962a This Report 4’ 26. Sandstone, gray, fine, thin bedded, rusty- te, fine, brown, tan and ferru- | fi VIII ginous stain. # Ss Zier 5 ees e) — > < 3 19’ 25. Sandstone, white to eo) gray, very fine, soft, ey rusty and lavender y-green Do) staining (sandy clay- , silty, vil 4 stone?). a4 <2 > e) J] RO Raters sighing eer ees a ce Se Ss 25’ 24. Sandstone, white to Pagmines tae or porn gray, fine to coarse and___!te to conglomeratic, cross- r bedded, Otter Creek -dded. VE) Sandstone. SLOW he Fy | | | Vv CHART II PUBLISHED SECTIONS: HYATTVILLE — TENSLEEP — NOWOOD CREEK AREA a Ne ey Nee weet (See Figure 2 for locations.) nses in t of IV(?) TN I ee eo ee =z S 79 23. Mudstone, pale gray- bias = nae inted Kx: 12’ 22. Sandstone, gray, very , < ne. = 7’ 21. Mudstone, dark-gray, VeTY 5 silty. oe 22’ 20. Sandstone, gray, sparkly. a 7’ 19. Sandstone, dark-gray. k-gray, III(?) 5 6’ 18. Sandstone, gray, soft. ‘k n 4’ 17. Sandstone, gray-green, /* ) fine. a) 7’ 16. Sandstone, dark-gray, y-green, : e) very fine, soft. itic, selenite. Sh ee dgreen, fine. 21’ 15. Sandstone, tan, very II fine to coarse, well- ] fine, 5 cemented. ginous = II(?) 4’ 14. Mudstone, gray, drab-gree EIN Be ete 3h 13. Sandstone, white, fine. 8'4Y-green 5’ 12. Sandstone, gray, olive-gre¢€TY Silty. 8’ 11. Sandstone, gray, soft. medium, 4’ 10. Sandstone, chocolate-brow SParkly. 2’ 9. Sandstone, tan, soft. to tan, I 8’ 8. Sandstone, gray, very fine. '€4- 17’ 7. Siltstone, dark-gray. pray I 25’ 6. Mudstone, red-brown, greet 2’ 5. Mudstone, olive-green. very 7’ 4. Sandstone, gray, soft. 6’ 3. Mudstone, gray and green. 8'@Y- 4’ 2. Sandstone, gray, soft. pown, 5’ 1. Sandstone, glauconitic. ray-green. Fold-out Placeholder This fold-out is being digitized, and will be inserted ata future date. ti 4 MILES NORTH OF THERMOPOLIS, WYOMING This report Love, et al., 1945 Report ) VIII By or sandstone of Rusty VIII eds. Vi) VII 18’ Variegated claystone. VII Z © tH _; EES coe aaa RTM PUI eA OE a 8 Dy chy Ce ad a =) 5 : 25’ Gray conglomeratic pratie. va 3 sandstone. ve val | —— — — me MY ----- --=-=-----=--- ------+---=-- a | 6 sjand- 4 id o V(?) 50’ Variegated claystone. 2 IW. with CHART III PUBLISHED SECTIONS: THERMOPOLIS AREA ss IES SO oe Dp Ss OR So ge EEA we (See Figure 2 for locations.) 38’ Gray conglomeratic sand- IV stone (sparkly quartz IV sandstone ). Ill 100’ = Light-green siltstone and Ill sandstone. 150’ Gray sandstone. II MORRISON FORMATION > 2 MILES NORTHWEST OF ORTH OF THERMOPOLIS oe : THERMOPOLIS, WYOMING WYOMING This Thi Fisher, 1908 fie ane ’ Gray massive ss., : wreaths tan. VII 60’ —_Rusty-brown, ripple- 9 Blue, drab shale. marked ss, VuI Thin-bedded sandstone. eoeera==-------- a ee fe) 5 < = 6 82’ i 4’ Variegated shale. VII : 2 Varierated deep red an yw 4 Q 8 oo ee =. oa (Sh ae Light-colored conglom- , : " Tale massive E VI 42’ Conglomeratic VI sandstone. sandstone. ea co ee a EEE eee MORRISON FORMATION (Not recorded) v Vv IV IV SSS Se Sn mee ee Er Zz 2) & < z 59 Greenish-brown shale. III 2 UI vA [e} 2 4 ~ tonic a o -1. a Seca =o Yellow-gray massive sandstone. II II MORRISON FORMATION (Undescribed ) CLOVERLY FORMATION MORRISON FORMATION @> 3.5 MILES NORTH OF > 4.5 MILES NORTHEAST OF THERMOPOLIS, WYOMING THERMOPOLIS, WYOMING This This Lee, 1927 Report Lee, 1927 Report 53’ Thin-bedded sandstone vu (Not described) and variegated shale. “Sandstone” VIII SSse5-5. 4... ee ee ee ey ee ° >t < = 4 55’ Red and bluish sandy wan OE (Not described) shale. Sy “Variegated shale” VII 4 (4 Q > (o} <7 4 - eee ee Giss= sas nee eae he 90’ Conglomeratic sandstone. VI 13, aE pera VI SRS Sa 5556. 5 eee ee —— tis Vv 20' Carbonaceous shale, V(?) lignitic. Mh a Conglomeratic sandstone. IV 25° Dark brown chert IV — Variegated shale. Ill 275’ Massive light-colored ll sandstone. I MORRISON FORMATION pebble conglomerate. Cs Variegated shale. III MORRISON FORMATION Cc, 10 MILES EAST OF THERMOPOLIS, WYOMING > 4 MILES NORTH OF THERMOPOLIS, WYOMING Variegated shale. lll MORRISON FORMATION This This Lee, 1927 report Love, et al., 1945 Report (Not recorded) VIII 5’ NE sandstone of Rusty VI PP A I OE = — ~._ ee eee fe) = i> < 2 6 Lal (Not recorded) VII 18’ Variegated claystone. Vil ral x z ts 4 > ie re) & I i gS ee ee = @----~--=-------=- - See 2S $- sa as a 5 25’ Sandstone, conglomeratic. VI & 29 Gray congiemeratic VI a E % i eo0-—_—_—— —_-—— 2 EN Sean poh et ee See - a 6 10’ Fine-grained white sand- 4 stone, light-colored Oo shale, 1.3’ Carbonaceous clay. 0.5’ Coal, impure. V(?) 50' Variegated claystone Vv 1.0' Carbonaceous shale with ~ coal. 2.7’ Coal, impure. CHART II — Dark shale PUBLISHED SECTIONS: THERMOPOLIS AREA SS oe a ee | A ae ee ee te e (See Figure 2 for locations.) 38° ay conglomeratic sand- IV stone (sparkly quartz IV sandstone). SS 100’ —_ Light-green siltstone and sandstone. Ill SOUTH OF CODY, WYOMING This Fisher, 1906 Report ?’ Sandstone. VIII ?’ Highly colored clay. VII VI CLOVERLY FORM i “Middle band of dark shale’’. W ?’ Highly colored clay. Ill (Not recorded. ) MORRISON FORMATION €) SOUTH OF CODY, WYOMING Highly colored clay. dle band of dark > SOUTH OF CLARK FORK CANYON SHOSHONE CANYON AT CODY, WYOMING This This Fisher, 1906 Report Hewett, 1914 Report > 60’ Sandstone, buff, indurated, J ripple-marked and thin- + (Not recorded.) vit £3 bedded. VIII ™ 25’ Shale, gray and sandy. a Jo eee O25’ _ Sandstone, buff, massive. 50’ Shale, maroon and gray, sandy. a 6’ Sandstone, buff. (Not recorded.) VIL 12’ Shale, gray, sandy. VII 4’ — Sandstone, buff. z 10’ Shale, gray, sandy. fe) = & Sipe te SES SSE ce Se a Eee eee et Ba = [24 2 » ” VI 8’ — Sandstone, buff, cross- VI bedded. ~ y ( i] > ° i 1) 50’ Clay, gray, sandy. 6’ Sandstone, buff, fine- grained, ripple-marked. uy 7 Vi 44’ — Clay, dark-brown to black, V saurian yertebrae, limb bones and gastroliths. 4 ° & ee eee ee KS ee ee ec = a eh 5 IV 2 IV 3, 3a al — B SO eee Rae 4 4 4 ie) = ” ” Ill Ill a sl as 80" BMastives ieecauhsetey Il 50’ Sand, gray, argillaceous. Il Qe eS Be ee er < = $ mB 55’ Clay, maroon, sandy. . c 25’ Sandstone, white, 6 60’ Greenish clay. ; homogeneous, : 4 DR i i t | 1’ Dark-gray limestone. wae Clay, ereven sLolive, i Fs bands, sandy. = > 2 MILES SOUTH OF Copy, WEST LIMB, HORSE CENTER EAST LIMB, HORSE CENTER MORRISON FORMATION buff, shale green with 2” coal. WYOMING SHOSHONE CANYON ANTICLINE ANTICLINE* Lee, 1927 Nectet hnson, 193 ae ee bi = 5 Pp Johnson, 4 Report Pierce and Andrews, 1940 Report Pierce and Andrews, 1940 Report a4 a . > (See note below) * 110’'+ Rusty- a ' AS + Rusty. pions tipple fe 110’ Buff sandstone, thin- tL 85’ Sandstone, tan, thin- 4 8 Sandstone, buff, ledge- >a TEAC oe IK bedded to massive Vir bedded, shale, sandy, VII &2 former. VIII 58 thin beds of shale. : s ud . Pa Pea OU Sandstone, gray, alternat- (is Sa es ae ee ee paomemmmmmmn OS XE cree se Ste ct mene, Ura SP ot See so ing with gray sandy sh. (2) B < Tl eColored material” Bre s 36’ Shale, red and gray. vailingly maroon wit VIt Waricoleredtal ith © 27’ Sandstone, rusty tan and dinosaur bones, stomach i Th BC CLOrea Gays) Wit VII & gray, thin-bedded shale, VII Not recorded VII stones and petrified (82’) many sandstone lenses. i BraUMniconT , (Not recorded. ) wood. 3 25’ Shale, gray and red, Q > ie} a aS REN ne am OO we mk ASE ee, wr emo se oe iam KE wm a (o>, -<--- = a ee 3 = Se Ree Pc a ee » ” 17’ Sandstone, tan, rusty, VI a3 VI cross-bedded. VI 2 VI B 2’ Conglomerate. Sa ee ee ee ee 2) la Se ees oe ara ————— te eee fe A | es < = Zz “4 ° © 70’ — Shale, variegated, massive, & purple, red and gray, $ a ” ” "3 os a nodular siliceous r Vj [ a 68’ Shale, gray and red. z ie i} fe) Z = s Q < (edt eS a ae Se eae SS AR NS eis eee nS eee ee ee Sy pat en S ---------------+------------ ic) < 3 ” » & ie) IV z Tr Iv IV Ss # 2 IV ne ae ee ee eee |. eee ae eee ae < Z zg z g z eg g g = 2 a fi “1 8 ’ III 263’ y 2 III A T lll ‘ III 4 x 6 g a 4 [-4 ees "a phe ES Saas ee | ea 2’ Light-colored, massive, 85’ Sandstone, light gray to : Ul cross-bedded, locally Il 440! ” » Il tan, massive and thin- II conglomeratic sand- bedded, cross-bedded. stone. 4 Se See wee ees —_ = i = = Ze es Ct Se) 77’ Shale, red, gray and light ‘i gray, sandy. — a Eg 47° Shale, gray and light gray, *( Pierce and Andrews, as , indstone. sted an additiona 240' Variegated beds. iE 180) Green sandy shale. I 17’ Sanditones shaly, tan to eanaicarte and shale units overlying these two sandstones land included them /n their CLOVERLY | FORMA TION.) CHART IV PUBLISHED SECTIONS: CODY AREA (See Figure 2 for locations.) Ss GYPSUM CREEK This Fisher, 1908 Report ?’ Sandstone, rust-colored, alternating with dark Vill snales. 15’ Shale, dark purplish. VII 70 Sandstone, gray, massive, VI with chert pebbles. Z. iS < = lad © ky 7 J fod ica) x e) oe Y 25) Concealed (shale?). 70’ Shale, bluish with lime- stone concretions con- taining chert. 12’ Shale, deep maroon. V 2’ Sandstone, pure white. 23’ Shale, red, sandy with gypsum. 40’ Sandstone, thin-bedded with chert pebbles. IV 50’ Sandstone, strong, hard, blue- gray, weathers pink and brown. MORRISON FORMATION (Not recorded ) III S, GYPSUM CREEK <> GYPSUM CREEK 4 MILES NORTH OF KANE, > , BETWEEN CROOKED AND GYPSUM a i: WYOMING CREEKS : j is This Thi Fisher, 1908 Report Washburn, 1909 Report Lee, 1927 Report Moberly, 1960 Rent Rerdetone, rust-colorcd as Loar ay interbedded brown . . > re) siltstone, rtz aren- eyemaung with dark VIII (Not recorded) VIII 75’ — Greybull sandstone. VIII we iteg andi prayahalel : Vill ce tA e (lowest strata of 136° a 2 SS eo ee 2 total) Shale, dark purplish. VII 15’ Dark purplish shale. VII it Red sandy shale VII 135’ Wariegated claystone VII Zz Zz S S ae nik Ick. 355 ee ee ; z . = ed 2 Ciara 4 os o> == a ain — nc ang Be ha : : : eer massive, VI & 70’ Massive gray sandstone. VI VI $ (Not recorded) VI — ge esses Sa Bees 2 2 > \ ° (e) | oncealed (shale?). | 3) 3) shale, bluish with lime- S stone conerctions con- 100 Bright, variegated clays g aining chert. to and soft sandstones with Vv 150’ 1 - A Vv 5 - ale, deep maroon. Vv 150° conerctions of limestone andstone, pure white. and chert. CHART V Shale, red, sandy with PUBLISHED SECTIONS: gypsum. CROOKED CREEK - GYPSUM GREE WARREN AREA (See Figure 2 for locations.) Sandstone. thin-bedded ee: = : ; awi - . with did pebbles. Iv io Massive eat IV 50’ Coarse-grained massive IV IV indstone, strong, hard, blue- ray, weathers pink and brown. RISON FORMATION (Not recorded) ON FORMATION MORRIS thin coal seam. MORRISON FORMATION (Not recorded) Il MORRISON FORMATION sandstone, cross-bedded. —_— Variegated shale. Ill Il 290° 2 Ge) I MORRISON FORMATION Ill — >. o. “NEAR BRIDGER E MILE CREEK This Bauer and Robinson, lher, et al., 1946 Sandstone, brown (Not described ) VIII — Mudstone, maroo J white with gree purple shale an¢ (Not described) VII of yellow and wi sandstone. stone, dark-gray peb- es of chert and quartz. cealed, gray shale. dstone, gray, fine. Vv? tone, gray, ashy. cealed. CHART VI PUBLISHED SECTIONS: BRIDGER —- PRYOR MOUNTAIN AREA (See Figure 2 for locations.) +t = General section, no specific locality given. 313’ 9 +B) iglomerate, gray to 10’ Black and white cght-brown, gray and IV pebble conglomack chert and quartz- E pebbles. 50’ Sandstone, buff, feealed. , grained and sofiistone, light-brown. III 129 Shale, buff, yello tone, greenish-gray. pink. 110’ Sandstone, yellowdstone, gray-white. II(?) ystone, red-brown. dstone, white soft. ystone, red, vari- plored. I dstone, white, light- rown. cealed. “NEAR BRIDGER, MONTANA” This Report Bauer and Robinson, 1923 55’ Sandstone, brown to gray. to VIII 110° Mudstone, maroon and 1 white with green and purple shale and lenses VII of yellow and white sandstone. =? ” ” ” UE d 313’ ” » » Vv 10’ Black and white chert Iv pebble conglomerate. Sandstone, buff, fine- grained and soft. Shale, buff, yellow and pink. 129" III(?) RED DOME wa This n Lee, 1927 Report | 2 12’ Sandstone. 2 to VII m 45! o a EE —— — Shaly beds, highly colored, Vi Zz ieee nla ra i 2 = Ss VI 4 (eo) (MISE 2 SSS 2635s ee ee > 4 4 aI Ing S S 2007 oo» ” ” Vv 10’ Hard, black, chert pebble to conglomerate, IV 45' ON FORMATION MORRIS > MORRISON FORMATION (Not described) Ill Kis NEAR BOWLER, MONTANA €) FIVE MILE CREEK + NORTHERN CARBON COUNTY, MONTANA : This Knappen and Moulton, 1930 Report 60° Rusty thin-bedded sand- Tr stone and sandy shale. VIII Sere, «,-\- 4 iam a By Ss rg eee ts = 3) > ° | 0 180’ oo» ” » Vv 45’ Black chert conglomerate Iv and yellow sandstone. — Yellow clay and shale and a soft sandstone. II Zz 2 & eens Je ce = x » oo» ” Sante Il Vit lo ee a =. ee ee 6--------- 2 -4 -4 (e) = 210° ae 2 u I This This Wilson, 1936 Report Gardher, et al., 1946 Report 70’ Thinly bedded brown VIII (Not described) Vill sandstone, it ee M 29> <= ~~~ eee a 2?” Varicolored clays, VII (Not described) VI Zz 2 < SS ------------ a _ z 7 Sandstone, dark-gray peb- (e) bles of chert and quartz aw VI 10’ Sandstone, dark-gray, VI > friable, poorly sorted, 2) quartz and black chert f= --==-- TOS Seas See ee ian (eee Bs 5 fe) 2 = e) & S| < < = 4 O 25’ Concealed, gray shale ” Vv Be I’ Sandstone, gray, fine Vv? o> 2’ — Siltstone, gray, ashy. = Ia (Garcealed CHART VI 5) PUBLISHED SECTIONS: 5 BRIDGER — PRYOR MOUNTAIN AREA re) (See Figure 2 for locations.) 3 Mm ae t = General section, no Specific locality given. 50’ Brown and yellow sand- 12" Conglomerate, gray to i i ; light-brown, gray and , stone with abundant IV black chert and quartz- IV black chert pebbles, ite pebbles Varicolored clays with two interbedded yellow Ill to buff sandstones, 25 iS} = Se wiS Sm Re aK emia Si Se & ee m iy II(?) Aca note ssa 2 4 x 2 200° - bss I MORRISON FORMATION ELE 8° 36° Concealed Sandstone, light-brown Il Siltstone, greenish-gray Sandstone, gray-white II(?) Claystone, red-brown Sandstone, white soft Claystone, red, vari- Cblored I Sandstone, white, light- brown Concealed ° ba ort? ean wi "ONT e yeas et ie on a - - 5 we ba S di — ¢ 7 4 7 a a 7 7 VII-FD i7 SEC: 21 (ee bo oe EG, MONTANA This Richards, 1955 Report (Not described ) VII! VII Z © H < = =a aS a Se es a SSS sss a assesses a ss a ae a a ss a Ss SS SS iS Ss i Sr SS SS SS SS faa ie a VI > 4 en ee Sate Le ee ee See ee ica} > 1@) | oO % < Vv CHART VII PUBLISHED SECTIONS: PRYOR — BEAUVAIS CREEK AREA (See Figure 2 for locations.) + = General section, no specific locality given. ++ = Section located outside of study area. 22’ Conglomerate, gray to light-brown, massive, IV pebbles of sandstone, quartz and chert. 38’ _Siltstone, greenish-gray, clayey, highly calcareous. 14’ Sandstone, white, calcareous. 28’ _—Siltstone, medium gray. 1’ Limestone, light gray, silty. III (?) 92’ — Siltstone and shale, gray. III(?) 89’ Concealed. 5’ Siltstone and claystone, yellow-brown. 1’ Sandstone, dark gray, calcareous. 15’ Siltstone, claystone, yellow. MORRISON FORMATION I cal ais tai sii in an Ri lle Ae i ea i ia ES | 11-4 + SOUTHERN CROW INDIAN 20 7 es eo RESERVATION : PRYOR, MONTANA MONTANA MONTANA SE I22 OS Ry Ata SEG, 21, T. 7.8, R. 81 B, This This This aH MONTANA MONTANA jauer and Robinson, 1923 Report Lee, 1927 a This i Bau po: ee, 192 Report Thom, et al., 1935 Report Thom, et al., 1935 Report Thom, et al., 1935 Report Richards, 1955 eres uy Sandstone. + Dome Sarnvic : fo VIII 45’ Sandstone. VIII pr ne, COAYSe, MASSIVE, i 12’ Sandstone, shaly, a irregular bedding. VIII (Not described) VIII with kell faeea VIII (Not described) VIII es Fe Eee cs _.:, . ee meee jb fo I et na Cin > > een a eee . Se e £ 23’ Shale, gray. ~ IS) 4’ — Shale, pink. 3 3 2" Sandstone, white — Variegated, purple and B B 55’ Shale, variegated, ay gee agp eee mesatiilenies © vig = 106" Colored shaly beds. Vil 1’ Limestone, white. vu Le VII black with 5 feet of vil of yellow and white ce > 50! Shale, variegated. hard, white shale in VIL sandstone. 4 4 z middle [4 , d 3) a vA 7 Shale, hard, white. z S SS ° 6’ Shale, gray, green, purple. ©} ° (e) fe 5’ Shale, red, weathers a | a A AS eee oS eee a=. See eS SSE es 5 OA ee ae eee purple < SS tesa re Se S 20’ Sandstone, light-colored, 5 B » » ” » r > cross-bedded, grades VI 20' Conglomerate. VI(?) laterally to conglom- VI =m VI VI 5 VI erate. ma 7 eer eer ee er a ee 9 Le s 10’ Shale, soft, light-gray 2 MORRISON FORMATION MORRISON FORMATION o) with chalcedony and ‘o (Not described) (Not described) 4 calcite concretions pa Y 6’ Shale, hard, gray, weathers — brilliant white 105" . ” ” ” 1’ Sandstone, hard, worm tracks. to We — Vv Vv Vv z 10° Sandstone, yellow. V CHART VII ! Y Ce a sy ee PUBLISHED SECTIONS: ere rea ona ABEL WALL PRYOR - BEAUVAIS GREEK AREA < ABE AETE (See Figure 2 for locations.) 7’ Coal z 3 19" Shale, dark-gr: t = General section, no specific locality given. fe) 2’ Shale, dark r +t = Section located outside of study area, ee ee ee eeste eee | eesti ceet 3 e565 5 ee ee eee a ee = —— eet - ; > 13’ Sandstone, dirty gray. 22’ conglomerate] gray to = 15 Sandstone, conglomerate, 4 7’ Sandstone, hard, coarse, ight-brown, massive, , ” Gonglomeratic sandstone, IV(?) i IV IV weathering darkbrown. 2Y black mineral grains Iv(?) pebbles of sandstone, IV > probably augite or hornblende. quartz and chert co ee i an aaa Soo"? an 9 38’ — Siltstone, greenish-gray, ~ 3) clayey, highly calcareous £ £ 14° Sandstone, white, calcareous. $ $ 28’ — Siltstone, medium gray. ) Hard, greenish-gray shale, 2 eo 1’ Limestone, light gray, silty ! aoe pink and purple nat 2 ime Ill © III 115’ Shale, red or purple. III(?) 4’ Sandstone, shaly. III(?) 92 Siltstone and shale, gray. III (?) shales, white and yellow 89 Jonceale: sandstones, Zz Zz 5’ Siltstone and claystone, (e) ie} z z yellow-brown Z) 3 () o) 1’ Sandstone, dark gray, 2 = o calcareous 5 5 = iets coe: ee eee < 15’ Siltstone, claystone, yellow. > -------------- Sp SPSS SS SIS SS I aaa aaa ade = 4 4 » » » 4 (e) 3’ Sandstone, cross-bedded, > Il O° Il Il J Il He fe light colored. II(?) iS re ee Sk ter Z ne nnn nnn eee ene ae eae 5 -) % 5 2 : : ” » ” I 23’ Shale, purple-gray. 1(?) I I I 216" I 75' Shale, pink or red. Kir} 4 MILES SOUTH OF PRYOR, 6 MILES SOUTH OF PRYOR, it Cp + * ) ,. i nS 4 Nv Ly, tL & _ ac Ye oe 4 - \e RONG 4 1] INSTI ) is P fz > iw \ 3 \% & +t by n <70n \ > NIAR S314 INVIIWWUTIZtTO ANS 1 SSN & “bj LI INSTI ars 4&4 4 [5 “mo 5 <7o8 EE ee, a cana = _. srr - —~e===== a a Ez °o NS vasnl7 = NN a > = Nose 7 > e SS 5 phe Lb 7. _INSTITUTION NOILOLILSNI_NVINOSHLINS S3!1YVYSIT LIBRARIES SMITHSONIAN_INSTITUTION P NOLLNLILSNI— = NVINOSHLIN 2 er aet ——— Zz = rat ” om ee > a ld sth, > a. ” Zz hy oe Fold-out Placeholder ed ata This fold-out is being digitized, and will be insert future date. Fold-out Placeholder ed at a future date. This fold-out is being digitized, and will be insert SMITHSONIAN WSTITUTION LIBRARIES WM 3 9088 01372 0255 vet ‘ ee Oh bee re seas AAA rere At +s Te UU NU “re my a it shade i Wee he ekes ve Oe ue oe * Saha Ae ~- + eee ee NA eee i ry a pal reetent eat ay 4-0/9 > TX tt Aen a We esire Geek ay ' Neg tor ve os ena h Pr OOOO ROI Ah LAA Pee Tne rf 7 i : : at ‘ ‘ ‘ * Ube tee hw dare ae ty vite - mech JUSDEME JS rye nn ‘eer