!lfr::x.i-: «.':.V,;',' •r:'--.i;^ W nil: ;:.•-■■■■. ■, •, ■,-,; ■;;'■ ■v. ''' '■. '.■'■'"■ ' ' ■*'■■'' 3',:"'' ,,•'':''-.',' .:!! .;':' l,(';;.:A'i-.i,:v.;r?',V,:.i :<'■■,. ■v.: .,, :■ •; N^ 'ifiiiSlJif;::-,- ■:■;:.;■;!'■;■ '■■..'I,-' /■ ■■■-■■ ?.,i,V/-,'f;;i-;';V, V.':,'', , : . . ., •■;■.;■ j,,.:j':(;tr::^':;-;';,>''>i;;';'; ' a-«^';:. ■ ■' ; \' > ■r^'h'- ■■,■!,', ';^''.'i-,'" t:;' '■' !: v.'';i'j-ii; " :-;l. .;■■ " 0 M E M < ) I l{ S i)V Tllh; Cal IfOHNIA AcADE] MY OF Scie:^ Vol V, No. 1 THE THALATTOSAURIA A ( T i; u I 1' () |- MARIN E R E 1' T 1 E E S ERG M TU I A SS I (• () I' (' A E I EO l{ N I A 'J 1 1 E Bv JOIIX (" MKKKEV.M I>M Kh May '.I. r.iil."> -^\X FKANCISCO V V K l,T- II i: 1' V.\ I II I A ' A 11 I, M Y C O ^I M I T T E E ON P U B L I G A T I O X IjUVErktt Mills Loomis, Chainnan Xi.vm-.vfi Kri.i, Joseph W. Hobsox THE THALATTOSAURIA A (ji-oui) of Marine Reptiles FKOM THK Triassic of ( 'alifoniia. By JOHN C. MERIUA.M. ('0NTENT8. I'l.ATKs i-vrrr. Introduction 8 Ordinal and Family ('HARAcrKus 5 Occurrence and Age 5 Materials Available 7 (Ienehal Skeletal STurcTCKE S Skull ; 8 Facial Jiet/ion 8 Front o-parietal Region 10 Temporal Region 11 Qiiadrute, Suspensorinni 12 Orbital Region 12 Palatine Region lo Mandilile 15 Dentition Id (Inalliir 15 ]'omerine 17 Pterygoid 18 Fv net ion 18 Vertol)i;u" 18 Ribs l!l Trve Rihx li» Alnhnninal Rihn li) ( 1 ) May •">, 1»). Ml Z ('ALIFt)]!>MA ACAIUOIV OF SCIKXCKS Linil)S and ( iirillcs 20 Pelvic Arrli initl I'lixtcriar Limh 20 Pectoral A irli 21 Anterior Limh 21 Habitat, L(k'cimhtiiin. I'don 22 Affixitiks 28 (_'oiu|>arisi nhasteiisis 85 Measurements 85 TliiiUilloaini riia perriiii 8(5 AVf'/().vv( )( ni.s- 8 ( Necfii.'ut it has resulted in giving us a fair representation of the most important tdements of the sktdeton. The acquisition of our knowledge of the Thalattosauria has been made possible through the generous assistance of Miss A. M. .Mexander. who has not only contribute(l the tinancial support of the field work, and in part also of the preparation of the material for puldication, but was hers(df the discoverer of the specimens which furnish the greater part of our knowle(lge of the fundamental skeletal structure of the representatives of this grouj). Acknowledgments for \aluable services in connection with this investiga- tion are also due to all the members of the University of ('alifornia licdd parties which have worked on the Triassic limestones. To Trofessor .lames Perrin Smith I am under obligation for the informatioii which led to the lirst ex[)lora- tion of the Shasta limestones in search of saurian remains, and for the loan of a valual)le type specimen. To Mr. K. L. l'\irloiig 1 am especially indebted for v<'rv efficient assistance e.xtt'iiding through every stage of the work, from the collection of the specimens to the final preparation of the material for study. I'r. T. \\ . Stanton has loaned nii important sjx'cimen for study and description. 1 E. Friiss, Ichthyosnurieid. deutschoii Trias & Jura Ablng., PI. in, figs. 1-4. 2 Science. !i. ser. v. 1.5, p. 411. s See Triassic IchthyoptcrvKia. linll. I>ci>t. Ccnl. fiiiv. Calif, v. :J, no. 4, p. 8.'i. Dentition. 4 CALlKOItXIA ACADKMV l>F SCIKXCES While pi-fpuring tliis report, sonie WH'eks were spent in examining. typical specimens of forms in related groups. For favors in connection with the study of such material, the writer would expi-ess his most sincere thanks to the follow- ing gentlemen: Professor 8. W. Williston, Dr. \. Smitii Woodward, Dr. C. W. Andrews, Dr. E. Frass, Dr. F. von Huene, I'rofessor E. Koken, Dr. Louis Dollo, Professor Henry F. Oshorn, Dr. Lortet. V)ii rcrxiiil (if CdJ ifoniHt . Marrli, J! )().',. Superorder DIAPTOSAURIA. Onlci- THALATTOSAIHIA.' Mariin' snuriaiis with a Khi'cvia t (■i pod i a 1 liiiil) segments, eloiigatcil facial rcuion, and nnMliaii cxtcrual narcs. Slvull with superior and lateral temporal opeiiiiins and a pineal foramen. I'revomers and pterygoids as well as jaw elements dentigerous. General structure of skeleton of the rhynchoceph- a 1 i a 11 t y [) e . The group is eonnioseil of specialized natatory forms known only from marine deposits. It stands in somewhat the same rcdation to the typical Rhynohoeephalia as tliat which the Mosasauria hear to the Lacertilia. Evidently derived from a primitive land or shore 1 )iaptosauriaii, it has taken somewhat the same course in evolution as was foUoweil later hy the Mosasaurs. Family TllA LATTUSAURIDAE." Skull elongated, with slender rostrum. External iiares sepa- rate and not far in front of the or hits. I'rema x i 11 a ries elongated and forming a large portion of the snout. I'reni a x i 1 1 a ries, maxil- laries an^. Arcixlrx. Ortlmfcrds. Xunfihi.-!. Atrdctifcs, Halobia, Rhynchonella, h^piriferina, Ciclarls. 1 Sec. 11 and 12, T. U N. It. 2 W, Mt. D. Mcrid. 2 Sw. 3."), T. 35 N, R. 2 W, Mt. 11. Mfrici. 3 Sec. :«, T. 3.5 N, R. 2 \V, Mt. I). Meriil. 4 Sec. 1, T. 3.T X. ami Sec. 3li, T. 'X, N', U. 2 \V, .Ml. I). Mciiil. 5 See Comparative Slratigraiihy of the Marine Trias of Western .\nieriea, I'roe. Calif, .\eail. Sei. M ser. lieoi, v. 1, no, 111, [>. 300. MKHIUA.M Till". TIIAI.ATTnsAlMMA / The iiivcrt('l)nitc faunas have Ix'tMi extensively studied Ky Professor Smith', and are referred 1)V him to the I'pper Triassic on the eviih^iee of general striking simihiritv of thi' fauna to that of the Alpine Triassie of Europe, even in some cases to the point of identity of speeies. Also in the ease of the lehthyo- sauria, almost uncjuestionable evidence of late Triassic age is Liixcii in the stage of evolution or specialization of various parts of the skeleton. In general this is near the stage i-eacheil hy the hditliyosauria of the latei- Triassic of Italy. This is particulai'lv noticealile in the structure of the lindis. girdles and vertel)i-al arches. The preseiKH' of innumi-rahle cephalopods with hracdiiopods and corals, in a limestone containing for the most jiart hut little argillaceous material, leaves no room for doul)t that the deposit was formed in a fairly (dear sea, into whicli there was but little drainage at this point. The reptilian forms whicdi we tind in these strata evidently Ixdonged to the typical marine fauna of tlu- late Triassic. MATEHIAbS AVAILAUI.E. The specimen whiidi has furnished the most satisfactory information in this investigation is the tvj)e of Tliahitfosdurus ukxcnidrae (No. ilOS;")). Excepting the anterior part of the skull and portions of the limbs and girdles, the skeleton had long been exposed and was larg(dy weathered away. The remaining part's include the anterioi' two thirds of the skull with a small jiart of one temporal region. Of the girdles and lindis there are present the scapula, coracoid, humerus, ulna, three l)ones wiii(di represent the lower part of the pelvis and possibly the fenuir, and some scattered ossicles which may be either carpals or phalanges. ()f the vertebral column there are pai'ts of about thirty vi-rtebrae extending in an interru})te.'; N/, si|uaiiiiisal ; 'i', (nunlrati/ ; . I/-, articular ; N'l, supra- angulav; ,1//, angular ; T^, dentary. Facial Rcj/idii. — As is shown in J'late i, the facial region of this skull is very slender. The snout was narrow, exhibiting some resend>lance to that of the long-headed Mosasaurs. MKi;i;i AM — Till-: tiia i, \ rn is. \ri;i a 9 ( )v('i' a laruc part of the external surface of both niaxiUaries ami [ireinaxil- laries, tlie rostral re, distinct |iits. 10 <'AT>IK(>i;XlA ACADK.MV OF S('IF,.\( 'KS Tlie iKisals are clearly shown in the type of Thdldftnsdtinis. They are not large and horder mainly the median and posterior sides of the superior mires. They do not meet medially but are separated by the frontals and premaxillaries. The posterior ends rest between the forks of the frontals. A tendency toward separation of the nasals by extension of the frontals and premaxillarit's is seen in many reptilian skulls, particularly in rhynchocephalian, lacertilian and sauro- pterygian forms, but such t'omplete sepai'ation as is shown here is so rare that it may be considered an important character. The neai'est approach to this structure is seen in the Sauropterygia. In that group the nares are situated close to the orbits and are either median or sul)tei'minal. in all cases the premaxillaries foi-m a large share of the snout. In the Nothosaurs the nasals have almost the same form as in Thalattosmiriis, and the premaxillaries are thrust back between the nares though not in contact with the frontals. In Pisfd.^aiiru.'^ the premaxillaries touch the frontals, separating the nares and the small nasals. In Plesiosaurns the pre- maxillaries ai'e in broad contact with the frontals. in /hilichorln/iichojis, vavvntly described by VVilliston. the premaxillaries extend hack to the parietals, sepa- rating even the frontals. Fig. '2. TlialdlldsadriiK iiU:iiui(lriii'. Kci'inistnictcil sUull, sn|i('rii>v view, X ^r. /')/(. |ireiiiaxillary ; .1/, maxillary; .V, nasal; ]C, .«uinTiiir nares; /', t'rcnital; /'/■, i>ariftal; I'li. iiincal fnranii'ii: /'/', iirt'fnintal ; P(o, liost-friintd-iirbital ; ./, jnijal; 7^, laclii'vnial ; /'/, jialatine ; N(/, si|nani(isal ; 't'. i|uaili'atr. Froiito-parietuI Region. — This region is particularly well shown in the speci- men of 'riidUtttnmnrus represented in Plate iii. Both frontals and parietals are distinctly i)aii'e(l and on both the superior surface is nearly smooth, being marked only by Hne lines and pits. The /Ve;/^//.s- are relatively large. Their postero-external angles reach far back and partly clasp the anterior ends of the parietals. Tlu' anterior ends are deeply incised for the reception of the nasals. The median anterior forks extend forward as far as the middle of the superior nares, while the lateral forks reach almost if not (piite to the outer border of the nares. .MKKKIAM Tin: Til A I, ATTOSA UKl A 11 The ixtrictuls art- iiiurli smaller than the t'ruiitals ami an- also scjuirated i)y a miMliaii suture. A large parietal foramen lies between the two elements, hut is a considerable distance behind the coronal suture. The posterioi- outei- angles of the parietals are produced backward around the outer side of the superior temporal openings for more than half the length of the upper temporal arch. In tigui'e 2a, Plate i\', what appears to be the squamosal is seen to reach forward over the post-fronto-orbital to touch the frontal. If this is the normal relation of these (di'ments, the outer border of the parietal is separated from the post-fronto-orbital. The median portion of the parietal is also })roduced back- ward as a slender arm and was probably in contact with the squamosal. The two posterior arms seem almost to have surrounded the upper temporal opening, giving to the skull an altogt'ther peculiar character in this region. Tcinporal Reginu. — The skulls appear to be characterized by the presence of both superior and lateral temporal openings. The ■mperior openings are con- siderablv smaller than the lateral. .ludgingfrom the specimen seen in I'late iii, the posterior ends of the pai'ietals wei'e very slender and were dropped some distance bcdow the level of the roof of the skull, so that the superior oj)enings faced backward somewhat, as in Belodaii. The anterioi- half or two thirds of this opening was enclosed by the parietal. The posterior boundaries have not been seen. They were probably formed by connection of the parietal and squamosal, though the supraoccipital may have intervened as seems to have been the case in SdH ra iindiDi. The rehitivtdy large hilcral fi'iiijionil iipoiiiKji^ are seen in two specimens (IM. Ill, tig. 2 and 1*1. iv, tig. 'l(i). The boundaries are not perfect, even in the more nearly complete specimens, owing to the absence of the quadratojugal. In both instances, however, the jugal sends backward a long and strong process extending more than half the distance to the ([uadrate, and in one specimen the posterior end of this process is roughened as if fi'om contact with a (juailrato- jugal. Under these circumstances it would lie ditHcult to believe that the iiifcriar liar was incomplete. Should we assume that it was not coin])lete it would l)e necessary to supfiose that it is caught, as it were, in thi' process of breaking down, as no form losing the lower i)ar retains a posterior jugal process similar to that shown here, lii reality there is hardly reason for supposing that the lower bar was even weak, as the posterior process sent out from the jugal is not stronger than it is here in many forms in which this arch is t-onsidcred w(dl developed. The iipjX'r fciiipiirdl Ixir is certainly made u]) to a gi'eat extent (.)f the large post-fronto-orbital and the s(Hiamosal. as seen in IMate IV. ligure 2(i. with the addition of the outer posterior pi'ocess of the parietal lying on the me(lian side 12 CAI.IKoliXlA ACADK.AIY ( H' SCIKXCKS of tlie bar. Even on tlie most coiuplete spcriuuMis (I'ls. in and iv) it has been impossible to determine certainly whether a prosquamosal is present or not, as the character of the bone is sucli that the sntnres immediately above the quadrate are very difficult to determine. On what is taken to be the quadrate in a frafiinent of the temporal retiion of the type of TliakiftosaKrii.-^ (1*1. ii, fig. 4) there rests a downwardly' projecting arm which appears to be a part of an ele- ment that belonged to the lower side of the upper temporal bar. Evidentlv it extended down the outer wing of tlie (|uadrate, almost if not quite to the quadratojugal. The inner side of this bone, as also of that resting on the summit of the (juadrate, is weathered away and it is not impossible that they were originally connected. If united, the squamosal must have had a form somewhat similar to tliat of SjiliciKxhui. If separated, the lower (dement is apparently a discrete prosquamosal. Quadrate, Suspensoriam. — The (jnadrate is well shown in position in one specimen (PI. in, fig. 2) and macerated out, though associated with the posterior end of the mandible and the cranium, in another (PI. ii, tigs. 2a and 2b). It is of distinctly rhynchocephalian ty{)e, though approaching the laccrtilian form in the development of a stronger posterior hook and a broad exterior wing. While the posterior side of the distal end is rounded upward the anterior side is dis- tinctly flattened as if from contact with a quadratojugal. The presence of a high extero-laternl wing seems to precdude the possibility of there having been a fenestra between the quadrate and (luadratojugal, as in the typical Rhynchoceph- alia, thovigh there may have been a small opening near the distal end. The relation of the quadrate to the temporal bones is such that it must have been immoval)le, in contrast to the general relations in the Squamata. Orhitdl H('!/iini. — Tlu' specinu'ns of 'rhdldftdsaiiriis show portions of large sclerotic plaf(.'< in the orbits. They are similar in form to those seen, in the Mosasaurs. In at least one instance a plate is deeply grooved on the margin, as occurs in forms in which the sclerotic ring is particularly heav}' and strong. In the boundaries of the upper side of the orbit the prefrontal and post- fronto-orbital come so close together that the frontal hardly appears on the rim of the orbit. The posterior boundary is formed by the heavy ascending process of the jngal, and a single uj)per element evidently representing both the post- frontal and the postorbital. No evidence has been obtainecl which would tend to indicate the existence of a separate jiostfrontal resting al)ove this bone. The apparent contact of the squamosal with the frontal might be interpreted to mean that a greatly reduced postfrontal is fusecl Avith the anterior arm of the squa- mosal, but until we have more definite proof of this it can be considered only as a mere possibility. MKIv'KIAM TllK THALATTOSAl'IUA 13 'r\w pirfniiita/s arc lari;c robust elements extending t'nini the middle of the upper boundary of the orl)it forward along tlu' inner side of the maxillary. The small hii'linjiiKtl, extending over only a limited area of the face, is well shown in the tvi)e of 'riidlnttomnrus (PL i, tig. 1, L). The laehrynuil foramen is also distinctly seen here. In cross-section /), Plate n, ligure 16, .1 there is seen a peculiar element apparently distinct from the nasals, maxillaries, premaxillaries and prt'vomer. If suidi is I'eally the ease, this is prohahly an anterior j)rolongation of the })refrontal. This would, however, rec^uire an extraordinary enlargement of the anterior end of this hone, and further evidence is i-e(|uired before its relations can be satisfactorily (letermine(l. Palatine Region. — It is in the palatine region that some of the most dis- tinctive characters are seen in the nieiidiers of this grou[i. The general aspect here is of a primitive form in which the rostral region, and in it pai'ticularly the vomerine dentition, exhibits distinctive specialization. The position and relations of the jiretWHer are iiest shown in the type of Thalattosaurus (Tl. i. tig. 2 and PI. ii, tigs. V> and Ir). It is here seen to lie largely between the maxillaries although reaching far foi'ward along the rostrum. It is much elongated antero-posteriorly and has in general a sphenoidal form. So far as can be determined from the sections no median suture is present, though the structure niav have been })aired. From the meilian portion of the posterior end three laniiinie project backward, the meilian plate being much smaller than the others. ()u either side of these laminae the posterior margin slimvs a regularly roun(le) is not such a contact as Avould occiu' if the correspond- ing element from the other side were met here. The presumption is that the anterior end of the pterygoid passing along the median l^ordi-r of the palatine was in contact with this surface. In none of the skulls examined have there l)een found any indications of the existence of teeth on the palatine. In two specimens (PI. in, fig. ."! and PI. IV, fig. 3) this element can be seen in place and has been followed backward for a considerable distance without showing any traces of teeth, though they are well shown on other elements. The teeth shown close to the palatine on Plate iv, figure •"> are entirely distinct from it. They prol)al)ly belonged to the ptervgoiil. One of the most remarkable features of the type specimen of ThalaftomiirKs is a peculiar dentigerous bone which lay below the palatine region and above the separated rami of the mandible, ('onsidering the position of the specimen. the character of the material, and the fact that no bones of other animals have been found in the matrix, there can he no reasonal)le doubt that it belongs to this skull. 'Hiis hone (JM. v, iigs. Ir;, ll> and Ic) is held to he the pteryf/oid. It consists of a narrow, thick plate, one border of which boi'e five rows of teeth. The MKIMMA.M TlIK Til A I,ATT< ISA T i; I A 15 !^ Opposite iiiar.iiiii of tlic plate supports a lii^li. tliin, ti-iaii^ular wiiii;- standing almost parallel witli the tootli-heariiig sui-faee. Tlie surfaee of this wiiig is marked on one side hv I'adiating sculpture sotnewliat like that of the maxillary, except- ing that it is larg(dy in ndief. The at'ute end of the wing is drawn out to a ver}' thin edge. The hroad end is eonsiderahly thicker and shows a deep groove wliere it was prohahly in contact with the (piadrate. The j)fciitition. The dentition is well shown in the tyite specimens of ThaJattosavrus, as also in the lower jaw of the type of Necfomnrun, and more or less imperfectly in most of the other specimens. In addition to the jaw elements, the pterygoid and prevouier are (U'litigerous while the palatines are not known to have carried teeth. Teetli oftheJav's. — The liisrrtioit of the teeth on the ui)])er and lower jaws varies considerably within the group. In ThalnHdmurus the teeth of both upper and lower jaws seem to rest in pits, which may be in elevated bases formed by the alveolar margin. In some cases they appear to be fused Avith the jaw bone. In T. perritii the teeth of both jaws rest in distinct pits. The depth of the pit and the general character of the insertion are to a considerable extent dependent on the form of the crown. The slender conical, anterior teeth are very deej)ly set in the jaws, while the pits for the low, broad-crowned, posterior mandibular teeth are much shallower. This may have been the case in T. xlexaudrae also, but the preservation of the anterior portion of tlu' jaw (jf the type specimen has not ])ermitted a satisfactory investigation of the insertion. One of the diagnostic features of Thahittosaurm is found in the remarkable differentiatiDU of the mandil)ular ) the (Iciititiuii df the luwi-r jaw shows ayain the foiiit-al anterior teeth with hiterally eoMii)ressed, low-crowiicd posterior teeth. The depression in tlie hitter is, liowever, very niucii less than in T. alc.randrae. Tn the upper jaw all of the teetli are eouieal. There do not appear to he any low-erowned or laterally compressed maxillary teeth. The most posterior [lortion of the maxillary was apparently I'drutulous ami it is evident that the posterior vomerine teeth were in contact with the posterior portion of the mandihular dentition. Jn the type of TltalaftoMtiiriis the perfectly })resi'i-ved ti|) of the crown of an anterior mandihular tooth shows very faint wrinkles in the enamel. ( )n the dej)ressed pcisterior teeth the wrinkling of the enamel is more pronounced and in some instances a faint tul)erculation is visihle. A single loose tooth found with tlie jaws of this specimen has an elongated, somewhat compressed crown covered with numerous strong longitudinal striae. Associated with the head hones of T. shafitensis are several loose teetli show- ins the form verv distinctlv. In all of these the crowns are conical, hut thev vary considerahly in length and thickness. The slender, curved teeth (IT. iv, fig. '2h) are prohaldy from the anterior portion of the jaws, and the shorter, heavier ones (Fl. iv, fig. 'Ic) from the middle region. The ci'owns are all sup- ported on heavy fangs, such as are present in teeth inserted in pits. The enamel is marked with numerous tine, longitudinal Avrinkles or striae somewhat finer than those on the corresponding teetli of T. akxandriw. In no case has anv evidence been ohtained which would tend to show that the l>ases of the teeth have a foldeil internal sti'ucture as in the Ichthyosauria and (Tioristodera. Vomerine Teeth. — In all specimens, so far as is known, vosterior vomerine teeth e\idently met the pos- terior teeth of the nnindii)le. The vomerine teeth are set in depressions and where seen in a cross-section of the j)revomer (Fl. ii, fig. Ic) they ai'e known to extend a considerable distance into ( 2 j May G, 19«j. 18 ('A]JFOi;>-IA ACADEMY OF 8('lKiN'CES tlic lione. The enamel is oniamented witli a lari;e number of line wrinkles radiating' from the apex of the erown. Pterygoid Dentition. — Closely set teeth were present in at least five rows on the heavy median plate of the pterygoid. They are of slender conical form and each is set in a distinct pit of considerable depth. Unfortunately the crowns have not been well preserved. They are all nearly circuhir in cross-section and the enamel seems to have been slightly wrinkled toward tiie base. Finirtion. — The dentition of the Thalattosaurs is evidently tliat of swiftly swimming fi>rms feeding in a large measure upon fish. The character of the posterior mandibular and vomerine teeth of Tlii><, indicating a crushing function, probably means that this type fed also in })art u}>on some creature with a shell which could be easily crushed. Such forms Avould have been found in the numberless cephalopods of this epoch, and they doubtless furnished a portion of the food of the Thalattosaurs. A'ertcbrae. ri.ATlO VII, FlOS. l-."!. In the type specimen of ThalaUosaurus alexaudrae parts of over thirty verte- brae are shown. They represent the cervical, dorsal and anterior caudal regions. A number of loose vertebrae in a fair state of preservation are associated with other specimens. In Tliahiftosanrvs the centra of the anterior dorsals (PL vii, figs. 1 and 2) are nearly circular in vertical, transverse cross-section. The anterior and posterior faces are concave but not so deeply excavated as in the Ichthyosauria, the wall betwet'n the two faces representing more than half of the antero-posterior diam- eter of the centrum. The upper arches are rather slender and are not greatly thickened. Tlie anterior margins are sharp. The posterior edges seem to be blunted or rounded. Strong zygapophyses are present. A characteristic feature of these vertebrae seems to be found in the closer attachment of the upper arches to the centra than we find in the Ichthyosauria. In this respect they resemble the vertebrae of the ]*lesiosaurs and (-rocodiles. An upper arch of T. shastensis (PI. vii, tig. 4) shows the structure of the neurocentra better than in any other specimen. The spine is wider antero- posteriorly and is not so high as in T. akxandrae. Possibly this is due in this case to the arch having occupied a more anterior position than the arch of alexandfrae figured (PL vii, fig. 1). The zygapophyses are large and strong and the facets well separated. Tlie ribs of TJialaffosaitrus articulate on a single wide apoj)liysis, the upper port ion (diapophysial) of which is situated above tlie middle of tlie ceiiti'um. MKi;l;lAM TIIK THALATTdSAriMA 19 The surface of artirulation is coiisideralily iiarrowcil in the iiiiddU' Imt the apoi)h- vsis is not seen to divide into distinet di- and i)ar- apopliyses. In the dorsal vertchrae examined, the uppermost portion of tlic ril) head lias heen in articu- lation with the hase of the neural arch. In the caudals of Thaluttofianru.i (IM. vii, i\. — In the pelvic regioM of the type specimen there are parts of several l)ones evidently re[)resenting a portion of the pelvis and probably some of the elements of a hind limb. Only two of these l)ones are complete enough to permit identification. Corresponding to one of them there are in tlie collections two much better specimens (1*1. vii, figs. 8 and 10) giving a fair idea of its form. This element is larger than the other and differs from it somewhat in form. It exhibits characters which are not particularly definite and might permit its identification as either of the inferior elements of the pelvic arch or possibly as the femur. It is narrowed somewhat below the })roxi- nial i^^nd or head and is considerably broadened distally. The expanded anterior margin of the distal end is thin and slightly decurved. The distal portion is thickened, excepting in the middle of the end, and is excavated along the distal border. The proximal end is also excavated. On the more strongly concave side of the neck there is a small foramen in all three specimens. This element shows some resemblance to a femur, and when first examined was thought to represent that element. It also resembles the pubis in the form of both ends, in the curvature of the shaft, and in the twist of the outer margin. The small foramen near the proximal end might o<'cur behind a trochanteric elevation of a femur or in the pubis. If this is the femur it represents a type of extremity quite different from that seen in the anterior lind), the distal end being turned sharply backward and slightly U})ward. Propodial elements of this kind nw not uncommon in natatory reptiles, but wiien pi'esiMit in the hind lind). the fore limb is usually, though not always, of a simihir character. Tlie other element belonging in this region (PI. vii, tig. 0) is again of some- what indefinite form. It is quite similar to the first mentioned element but is smaller and shows a greater expansion of the median ])ortion, producing a prominent wing. This bone might l)e either pubis or ischium but is probably the latter. A fragment of another large element lying next the ischium may represent the ilium or the femur. It is nearly straight and appears to be almost circular in cross-section. However we may interpret the elements which have been discusser!, it is evident that at least one of them must belong in the inferior poi'tion of the MKl;i;iAM THK THAI.ATTdSAriil A 21 pelvis, and that the characters of either or l)oth of them are such as to show- that the pelvis was not of the i>late-like form usually seen in the primitive Diaptosauria. Both of the elements (lescril)e(l from the pelvic rei-ion of the type specimen are large comi)are(l with the coi-aeoid, sea}iula and humerus. No matter how we interpret them, they show that the posterior lind)s were possibly more powerful than the anterior, reminding us of tlie peculiarly s[)eciali/,e(l Thalatto- suehia of Frass. Pectoral Arch. — The ]>ectoral girdle is represented hy the eoracoid and scapula. No clavicle or intertdavicle has as yet been discovered. Several fragments of large l)ones associated with the jx'ctoral girdle mav represent one or hotli of these elements. The eoracoid (PI. viu, fig. 1) is reniforni and has some- what the form of the eoracoid in the ichthyosaurian genus Merria)ina from the same horizon. It is, how- ever, more distinctly reniforni, having a sliarply conca\-e exterior margin. The scapula (I'l. viii. Hgs. 2 and ;>) is comparatively narrow reseml)ling that of the ( "roeodilians, Farasuchi- ans, the later Ichthyosaurs, and most of the rhyncho- cephalian forms. It differs from that of the Triassic hdithvosaui's in lacking the considerahle distal expan- sion. The structure of the pectoral arch, so fai' as known, seems more primiti\'e than that of the Ti'iassic Ichthvo.saurs and is of distinctiv rhvnehocephalian tvi)e. ^V^ '^^ Jl"^^''ttom,'ru. ale,- • ' . ^ 'I iiiulrne. A portion ol the n>:lit Anterior Limb. — Elements belonging to the anterior |„.,toial arch and limb seen limbs are found in the type and in two other specimens. In the tvt)e the humerus and tlu' ulna are present. In another specimen both the humeri are widl preserved and with them is, a nearly perfeet radius. The Jtiiinrrai^ (PI. vin, figs, 4" and 4/^ is consideralily expanded dorso- vi'utrally at the proximal end through the devipodial liones. Such indications as are given in the possible char- acter of the phalanges would also point in this direction. The specialization of the lindi is greater than that in the I'roganosauria, ( -horistodera or Parasuchia. It can perhaps be best compared with that of the Plesiosaurs or with the Triassic Ichthyosaurs. The humerus is, however, a little more slender medially than in the Ichthyosaurs. If tin- rounded ossicles are really phalanges, it is evident that the limb was no longer serviceable to any extent for land or shore locomo- tion but had become the specialized paddle of a purely aquatic type. HABITAT, LOCOMOTION, FO(JI). The remains of Thalattosaurs are known only in purely marine deposits containing little or no material of terrestial origin. They are associated with a fauna consisting of numerous forms, both vertebrate and invertebrate, which are not known to have existed away from marine areas. In the structure of the skeleton we find the abbreviated and broadened proximal segments of the limbs, the slender snout with prehensile terminal teeth, and the median superior nares, indicating a j^urely aquatic type. There can scarcely be room for doui)t that the Thalattosaurs as a group were typical marine forms. The larger and more specialized species comprised in the genus Thalaito- saurus were strictly ]iatatory. They may have visited the shore but, like the Plesiosaurs, were better fitted for swimming than for crawling. Of the smaller Nectosmirus we unfortunately do not know the limbs. They ma}' have been con- siderably less specialized than in the other genus, and the animal to a corre- MERRIAM THK THALATTOSAT'TilA Zo spondingly greater degree a shore dweller. NectosaurnH is, however, found in the same deposits with the otlier forms and appears to he as common as the others; so that it is safe to eonsitless to he correlated with difference in liahits; in other words, they may he ascribed to somewhat different kinds of adaptation. The Ichthyosaurs were largely fish eaters. They therefore had no great nee(l of a liea\-y vomerine den- tition. In the same way the presence of a strong coronoid projection on the thalattosaurian jaw may be correlated with somewhat increased muscular power used in crushing with the broad teeth of the prevonier and of the posterior por- ti(m of the dentarv. ()ther differences may be due to great increase in the size of the orbits in the Ichthyosaurs, although this may be considered as due to better opportunity for increase in size in that group owing to fundamental difference in the original structure of the skull. These facts are particularly significant when we ccmsider their bearing on questions concerning the origin and relationships of the Ichthyosaurs. If the Thalattosaurs and Ichthyosaurs were both derived from the primitive Diaptosauria and were both typical marine forms following somewhat similar lines of adapta- tion, Avlw ai"e they so different? With similar environmental conditions we would expect l)ut little divergence. It is evident that in this case we have one of the following possibilities: 1. The Thalattosaurs and Ichthyosaurs have come from the same stock but have followed quite different lines of adaptation; 2. They have come from the same stock and have followetl only slightly different lines of adaptation, but have, one or l)oth. been in existence for a very long period; 3. They have originated in different groups. Concerning the first possibility — there is reason to believe that the groups differed somewhat though not greatly in food hal)its, but that in a broad way the kind of adaptation was the same. It was such as wtuild generally tend to jiroduce a certain degree of convergence. Th<' kinds of adaptation we should presume to differ less than among the Cetacea, while the structural differences are as great or greater than we find produced in not h^ss than four periods of evolution in that more rapidly living aquatic grouj). Regarding the second case — we unfortunately know as yet but little con- cerning the early history of either group. Thalattosaurs are known as early as the beginning of the Upper Triassic, and the oldest h'hthyosaurs which we know are found in the lower part of the Middle Triassic. The Ichthyosaurs certainly appear to be somewhat more specialized than the Thalattosaurs and are pre- sumably someAvhat older, so that we could imagine a slight difference in adapta- tion acting through a long period as having resulted in llie prtxluction of these 26 CALIFORNIA ACADEMY OF SCIENCES veiy different types out of tlie same stock. The Iclitlu'osaurs may have taken to the sea earher, and the Tlialattosaurs have originated from a later and there- fore somewhat different pliase of the same group. On tlie otlier liand the development of such differences as we see here must have required much time, and it may well he questioned whether the time of origin of the lehthyosaux's may not date back so far that it would be straining a point to call its ancestors Diaptosaurian or even Diapsidan. The remaining situation, in wliicli we would have the two groups converging from fundamentally different stocks, seems in many respects the most natural relation. At any rate, the two groups must be considered as widely separated, and neither may be judged to be ancestral to the other. If they are not closely related ami it should appear that of the two the Tlialattosaurs are nearer to the Rhynchocephalia, we ma}- perhaps reasonably (juestion the rhynchocephalian or diaptosaurian origin of the Ichthyosaurs. ParasKcJilcni Characters. — The general skull structure of the Tlialattosaurs has a certain degree of resemblance to tliat in Belodon, particularly in the rostral and temporal regions. The position of the nares is similar, as also tlie general form of the premaxillaries and maxillaries, though the premaxillaries do not separate the nasals and reach the frontals. The superior temporal openings are similarly situated low down between the upper temporal bars, and the parietals bound the anterior side to a greater extent than is usual. There is also some similarity in the structure of the palate, and the gnathic dentition of Behxlon is not unlike that of Thakittnsanrus pc^rini. Taken as a whole, however, the two skull types are very dissimilar. The superior nares of Belodon are in the large nasals; the premaxillaries do not reach hack to the frontals; large antorl)ital vacuities are present; the lachrymals are large, while the prefrontals, frontals and parietals are relatively very small; the postorbital and postfrontal are separate; tliere is no pineal foramen; the form of the quadrate is very different from that of Tlta- lattosavnis; the palatine borders the inferior nares externally; the coronoid is small and inferiorly situated; there are no teeth on the prevomers or pterygoids; and there is a large mandibular vacuity. These differences together with the total dissimilarity in the structure of the vertebrae, ribs and lindjs show that the two groups are ordinally distinct. The general outlines of the structure in both arc those of the primitive diapsidan Reptilia. Both are aquatic types and to a slight extent this has tended to bring them nearer together. The possibilities of evolution in the marine Thalattosauria were, however, much greater and also specifically different from those open to the fresh ivater Parasuchians, and the result of specialization has been the production of very different forms. As different as these two ai'e. it may he noted that they are at least as near together as the Tlialattosaurs and the Ichthyosaurs, although the latter are marine. MERRIAM — THE THAIrATTOSAT'inA 'It Relationship to Squamata. — Althougli tliu Tluilattt)saurs evidently possessed two temporal openings, with a complete lower temporal bar, their resemblance to the lacertilian and mosasaurian branches of the S([uaiiuita arc so prominent as to demand consideration of possible relationship to them. The general aspect of the mandilile is that of a rej)resentative of the S(jnamata, though it is also approached in the Rhynchocephalia. The form, situation, and prominence uf the coronoid are such that the posterior portion of tli» jaw taken alone could scarcely l)e considered as other than lepidosaurian. ( )n the superior side of the skull there is a noticeable similarity to the Mosasauria. In both the Thalattosaurs and Mosasaurs the rostral region is narrow ; it is generally somewhat elongated and acute terminally. The nares are set w(dl back and the premaxillary is produced posteriorly as a stem or bar which meets tlie frontals. There are no discrete nasals in the Mosasaurs and they are generally supposed to be united with the posterior end of the premaxillary bar as in ]"aranus. Should it appear that they have been lost and the fronto- premaxillary connection be immediate, the structure in this region would be very similar in the two groups. In the posterior part of the Mosasaur skull the l)road frontals are often partly arched around the anterior ends of tlie parietals as in the Thalattosaurs, while the postfrontal and postorbital have partly united. So far as can be determined, there is room to suppose tbat tlie upper portion of the temporal region may not differ greatly in the two groups. The quadrate of the Thalatto- saurs is in general of rhynchocephalian type and the widely extended anterior wing is not seen in the Sc^uamata, but the presence of a strong external wing and the incipient development of a posterior hook make it begin to show resem- blance to the type seen in the Mosasaurs and Lizards. In the characters of the limbs and arches there is much that is similar. The vertebrae and ribs differ, Init perhaps not so fundamentally as would a])])ear from superficial examination. On the whole the resemblance to the aquatic Squamata is v<'rv striking; but it can not ove~rbalance such characters as the evident presence of a lower temporal arch, the existence of a strongly developed vomerine dentition, an immovably lixed mainly rhynchocephalian (quadrate, abdominal ribs and very })rimitive vertelirae. While it is not possible to place the Thalattosaurs in the S(|uamata. as that grou}) is at present defined, it is not improl)able that the primitive Lacertilians were closely related to or derived from the land or shore forms from which the Thalattosavirs were deriveil. Adaptation to a(|uatic life would tend to make the Thalattosaurs take on rapidly a certain set of characters which would appear 28 OALIFOKNIA ACADEMY OF SCIKXCKS again in the Mosasaurs. This specialization would at the same time take tlic Thalattosaurs out of the direct line of I'volution. It is to be noticed in this connection that the smallest and least specialized form, seen in Nectosaurus, is nearer the Lacertilia than the large]- and more specialized Thalattosaurus. In PaligiuDia Broom, of the South African Triassic, we have represented an undoubted Lacertilian with the lower temporal arch absent and only a minute process projecting from the posterior side of the jugal. Tlie ([uadrate is typically lacertilian as are also the relations of the elements in the upper temporal bar. This form shows that the characteristics of the Squamata were expressed very early and makes more probalile the discovery of lacertilian tendencies in early diaptosaurian groups. Relationshi-p to the Proganosauria. — As possible close relatives of the Thalat- tosaurs, the Proganosauria claim especial notice,- being a group of ratlicr prim- itive aquatic forms having affinities with the Rhynchocephalia and occurring earlier in geological time than the Thalattosaurs, and therefore possibly ancestral to them. Ihifcn-tunately the part of the thalattosaurian skeleton of which we have the best knowledge, viz. the skull, is the most imperfectly known part in tlie Proganosauria. Osborn considers the skull probably double-barred, though the structure of the temporal region is as yet unknown. The position of the superior nares and the .structure of the palate are likewise unknown. Teeth are present on the roof of the mouth on what are supposed to be the palatines, while in the Thalattosaurs they are absent from the palatines, and present on the prevomer and pterygoids. The skull is considerably longer and more slender in tlie Pro- ganosauria and the long, slender teeth are more numerous. In the structure of the better known parts of the sktdeton of the Progan- osaurs the separation is wide. The small centra and greatly expanded upper arches of the vertebrae and tlie peculiar narrow-headed ribs of the Proganosaurs stand in strong contrast to the relatively small upper arches and the broad- headed ribs of the Thalattosaurs. In the pectoral girdles of the two there is some similarity excepting in the scapula. The plate-like pelvis of the Progan- osaurs is much more primitive than that of the Thalattosaurs and the limlis of the former have not gone nearly so far in specialization, particularly in the shortening and broadening of the epipodial elements. Relationship to the Choristodera. — The aquatic diaptosaurian forms included in the Choristodera resemble the Thalattosaurs mainly in that they are acjuatic and have rhynchocephalian affinities. Here, as in the Thalattosaurg, there is a vomerine dentition l)ut the teeth are small, very numer(nis, of an entirely differ- ent form, and are set in several rows. The pterygoitl dentition is also different and the palatines bear teeth. The Choristodera are farther distinguished from Mi;i!i;iA>[ THK THALATTDSATItIA 29 the Thalattosaurs bv the more skMuk'r snout, the terminal jiosition of tlie nares and tlie corresjjondintilv different structure of tlie rostral re,s;ion, the absence of a j)ineal foi-anicn and of a coronoid process, the robustness of the ribs and the bicipital ai'tieidation of those in the anterior dorsal region, tbe different form of the elements in botb pectoral and peh'ic arches, and the rclativ<'ly but little specialized limbs. In the lenjfthening of the snout tbe ( 'iioristodera are more specialized than the Thalattosaurs. l)Ut the ternnnal position of the external nares shows the kind of specialization which we hnd mainly in aquatic reptiles belonging in fresh water, while the position of the nares in the Thalattosaurs is the form of special- ization seen generally in marine types. Wlien we consider along with other things that tlic ( "Iioristodera are in some respects much less specialized than the Thalattosaurs, and that they occur two geological periods later, it is evident that they are not closely related. Reseviblaiice to Proterusuchus. — Some interesting resemblances to the Thalatto- saurs are shown in Pmternsxchvs recently described l)y Broom. ^ This important form is known oidv from the anterior portion of a skull reciMitly discovereil in the Karoo beds of Tarkastad, South Africa. In it we find dentigerous prevomers and pterygoids with edentulous palatines. The prevomers reach back to meet the pterygoids broadly. On the upper side of the pterygoids are high, thin vertical plates. The characters of this form am[)ly justify its determination by Broom as "a primitive Rhynchocephalian which shows a considerable degree of specialization along a line which gave rise to the crocodiles. . .'" The cond)ination of characters found in Prdfcrdsuclnis is in som(> respects similar to that seen in Th((laftosaurus, and as is shown i)y i>room for Proterosiirlnix, the palatine region exhibits a general resend)lance to that of Pnivolojilioti. In other characters, as in the presence of large antorbital vacuities, the anterior position of the external nares, the position of the internal nares farther forward and separated by the main bodies of the prevomers, in the absence of a coronoid process, and in the large size and hcavv fangs of the slightly differentiated teeth, Proferosuclius shows itself to be quite different from Thalattosaurus. The resem- blance exhibited by these forms is evidently in the main due to their approxima- tion to the type of the primitive Rynchocephalia. Such similarities as we tind are not sufficient to permit our including them both in the same order. In adaptation to acjuatic conam. Plates I, II; Plate IV, Vu:. 1 ; Plate V, Figs, lfi-2/,; Plate VI; Plate VII, Figs. 1-.3, 8-9; Plate VIII, Figs. 1-2, -ta-6. Bull. Drpt. Ccdl. Univ. Calif, v. 3, no. 21, p. 419. Type spediiK'n No. 9085 Univ. Calif. Palae. Coll. Tliis is tlie largest species of tlu' group. The known siieeinicns appear to represent individuals attaining a length not far from two metres. Neural spines of vertebrae not greatlv widened. Propodial and epipodial limb elements and scapula considerably expanded. Nasal openings long, portion of nasal elements behind the nares relatively short. Slender anterior teeth with widely' spaced striae. Posterior mandibular teeth ver\' low-crowned, l)utton-like. The number of teeth on the dentary appears to have been eighteen. A large part of our knowledge of the Thalattosauria has been obtained through the study of this species, of which several representative specimens are known. All of the material representing this form has been obtained in the Trachyceras horizon of the Hosselkus Limestone. No occurrences are known outside the Shasta region of California. MEASUREMENT.S. Vertebrae. mm. Anterior dorsal (No. 9084), height of centrum 20 width " " 23 length" " 16 " " " height of upper arch 46 " " " antero-posterior diameter of upper arch at middle height of spine 13 " " " transverse diameter of uj)per arch at middle height of spine V(5 Anterior caudal (No. 9085), height of centrum 30 " " " width " " 13 length" " 18 " " " height of upper arch 48 " " " antero-posterior diameter of upper arch at middle height of spine 8 , " " " transverse diameter of upper arch at middle height of spine 6 la, approximate. MERRIAM THE THALATTOSAURIA 35 Arches. Coracoid (No. 9085), antero-posterior diameter 65 transverse diameter of median portion 33 Scapula " greatest length 55 Ischimn (?) " " " 72 '• " width 26.5 Pubis(?) (No.9044), " lengtli 106 " width 47 Linihs. Humerus (No. 9084), greatest length 75 " '• " width, proximal end 39 " " " " median portion 21 " " " " distal end 52 thickness of distal end '. 18.5 Radius " " length V,40 " " " width, distal end a29 " " " " median portion 15.5 Ulna (No. 9085), greatest length 40 " " width, median portion 25 Thalattosaurus shastensis, n. sp. Plate III; Plate IV, Figs, lio-e; Plate VII, Fios. 4, 7; Plate VIII, Figs. 3, 7, 8. Type specimen No. 9120 Univ. Calif. Palae. Coll. Conipai'ed with T. akxandrae tlie individuals are consideral)ly smaller: the scapula, liunierus and ulna more slender; the nasal openings shorter and that portion of nasal bones behind the openings longer and broader; the neural s})ines of the dorsal vertebrae are possibly shorter. The conical teeth associated with the type specimen show more numerous and more closely set longitudinal striae than are seen in tlie jaw teeth of T. alexandrae. There is of course a possil)ility that these teeth belong to the pterygoids and not to the jaws. This species appears to be very near the type form of the genus and may be shown later to be identical with it, possibly representing young individuals. There are, however, several specimens in the collection which seem to have the same characters and to be slightly removed from T. alexandrae. This form is not uncommon, and ranges from the Trachyceras horizon almost if not quite to the top of the Hosselkus Limestone. It is known only from the Triassic of Sha.sta County. la, approximate. 36 - oaltfornia academy of srie>m'ks Measurements. mm. HuniiTUs (No. 9120), length 32 Ulna " " 21 greatest width 11 Thalattosaurus perrini, n. s]). Plate IV, Fiu. 3; Plate V, Fig. 3; Plate VII, Fi(i. 6. Posterior mandibular teeth with hiterally compressed and obtuse but not greatly depresssed crowns, grading anteriorly into a slender conical form on the anterior portion of the jaw. Maxillary teeth slender conical, set in deep pits. The dentition of the dentary and the maxillary are well shown. The den- tarv holds an interrupted series of twelve teeth with spaces for several more among them. The entire number lias probably been sixteen to eighteen. The posterior ones have low, broad, laterally compressed crowns. Tlic individuals in the middle of the series were short, broad, and leaf-like, their margins being verj' close together. The anterior members of the series have a shorter antero-posterior dianreter, higher crowns, and a slender conical form without lateral compression. The most anterior tooth, seen only in oblique section, shows strong longi- tudinal striations or ridges on its surface. The most posterior teeth are close together and in shallow pits. The anterior ones are deeply set and are more widely spaced. On the maxillary there are five teeth of slender conical form, witli spaces for one or two more. They are in deep, distinct pits. As much of the vomerine dentition as is known is very similar to that of Tha laftosauru s a lexandrae. The general characters of this form are tliose of a typical Thalattosaurian. The type specimen, the only known sjiecimcn of this species, was the first Thalattosaurian discovered. It was found by Professor James Perrin Smith in the Trachyceras beds of tlie Hosselkus Limestone at Smith Cove, near Scjuaw Creek, Shasta County. There was exposed on the slab only a prevomer with its peculiar, bhmt teeth. Later the portion of tlie skull sliown on Plate iv, figure 3 was exposed by preparation witli steel points and l)v etching with very dilute hydrochloric acid. After the jaws had been partly uncovered, the writer pub- lished a note on the Triassic Reptilia from Northern California,^ in which this specimen was referred to as a Shasfasaurus with a heterodont dentition. Later it was discovered that it could not belong to the Ichthyosauria, but the true affinities were not known until after the discovery and study of the type of Thalattosaurus alexandrae. I Science, n. ser. t. 15, p. 411. MERRIAJr THE TH ALATToSA ri! I A 37 This species is (|uite distantly removed from T. alcxandruc in dental char- acters, and may he found to represent a distinct genus.' Although the posterior mandilnilar teeth differ mucli from those of T. alezandrae the difference is only one of degree. So far as known the character of the maxillary teeth seems to he quite different hoth as regards form and insertion. Satisfactory comparison can not he made, however, until we know more of the dentition of T. alerandrae. NECTOSAURUS, n. ovn, Nectosaurus halius, n. p;en. ami sji. Platk I\", Fic. 4((-.'); Plate V, Figs. 4, (i; Pi.atk \'II, Fig. -5. Type specinu'ii No. 9124 Tniv. Calif. Palac Coll. Fronto-parietal region simihir to that of 'f/i(il. Right quadrate, outer side. Fig. 3. Posterior end of premaxillary. T. alcrandrac {'!) Fig. 4. Fragment of cpiadrate and temporal region of type sj)ecimen. Legend. i1/, maxillary /V, palatine Pm, premaxillary L, prevomer A^ nasal ' T. tooth 7'', frontal <^. quadrate /'/', jircfrontal Sij. .slates Memoirs CalAcad SciYdlV [Merfuam] Plate III. 44 CALIFOKNIA ACADEMY OF SCIENCES EXPLANATION OF PLATK IV. Fig. 1. Anterior jaw tooth associated with type specimen of T. nlcm)idr!-■:■■'<. •V'V ;■>'.,■ ':sll. 1/ 'I ' I ■■".'.' ,, ■ ,. • r-'. I /■',;■,■,:.■,■,■;., '/,-f,:0 ^1 : ^:; a, i",','.-,'^./i ::i;-^':'r::.'':!,.'i ^'■'/:i:.iM,:?