5ST0.5- /- F1ELDIANA Geology NEW SERIES, NO. 42 New Interatheriines (Interatheriidae, Notoungulata) from the Paleogene of Central Chile and Southern Argentina Ralph B. Hitz Marcelo A. Reguero Andre R. Wyss John J. Flynn January 31, 2000 Plication 1506 1 JBLISHED BY FIELD MUSEUM OF NATURAL HISTORY Information for Contributors to Fieldiana General: Fieldiana is primarily a journal for Field Museum staff members and research associates, although manuscripts from nonaffiliated authors may be considered as space permits. The Journal carries a page charge of $65.00 per printed page or fraction thereof. Payment of at least 50% of page charges qualifies a paper for expedited processing, which reduces the publication time. Contributions from staff, research associates, and invited authors will be considered for publication regardless of ability to pay page charges, however, the full charge is mandatory for nonaffiliated authors of unsolicited manuscripts. 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Author-generated changes in page proofs can only be made if the author agrees in advance to pay for them. © This paper meets the requirements of ANSI/NISO Z39.48-1992 (Permanence of Paper). FIELDIANA Geology NEW SERIES, NO. 42 GEOLOGY LIBRARY New Interatheriines (Interatheriidae, Notoungulata) from the Paleogene of Central Chile and Southern Argentina Ralph B. Hitz Earth Sciences Department Tacoma Community College 6501 South 19th Street Tacoma, Washington 98466 U.S.A. Andre R. Wyss Department of Geological Sciences University of California Santa Barbara, California 93106 U.S.A. Marcelo A. Reguero Departamento Cientifico de Paleontologia Vertebrados Museo de La Plata Paseo del Bosque s/n, 1900 La Plata, Argentina John J. Flynn Department of Geology Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 U.S.A. Accepted November 9, 1998 Published January 31, 2000 Publication 1506 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 2000 Field Museum of Natural History ISSN 0096-2651 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents Abstract 1 Introduction 1 Systematic Paleontology 3 Interathere Phylogeny 24 Conclusions 24 Acknowledgments 25 Literature Cited 25 List of Tables 1. Localities and references 2 2. Argyrohyrax acuticostatus, upper denti- tion mensural data 5 3. Santiagorothia chiliensis, upper denti- tion mensural data 17 4. Santiagorothia chiliensis, lower denti- tion mensural data 18 5. Santiagorothia chiliensis, cheek tooth crown height 18 6. Proargyrohyrax curanderensis, upper dentition mensural data 20 7. Proargyrohyrax curanderensis, lower dentition mensural data 20 8. Eopachyrucos plicifera, lower dentition mensural data 22 List of Illustrations 1. Interathere phylogeny after Hitz (1997) 2. macn A52-626, Argyrohyrax acutico- status, type; Eohyrax platyodus, oc- clusal and lateral views 5 3. Tentative correlation of Abanico For- mation (central Chile) and middle Ce- nozoic Patagonian mammalian bio- stratigraphy 8 4. sgopv 2914, Santiagorothia chiliensis, holotype, lateral, dorsal, and posterior views 9 5. sgopv 2812, Santiagorothia chiliensis, occlusal view 10 6. sgopv 2861, Santiagorothia chiliensis, occlusal view 11 7. sgopv 2821, Santiagorothia chiliensis, lateral and occlusal views 12 8 . -sgopv - 2826, Santiagorothia chiliensis, ^occlusal view ' 13 9. sgqpv 2827, Santiagorothia chiliensis, -kteral and occlusal views 14 10. mlp 91-LX-5-15, Santiagorothia chi- liensis r 15 11. mlp 91-IX-5-14b, Santiagorothia chi- liensis; mlp 91-LX-5-14a, Santiagoro- thia chiliensis; mlp 61-VIII-3-314, Santiagorothia chiliensis 16 12. mlp 61-VIII-3-27, Proargyrohyrax cur- anderensis, holotype; mlp 61 -IV- 14-1, Proargyrohyrax curanderensis 20 13. mlp 12-1529, Eopachyrucos plicifera, occlusal and lateral views; macn A55- 12, Eopachyrucos plicifera, holotype, occlusal and lateral views 23 in New Interatheriines (Interatheriidae, Notoungulata) from the Paleogene of Central Chile and Southern Argentina Ralph B. Hitz Marcelo A. Reguero Andre R. Wyss John J. Flynn Abstract Two new interatheriines (Interatheriidae, Notoungulata), Santiagorothia chiliensis and Proar- gyrohyrax curanderensis, are described from the transitional Eocene/Oligocene Tinguiririca Fauna, central Chile, and from roughly coeval localities in Chubut and Rio Negro provinces, Argentina. The former occurs in both central Chile and Argentina, whereas the latter occurs only in Argentina. Several Argentine specimens are referred to Eopachyruchos, an interatheriine for which an emended diagnosis is presented. The taxonomic status of Argyrohyrax acuticosta- tus is discussed and an emended description is provided. Additionally, we propose a phylo- genetic taxonomic definition for the name Interatheriinae. The transitional Eocene/Oligocene localities under consideration here occur within a poorly known interval of the South American Land Mammal Age (SALMA) sequence, intermediate between the Mustersan and Deseadan SALMAs. This temporal interval spans a transition in South American mammal evolution between older faunas dominated by various archaic, den- tally conservative herbivores and younger faunas dominated by later diverging clades of more hypsodont forms. The Tinguiririca Fauna, the age of which is bracketed radioisotopically, re- cords the first or last occurrence of seven subfamilial or higher level taxa. Although the Ar- gentine localities are unconstrained geochronologically, similar faunal composition allows ten- tative correlation to the Tinguiririca Fauna. Not unexpectedly, therefore, Santiagorothia chi- liensis and P roar gyrohy rax curanderensis represent the earliest known interatheriines, a group previously restricted to Deseadan SALMA (Late Oligocene/Early Miocene) and younger faunas. Santiagorothia chiliensis and Proargyrohyrax curanderensis are considered interatheriines based on their possession of the following diagnostic features of the clade thus named: deep parastyle/paracone groove on P2-4; very shallow parastyle/paracone groove on upper molars; smooth posterior ectoloph on upper molars; very high-crowned cheek teeth; distinctly bilobed p3-m3 with persistent labial and lingual sulci; auditory bulla lapping posteriorly onto the paraoccipital process; and maxilla excluded from the superior orbital border by a silver of anteriorly projecting frontal (although Proargyrohyrax curanderensis is known only from den- tal remains). Santiagorothia chiliensis and Proargyrohyrax curanderensis are most readily dis- tinguished from other interatheriines in possessing cheek teeth with closed roots. Another dis- tinction concerns the pattern of upper molar wear in Santiagorothia chiliensis and Proargy- rohyrax curanderensis: as wear proceeds, a lingual sulcus closes to form an isolated fossette, whereas in other interatheriines this sulcus remains open. Introduction sitional Eocene/Oligocene localities in central Chile and from Chubut and Rio Negro provinces of Ar- Herein we describe two new interatheriines, San- gentina (Table 1). Also presented is an emended di- tiagorothia chiliensis and Proargyrohyrax curan- agnosis of Eopachyruchos (formerly considered a derensis (Interatheriidae, Notoungulata), from tran- hegetothere; Simpson, 1967), to which specimens FIELDIANA: GEOLOGY, N.S., NO. 42, JANUARY 31, 2000, PP. 1-26 1 Table 1. Localities and references. Locality Reference Portezuelo El Fierro, Tinguiriri- ca River Valley, Chile (34°59'S; 70°26'W: town of Termas del Flaco) Lomas Blancas, Chubut, Argen- tina (44°11'S; 69°38'W) Canadon Blanco, Chubut, Ar- gentina* (unknown coordi- nates) Laguana La Bombilla, Chubut, Argentina (44°16'S; 69°12'W) Gran Barranca, Chubut, Argenti- na (45°42'S; 68°44'W) Rocas Bayas, Rio Negro, Argen- tina (69°02'S; 41°01'W) Wyss et al., 1994 This paper Roth, 1901, 1903; Ameghino, 1906; Reguero, 1993 Pascual, 1965b Cifelli, 1985b Pascual et al., 1984 * The exact geographic position of this locality is un- known. Only Roth collected at Canadon Blanco, and he left no information about the geographic provenance of the fossils from this locality. Ameghino (1906) showed the probable location of Canadon Blanco. A map of this region, drawn by Mr. Fulgencio Dommguez in 1924 and copied by G. G. Simpson, exists in the Simpson Library at the Florida Museum of Natural History but is too imprecise to locate Canadon Blanco. from transitional Eocene/Oligocene localities in Chubut and Rio Negro provinces of Argentina are referred. The new interatheriine Santiagorothia chi- liensis provides an important biostratigraphic tie be- tween volcaniclastic deposits from the western slope of the Andean Main Range and classic mammal- bearing deposits of Patagonia. Although the South American Cenozoic mammal record has been extensively studied for more than a century, some temporal intervals remain poorly known, most notably an approximately 15 million year hiatus between the Mustersan and Deseadan South American Land Mammal Ages (SALMAs) (Flynn & Swisher, 1995). The Tinguiririca Fauna (the first record of fossil mammals from the Andean Main Range of central Chile) occurs within this hi- atus and provides valuable radioisotopic calibration points for this portion of the SALMA sequence (Flynn et al., 1991; Novacek et al., 1989; Wyss et al., 1990, 1992, 1993, 1994). The Tinguiririca Fauna thus represents a new, currently unnamed South American mammalian biochronologic unit (Wyss et al., 1994; Flynn & Swisher, 1995), which also helps constrain the age of a major Eocene-Oligocene fau- nal turnover event and the immigration of rodents to South America. Descriptions of taxa (like the in- teratheres in this paper) from the Tinguiririca Fauna and correlative units elsewhere will enable formal erection and definition of a Tinguirirican SALMA in the future. Several pre-Deseadan/post-Mustersan-age faun- ules are known from Chubut and Rio Negro prov- inces of Argentina (Table 1); together with the Chilean fauna these are critical to establishing the outlines of mammal evolution during the afore- mentioned hiatus. Although independent geochro- nologic information for the Argentine faunules is currently lacking, they show close taxonomic sim- ilarity to the Tinguiririca Fauna and are tentatively correlated to it on that basis (Wyss et al., 1994); see the systematic paleontology section for a more complete discussion). Interatheres (Interatheriidae, Notoungulata), small to medium-sized herbivorous notoungu- lates, are well represented in most South Ameri- can Cenozoic mammal faunas. The group first ap- peared in the ?Itaboraian SALMA (?Middle Pa- leocene) (Bond et al., 1995) and persisted into the Huayquerian SALMA (Late Miocene). A signifi- cant radiation of hypsodont forms occurred during the Oligocene (Cifelli, 1985a; Marshall & Cifelli, 1990). Interatheres are traditionally divided into two groups (Simpson, 1945), Notopithecinae (low-crowned Paleogene forms) and Interatheri- inae (Late Oligocene and younger, hypsodont and hypselodont forms). Interatheriinae constitutes a monophyletic group (Cifelli, 1993; Hitz, 1994, 1995, 1997; Reguero et al., 1996), whereas taxa generally referred to the Notopithecinae probably form a paraphyletic assemblage (Hitz, 1994, 1995, 1997). Santiagorothia chiliensis and Proargyrohyrax curanderensis represent the earliest known inter- atheriines (as that name is defined below), a group previously known from Deseadan and younger SALMAs (Cifelli, 1985a). This is consistent with the numerous other first and last occurrences of higher level taxa in the Tinguiririca Fauna, a fact reflecting its biostratigraphic distinctiveness (Wyss et al., 1994). Below we present a systematic description of both new taxa and an emended diagnosis for Eopachyruchos. We also present an emended de- scription of the taxon Agyrohyrax acuticostatus, which is represented by a single specimen that resembles both Santiagrothia and Proargyrohy- rax. The material for A. acuticostatus, however, is insufficient to determine whether it is synony- mous with either taxon. A reference collection of casts of all the Chilean material will be acces- sioned into the Field Museum collections. Mate- rial considered in this study is housed in the Los FIELDIANA: GEOLOGY Angeles County Museum of Natural History; the Florida Museum of Natural History; the Yale Pea- body Museum; Servicio Geologico de Bolivia; Museo Nacional de Historia Natural, Bolivia; the Field Museum of Natural History; the American Museum of Natural History; the University of California Museum of Paleontology; Museo Na- cional de Historia Natural, Santiago; Museo Ar- gentino de Ciencias Naturales, Buenos Aires; and the Museo de La Plata. Abbreviations The following abbreviations are used in the text. sgopv Museo Nacional de Historia Natural, San- tiago macn Museo Argentino de Ciencias Naturales, Buenos Aires amnh American Museum of Natural History, New York mlp Museo de La Plata, La Plata Systematic Paleontology Notoungulata Roth, 1903 Typotheria Zittel, 1893 Interatheriidae Ameghino, 1887 Interatheriinae Simpson, 1945 As a preamble, it bears mention that none of the taxonomic names listed above have previously been defined phylogenetically (sensu de Queiroz & Gauthier, 1990, 1992). Among its objectives, phylogenetic taxonomy (as this approach is termed) emphasizes the distinction between the naming of clades (definition) and the recognition of those clades in the first place (diagnosis). Here we consider only the name Interatheriinae. One of the many plausible ways to translate this name (as traditionally used, Simpson, 1945) into phyloge- netic taxonomic terms would be to define Inter- atheriinae as the name referring to the clade stem- ming from the most recent ancestor of Interath- erium and Protypotherium, plus all of its descen- dants. Such a definition describes a clade including all previously described interatheriines. Hitz (1997) demonstrated that Santiagorothia chi- liensis is the nearest outgroup to this clade (Fig. 1). For reasons elaborated below and in Hitz (1997), we chose a slightly more inclusive defi- nition of Interatheriinae, namely as the clade stemming from the most recent ancestor of San- tiagorothia chiliensis and Interatherium, plus all of its descendants (a node-based definition sensu de Queiroz & Gauthier, 1990, 1992). Compared to earlier diverging interatheres, in- teratheriines are typified by larger size and hy- podont or hypselodont cheek teeth [although de- veloped convergently in numerous other notoun- gulate clades as well (Cifelli, 1985a)]. Indeed, these are the characters typically associated with interatheriines by most workers (e.g., Cifelli, 1985 a). The Tinguiririca Fauna is the earliest in South America, and globally, to be dominated by hypsodont herbivores (including, most notably, interatheres and archaeohyracids) (Wyss et al., 1994). It is fitting, then, that the earliest known large hypsodont interathere is a member of the clade here linked to the name Interatheriinae. Members of this clade may be diagnosed by the following synapomorphies: deep parastyle/para- cone groove on P2-4; very shallow parastyle/ paracone groove on Ml -3; smooth posterior ec- toloph on Ml -3; very high-crowned cheek teeth; distinctly bilobed p3-m3 with persistent labial and lingual sulci; auditory bulla lapped posteri- orly onto the paraoccipital process; maxilla ex- cluded from the superior orbital border by an an- teriorly projecting sliver of frontal. Finally, in our descriptions of the new interath- eriines, Linnean taxonomic ranks are not recog- nized (sensu de Queiroz & Gauthier, 1990, 1992). Accordingly, the names of the new taxa should not be considered strict Linnean binomials, com- prised of a genus name and a species name. Rath- er, they are simply two-part names referring to a single taxon. If readers strongly object to this ap- proach, the names may be considered equivalent to Linnean binomials, but that is not the intent of the authors. Argyrohyrax acuticostatus Ameghino 1901 1901 Argyrohyrax acuticostatus, Ameghino, p. 15. Type— macn A52-626, right dP3-4, Ml -2. Type Locality — "Golfo de San Jorge," Chu- but, Argentina. Known Distribution — Known only from the type locality, "Golfo de San Jorge." Remarks — Ameghino (1901) briefly described HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES Fig. 1. Interathere phylogeny after Hitz (1997). For a character matrix, tree statistics, and identification of syn- apomorphies for the various interathere clades recognized herein, refer to Hitz (1997). Several nomenclatural issues need highlighting. Plagiarthrus (as used here) is probably synonymous with Argyrohyrax proavus (for a discussion see Marshall et al., 1986), and Argyrohyrax (as used here) is probably synonymous with Progaleopithecus tournoueri (also see Marshall et al., 1986). Finally, several taxa are not yet formally described (but see Hitz, 1997, for informal descriptions), namely two interatheriines from the Upper Oligocene Salla beds of Bolivia and two non-interatheriine interatheriids from the Paleogene of central Chile. (but did not figure) a single maxillary fragment (macn A52-626), designating it the holotype of Argyrohyrax acuticostatus. A vague, handwritten provenance accompanies the specimen; it reads, "Golfo de San Jorge, Chubut." His description of the specimen is accurate, save for its reference to three molars (macn A52-626 presently has only two molars, so M3 has evidently since been lost) and its failure to mention dP3-4. No other ma- terial in the macn is catalogued as pertaining to Argyrohyrax acuticostatus. The Ml and M2 of macn A52-626 very closely resemble those of both Santiagorothia chiliensis and P roar gyrohy rax curanderensis (treated be- low). In fact, upper molar morphology alone is insufficient to distinguish the latter two taxa, which are unmistakably distinct in other respects. This is a common problem for interatheriines; both upper and lower molar morphology tend to be similar across many taxa, and sound identifi- cation often requires the preservation of addition- al anatomy, macn A52-626 may indeed pertain to one of the interatheriine taxa described below, but its fragmentary condition prevents conclusive comparisons. Additionally, as mentioned above, the provenance of macn A52-626 is exceedingly sketchy, making it highly unlikely that more com- plete material will be found to augment the type specimen. Given the limited comparisons afforded by macn A5 2-626, we believe the best course of ac- tion is to recognize two new taxa, both of which are known from significantly more complete ma- terial than macn A52-626, rather than refer new additional specimens to Agyrohyrax acuticostatus. Although this approach introduces two new names to interatheriine nomenclature, the excel- lent material on which they are based will well FIELDIANA: GEOLOGY Table 2. Measurements of the upper cheek teeth of Argyrohyrax acutieostatus (mm). Tooth MACN A52-626 B Fig. 2. A. macn A52-626, Argyrohyrax acutieosta- tus, type (and only) specimen, RdP3-4, RM1-2. B. macn A10908e, Eohyrax platyodus, occlusal and lateral views. Scale = 0.5 cm for all views. serve future comparisons (e.g., the type for San- tiagorothia chiliensis is a complete cranium). We emphasize that, although Agyrohyrax acu- tieostatus may indeed be the senior synonym for one of the new taxa we describe below, the ho- lotype (and only known specimen) is insufficient for such a determination. We strongly suggest that, in the future, recognition of new interather- iine taxa (and other notoungulate taxa as well) be limited to circumstances where relatively com- plete dentitions are known, thereby preventing the problem discussed above. A discussion regarding material needed for erecting new taxa is presented by Pascual (1965a). Emended Description — Ameghino (1901, p. 15) briefly described the three upper permanent molars of Argyrohyrax acutieostatus as follows (translated from French): "A little smaller than dM3 AP dM3 TR dM4 AP dM4TR P4 AP P4TR Ml AP Ml TR M2 AP M2TR M3 AP M3 TR 8.1 5.2 7.7 5.4 7.3 4.0 6.9 4.0 5.19 2.73 AP = anteroposterior; TR = transverse Argyrohyrax proavus. Upper molars more com- pressed, trilobed lingually, and with the perpen- dicular anterior margin of the ectoloph turned out- side forming a very salient perpendicular ridge. The three upper molars are 21 mm in length. Py- rotherium Beds." Ameghino did not mention the deciduous pre- molars, a description of which follows. Deciduous Upper Dentition (Fig. 2) — The de- ciduous P3-4 are quadrangular and broad, low- crowned, closed rooted, and molariform. The large parastyle is obliquely oriented and short. A deep parastyle/paracone groove is present on dP3, as is a shallower one on dP4. Paracone and meta- cone folds are well developed on both teeth, cre- ating a sinuous ectoloph. Two labial fossettes are present (the posterior one being smaller), as is a small, bifid lingual sulcus. The hypocone is higher than the paracone and metacone and is separated from the short, straight metaloph by a deep lin- gual groove (mensural data are in Table 2). Santiagorothia chiliensis, new taxon Holotype — sgopv 2914: cranium and mandi- bles, dentition complete except for LI 2-3, RI1- 2, and Ril-3, displaying moderate wear. Paratypes — sgopv 2827: complete upper den- tition and palate, anterior dentition poorly pre- served, dP3-4 present, sgopv 2861: RM1 (bro- ken)-M3, lightly worn, sgopv 2812: cranium with upper dentition, RI3-M3, LP1-2, LP4-M3, basi- cranium preserved, sgopv 2821: complete skull and mandibles, atlas and axis, prepared upper dentition includes RI3-M3, prepared lower den- HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES tition includes Ri3 (broken)-m3. Dentitions are little worn, sgopv 2821 includes an unprepared postcranial skeleton. Referred Material — sgopv 2816: cranium and mandible, only the left side of which is pre- pared, posterior cranium missing, sgopv 2826: mandibles, left side only prepared, Ril-c, Lil- m3, highly worn, sgopv 2862: right mandible, dis- torted, Rp3-m3, with light wear, sgopv 2968: right mandible, Rp2-m3, moderate wear. The fol- lowing specimens remain unprepared but are suf- ficiently observable that they can be referred to this taxon. sgopv 2819: three maxillary teeth. sgopv 2841: skull and partial skeleton, sgopv 2845: mandible preserving two teeth, sgopv 2846: partial skull and mandible, sgopv 3016: partial palate, sgopv 3034: lower jaw fragment, sgopv 3040: maxilla with two teeth, sgopv 3042: skull and partial skeleton, sgopv 3048: maxilla with 7P4-M1. sgopv 3079: rostrum, sgopv 3098g: mandibular fragment, sgopv 3125: mandibles pre- serving several crowns, sgopv 3139: mandible with anterior dentition. A number of specimens from post-Mustersan/ pre-Deseadan SALMA localities in Argentina are also referred to this taxon. mlp 91-IX-5-15, left maxilla with PI (root), P2-3 (broken), P4-M3, and anterior portion of the left zygoma, mlp 61- VIII-3-314, left Ml. mlp 83-1-12-1, maxillary fragment with broken left P2-M2. mlp 91-IX-5- 14a, mandibular fragment with left p4 (roots), ml-2. mlp 91-IX-5-14b, mandibular fragment with left ml-2. mlp 93-XI-25-8, left Ml or M2 (broken). The following specimens are also ten- tatively referred to this taxon: macn A 10908a, left m3 (paralectotype of lEohyrax platyodus); macn A 10908b and c, two isolated p3. Etymology — Santiagorothia after Santiago Roth, in honor of his contributions to South American mammalian paleontology, and chilien- sis for Chile, where the majority of the specimens were recovered. Diagnosis — Synapomorphies outlined earlier that are diagnostic of the Interatheriinae serve to identify Santiagorothia chiliensis as a member of this clade. Santiagorothia chiliensis is most easily distin- guished from other interatheriines (except Proar- gyrohyrax curanderensis) in possessing cheek teeth with closed roots, whereas the cheek teeth are hypseledont in other interatheriines. During wear, the upper cheek teeth of Santiagorothia chi- liensis, which are initially longer than wide, be- come equidimensional, and the lingual sulcus on the upper molars closes. In other interatheriines (except Proargyrohyrax curanderensis), the upper molars retain a more rectangular (longer than wide) form throughout their ontogeny, and the lin- gual sulcus remains open throughout wear. The labial fossettes of the upper molars are more per- sistent in Santiagorothia chiliensis than in other interatheriines (again, save Proargyrohyrax cur- anderensis). Compared to Proargyrohyrax curanderensis, Santiagorothia chiliensis has upper and lower pre- molars that are significantly smaller than the mo- lars (less molarized), a significantly narrower (an- teroposteriorly) anterior zygomatic root, and is slightly smaller (best seen in the lower dentition). Type Locality — Portezuelo El Fierro, Abanico (= Coya Machalf) Formation, Tinguiririca River Valley, central Chile (see Wyss et al., 1994). Known Distribution — Known from the type locality (all sgopv specimens) [radioisotopic de- terminations bracket its age between approximate- ly 37.5 and 31.5 Ma (Wyss et al., 1994)] and sev- eral localities in Patagonia, Argentina. These post- Mustersan/pre-Deseadan SALMA (but isotopical- ly undated) faunules from Chubut and Rio Negro provinces are probably roughly temporally equiv- alent to the Tinguiririca Fauna and include "As- traponoteen plus superieure" level at Gran Bar- ranca (south of the Lake Colhue Huapf) (Bond et al., 1996), Puesto Almendra, Departamento Sar- miento, Chubut province (macn A10908a,b,c); Lomas Blancas, La Curandera, Chubut province (mlp 93-XI-25-8); Rocas Bayas, Departamento 25 de Mayo, Rio Negro province (mlp 91-IX-5-15, mlp 83-1-12-1, mlp 91-IX-5-14a, mlp 91-IX-5- 14b); and Laguna La Bombilla, Departamento Paso de Indios, Chubut province (mlp 61-VIII-3- 314). Remarks — Systematic — Wyss et al. (1994) re- ported the presence of a second smaller interath- eriine, "Tinguiririca interatheriine new taxon B," represented by a single specimen, sgopv 3065. More detailed examination of this specimen re- veals it to probably represent an archaeohyracid, possibly referable to "Bryanpattersonia sulci- dens," a taxon currently being revised by one of us (M.R.). There is considerable variation within the sam- ple from the Tinguiririca Fauna, most of it having no taxonomic significance. Three mandibles, sgopv 2862, sgopv 3032, and sgopv 2868, seem to have been compressed during deposition or subsequent tectonic activity. All three are com- pressed transversely, lending the teeth a narrow FIELDIANA: GEOLOGY and somewhat distorted morphology. A second source of variation is the high degree of hypso- donty in this taxon, with both the shape and di- mensions of the teeth changing significantly with wear. A few specimens display minor differences (noted in the description) not attributable to wear or geologic deformation. However, because of the small size of our sample, which limits a thorough assessment of variation, it seems appropriate to provisionally refer them to a single taxon. Stratigraphic — In his original studies of fossil mammals from the Gran Barranca, Florentino Ameghino (1901, 1902) recognized two strati- graphic intervals within his "Couches a Astra- ponotus'" (now termed the Mustersan SALMA), the upper of which he called "Partie superieure des couches a Astraponotus." In works published after 1906, however, he ceased recognizing the two intervals as distinct. Recent evidence suggests that the "Partie superieure des couches a Astra- ponotus" level is indeed distinct, corresponding to a level recognized by Simpson in his field notes from the Scarritt Patagonian expeditions (Profile M, p. 40; this information is also presented in Ci- felli, 1985b: section V, sites 16 and 17, fig. 5, p. 11). In 1996 one of the authors (M.R. and col- leagues) collected fossil mammals from the "up- per channel level" in Simpson's Profile M (sites 16 and 17 of Cifelli, 1985b) at the Gran Barranca. This work confirms the existence of a stratigraph- ic level containing the same taxa as described by F. Ameghino in 1901 (Pseudopachyrucos fdlifor- mis) and 1902 (Jnterhippus deflexus), with the provenance of "Partie superieure des couches a Astraponotus" (or "Astraponoteen plus superi- eure," as termed by Bond et al., 1996). Other taxa from this level [listed in Cifelli (1985b) as recov- ered from sites 16 and 17] are Eomorphippus ob- scurus, IE. pascuali, Anisotemnus distentus, and Pleurostylodon sp. indet. Most of these taxa are regarded as Mustersan in age except for Pleuros- tylodon and Anisotemnus, which are Casamayor- an. Of special note is that Eomorphippus obscurus is found only in the latest Mustersan deposits and is not known from typical Mustersan deposits that have been well sampled (Wyss et al., 1994; Bond, pers. comm.). In addition, E. obscurus is known from Canadon Blanco and the Tinguiririca Fauna. Both faunas are regarded as post-Mustersan/pre- Deseadan in age (Wyss et al., 1994). The Tingui- ririca Fauna also contains a specimen of Eomor- phippus. cf. pascuali, likely further extending its biostratigraphic range (Wyss et al., 1994). Recent work by Goin and Candela (1997) re- veals a diverse marsupial fauna from the "Astra- ponoteen plus superieure" level. Goin and Can- dela report that these specimens appear morpho- logically intermediate Mustersan and Deseadan taxa. Moreover, they identify an argyrolagid that strikingly resembles ?argyrolagid specimens from the Tinguiririca Fauna. Finally, the "Astraponoteen plus superieure" level has produced several interathere specimens (macn A10908a,b,c) that are tentatively referred to Santiagorothia chiliensis, the most common taxon in the Tinguiririca Fauna. In sum, the "Astraponoteen plus superieure" level and its associated fauna (including both the recent collections and Ameghino's original spec- imens) suggests the presence of a post-Mustersan/ pre-Deseadan SALMA temporal interval in Ar- gentina which, based on faunal similarity, is likely correlative with the Tinguiririca Fauna (Bond et al., 1996). Like the Tinguiririca Fauna, the "As- traponoteen plus superieure" level displays an odd mix of "archaic" taxa and clearly younger forms. We suggest here that the several other Ar- gentine localities listed in the Known Distribution section above may correlate to the "Astrapono- teen plus superieure" level at the Gran Barranca (and thus also to the Tinguiririca Fauna) as well. Such a temporal correlation is least secure for the Rocas Bayas locality, which is faunally distinc- tive. Our suggested correlations are summarized in Figure 3. Description — Material — Santiagorothia chi- liensis (Figs. 4-11) is known from superb dental and cranial material. Several nearly complete skulls are known, as are several complete palates and mandibles (mensural data are in Tables 3-5. Postcranial material is also known from Chile, but it remains unprepared due to the tenacity of the volcaniclastic matrix. Upper Dentition — The anterior upper dentition shows minor variation between specimens. II is the largest incisor in all specimens examined. Al- though 12 is not preserved, in sgopv 2914 the al- veoli of 12 and 13 are subequal, indicating that the teeth were probably similar in size. The upper ca- nine in sgopv 2914 is considerably larger than 12- 13 (as inferred from alveoli), whereas in sgopv 2812 and sgopv 2821, it is only slightly larger. II, 13 (and 12 presumably as well), and C are laterally compressed. 13 displays a distinct anteroexternal vertical ridge in sgopv 2812 and sgopv 2821, whereas in sgopv 2914 it does not. A similar ridge occurs on the upper canine. II and 13 lack enamel HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES Epoch MA c 9 i — 20 Ma — V c G 0 o .2° O — 25 Ma — - 30 Ma - e 4> y o W — 35 Ma — — 40 Ma — — 45 Ma — — 50 Ma — Abanico Formation (Chile) Las Lcnas Fauna (20.09 +/- 0.27) Tinguiririca Fauna New LMA (31.5-37.5 Myr) Tapado Fauna (undated) Patagonian Biostratigraphy Colhuehuapian Casamayoran Lomas Blancas I- -• - Caiiadon Blanco I — -I Paso de Indios \ Rocas Bayas ? Divisaderan SALMA ""Astraponoteen plus superieure" level Fig. 3. Tentative correlation of the Abanico (= Coya Machalf) Formation in central Chile (and the faunas pre- served in it) and middle Cenozoic Patagonian mammalian biostratigraphy [after Flynn & Swisher (1995)]. The Abanico Formation is 1 ,000-2,000 m thick and appears to lack unconformities through its ?Paleogene-?early Neogene span, although as yet, mammal remains are known only from three localities (Flynn et al., 1995; Wyss et al., 1994). Dashed boundaries with accompanying questions indicate lack of radioisotopic and paleomagnetic information, and gray regions represent hiatuses. The Las Lefias Fauna (Flynn et al., 1995), located about 60 km NNE of the Tingui- ririca Fauna (Wyss et al., 1994), has an associated Ar^'/Ar39 determination of 20.09 ± 0.27 Ma, arguing for its approximate tie to the Colhuehuapian SALMA [which is bracketed by the Santacruzian SALMA (above) and the Deseadan SALMA (below), both of which are dated (Flynn & Swisher, 1995)]. As discussed in the text, we tentatively correlate the Tinguiririca Fauna (and an as yet unnamed land mammal age based on it) to the "Astraponoteen plus superieure" level recognized by Ameghino (1901) and Bond et al. (1996). Traditionally this level was considered uppermost (latest) Mustersan, including by Ameghino himself (1906), but Bond et al. (1996) argued that it is faunally distinct and warrants recognition as a new temporal interval. We tentatively correlate several post-Mustersan/pre- Deseadan Patagonian localities to the "Astraponoteen plus superieure" level as well (see Table 1 for references to these localities). Correlation of the radioisotopically dated Tinguiririca Fauna with the "Astraponoteen plus super- ieure" level potentially moves at least part of the Mustersan SALMA (that directly underlying the "Astraponoteen plus superieure" level) into the Late Eocene, further complicating temporal placement of the problematic Divisaderan SALMA. The Divisaderan has been considered earliest Deseadan or latest pre-Deseadan (MacFadden et al., 1985; Marshall et al., 1986) based on several taxa common to the two SALMAs. Bond (1991), however, argues the Divisaderan to be considerably older than the Deseadan, and Wyss et al. (1994) argue that it predates the Tinguiririca faunal interval. If a post-Mustersan pre-Tinguiririca Fauna age for the Divisaderan is accepted and the "Astraponoteen plus superieure" level (which superposes Patagonian Mustersan deposits) is considered temporally equivalent to the Tinguiririca Fauna (as suggested here), then there is no room in which to place the Divisaderan within the Patagonian SALMA sequence (hence, its ambiguous placement). The oldest biostratigraphic interval in the Andean sequence identified to date is the Tapado Fauna, located about 12 km NW of the Tinguiririca Fauna; an approximate Casa- mayoran age has been suggested for it (Wyss et al., 1994), but detailed taxonomic description and radioisotopic calibration are pending. Fig. 4. A. sgopv 2914, Santiagorothia chiliensis, holotype, complete dentition except for LI 1-2, RI1-2, Ril-3, lateral view. B. sgopv 2914, dorsal view. C. sgopv 2914, posterior view. Scale = 1.0 cm. FIELDIANA: GEOLOGY HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES B ^<®&®& Fig. 5. A. sgopv 2812, Santiagorothia chiliensis, cranium with RI3-M3, LP1-2, P4-M3, heavy wear. B. sgopv 2812, occlusal outline of RP3-M1. Scale = 1.0 cm. on their lingual faces. 13 and C are imbricate, the posterior margin of 13 laying labial to the anterior margin of C. The first premolar does not appear to be re- placed, which is inferred from its extreme state of wear in most specimens, sgopv 2827 is an excep- tion, however, and the PI bears a distinct para- cone and is broader transversely than the preced- ing teeth. The deciduous premolars (dP2-4) have not yet been replaced in sgopv 2827 and are heavily worn. dP2 has a well-developed paracone and metacone with correspondingly strong undula- tions on the ectoloph. It also displays an anteriorly projecting parastyle and a single central fossette. The crown is roughly rectangular in outline save for the anterior projection of the parastyle. dP3 and dP4 resemble one another as well as the per- manent molars: the paracone and metacone are distinct and the parastyle is salient. The ectoloph resembles that of dP2, with distinct undulations corresponding to the cusps. A fossette forms from a lingual sulcus between the protocone and the hypocone after heavy wear. The crowns are roughly rectangular (but more elongate than dP2) except for the strong, anteriorly projecting para- style. P2-4 are known only from moderately worn examples. The P2-4 sequence increases gradually in size posteriorly. The paracone and parastyle are expanded anteriorly, with a deep groove dividing the two. This parastylar expansion produces a 10 FIELDIANA: GEOLOGY B & Fig. 6. A. sgopv 2861, Santiagorothia chiliensis, RM1 (broken)-M3, light wear. B. sgopv 2861, occlusal outline of RM2. Scale bar = 1.0 cm. tooth that is longer than wide during early wear stages but later becomes roughly equidimensional. The ectoloph is relatively smooth, the metacone column being very low. The paracone column is low on sgopv 2914 but is slightly more distinct on sgopv 2812 and sgopv 2821. A bifid lingual sulcus is short-lived; it rapidly closes off to be- come a persistent U-shaped internal fossette, the bend of which points lingually. An anteroexternal fossette is present on P3-4; it persists until late wear stages but ultimately disappears. A high pos- terior cingulum merges early in wear with the re- mainder of the crown. Other cingulae are lacking. P2-4 are hypsodont but form closed roots. The five specimens listed below form a fairly complete wear series from relatively light to heavy wear (light — sgopv 2827 > sgopv 2861 > sgopv 2821 > sgopv 2914 > sgopv 2816 > sgopv 2812 — heavy). This series provides a fairly com- plete record of the transformations of molar crown morphology throughout wear. Ml -3 all bear a very smooth ectoloph with a shallow para- cone/parastyle groove and only slight undulations corresponding to the paracone and metacone. A bifid lingual sulcus between the protocone and hy- pocone persists until moderate wear stages, at which point it closes off to become a U-shaped lingual fossette, as on the premolars; this structure persists throughout the remaining wear stages. An anteroexternal fossette and a smaller posteroex- ternal one are present initially but disappear after moderate wear, the posterior one being obliterated first. A high, very broad posterior cingulum is dis- tinct from the hypocone early in wear but rapidly merges with the rest of the crown as wear pro- ceeds. A transverse fossette is created upon merg- ing of the posterior cingulum with the metaloph, but it rapidly disappears with wear. Other cingula are lacking. The occlusal surface is considerably longer than wide in little-worn teeth, with the HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 11 Fig. 7. A. sgopv 2821, Santiagorothia chiliensis, Ri3-m3, light wear, lateral view. B. sgopv 2821, occlusal view. C. sgopv 2821, occlusal outline of RP1-M3. Scale bar = 1.0 cm. 12 FIELDIANA: GEOLOGY B Fig. 8. A. sgopv 2826, Santiagorothia chiliensis, Ril-c, Lil-m3, heavy wear. B. sgopv 2826, occlusal outline of Lp3-m3. Scale bar =1.0 cm. paracone and parastyle expanded anteriorly and the protoloph running posterolingually from the anteroexternal corner. These dimensions become approximately equidimensional after moderate wear as the crown approaches the roots. The crown of RM1 of sgopv 2827 is exposed along its entire length, clearly showing the anteropos- terior narrowing of the crown rootward. All mo- lars are hypsodont and form closed roots. M3 resembles the other molars strongly despite its considerably smaller size. In contrast to the anterior molars, M3 has a posteriorly projecting metastyle. Some aspects of M3 vary considerably between specimens. In particular, the M3 of sgopv 2821 and mlp 91-XI-5-15 have anterior and pos- terior labial fossettes that are less persistent than in the other specimens; they disappear after light wear, leaving a featureless occlusal surface. In ad- dition, the lingual sulcus of these two specimens is not bifid and the tooth thus lacks a "median lobe." Lower Dentition — The il is slightly smaller than i2, whereas i3 is considerably larger than both. Although i 1 and i2 are too worn or obscured in presently available specimens to reveal details of crown morphology, i 1 appears nearly cylindri- cal, whereas i2 is broader and more incisiform. The i3 has a shallow central vertical lingual groove dividing the tooth into two portions, the posterior of which is slightly larger. The canine is HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 13 'O 14 FIELDIANA: GEOLOGY Fig. 10. mlp 91-IX-5-15, Santiagorothia chiliensis, LP1-M3, moderate wear. Scale bar = 1.0 cm. larger than i3; it likewise consists of two portions, but it also has a small posterior heel. The i3 and c are imbricate, the posterior portion of each tooth lying labial to the anterior portion of the succeed- ing tooth. The pi is long and narrow; two vertical lingual grooves, an anteriorly positioned one and a less deeply incised posterior one, divide the tooth into three portions. The external face is smoothly con- vex except for a very shallow labial, vertically oriented groove occurring opposite the posterior lingual one. No diastemata are present in the an- terior tooth row. The p2 is similar to pi except that a metaconid is clearly differentiated and the posterior lingual groove is accompanied by a distinct labial one and so defines a very small talonid. The third and fourth lower premolars are sim- ilar, both possessing a large trigonid and a dis- tinctly smaller but well-developed talonid. The tri- gonids are roughly triangular in outline and the talonids are round. The trigonid and talonid are separated by strong labial and lingual sulci, lend- ing a bilobed appearance to the teeth. On p3 the labial sulcus is positioned slightly anterior to the lingual sulcus, whereas on p4 they are opposite one another. On both teeth a vertical groove sep- arates the anterior margin of the trigonid from the metaconid. The metaconid is robust and swings posteriorly along its lingual margin. Extreme wear (sgopv 2826) obliterates the anterointernal groove and lingual sulcus, but the labial sulcus persists. The p4 has approximately the same dimensions as the molars. The p3 is about the same length an- teroposteriorly as p4 but is distinctly narrower transversely. The molar trigonids are square in outline and are separated from the rounded talonids by strong labial and lingual sulci, again producing a bilobed appearance. On the molar trigonids there is a shal- low groove between the anterior margin of the tooth and the metaconid, which disappears with wear. The metaconid extends nearly transversely without swinging posteriorly at the lingual margin as it does on the posterior premolars. No hypo- conulid is observed on ml or m2, but completely unworn specimens are not presently known, and this feature may simply be highly transitory. The talonids and trigonids are subequal on ml and m2, but on m3 the talonid is considerably larger. The m3 talonid is roughly elliptical, its outline inter- rupted by a shallow posterolingual groove sepa- rating a hypoconulid from the remainder of the talonid. All lower cheek teeth are hypsodont and form closed roots. Cranium — The skull roughly resembles a larg- er version of Notophithecus, a Casamayoran non- interatheriine interatheriid described in detail by Simpson (1967). General differences seen in San- tiagorothia chiliensis (apart from its much larger size) include a longer rostrum, a slightly more lat- erally expanded braincase, less extreme postorbit- al constriction (although still quite marked), and a less laterally expanded occipital region. The premaxilla, moderately well preserved in several specimens, shows considerable variation. On the facial region of sgopv 282 1 the suture be- tween premaxilla and maxilla slopes posteriorly and a small process of the premaxilla projects into the maxilla posterodorsally. On sgopv 2812 and sgopv 2914 the premaxilla/maxilla suture is ori- ented nearly vertically (the posterodorsal region is not preserved so no process may be discerned). On the palate the premaxilla/maxilla suture occurs immediately posterior to 13. The palatine/premaxilla suture is discernible only in its extreme anterior portion where it reach- es about as far anteriorly as the posterior margin of P4. The internal choanae are not preserved but Fig. 9. A. sgopv 2827, Santiagorothia chiliensis, palate and permanent upper dentition save dP3-4, very light wear, occlusal view. B. sgopv 2827, lateral view. C. sgopv 2827, occlusal outline of RM2. Scale bar = 1 .0 cm. HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 15 A B D * ** 16 FIELDIANA: GEOLOGY Table 3. Dental measurements for the upper dentition of Santiagorothia chiliensis (mm). MLP SGOPV SGOPV SGOPV SGOPV SGOPV MLP MLP 61-VIII-3- MLP Tooth 2821 2861 2812 2827 2826 83-1-12-1 91-IX-5-15 314 93-XI-25-8 11 AP 11 TR 12 AP 12 TR 13 AP — — — — — — 5.19 — — — 4.73 — — — — 13 TR 2.73 — — — 1.85 — — — — CAP 5.27 — 5.66 — 5.19 — — — — C TR 3.00 — — — 2.00 — — — — PI AP 5.85 — — 5.34 — — — — — PI TR 3.18 — — 3.00 — — — — — P2 AP — — 5.77 d5.74 — — — — — P2 TR — — 5.13 d4.79 — — — — — P3 AP 7.09 — 7.02 d7.35 6.16 — 5.5* — — P3 TR 4.92 — 6.24 d5.41 4.91 — 6.0* — — P4 AP 7.45 — 6.89 d7.60 6.58 6.3* 6.6 — — P4TR 5.66 — 6.99 d5.38 5.94 5.5* 5.6 — — Ml AP 6.29 — 6.47 7.95 6.41 7.1 5.8 — — Ml TR 5.76 — 7.06 4.33 5.72 5.4 5.6 — — M2 AP 7.54 8.70 7.18 7.76 7.00 7.0 6.8 7.2 7.7 M2TR 5.68 5.61 6.82 3.64 5.45 5.2 4.7 4.9 4.8 M3 AP 6.47 7.85 7.40 — 6.24 — 6.4 — — M3TR 4.88 4.42 5.73 — 4.28 — 4.1 — — Estimated. must have had a relatively posterior position, well beyond the posterior part of M3. The palantine notches are narrow and short anteroposteriorly, extending anteriorly to the posterior part of M3. The rostral portion of the maxilla is quadrate and mildly excavated anterior to the orbit. The infraorbital foramen is large and positioned above P4. The orbital rim is preserved completely only in sgopv 2914. This specimen shows that a pos- teriorly projecting maxillary process is excluded from the rim of the orbit by a very thin sliver of frontal, which projects anteriorly to contact the lacrimal. The lacrimal is poorly preserved in all speci- mens but is apparently positioned largely within the orbit, only a very small portion extending onto the orbital rim and slightly beyond. The lacrimal foramen cannot be discerned. The nasals are narrow and elongate, broadening posteriorly. They are confined to the superior part of the rostrum and are slightly convex mediolat- erally. sgopv 2821 shows the nasal and frontal suture to be roughly transverse, undulating slight- ly with two mild excursions. On sgopv 2812 and sgopv 2914 the suture is different. From the junc- tion of the nasal and nasal-frontal sutures it runs a short distance anteriorly then sharply posteri- orly, forming a strong posteriorly projecting pro- cess on the lateral margin. The zygoma displays the hallmark interathere pattern: a jugal which both excludes the maxilla and extends posteriorly between the maxilla and squamosal (Riggs and Patterson, 1935). The max- illa extends along the ventral margin of the zy- goma nearly to its posterior root. The squamosal extends anteriorly about as far as the level of the supraorbital process. The anterior root of the zy- goma projects posteriorly and transversely away from the skull at about 60°. The remainder of the zygoma nearly parallels the braincase. The posi- tion of the anterior root of the zygoma on the rostrum varies between specimens, reaching from mid-M3 to anterior Ml on sgopv 17-89-12 and sgopv 2914 and from anterior M3 to posterior Ml Fig. 11. A. mlp 91-IX-5-14b, Santiagorothia chiliensis, Lml-2. B. mlp 91-IX-5-14a, Santiagorothia chiliensis, Lml-2. C. mlp 61-VIII-3-314, Santiagorothia chiliensis, ?M1 or M2, occlusal view. D. mlp 61-VIII-3-314, anterior view. Scale bar = 0.5 cm. HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 17 Table 4. Dental measurements for the lower dentition of Santiagorothia chiliensis (mm). Tooth SGOPV SGOPV MLP MLP MACN MACN MACN 2821 2826 91-IX-5-14a 91-IX-5-14b 10908a 10908b 10908c il AP — — — — — il TR — — — — — i2 AP — — — — — i2TR — — — — — i3 AP — 4.23 — — — i3 TR — 1.95 — — — c AP 5.57 5.10 — — — cTR 1.94 1.80 — — — pi AP 5.57 — — — — pi TR 2.79 — — — — p2 AP 5.94 5.46 — — — p2TR 2.66 2.34 — — — p3 AP 6.24 6.30 — — — p3 TR 3.14 3.32 — — — p4 AP 6.71 6.47 6.4 — — p4TR 3.70 3.73 4.1 — — ml AP 6.93 5.79 6.7 6.7 — ml TR 4.05 3.59 3.5 4.1 — m2 AP 7.34 5.99 — 6.2 6.2 m2TR 3.67 4.12 — 3.7 4.0 m3 AP 8.22 8.22 — — — m3 TR 3.53 3.81 — — — 6.2 3.4 6.0 3.5 on sgopv 2821. A small but distinct descending process is present on the anterior zygomatic root in sgopv 2821 but is more weakly expressed in the other specimens. This process is continuous with a very low, laterally projecting blade that runs posteriorly on the lateral zygomatic margin. The rectangular frontal is considerably elongate anteroposteriorly. The nasal-frontal suture is po- sitioned well anterior of the orbit. A moderately sized supraorbital process projects posteriorly. The anterior orbital rim is sharp and bears a large supraorbital foramen about midway along its length. The parietal narrows posteriorly and bears a low sagittal crest. The squamosal region is mod- erately inflated, the pars epitympanicus forming a flattened triangular region with sharp dorsal and posterior borders. The occiput contains greatly en- larged epitympanic sinuses and is very broad. The moderately inflated, fully ossified bullae form the dominant feature of the basicranium. The glenoid fossa is anteroposteriorly narrow and deep, its posterior border being very steep and slightly excavated. The postglenoid process forms a short, transverse ridge extending medially to the bulla. A probable postglenoid foramen lies near the bulla on the postglenoid process. This basicranial region is compressed anteroposterior- ly, with the meatus and postglenoid process tight- ly fused. The meatus itself is short and projects posterodorsally. A transversely compressed para- occipital process arises directly posterior to the Table 5. Cheek tooth crown height for a sample of Santiagorothia chiliensis (mm). Uppei jaw Tooth Lower jaw SGOPV 2862 (light wear, crown incompletely exposed) SGOPV 2821 Tooth SGOPV 2827 (unworn, crown completely exposed) SGOPV 2861 (slightly worn, crown incompletely exposed) (moderate wear, crown incompletely exposed) P4 Ml M2 M3 11.60 12.50 11.70 p4 ml m2 m3 7.80 10.10 5.90 5.00 18 FIELDIANA: GEOLOGY bulla, such that the bulla abuts its anterior border. The posterior lacerate foramen lies medial and ad- jacent to the paraoccipital process. Posteromedial to the posterior lacerate foramen occurs a con- dylar foramen. No foramina occur along the bul- la's medial border, but two occur anteriorly; in these respects the bulla closely resembles Proty- potherium (Patterson, 1936). The foramen ovale is large and lies in the fissure between the bulla and alisphenoid. Ventral and slightly lateral to the foramen ovale lies the external eustachian open- ing, the two being separated by a thin sliver of bone. Ventral to the eustachian foramen lies a shelf of bone which Patterson (1936), in describ- ing Protypotherium, termed a styliform process, acknowledging, however, its uncertain homology. The medial margin of the foramen ovale contains a septum, perhaps demarcating an additional fo- ramen. Simpson (1967) noted a similar septum in what he interpreted as the medial lacerate foramen of Notopithecus, suggesting that it may have sub- divided the foramen in two, thereby demarcating also the anterior lacerate foramen. A canal ap- pears to run immediately lateral to the foramen ovale, along the fissure of the tympanic/alisphe- noid suture; poor preservation of this canal pre- cludes further interpretation. Patterson (1936) described two additional, very small foramina medial and ventral to the foramen ovale in Protypotherium, interpreting one of these as the anterior carotid foramen. Patterson (1936) thus regarded the course of the carotid artery as being intrabulla. The similarity between Santia- gorothia chiliensis and Protypotherium, with re- spect to position of the basicranial foramina, sug- gests a similar pattern of carotid circulation in the two taxa. Proargyrohyrax curanderensis, new taxon Holotype — mlp 61-VIII-3-27, left maxillary fragment with P4-M3, preserving anterior root of the left zygoma. Paratypes — mlp 61 -IV- 14-1, left mandible with p3-m3; mlp 61-VIII-3-24, left mandible with p2-m3. Referred Material — mlp 93-XI-25-19, right ml; mlp 93-XI-25-3, right p3-4. Etymology — Proargyrohyrax for its similarity to the interathere taxon Argyrohyrax (although no strict phylogenetic relationship is implied) and curanderensis for the geographic location near which the fossils were recovered. Type Locality — Lomas Blancas, near La Cur- andera, Departamento Paso de Indios, Chubut province, Argentina. Known Distribution — Known only from the type locality. This locality is probably biostrati- graphically correlative to the "Astraponoteen plus superieure" level at Gran Barranca, Chubut, and the Tinguiririca Fauna of central Chile. Diagnosis — Synapomorphies outlined earlier that are diagnostic of the Interatheriinae serve to identify Proargyrohyrax curanderensis as a mem- ber of this clade. Proargyrohyrax curanderensis has the follow- ing attributes, distuingishing it from other inter- atheriines except Santiagorothia chiliensis: cheek teeth that form closed roots, upper cheek teeth that become more equidimensional with wear, and persistent labial fossettes on the upper molars. Like Santiagorothia chiliensis, the parastyle on Ml -2 in Proargyrohyrax curanderensis curves and projects labially and p3 has a strong post- metastylid crest projecting posteriorly. Proargyrohyrax curanderensis can be distin- guished from Santiagorothia chiliensis by the fol- lowing features in Proargyrohyrax curanderensis: larger overall (the absolute size difference varies considerably from between teeth and specimens, but a difference of 10% may serve as an approx- imation), upper and lower premolars (particularly the posterior premolars) more molariform (close in dimensions to the molars), labial fossettes on the upper molars more persistent, trigonids on p3- 4 squarer in occlusal outline, and anterior root of the zygomatic arch well expanded anteroposteri- orly and laterally, much more so than in Santia- gorothia chiliensis. Remarks — Although there is no direct associ- ation of upper and lower dentitions, the specimens referred to Proargyrohyrax curanderensis are tak- en to represent the same taxon, given compatibil- ity in size. In addition, the maxilla (mlp 61 -VIII- 3-27) occludes well with the mandibles (mlp 61- VIII-3-24 and mlp 61 -IV- 14-1). Description — Material — Proargyrohyrax cur- anderensis is represented by cheek teeth and a portion of the maxilla (Fig. 12). Given the less complete material from which it is known, Proar- gyrohyrax curanderensis can be described in much less detail than Santiagorothia chiliensis (for example, a complete wear series for the cheek teeth is unavailable for the former). Mensural data are presented in Tables 6 and 7. Upper Dentition — P4 is molariform and quad- rangular. A well-developed parastyle curves labi- HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 19 B J32b'S ^ Fig. 12. A. mlp 61-VIII-3-27, Proargyrohyrax cur- anderensis, holotype, L maxillary fragment with P4- Ml, moderate wear. B. mlp 61 -IV- 14-1, Proargyrohyrax curanderensis, left mandible with p3-m3, light wear. Scale bar = 1.0 cm. ally and connects to a moderately developed para- cone column. The paracone and parastyle are sep- arated by a deep groove. Small anteroexternal and posteroexternal fossettes are present, the anterior of which is larger. The protoloph contacts the ex- treme lingual margin of the metaloph but is not fully united with it. Together, the protoloph and metaloph demarcate a central, heart-shaped fos- sette. The anterior portion of this fossette ap- proaches but does not contact the anteroexternal fossette. A lingual sulcus is absent, although it is probable that the lingual fossette represents a sul- cus that closed through wear. The posterior cin- gulum is moderately distinct and is lower than the metaloph. It joins the metaloph labially and lin- gually, forming a posterior fossette that is trans- versely elongate. The molars are longer than wide and are inter- rupted lingually by a deeply bifid sulcus. They are generally similar in morphology except as noted below. Ml, the largest tooth of the series, is elongate and bears a large anteroexternal fossette near the paracone. A small posteroexternal fossette lies close to the metacone. The parastyle is salient and projects labially. The lingual sulcus is narrower and the median lobe smaller than on M2. The transverse dimension becomes greater as wear ap- proaches the roots. Ml has a thick internal root and two fused external roots. M2 is narrower transversely than M 1 . Although the parastyle is smaller than on Ml, it still curves labially. The parastyle/paracone groove is larger than on Ml but still shallow. The well-developed paracone is more prominent than the metacone. The short protoloph is oriented obliquely, its lin- gual margin being free. The lingual sulcus is nar- row. A small medial lobe occurs internally and with significant wear merges with the internal face of the protoloph. Anteroexternal and posteroex- ternal fossettes are present as is a transverse fos- sette between the metaloph and the posterior cin- gulum. M2 has three roots. M3 is the smallest molar. Its lingual sulcus is Table 6. Measurements of the upper cheek teeth of Proargyrohyrax curanderensis (mm). Tooth dM3 AP dM3 TR dM4 AP dM4TR P4 AP P4TR Ml AP Ml TR M2 AP M2 TR M3 AP M3 TR MLP 61-VHI-3-27 7.7 6.4 8.1 6.7 7.9 5.6 6.8 4.0 Table 7. Measurements of the lower cheek teeth of Proargyrohyrax curanderensis (mm). MLP 61- MLP 61- MLP 93- MLP 93- Tooth VIII-3-24 IV-14-1 XI-25-3 XI-25-19 p2 AP 7.1 — p2TR 3.5 — — — p3 AP 7.5 7.2 7.4 — p3 TR 4.4 3.9 4.3 — p4 AP 7.7 7.1 7.6 — p4TR 4.5 4.0 4.4 — ml AP 7.6 7.3 — 7.4 ml TR 5.0 4.4 — 4.5 m2 AP 8.1 7.4 — — m2 TR 4.8 4.1 — — m3 AP 7.7 8.8 — — m3 TR 3.6 3.5 — — 20 FIELDIANA: GEOLOGY bifid but has a very small posterior limb. Like the other upper molars, M3 bears a posteriorly pro- jecting metastyle. Lower Dentition — The lower dentition is not known anterior to p3 for Proargyrohyrax curan- derensis. The p3 is molariform, the trigonid and talonid being enlarged, equidimensional, and close in size to the molars. The trigonid is square in outline and open lingually (anterointernal groove). The protoconid and metaconid, the for- mer of which is more distinct, are joined by a short, straight metacristid. A crest, termed a post- metastylid by Marshall et al. (1983), extends pos- teriorly from the metaconid. The trigonid and tal- onid are unconnected during initial wear stages, but an isthmus quickly forms thereafter. A narrow, deep labial sulcus separates the trigonid and tal- onid. A low cristid obliqua extends posterolabially from the medial part of the metacristid. The groove on the posterointernal margin of the tal- onid is a weak. The p4 resembles p3, the main difference being that the postmetastylid on p4 is less developed and projects less posteriorly. The labial sulcus be- tween the trigonid and talonid is wider than on p3. The ml and m2 are similar, although ml dis- plays a broader anterointernal groove. They re- semble p4 except that the trigonid is relatively larger and rounder. In addition, ml -2 lack the postmetastylid of the premolars. On m3 the metacristid is shorter than on ml -2 and the talonid is considerably larger than the tri- gonid. The wide, transverse entolophid is flanked by two moderately deep sulci, the posterior deeper than the anterior. Cranium — The anterior root of the zygoma is the only part of the cranium of Proargyrohyrax curanderensis known. It is broad both laterally and anteroposteriorly. Its anterior margin is even with the anterior margin of P4 (the anterior border of the orbit is in line with the anterior margin of P4 as well). The maxilla forms the anterior and anteroventral portion of the orbit. The zygomatic root bears a small descending process. Judging from preserved sutures, the jugal lay lateral to the zygomatic process of the maxilla. The infraorbital foramen is large, arising from the base of the orbit and situated adjacent to P3. Eopachyrucos, Ameghino 1901 1901 Eopachyrucos, Ameghino, p. 370. 1906 Eupachyrucos [lapsus], Ameghino, p. 469. Type — Eopachyrucos pliciferus Ameghino, 1901. Emended Diagnosis — "Upper molar hypso- dont; tapering rapidly from roots to apex; wear surface near apex longer than wide; labial surface of ectoloph with strong, subequal paracone and metacone ridges; two circular, equal labial fosset- tes retained to late wear stage; deep bifid groove between protocone and hypocone retained (open and not as fossa) to late wear stage" (Simpson, 1967, p. 116). Lower premolars and molars high crowned but have very long roots; anterointernal groove of the trigonid persistent. The p3 trigonid with paracristid reduced and metacristid well de- veloped and straight. Talonid of the premolars and molars shorter and less rounded than those of Proargyrohyrax curanderensis and Santiagoro- thia chiliensis. Known Distribution — Patagonia: Gran Bar- ranca, Departamento Sarmiento, Chubut province; Canadon Blanco, Chubut province, Argentina; Rocas Bayas, Departamento 25 de Mayo, Rio Ne- gro province, Argentina. Remarks — Florentino Ameghino referred Eopachyrucos pliciferus to the Hegetotheriidae (1901, 1906) believing its occlusal morphology to closely resemble the Santacrucian Pachyrukhos (Hegetotheriidae, Pachyrukhinae) of Patagonia. Eopachyrucos pliciferus was included by Simp- son (1967) as ?Hegetotheria incertae sedis. Ac- cording to Ameghino's handwritten label that ac- companies the fossil ("Eoprotypotherium" sou- che Protypotherium Astraponoth) this specimen was collected by Carlos Ameghino in rocks of Mustersan (Astraponotus beds) age. "Eoproty- potherium" is an unpublished name that Amegh- ino used in an informal phylogenetic sense, to em- phasize his notion of the ancestry of this form with respect to Protypotherium (eventually Ameghino decided to use the name Eopachyru- cos). As Simpson realized, however, the prove- nance of several specimens in the Ameghino Col- lection, for various reasons, was confused or lost and should be treated with caution. In his description of the type species of Eopa- chyrucos, Ameghino (1901) mentioned various lower teeth and mandibular fragments (macn A55-12) although the type, as catalogued in the macn, is an upper molar. The latter is very similar to the unworn upper molar of Argyrohyrax acu- ticostatus, but much smaller. The upper molar of Eopachyrucos is also similar to the molars of Gui- lielmoscottia (a Mustersan SALMA non-interath- eriine interathere) but is more hypsodont. Eopa- HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 21 chyrucos is an interathere, its inclusion in the In- teratheriinae being based mainly on its hypsodon- ty. macn A55-12 also displays a very shallow parastyle/paracone groove, which is additional ev- idence for its interatheriine affinities (see diag- nosis of Santiagorothia chiliensis, including the list of tentative interatheriine synapomorphies). Eopachyrucos pliciferus Ameghino 1901 1901 Eopachyrucos pliciferus, Ameghino, p. 370. 1967 Eopachyrucos pliciformis, Simpson, p. 116, lapsus pro pliciferus. Type — macn A55-12, isolated left Ml or M2. Paratypes — mlp 12-1529, incomplete mandib- ular fragment with alveoli of right il-2, and left pl-4, and four isolated cheek teeth: right p4, ml and m3, and left ml, apparently of the same in- dividual; mlp 91-IX-5-17, an isolated right p2. Type Locality — ?Gran Barranca, Chubut prov- ince, Argentina. Known Distribution — Known from Patagonia, Argentina. The type, macn A55-12, was likely collected at the "Astraponoteen plus superieure" level (Bond et al., 1996), Gran Barranca (south of Colhue-Huapi Lake), Departamento Sarmiento, Chubut province; mlp 12-1529 comes from Can- adon Blanco, Chubut province; mlp 91-IX-5-17 is from Rocas Bayas, Departamento 25 de Mayo, Rio Negro province. Diagnosis — Small with high-crowned cheek teeth. Anterior lower premolars are similar to Cochilius. Similar also to Guilielmoscottia but higher crowned and with well-developed meta- cristid on the lower molars. The m3 entoconid more expanded than in Santiagorothia chiliensis and Proargyrohyrax curanderensis. Remarks — Ameghino's holotype consists of an isolated upper molar, the principal diagnostic characters of which are listed above in the diag- nosis. The Cafiadon Blanco and Rocas Bayas specimens are similar in size to the holotype and occlude well with it; on this basis we refer these specimens to this taxon. Ameghino's original description (1901 p. 123) of the molars of E. pliciferus is excerpted as fol- lows: "... presentan el mismo contorno que los de Pachyrukhos, pero poco arqueados, de corona mas corta y provistos de raices separadas aunque muy cortas," [has the same outline as Pachyru- khos but has a shorter crown and stocky, but sep- Table 8. Measurements of the lower cheek teeth of Eopachyrucos pliciferus (mm). Tooth MLP 12-1529 MLP 91-IX-5-17 pi AP 4.1 pi TR 1.6 — p2 AP 4.1 3.9 p2TR 1.9 1.6 p3 AP 4.4 — p3 TR 2.4 — p4 AP 4.0 — p4 TR 2.4 — ml AP 4.1 — ml TR 2.5 — m2 AP — — m2TR — — m3 AP 5.3 — m3 TR 2.5 — arate roots] . Other features mentioned by Amegh- ino include (1) "ectolofo sinuoso terminando . . . en dos cuspides en forma de V" [ectoloph sinu- ous, terminating ... in two cuspids which have the form of a V], (2) "cara lingual dividida en dos lobulos por . . . un surco que se ensancha hacia abajo y penetra en la corona formando un pliegue de esmalte" [the lingual face is divided into two lobes ... a groove which broadens and penetrates the crown forming a fold of enamel], and (3) "presencia de dos fosetas de esmalte, una anterior y otra posterior" [presence of two fos- settes, an anterior and posterior]. Description — Material — Eopachyrucos plici- ferus is known from isolated upper and lower cheek teeth (Fig. 13). Mensural data are provided in Table 8. Upper Dentition — The type (Ml or M2) is similar to the molars of Argyrohyrax acuticosta- tus, Santiagorothia chiliensis, and Proargyrohyr- ax curanderensis but is much smaller, narrower, and slightly more elongate. It is decidedly hyp- sodont and lacks a deep paracone/parastyle groove. An anterior labial fossette and a smaller medial labial fossette are present. A third smaller, lingually positioned fossette is present, likely forming from the merger of the postcingulum and metaloph (measurements of macn A52-12: inter- oposterior, 3.9 mm; transverse, 2.6 mm). The crown height is 6.1 mm. Lower Dentition — The lower dentition is sim- ilar to that of Cochilius, but the molar trigonids of E. pliciferus generally have a broader anteroin- ternal groove and a much larger metacristid, the overall outline thus markedly more square. The p2 is narrow, displaying a well-developed 22 FIELDIANA: GEOLOGY B Fig. 13. A. mlp 12-1529, Eopachyruchos pliciferus, partial left mandible and associated teeth, Lp2-p4, Lml, Rml-3, light to moderate wear, scale = 1.0 cm. B. mlp 12-1529, Eopachyruchos pliciferus, Lm2, light to moderate wear, scale = 0.1 cm. C. macn A55-12, Eopachyruchos pliciferus, holotype, LM1 or LM2, light wear. Scale bar = 0.1 cm. trigonid with a distinct protoconid and raised an- teroexternal margin, a lingually projecting meta- conid, and a transversely oriented metacristid con- necting protoconid and metaconid. A small round- ed talonid connects directly to a wide metaconid by a narrow isthmus and is bounded on either side by two sulci. The p3 is molariform with the trigonid being slightly more triangular in outline than the square outline of ml -2. In contrast to the molars, the HITZ, REGUERO, WYSS, & FLYNN: NEW INTERATHERIINES 23 paracristid is reduced. The first and second molars display a transverse metacristid with a lingually projecting metaconid, the latter of which is much larger on m2. Both teeth are distinctly bilobed with persistent lingual and labial sulci; the trigo- nid and talonid are connected by a narrow isth- mus. The talonid on both is square in occlusal view. The m3 trigonid is square in outline and smaller than on ml and m2. The hypoconulid is well developed on m3, and a distinct persistent groove separates it from the entoconid. The m3 talonid forms an elongate oval outline and is more than twice as large as the trigonid. Interatheriidae incertae sedis "lEohyrax" platyodus Ameghino 1904 1904a Eohy rax platyodus, Ameghino, p. 200. 1967 1 Eohy rax platyodus, Simpson, p. 108. Lectotype — ? Eohy rax platyodus: The left ml (macn A10908e), upon which Ameghino (1904) based most of his observations, was taken by Simpson (1967) as a lectotype (Fig. 2). Type Locality — ?Gran Barranca, Departamen- to Sarmiento, Chubut province, Argentina (al- though the provenance is not reliable). Remarks — According to Simpson (1967, p. 108) lEohyrax platyodus is an archaeohyracid more primitive than Eohyrax rusticus from the Casamayoran of Patagonia, and "[i]ts presence in the Mustersan would be anomalous." Simpson designated an interatheriine lower molar (macn A10908e: left ml) as lectotype. This tooth is low- er crowned than the other interatheriine teeth from the sample. The material supposedly pertaining to lEohyr- ax platyodus evidently represents a mixture of several individuals assignable to at least three dif- ferent taxa. Six teeth (macn A10908a-f) represent the syntypes of lEohyrax platyodus. Five of these are referable to the Interatheriinae and the sixth to the Archaeohyracidae. macn A10908a,b,c are tentatively referred to Santiagorothia chiliensis, and macn A10908d is referred to Archaehyraci- dae cf. Pseudhyrax. Interathere Phytogeny Apart from one numerical cladistic study based largely on dental characters (Cifelli, 1993), there has been little phylogenetic study of the Interath- eriidae. Cifelli identified rampant homoplasy in this group, the only resolved node in his study being a clade distinguishing the Interatheriinae (all hypsodont forms) from Notopithecus (a low- crowned Casamayoran taxon). As in previous studies (Cifelli, 1985a; MacFadden et al., 1985; Marshall et al., 1986), Cifelli (1993) suggested the probable existence (although not borne out by his analysis) of two monophyletic groups within the Interatheriinae: an Interatherium and allies clade and a Protypotherium and allies clade. Results from more recent phylogenetic analyses of inter- atheres (Hitz, 1994, 1995, 1997; Reguero et al., 1996) support the monophyly of the Interatheri- inae and suggest that "Notopithecinae" represents a paraphyletic assemblage (see the diagnosis of Santiagorothia chiliensis for a tentative list of in- teratheriine synapomorphies). In Hitz's analyses (1994, 1995, 1997) Santiagorothia chiliensis (re- ferred to in Hitz (1997) as Tinguiririca New Tax- on A) is placed as the nearest outgroup to all taxa previously included in the Interatheriinae (Fig. 1). Conclusions The taxa discussed above are derived from a very poorly known temporal interval in the South American mammalian fossil record. This interval (between the Mustersan and Deseadan SALMAs) spans a transition in South American mammal evolution between older faunas, with lineages generally characterized by primitive features, and younger faunas whose members display more pro- gressive attributes such as hypsodonty (Pascual et al., 1985). By far the best represented of the fau- nas treated here is the Tinguiririca Fauna from Chile, which contains a biostratigraphically novel assemblage of taxa including the first or last ap- pearances of at least seven subfamilial or higher taxa. The Patagonian faunules are less diverse but may well show a similar pattern when better known. The new interatheriines described here are exemplary in illustrating the transitional nature of these newly recognized post-Mustersan/pre-De- seadan-age faunal horizons; although they repre- sent the earliest known interatheriines, they are plesiomorphic in important features compared to later forms (e.g., in possessing cheek teeth with closed roots). The occurrence of Santiagorothia chiliensis in geographically disparate localities (central Chile 24 FIELDIANA: GEOLOGY and Patagonia) supports their temporal correlation and strengthens the case for recognition of a new land mammal age encompassing at least a portion of the post-Mustersan/pre-Deseadan hiatus within the South American land mammal sequence (Wyss et al., 1994; Flynn & Swisher, 1995). Acknowledgments The authors acknowledge the financial support of the National Science Foundation (DEB 9020213, 9318126, 9317943), the National Geo- graphic Society (3932-88), the Department of Geological Sciences, University of California, Santa Barbara (graduate student research grant), and the American Museum of Natural History (collections study grant). Our thanks also go to the Department of Geology, the Field Museum, for its support, and for the exceptional preparation work on the Tinguiririca fossils by Andrew Le- man, Bob Masek, Steve McCarroll, and Bill Simpson. We thank Richard Kay, Richard Mad- den, and Maria Guiomar Vucetich for valuable in- formation concerning the Rocas Bayas and Lomas Blancas localities and for permission to describe specimens from these localities (their field re- search was supported by the National Science Foundation). We thank Mariano Bond for his in- valuable help and expertise on notoungulates. We also thank Daniel Frassinetti and the President of the Museo Nacional de Historia Natural, Santiago, for their long-term cooperation and sponsorship of our work. We thank the many individuals, too numerous to mention here, who provided invaluable assis- tance in the field, both in Chile and in Argentina, without whom this work could not have been completed. Among them we make special men- tion of Gabriel Carassco, whose efforts and skill have greatly benefited our Andean project. We are grateful to our colleague Professor Reynaldo Charrier for his assistance in unraveling the myr- iad complexities of Andean stratigraphy and for unflagging enthusiasm for finding mammal bones in rocks that shouldn't contain them. Literature Cited Ameghino, F. 1901. Notices preliminaires sur les on- gules nouveaux des terraines cretaces de Patagonie. Boletfn de la Academia Nacional de Ciencias de Cor- doba (Buenos Aires), XVI: 2-80. . 1902. Notices preliminaires sur des mammifer- es nouveaux des terrains cretaces de Patagonie. Bol- etfn de la Academia Nacional de Ciencias de Cordoba & (Buenos Aires), XVII: 3-68. 1904. Nuevas especies de mamfferos, cretaceos y terciaros de la Rcpublica Argentina. Analcs de la Sociedad Cientifica Argcntino, 57: 162-175, 58: 35- 41, 56-71, 182-192, 225-290. . 1906. Les formations sedimentaires du Crdtace superieure et du Tertiaire de Patagonie avcc un par- allel entre leurs faunes et celles de l'ancien continent. Anales Museo Nacional, Buenos Aires, 15: 1-568. Bond, M. 1991. Sobre las capas de supuesta edad Div- isderense en los "Estratos de Salla," Bolivia, pp. 701- 705. In Suarez-Soruco, R., cd., F6siles y facies de Bolivia. Revista Tecnica de YPFB, Santa Cruz. Bond, M., A. A. Carlini, F J. Goin, L. Legarreta, E. Ortiz Jaureguizar, R. Pascual, and M. A. Uliana. 1995. 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