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AMERICAN MUSEUM Novitates PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY CENTRAL PARK WEST AT 79TH STREET, NEW YORK, N.Y. 10024 Number 3179, 14 pp., 8 figures, 2 tables August 23, 1996

Some Carnivorous Mammals from the Paleogene of the Eastern Gobi Desert, Mongolia, and the Application of Oligocene Carnivores to Stratigraphic Correlation1

DEMBERELYIN DASHZEVEG2

ABSTRACT A right mandible with P4-MI ofa new viverrid and Khoer Dzan localities (Ergilin Dzo Forma- (Carnivora) from the Alag Tsab, late Eocene ofthe tion, Ergilin Member, early Oligocene, Mongolia). eastern Gobi Desert is described. It represents a Biostratigraphic correlation is suggested for the new species, Stenoplesictis indigenus, belonging to Oligocene of Mongolia with similar deposits in a genus previously known only from the Oligocene western Europe based on fossil carnivorous mam- in western Europe. Another species, Stenoplesictis mal remains. The Ergilin Dzo and Khoer Dzan simplex, n. sp., is described from early Oligocene localities (Ergilin fauna) correlate with MP2 1 deposits in the eastern Gobi Desert (the locality (Soumailles) and the Ulaan Khongil and Schunkt of Ergilin Dzo). localities (Hsanda Gol fauna) fauna with MP22 A nimravid feliform, Nimravus mongoliensis (Villebramar) in western Europe. (Gromova, 1959) is described from Ergilin Dzo

INTRODUCTION Despite progress in the study ofMongolian description of Carnivora from the Hsanda Paleogene mammals, the Carnivora have not Gol Formation in the Valley ofthe Lakes was been studied adequately and few publications given by Matthew and Granger (1924). Gro- have focussed on this group. The first brief mova (1959) described Aelurogale (= Nim-

I This is contribution number 22 of the Mongolian Academy of Sciences-American Museum of Natural History Paleontological Project. 2 Geological Institute, Mongolian Academy of Sciences, Ulaanbaatar, Mongolia.

Copyright © American Museum of Natural History 1996 ISSN 0003-0082 / Price $2.00 2 AMERICAN MUSEUM NOVITATES NO. 3179 ravus) mongoliensis from the Khoer Dzan faunal localities, were reviewed by Russell locality in Mongolia. Yanovskaya (1970) and Zhai (1987). The localities containing the made a more precise characterization of Cy- fossil remains ofcarnivorous mammals listed nodictis (= Amphicynodon) from the Tatal below are described in Dashzeveg (1985, Gol locality on the basis of material found 1991, 1993). by the Mongolian Paleontological Expedi- ALAG TSAB: The remains of Stenoplesictis tion. Lange-Badre and Dashzeveg (1989) de- sp. were found in light-gray sand in the main scribed some ofthe Carnivora and Creodonta exposures of Alag Tsab, associated with discovered by the Polish-Mongolian Pale- Hyaenodon sp. and Ardynomys sp. This lo- ontological Expedition in 1964. cality is definitely older than the lower beds In September of 1989, a paleontological of the Ergilin Dzo Formation as exposed at field party organized by the Geological In- the classical localities at Ergilin Dzo and stitute ofthe Mongolian Academy ofScience Khoer Dzan. A late Eocene age is accepted collected remains of Oligocene mammals at for the Alag Tsab locality from a sequence the Ergilin Dzo and Khoer Dzan localities of that correlates with the Ula Usu locality the eastern Gobi Desert. Within the sample (Shara Murun Formation) ofnorthern China ofmammals recovered were a few specimens (Dashzeveg, 1985, 1991). of Carnivora, some of which are described ERGILrN Dzo: Fossils here were discovered below. in two exposures: (a) Ergil Obo. Stenoplesictis elegans was Abbreviations found in 1990 in yellow sands of the Ergilin AMNH American Museum of Natural History Member, containing remains of Hypsamy- CAE Central Asiatic Expedition ofthe Amer- nodon cessator. ican Museum of Natural History (b) Bayan Tsab. Nimravus mongoliensis is MNHN Museum National d'Histoire Naturelle, known from this exposure. Ronzotherium ori- Institut de Paleontologie, Paris entalis, Cadurcodon, and Bothriodon were MPE Mongolian Paleontological Expedition, also discovered in the Ergilin Member grav- 1946-1949, Academy of Science of the USSR els from the Bayan Tsab exposure (Dashzev- PIN Paleontological Institute, USSR Acad- eg, 1991). emy of Science, Moscow KHOER DzAN: Fragments of Nimravus PMPE Polish-Mongolian Expedition, Acade- mongoliensis were found in the Ergilin Mem- my of Sciences of the USSR and Mon- ber gravels from the western slopes of Khoer golian Academy of Sciences Dzan. The specimen of Nimravus mongo- PSS Paleontology and Stratigraphy Section liensis described by Gromova (1959) most of Geological Institute, Mongolian likely came from these gravels. Academy of Sciences, Ulaanbaatar The boundary between the Eocene and Oli- gocene in the section ofErgilin Dzo and Khoer MATERIALS AND METHODS Dzan ofthe eastern Gobi Desert is below the The material described here was compared Ergilin Member, where early Oligocene gen- with material housed in the collections ofthe era of mammals are first observed. The re- American Museum of Natural History and lationship ofthis boundary to intercontinen- the National Museum of Natural History, tal faunal correlations and the Eocene/Oli- Paris. Dental measurements were made with gocene boundary in Europe and North Amer- needle-point dial calipers to the nearest 0.1 ica is extensively discussed in Dashzeveg mm. Tooth nomenclature follows Maclntyre (1991), Dashzeveg and Devyatkin (1986), and Dashzeveg and Russell (1992). See also dis- (1966). cussion below. ULAAN KHONGIL (= Tatal Gol): Two fau- LOCALITIE$ AND GEOLOGICAL nal assemblages of different ages can be dis- SETTING tinguished in this locality: (fig. 1) (a) Older assemblages with a large number The Mongolian Paleogene deposits, partic- ofrodents, including Cricetops dormitor, Se- ularly the Eocene and Oligocene terrestrial lenomys mimicus, and others, from lenses of 1 996 DASHZEVEG: CARNIVOROUS MAMMALS FROM GOBI DESERT 3

mmmmopomq 0 m Amphicynodon teilhardi /Palaeoprionodon gracilis I Shand 0I 2 - Stenoplesictis elegans, Palaeogale parvula L- I Mbr I Stenogale n. sp. 0 - *4 4fi 31 32 106 M.Y. 0 ILU Amphicynodon teilhardi z cn Tatal 00-Palaeoprionodon gracilis Iu-i Mbr Stenoplesictis elegans I IU Palaeogale ulysses, Palaeogale parvula I0 Stenogale n. sp., Nimravus sp. I Khetsu Tsab Mbr

I0 - Ergilin .I- Stenoplesictis simplex Mbr I L.: Nimravus mongoliensis

I Shavag < -cI Mbr Sevkhul

LLJI Mbr

z Zangut Mbr ui 0 L Khubsugul Mbr

*-I-- Stenoplesictis indigenus Alag Tsab

- _ 0m Fig. 1. Generalized scheme of stratigraphy of upper Eocene and lower Oligocene beds of Mongolia containing fossil carnivorous mammal remains. (1) Ulaan Khongil and (2) Schunkt localities. light-brown sands and gravels in brown mud- dens from the Shand Member of the Hsanda stone ofthe Tatal Member ofthe Hsanda Gol Gol Formation (McKenna et al., MS). Formation. In 1989-1990, Dashzeveg collected re- (b) A younger assemblage with Tachy- mains of Palaeoprionodon gracilis, Steno- oryctoides obrutschewi and Tataromys prici- plesictis elegans, Amphicynodon teilhardi, and 4 AMERICAN MUSEUM NOVITATES NO. 3179

SCHUNKT: The remains ofPalaeogale, Pa- leopriondon, Amphicynodon, and Stenople- sictis were found in the brown gravels in the sections of the Schunkt locality. Moreover, the rodents Tatatomys plicidens and Tachy- oryctoides obrutschewi were obtained here. The fauna is analogous to that known from the Shand Member at the classic locality of Ulaan Khongil of the Valley of Lakes. The presence of Tatatomys plicidens and Tachy- oryctoides obrutschewi makes it possible to assign the brown gravels of Schunkt locality to the Shand Member (Hsanda Gol Forma- tion) of the early Oligocene of Mongolia. Therefore, the abovementioned genera of Carnivora are contemporary with the Hsan- da Gol Formation of the early Oligocene.

SYSTEMATICS ORDER CARNIVORA INFRAORDER FELIFORMIA KRETZOI, 1945 SUPERFAMILY FELOIDEA SIMPSON, 1931 FAMILY VIVERRIDAE GRAY, 1821 SUBFAMILY STENOPLESICTINAE SCHLOSSER, 1923 Stenoplesictis Filhol, 1880 Stenoplesictis indigenus, new species (Figure 2, table 1) Fig. 2. Stenoplesictis indigenus, n. sp. Frag- ment of right lower jaw with p4-m 1, PSS no. 40- HOLOTYPE: PSS, no. 15. A, Occlusal view; B, labial view; C, lingual 40/15, a fragment of view. the right lowerjaw with p4-m 1; eastern Gobi Desert, Alag Tsab locality (Dashzeveg, 1985). REFERRED MATERIAL: None. AGE: late Eocene. ETYMoLOGY: indigenus, from the Latin term for local. DIAGNOsIs: Stenoplesictis indigenus differs Paleogale sp. in the gravels ofthe Tatal Mem- from European Stenoplesictis cayluxi and S. ber from the main exposures of the Ulaan minor (Teilhard de Chardin, 1915) in having Khongil locality. Specimens of Nimravus sp. a more obtuse angle between the protoconid described by Toohey (1959) apparently came and paraconid on ml and differs from the from the lower bone-bearing level of this lo- Asian species, S. elegans (Matthew and cality (Mellett, 1968). Granger, 1924), in being slightly smaller and A basalt dividing the Shand Member from in having a larger talonid on ml. the Tatal Member of the Hsanda Gol For- DEscRIPTION: The last premolar is simple mation (fig. 1) has a K-Ar date of 31.2-32.7 and symmetrical, and the anterior accessory Ma (Evernden et al., 1964; Mellett, 1968). cusp is small and low. The posterior acces- 1 996 DASHZEVEG: CARNIVOROUS MAMMALS FROM GOBI DESERT 5 sory cusp is positioned comparatively high TABLE 1 on the buccal flank of the main cusp, from Measurements of Lower Cheek Teeth and which it is separated by a short but distinct Mandibles of Stenoplesictis simplex and notch. The talonid is massive and low. Stenoplesictis indigenus ml has a high protoconid and lower para- S. conid. The metaconid is well expressed, but S. simplex indigenus smaller than the paraconid. The talonid is no. 27-25 no. 40-75 narrower than the trigonid and the hypoconid p4 Length 8.0 6.7 is the largest talonid cusp. m2 is not pre- Width 3.2 2.4 served but, judging from the alveoli, it was ml Length 10.0 8.4 two-rooted. Width 4.5 4.4 DISCUSSION: The Stenoplesictinae are as- m2 Length 4.0 4.0 signed to Viverridae here, acknowledging Width 3.0 2.8 some of the uncertainties of relationships Height of ramus below p3 13.0 among early aeluroid Carnivora. In a detailed Height of ramus below ml 13.4 9.4 analysis, Hunt (1989) favored a closer affinity Width of ramus below p2 5.0 between stenoplesictines and living viverrids Width of ramus below ml 5.6 4.4 than between this subfamily and felids. The reference of this jaw to Stenoplesictis is in- dicated by the high piercing protoconid on DEscRIPTIoN: The mandible is thin; the ml, the high ratio oftrigonid width to talonid lower edge ofthe mandibular corpus is prom- width, and the absence of m3. The dentition inent under ml -2. The masseteric fossa is shows a structure correlated with an empha- well developed. p4 is asymmetrical with the sis on shearing, or "hypercarnivory," origi- posterior cutting edge sloping more gently nally ascribed to Stenoplesictis and other than the anterior. The first molar is very elon- stenoplesictines by Teilhard (1915). Steno- gated (width/length = 0.45). The shearing plesictis indigenus is older than all the other edges of the paraconid and protoconid form known species of Stenoplesictis and it is suf- an obtuse angle, open inside. The metaconid ficiently generalized morphologically to be a is well developed, separated from the pro- plausible common ancestor of European and toconid, and is situated against the posterior Mongolian forms. internal side ofthe latter. There is a cingulum on the external side at the base of the crown. Stenoplesictis simplex, new species The talonid is ¼ the length ofthe ml and the (Figures 3, 4; hypoconid is well developed. The m2 has two table 1) roots and is bunodont; the paraconid, pro- HOLOTYPE: PSS, no. 27-25, a fragment of toconid, and metaconid are of almost equal the right lowerjaw with p4-m2; eastern Gobi size. Desert, Ergilin Dzo, Ergil Obo locality. DISCUSSION: The new species, Stenople- REFERRED MATERIAL: None. sictis simplex, is easily distinguished from AGE: early Oligocene: Ergilin Dzo For- most species of the genus by its larger size mation, Ergilin Member. and the more robust talonid on m 1. The fact ETYMOLOGY: simplex, from the Latin term that S. simplex and S. indigenus are only rep- for simple, dull. resented by holotypes reflects a need for con- DiAGNosIs: Slightly larger than S. cayluxi tinued sampling at the eastern Gobi localities and considerably larger (about 45-50%) than of Alag Tsab and Ergilin Dzo. S. minor. Differs from the two western Eu- ropean species in having more developed metaconids on ml and a more elongated m2. Stenoplesictis elegans Differs from the Mongolian S. elegans and (Matthew and Granger, 1924) S. indigenus in being 40% larger in linear Cynodictis elegans Matthew and Granger, 1924. dimension and having a more massive tal- Cynodictis elegans Mellett, 1968. onid on ml. Viverravus constans Matthew and Granger, 1924. 6 AMERICAN MUSEUM NOVITATES NO. 3179

Fig. 3. Stenoplesictis simplex, n. sp. Fragment of right lower jaw with p4-m2, PSS no. 27-25. A, Occlusal view: B, labial view; C, lingual view.

REMARKs: Matthew and Granger (1924) nior synonym of Amphicynodon teilhardi provided the first description of two carniv- (Lange-Badre and Dashzeveg, 1989). orans, Cynodictis elegans and Viverravus The specimens from the Oligocene of Er- constans, from the Oligocene Hsanda Gol gilin Dzo and Ulaan Khongil localities, Mon- Formation, Mongolia. Later, Mellett (1968) golia, differ from the typical forms of-Cyn- synonymized V. constans with C. elegans. odictis in the absence ofm3. The presence or Yanovskaya (1970) described Cynodictis absence of m3 is a diagnostic indicator of mongoliensis from the Ulaan Khongil (= Ta- phylogenetic divergence in the order Carniv- tal Gol) locality. There are no significant ora, and in this case it serves to distinguish morphological differences between C. mon- Stenoplesictis from typical Cynodictis. The goliensis and Amphicynodon teilhardi Mat- high, piercing trigonid and emphasis of pre- thew and Granger from Hsanda Gol. Con- vallid shear on ml, the presence of both a sequently, Cynodictis mongoliensis is a ju- well-developed trigonid and narrow tren- 1 996 DASHZEVEG: CARNIVOROUS MAMMALS FROM GOBI DESERT 7

_ _ | L 9:-~7..9~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fig. 4. Stenoplesictis simplex, n. sp. Fragment of right lower jaw with p4-m2, PSS no. 27-25. A, Occlusal view; B, labial view; C, lingual view. chant heel on the much smaller m2, and the 21-34, a fragment of left lower jaw with p4- absence ofm3 support the assignment of Cy- ml (lacking the protoconid); Khoer Dzan, nodictis elegans to the genus Stenoplesictis. PSS, no. 27-81, a fragment of left lower jaw The latter is well known from the Oligocene with alveoli of p4-m2. of western Europe (Teilhard, 1915). AGE: early Oligocene, Ergilin Dzo For- mation, Ergilin Member. DIAGNOSIS: Differs from western European FAMILY NIMRAVIDAE TROUESSART, N. intermedius and North American N. 1885 brachyops in being slightly smaller and in Nimravus Cope, 1879 having a short diastema between the c and Nimravus mongoliensis (Gromova, 1959) p1, and by the presence of p1 and a well- (Figures 5, 6, 7; table 2) developed m2. The latter is usually reduced Aelurogale mongoliensis Gromova, 1959: 65, fig. 1. in the other species. DESCRIPTION: Medium-sized compared HOLOTYPE: PIN, no. 1379-7, a fragment of with the abovementioned species, length of the left lower jaw with p2-m2; Khoer Dzan ml 18 mm. Massive mandibular corpus; its locality, eastern Gobi Desert. ventral edge is convex under p4 and m 1. The REFERRED MATERLAL: Ergilin Dzo, PSS, no. anterior mental foramen is 12 mm below p1 8 AMERICAN MUSEUM NOVITATES NO. 3179

Fig. 5. Nimravus mongoliensis (Gromova, 1959). Fragment of left lower jaw with p4-m1, PSS no. 27-34. A, Occlusal view; B, labial view; C, lingual view. and the posterior one is 11 mm behind the paraconid and protoconid form an obtuse an- former. The diastema between c and p1 is 4 gle. The talonid of ml is trenchant, with a mm, between pl and p2 is 2 mm, and be- well-developed hypoconid. Because the tooth tween p2 and p3 is 3.5 mm. There are alveoli is broken, it is impossible to discern the pres- for il and i2, which indicates that il was ence of a metaconid. Gromova (1959) noted slightly larger than i2. The canine root is large the presence of the rudimentary metaconid and oval in cross section. p1 is small and with on ml in the holotype (PIN no. 1379-9) from one root, p2 has two roots, and p3 is much Khoer Dzan. larger than p2. The last premolar is massive, REMARKS: Toohey (1959) gave the first de- and the anterior and posterior slopes of the scription of Nimravus sp. from the material main cusp form shearing surfaces. The main ofthe Central Asiatic Expeditions (CAE) from cusp is almost symmetrical and the anterior the Oligocene of Hsanda Gol, Mongolia. In and posterior accessory cusps are well de- the absence of an illustration, one cannot veloped. The first lower molar is large; its judge its relationship with N. mongoliensis. length is 2.5 times its width. The tips of the Assignment of N. mongoliensis to Nimravus 1 996 DASHZEVEG: CARNIVOROUS MAMMALS FROM GOBI DESERT 9 A

B 3cm

Fig. 6. Nimravus mongoliensis (Gromova, 1959). Fragment of left lower jaw with p4-mi, PSS no. 27-34. A, occlusal view; B, labial view. is supported by its possession of a very deep mandible (which is particularly robust under TABLE 2 p4-mi), a high-crowned p3, a massive shear- Measurements of Lower Teeth and Mandibles of ing p4, the obtuse angle between the para- Nimravus mongoliensis conid and protoconid of the large ml, the absence or only rudimentary development of No. No. No. 1379-7 21-34 27-81 the metaconid on m 1, and the very trenchant talonid with a well-developed hypoconid on c length 12.0 12.0 ml (see diagnosis of Nimravus in Toohey, width 6.5 6.2 1959). p1 length 5.5* 3.5* width 2.5 2.8 p2 length 6.7* 5.2* BIOSTRATIGRAPHY AND width 3.5 3.2 CORRELATION p3 length 12.5* 12.0 The Oligocene fauna of Eurasia is domi- width 5.7 5.2 nated by camivorans ofthe family Viverridae 4 length 14.2 13.2 14.8a (Palaeoprionodon and Stenoplesictis), Nim- width 5.1 5.6 6.8 ml length 18.2 18.4 22.2a ravidae (Nimravus), Ursidae (Amphicyno- width 7.2 7.0 8.2 don), and "Mustelidae" (Palaeogale), in m2 length 4.3 4.5 3.6a addition to the rhinos (Ronzotherium and width 2.3 3.0 2.8 Tenisia), entelodonts (Entelodon), and an- Diastema between c and p1 60.5 4.2 thracotheres (Bothriodon). Among small Height of mandibular ramus mammals, rodents have biostratigraphic sig- at level p2 and p3 5.2 26.0 nificance, but they have not been adequately Height of mandibular ramus studied. Their endemic character in the Oli- below ml 25.0 25.0 22.0 gocene of Asia is likely to limit their use in Width of mandibular ramus intercontinental correlations. below ml 12.0 12.0 12.0 The following taxa are important for def- a By alveoli. to AMERICAN MUSEUM NOVITATES NO. 3179 A

3 cm Fig. 7. Nimravus mongoliensis (Gromova, 1959). Fragment ofleft lower jaw with p2-m2, (holotype, PIN no. 1379-7). A, Occlusal view; B, labial view. inition of the early Oligocene in Mongolia their intensive dispersal in the early Oligo- and China: Nimravus, Stenoplesictis, Ron- cene across the former water barrier allows zotherium, Entelodon, and Bothriodon. biostratigraphic correlation between the con- Widely distributed in Central Asia, they char- tinents. acterize a rather short stratigraphic interval. The early Oligocene mammalian standard These factors allow them to be used in cor- level for the Paris Basin is based on the faunal relations. assemblage at the classic locality of Ronzon. According to Darlington (1957), dominant Its age equivalents are well documented by animal groups have a large areal extent and early immigrants after the "Grande Cou- an abundance of certain species. These oc- pure." Of these, the most common are the cupy new territory, and also fragment into Asiatic genera Eucricetodon, Stenojiber, En- subordinate taxonomic groups across their telodon, and Bothriodon, which first appeared large zoogeographic range. in Europe in lower Oligocene (Russell et al., A biostratigraphic scheme for the Oligo- 1982; Brunet and Vianey-Liaud, 1987). cene continental deposits ofCentral Asia can Elsewhere, the author made an attempt to be proposed with reference to the western relate the Ergilin fauna of Mongolia to the European Oligocene (fig. 8). The Paleogene referred Oligocene standard levels of Europe terrestrial biostratigraphy of western Europe (Dashzeveg, 1991). It is notable that Ente- provides a succession of key horizons deter- lodon orientalis from the Ergilin Member at mined by different mammalian groups (Bru- the Khoer Dzan and Ergilin Dzo localities is net, 1979; Brunet and Vianey-Liaud, 1987; very similar to E. magnum from the standard Cirot and de Bonis, 1992; Russell et al., 1982). level of Ronzon in western Europe. Bothrio- During the Eocene, the Asian and Euro- don from the same beds of the Ergilin Dzo pean land areas were separated from each Formation resembles B. velaunus from Ron- other by a water gap at Turgai Straits. In- zon. Co-occurrence of Nimravus mongolien- dependent evolution of terrestrial mammals sis and Stenoplesictis elegans with Ronzo- in the two areas precludes direct correlation therium orientalis in the Ergilin Dzo and of the Asian Eocene with that of Europe. Khoer Dzan localities of Mongolia allows us However, rapid evolution of mammals and to confidently assign the Ergilin Member to 1 996 DASHZEVEG: CARNIVOROUS MAMMALS FROM GOBI DESERT I1I

Fig. 8. Correlation of Oligocene deposits in central Asia (Mongolia) and western Europe (France) based on fossil occurrences of carnivorous mammals. the base of the lower Oligocene and to cor- overall comparisons of the faunas (see be- relate the Ergilin fauna to the reference level low). MP21 (Soumailles) of western Europe Palaeogale sectoria is considered a char- (Schmidt-Kittler, 1987). acteristic species ofthe Oligocene deposits of The Asian carnivores, Nimravus mongo- western Europe. The oldest occurrences of liensis, Stenoplesictis simplex, and Palaeo- Palaeogale sectoria are from two localities in prionodon gracilis, are more primitive ana- the Phosphorites of Quercy, La Plante and tomically than closely related western Euro- Mas de Got, in France (Remy et al., 1987; pean forms from reference level MP23 (Itar- Lange-Badreand Dashzeveg, 1989). Accord- dies). This is consistent with an age earlier ing to the latest mammalian biozonation of than MP23 for the Mongolian faunas. the western European Paleogene, these lo- DeBonis (1981) has identified Palaeogale calities correspond to the second half of the parvulus and P. ulysses from Mongolia and early Oligocene (MP22, the Villebramar lev- P. sectoria Gervais from the Oligocene de- el). The upper limit ofthe stratigraphic range posits of western Europe. This identification ofP. sectoria coincides with zone MP24. Thus was supported by Lang-Badre and Dashzeveg the vertical range ofP. sectoria is rather broad (1989). However, the previous study showed in western Europe (Brunet and Vianey-Liaud, the primitive morphology (smaller size and 1987; Remy et al., 1987). Presumably, these larger m2) of the Mongolian P. parvulus and carnivorans migrated from Asia to western P. ulysses when compared with the European Europe in the early Oligocene. In Europe the P. sectoria. This comparison would suggest a migrants then evolved rapidly, showing a slightly older age for the Hsanda Gol assem- great diversity of form. blage than MP 22-24 ofwestern Europe, but It is important to note that most of the this conclusion must be assessed in light of specimens ofPalaeogale parvulus, P. ulysses, 12 AMERICAN MUSEUM NOVITATES NO. 3179

Palaeoprionodon gracilis, and Stenoplesictis the enormous intracontinental basin of Par- elegans are restricted to the Tatal Member, atethys. Tectonic transformations that oc- beneath the basalt flow in the Ulaan Khongil curred in the Alpine geosyncline have pro- sections. moted redistribution of land and sea masses Thus, the Tatal and Shand members ofthe as well as regional paleogeographic changes. Hsanda Gol Formation are younger than the So, the continental massif of the Alpine Ronzon standard level and older than the orogenic belt may serve as a bridge for early Itardies level (MP 23) of western Europe. Oligocene mammalian migrations from Asia These Asian deposits occupy an intermediate into western Europe (Heissig, 1979). The fau- position between these standard levels. nal migration seems to have gone through Judged by their stage of evolution, Amphi- the Turgai trough, South Urals, Caucasus, and cynodon teilhardi and Stenoplesictis elegans the Transylvanian belt. After reaching west- can be assigned to an interval equivalent to ern Europe, these immigrant mammalian taxa the Villebramar standard level in western flourished and diversified. rope, even though these species are not pres- ent in western Europe. According to the des- CONCLUSIONS ignation, the Eocene/Oligocene boundary proposed by Swisher and Prothero (1990), 1. Two species of Carnivora (Feloidea)- the radiometric age of the basalt of the lava Stenoplesictis simplex, n. sp., and Nimravus separating the Tatal Member from the Shand mongoliensis Gromova, 1959)-from the Member ofthe Hsanda Gol Formation would early Oligocene of the eastern Gobi Desert, be early Oligocene. Mongolia have important biostratigraphic On the basis of key genera of Carnivora, significance. the Hsanda Gol fauna (Ulaan Khongil and 2. Stenoplesictis indigenus, n. sp., is estab- Schunkt localities) is correlated with the Eu- lished for the first time in the Late Eocene of ropean Paleogene mammalian reference level Alag Tsab, Mongolia. It is the oldest occur- (niveaux-reperes) of Villebramar (MP22) in rence ofthe genus, suggesting a possible Asian the standard western European Oligocene se- origin. quence (see Schmidt-Kittler, 1987, for defi- 3. The Ergilin fauna from the Ergilin Dzo nition). Consequently, the Hsanda Gol For- and Khoer Dzan localities, eastern Gobi Des- mation, regarded as entirely middle Oligo- ert, is correlated with the standard level MP2 1 cene by Mellett (1968), Savage and Russell (Soumailles) and the Ulaan Khongil fauna (1983), and Russell and Zhai (1987), should from the Valley ofLakes to the standard level instead be dated as ranging from latest early MP22 (Villebramar) of western Europe. The to earliest middle Oligocene according to the Ergilin fauna is placed in the first part of the tripartite division ofthis epoch as defined on early Oligocene and the Ulaan Khongil fauna mammal faunas by Savage and Russell (1983). in the last part of the early Oligocene. This would place it entirely within the early Oligocene of most marine workers, who rec- ACKNOWLEDGMENTS ognize a bipartite division of the epoch. I have profited from many discussions with The Carnivora discussed herein can be Dr. Richard Tedford. I am grateful to him considered to have migrated into western Eu- for reading the manuscript and offering help- rope from Asia in early Oligocene. Significant ful suggestions. I thank also Dr. David Polly tectonic events occurred near the Eocene/Oli- for reviewing the manuscript and correcting gocene boundary, destroying connections be- the English. Dr. D. E. Russell kindly per- tween central Asian epicontinental seas and mitted access to specimens under his care. the Tethys. This resulted in compression of The figures are by Lorraine Meeker, and the the western European basin and formation of manuscript was typed by Suzi Zetkus. 1996 DASHZEVEG: CARNIVOROUS MAMMALS FROM GOBI DESERT 13

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