The Late Paleocene Gashato Fauna, Mongolia

Home , Catopsalis, Cimolomyidae, Deltatheridium, Dinocerata, Djadochta Formation, Ptolemaia

BEGINNING OF THE AGE OF MAMMALS IN ASIA: THE LATE PALEOCENE .~ GASHATO~ 1 FAUNA,F. l MONGOLIA

FREDERICK S..SZALAY AND MALCOLM C. MCKENNA

BULLETIN OF THE AMERICAN MUSEUM. OF NATURAL HISTORY VOLUME 144 : ARTICLE 4 -N.NEW YYORK:: 1971

BEGINNING OF THE AGE OF MAMMALS IN ASIA: THE LATE PALEOCENE GASHATO FAUNA, MONGOLIA

FREDERICK S. SZALAY Research Associate, Department of Vertebrate Paleontology The American Museum ofNatural History Assistant Professor, Department of Anthropology Hunter College, City University of New rork

MALCOLM C. MCKENNA Frick Curator, Department of Vertebrate Paleontology The American Museum ofNatural History

PUBLICATIONS OF THE ASIATIC EXPEDITIONS OF THE AMERICAN MUSEUM OF NATURAL HISTORY CONTRIBUTION NUMBER 164

BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY VOLUME 144: ARTICLE 4 NEW YORK : 1971 BULLETIN OF THE AMERICAN MUSEUM OF NATURAL HISTORY Volume 144, article 4, pages 269-318, figures 1-35, tables 1-3

IssuedJune 18, 1971

Price: $2.00 a copy

Printed in Great Britain by Lund Humphries CONTENTS

INTRODUCTION ...... 273 Acknowledgments ...... 273 THE GASHATO FAUNA ...... 274 Extension of the Gashato Fauna to the Nemegt Valley Sites ...... 276 Other Asian Paleocene Mammal Sites ...... 277 The Age of the Gashato Fauna ...... 277 Comments on Correlative Value of Gashato and Nemegt Mammals ...... 278 Sparnacian Faunal Replacement ...... 280 PALEOGENE NORTHERN DISPERSAL ROUTES AND THE GEOLOGICAL EVIDENCE ...... 282 SYSTEMATICS ...... 286 Order Insectivora ...... 286 Superfamily Palaeoryctoidea ...... 286 Family Deltatheridiidae Gregory and Simpson, 1926 ...... 286 Sarcodon Matthew and Granger, 1925 ...... 286 Sarcodon pygmaeus Matthew and Granger, 1925 ...... 288 Hyracolestes Matthew and Granger, 1925 ...... 293 Hyracolestes ermineus Matthew and Granger, 1925 ...... 294 Anagalida, New Order ...... 301 Family Zalambdalestidae Gregory and Simpson, 1926 ...... 301 Praolestes Matthew, Granger, and Simpson, 1929 ...... 301 Praolestes nanus Matthew, Granger, and Simpson, 1929 ...... 302 Family Anagalidae Simpson, 1931 ...... 305 Khashanagale, New Genus ...... 305 Khashanagale zofiae, New Species ...... 310 ?Khashanagale, New Unnamed Species ...... 311 Order Condylarthra ...... 312 Superfamily Mesonychoidea ...... 312 Family Mesonychidae Cope, 1875 ...... 312 Subfamily Mesonychinae Cope, 1875 ...... 312 ?Dissacus sp...... 312 Order Dinocerata ...... 312 Family Uintatheriidae Flower, 1876 ...... 312 Subfamily Prodinoceratinae, Flerov, 1952b, New Rank ...... 312 SUMMARY ...... 313

REFERENCES ...... 314

271

INTRODUCTION FOSSIL MAMMALS FROM THE CRETACEOUS and The original draft of the systematics section of early Tertiary ofthe Mongolian People's Repub- this paper was prepared by Szalay. The other sec- lic have long fascinated students of mammalian tions were prepared by McKenna. Both authors phylogeny and paleogeography, partly because have modified each other's texts extensively, and of the strangeness of certain forms and partly the responsibility for the final draft is shared. because of the unexpected occurrence in Mon- golia of families and genera known from other ACKNOWLEDGMENTS continents. These Cretaceous and early Tertiary We thank the late Y. A. Orlov of the Soviet Mongolian mammals were discovered mainly by Academy of Sciences, Moscow; K. K. Flerov, the Central Asiatic Expeditions of the 1920's, Director of the Paleontological Museum, Pale- but since World War II expeditions from the ontological Institute, Moscow; Z. Kielan- Academies of Sciences of the Union of Soviet Jaworowska, Director of the Paleozoological Socialist Republics and Poland have visited Division of the Polish Academy of Sciences, Mongolia, participating in joint paleontological Warsaw; K. Kowalski, Director of the Natural expeditions with the Mongolian Academy of History Museum, Cracow, Poland; R. E. Sloan, Science, and Mongolian scientists themselves University of Minnesota, and J. S. Mellett, New have begun paleontological work. As a result, York University, for their many courtesies and important new collections from both new areas for stimulating discussions. The Foreign Ex- and old are now available for study. Meanwhile, change Program of the National Academy of the value of the original collections has been Sciences made possible an inter-academy ex- increased by the additional preparation of rare change which permitted McKenna to work in and delicate specimens and by the study of Moscow for one month during April, 1965. previously unreported fossils long dormant in Research was partly supported by National the collections. The series of short descriptive Science Foundation Grant GB 7418 to Szalay. papers published by the American Museum of The photographic illustrations were prepared by Natural History in the 1920's and 1930's was S. Gustav. The map was adapted by R. Gooris never completed, nor was there a comprehensive from cartography made available by the Mon- review of all Mongolian fossil mammals or even golia Society, and the drawings were skillfully of individual faunas. That work was postponed executed by B. Akerbergs and H. Hamman because of the deaths of Matthew, Osborn, and (fig. 27). Granger; lack of funds; World War II; and R. H. Tedford, M. K. Hecht, M. Talwani, competing research programs. Within the last M. 0. Woodburne, D. E. Savage, D. E. Russell, two decades, however, there has been a revival R. G. Zweifel, P. V. Rich, T. H. Rich, and of interest in late Mesozoic and early Tertiary W. C. Pitman, III, offered suggestions helpful in mammals, and as the result of numerous new improving the manuscript. discoveries and interpretations it has become imperative to study anew the collections made in Mongolia by the Central Asiatic Expeditions. The following abbreviation is used to desig- The present paper, therefore, attempts to bring nate an institutional collection: into sharper focus the perplexing late Paleocene A.M.N.H., the American Museum ofNatural History, mammals of Southern Mongolia (fig. 1). Department of Vertebrate Paleontology

273 THE GASHATO FAUNA

THE EARLIEST TERTIARY vertebrate fauna dis- multituberculates and therefore indicative of covered in Asia was found in the GashatoForma- Paleocene or Cretaceous age. Synonymy of the tion of southern Mongolia by F. K. Morris in lagomorph-like genus Baenomys with Eurymylus 1923 while he was studying the stratigraphy of was not yet discovered, and only the lower jaw sediments overlying the Djadochta Formation. ("Baenomys") was believed to have lagomorph The latter formation is a Cretaceous unit famous affinities. The type maxilla of Eurymylus laticeps for its excellently preserved dinosaurs, dinosaur was compared favorably with Eocene tarsioids eggs, and fossil mammal skulls. A preliminary and plesiadapids, but was referred to the Meno- paper on the Gashato fauna by Matthew and typhla because ofthe complexity ofthe premolar Granger was published in 1925, but while that pattern. Phenacolophus was compared with vari- paper was in press a second Gashato collection ous ungulates, but no detailed comparisons with was made by the 1925 Central Asiatic Expedi- Pantodonta or Dinocerata were made. Hyra- tion. This permitted additional work on the colestes and Sarcodon were described in the same Gashato fauna and modified the conclusions paper, but Matthew and Granger's discussion of reached in the first paper. It is of interest to them was of necessity rather inconclusive. follow the development of our knowledge of the Several years later Matthew, Granger, and Gashato fauna and its significance. Simpson (1928), on the basis of the 1925 collec- In their first paper Matthew and Granger tion, described the upper and lower molars of were rather cautious about both the affinities and the multituberculate Prionessus, confirming its the age of the Gashato fauna. The notoungulate similarity to the American Catopsalis and Taenio- Palaeostylops was known from one species stated labis. They also described a new multitubercu- to be ancestral to the American "Wasatch" late genus and species, Sphenopsalis nobilis, which genus Arctostylops and therefore believed to be they regarded as a somewhat divergent taenio- indicative of Paleocene age.' The taeniolabidid labidid and which now is regarded as a cimolo- multituberculate Prionessus lucifer was discussed myid (Van Valen and Sloan, 1966). as a possible ancestral form for the taeniolabidid The bulk of the 1925 Gashato collection was 1The Rio Chico fauna of Patagonia was not yet known discussed by Matthew, Granger, and Simpson in in 1925. Matthew and Granger (1925) and Matthew 1929. An additional species of Palaeostylops (P. (1928) believed that the presence of a notoungulate at new Gashato confirmed the theory that the South American macrodon) and four genera and species of Tertiary hoofed mammals were derived from the north. other mammals were named. The synonymy of Patterson (1958, p. 12) and Patterson and Pascual (1968, "Baenomys" with Eurynylus was recognized and p. 418) still accept a non-South American origin for noto- the distinctiveness of Eurymylus was emphasized ungulates as such. Although this contention is logical and may be supported by other evidence, the molars of Palaeo- by the creation of a monotypic family. The stylops are more advanced than any in the earliest South exact taxonomic position of the Eurymylidae American notoungulates and probably indicate dispersal in was not fully determined, however, and several the opposite direction after the origin of notoungulates in arguments against lagomorph affinities were South America from condylarth stock of northern derivation. There is no physical evidence as yet that noto- briefly reviewed. ungulates were present prior to the late Paleocene on any The four new genera named in 1929 were continent, but the probability is far greater for South Praolestes, Pseudictops, Opisthopsalis, and Prodino- America where early and medial Paleocene deposits have ceras. Praolestes was based on a tiny lower jaw yielded no mammal remains whatever than for North with three teeth mistakenly to be America. There is evidence, however, that notoungulates thought did not continue to flourish for very long after their initial P4-M2 but actually P3-M1. Pseudictops was appearances in North American and Asian Paleocene based upon two specimens, the type consisting deposits. In North America this might be attributed to ofa lowerjaw with P3-M3, and a maxillary frag- swamping by the Sparnacian faunal overturn. In Asia, ment with two teeth.2 Both Pseudictops and however, many of the older endemics lingered, long past that time, yet notoungulates apparently did not. We regard 2Several additional American Museum specimens of notoungulates as unsuccessful Paleocene immigrants to Pseudictops from Gashato have been identified recently in Asia, not as ancient and ecologically entrenched inhabit- the course of additional preparation of the original ants of either Asia or North America. collection. 274 7O

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a; 0 276 BULLETIN AMERICAN MUS5EUJM OF NATURAL HISTORY VOL. 144 Praolestes were placed in the Insectivora, sensu evidence of late Paleocene age of the Gashato lato, but with doubt. Opisthopsalis was referred to fauna, bolstering the conclusions reached on the the Hyaenodontidae with a query, mainly on the basis of comparison of Palaeostylops to the Amer- basis of resemblance to Sinopa (except P4). In ican earliest Eocene genus Arctostylops.l contrast to the previously discussed genera, the Continued research on New World Paleocene known remains of Prodinoceras proved to be faunas has resulted in various minor advances in similar, although differences were noted, to our understanding of the Asiatic Gashato fauna, those of an American genus of primitive uinta- notably as the result of discovery of late Paleo- theres, Probathyopsis, at that time the earliest cene faunas at Rlo Chico in Patagonia and known uintathere. The angle of implantation Itaborai, Brazil, and of uintatheres such as and less distinct metacone of p2, complete molar Bathyopsoides and Prouintatherium in various late cingula, relatively labial position of the molar Paleocene and early Eocene localities in the hypocones, nature of the M3 talonid, distinctive United States. The notoungulates of the South zygoma, and smaller size distinguish the Ameri- American faunas have a direct bearing on the can type specimen ofProbathyopsis praecursor from Palaeostylops problem, and such South American that of the Mongolian Prodinoceras martyr. Pre- genera as Carodnia and Shecenia conceivably could sumably these differences are in themselves have a bearing, although we doubt it, on the sufficient to merit maintenance of separate problems of the affinities of uintatheres and genera, and are now reinforced by differences in Phenacolophus. astragali not known in 1929, but the similarity of 1A late Paleocene Arctostylops from Wyoming has recently these two uintatheres was accepted as welcome been reported (Jepsen and Woodburne, 1969, p. 544).

EXTENSION OF THE GASHATO FAUNA TO THE NEMEGT VALLEY SITES Significant advances in understanding the Archaeolambda from the same deposits at Naran earliest known Tertiary mammals of Mongolia Bulak and Ulan Bulak in the Nemegt Valley, have come from new studies of the previously and Flerov (1957a) published on additional described Gashato material, notably Wood's material ofPhenacolophus (=Procoryphodon Flerov, (1942; 1957) work on Eurymylus, and especially 1957a; see Simons, 1960, p. 10) from Gashato. fromrenewed collecting bythe Russians and Poles The Soviet work in the Nemegt Valley result- in cooperative expeditions with the Mongols ed in acceptance by the Russians of two suppos- at Gashato (=zKhashiat, Khashaat, trans- edly significantly different faunal levels, roughly literated Russian and Polish equivalents, respec- equivalent to the American "Gray Bull" and tively, for the Mongolian xaumaam, a corral) and "Wind River" according to Flerov (1957b), on at various localities at slightly different strati- the basis of Mongolotherium efremovi in the lower graphic levels in the Nemegt Valley, Mongolia, level and M. plantigradum in the upper, but this about 250 kilometers west-southwest of Gashato was clearly going beyond the evidence. Polish- (Novozhilov, 1954; Gradzinski, Kazmierczak, Mongolian collections obtained by cooperative and Lefeld, 1969). Trofimov (1952) described expeditions from the upper fossiliferous horizon new material of Pseudictops lophiodon Matthew, at Naran Bulak, separated stratigraphically from Granger, and Simpson, 1929 (=P. arilophiodon the lowerfossiliferous horizon by about 13 meters, Trofimov, 1952), from both Gashato and Naran contain Pseudictops lophiodon, Eurymylus laticeps, Bulak (presumably from the White Beds of both species of Palaeostylops,2 and an edentulous et Gradzinski al., 1969 =upper part of the 2Simpson (1936, p. 8) appears to have been the first to white sandy-clayey series, bone-bearing series, suggest that the two species of Palaeostylops may represent Naran-Bulak Beds of Novozhilov, 1954, pp. 36, two closely related genera. Gradziniski, Kazmierczak, and 37; Naranbulak Formation of Flerov, 1957b, Lefeld (1969) listed only Palaeostylops iturus from their p. 37, in the Nemegt Valley). Flerov (1952a) upper fossiliferous horizon in their White Beds. That both species are present is McKenna's conclusion based upon and Kielan-Jaworowska (1969a) described sev- preliminary examination of both the Russian and Polish- eral specimens of the small barylambdid genus Mongolian collections. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 277 multituberculate jaw identified as Prionessus mistoma multidentata Young, 1964 (emended from (Kielan-Jaworowska and Dovchin, 1969, p. 17; Eotomiostoma, a lapsus). Possibly the locality is Gradzin'ski et al., 1969) or ?Prionessus (Sulimski, earlier than late Paleocene, as Chow and Young 1969, p. 101). Flerov's two levels (at Naran Bulak) speculated, but further comment is inappropri- are said by him to be separated by only about ate until the mammalian evidence is fully pub- 30 meters (K. K. Flerov, personal commun.), lished. The rocks from which these remains have which would place both levels within the White been recovered are variously known as the Beds and suggests strongly that they are identical Tanya group or Luofuzhai (=Luofucai) series. with the two horizons of the Polish geologists. It Biryukov and Kostenko (1965) have indicated may not even be necessary to regard Mongo- the presence of a Paleocene site in the Zaysan lotherium plantigradum (upper level, Naran Bulak Depression of eastern Kazakhstan, but the and Ulan Bulak) as the direct descendant of evidence has not been presented. M. efremovi (lower level, both localities), especially because the Nemegt deposits were rapidly THE AGE OF THE GASHATO FAUNA deposited (K. Kowalski, personal commun.). The age of the Gashato fauna is clearly either For convenience, it may suffice to regard the latest Paleocene or early Eocene, but it is diffi- various Nemegt localities as essentially of a cult at present to correlate continental deposits single age, either equivalent to, or only slightly from Central Asia to either Europe or North younger than, the Gashato fauna. Although the America with sufficient resolution to settle the assemblages at Gashato and the Nemegt Valley matter. We have attempted to date the basaltic are poorly known and probably far from com- lava mentioned by Berkey and Morris (1927, plete, they do share at least Pseudictops, Eurymylus, pp. 317, 358) by the Potassium/Argon method, and Palaeostylops, all represented by identical but have been thwarted by the weathered nature species. A fourth genus, Prionessus, is also shared, and consequent geochemical unsuitability of the but the species cannot yet be identified. three samples collected by those authors. At our suggestion attempts to obtain adequate samples OTHER ASIAN PALEOCENE have been made by the Polish geologist Lefeld, MAMMAL SITES but the lava has not yet been relocated in the Paleocene localities also have been found in field. It would be a service to paleontology if China; first in the Turfan Basin of Sinkiang some future worker would collect and date an (Chow, 1960) and later in the South China adequate unweathered sample of the 6-meter coastal province of Kwangtung (Young and thick basalt occurring (fide Berkey and Morris, Chow, 1962; Chow and Young, 1963; Young, 1927) about 40 meters above the base of the 1964). Prodinoceras turfanensis Chow, 1960, is the Gashato Formation. An oriented sample should only Paleocene mammal to be reported thus far also be collected for the purpose of determining from Sinkiang. The species is based upon a single the virtual geomagnetic pole position at the time individual, slightly smaller than the type speci- the flow cooled. men of Prodinoceras martyr from Gashato. Chow Paleontological arguments concerning both (Ibid., p. 100) could find little reason for naming the Gashato occurrence and the Nemegt Valley a new species distinct from P. martyr. The age of occurrences must deal with problems of ecology the Sinkiang deposits, reported to be "sand- (including paleolatitude, paleoclimate, and stones composed of clean white coarse grained paleoaltitude), with evidence of widespread sands probably of lacustrine origin," is therefore dispersal of Sparnacian vertebrates between essentially the same as that ofthe Gashato fauna. Europe and North America at the beginning of The age ofthe Kwangtung locality is less certain. Eocene time, with evidence of dispersal between No descriptions of the mammals have been Asia and the Americas at about the same time, published. Chow and Young (1963) reported a with current theories of global tectonics, and mesonychid resembling Dissacus, a small primi- with problems of collecting bias. Not all of these tive pantolambdid-like pantodont, turtle re- can be dealt with satisfactorily at present. mains having earlier received the name Anosteira Table 1 attempts to assess each taxon of the lingnancia Young and Chow, 1962, and three complete faunal lists from Gashato and the crocodilids: Asiatosuchus nanlingensis Young, Nemegt Valley from the standpoint of correlat- 1964; Eoalligator chunyii Young, 1964; and Eoto- ive usefulness at present. 278 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 TABLE 1 MAMMALIAN TAxA FROM GASHATO AND THE NEMEGT VALLEY, SOUTHERN MONGOLIA Gashato Nemegt Correlationa Multituberculata Taeniolabididae Prionessus lucifer x Cimolomyidae Sphenopsalis nobilis x Insectivora Palaeoryctoidea Deltatheridiidae Hyracolestes ermineus x I/?E Sarcodon pygmaeus (= Opisthopsalis vetus) x I Anagalida, new order Zalambdalestidae Praolestes nanus x I Eurymylidae Eurymylus laticeps x x I Pseudictopidae Pseudictops lophiodon (=Pseudictops arilophiodon) x x I Anagalidae Khashanagale zofiae, new genus, new species x I ?Khashanagale, unnamed new species x Condylarthra I Mesonychidae ?Dissacus sp. x I Pachyaena sp. x I/?E Unnamed new familyb Phenacolophusfallax (= Procoryphodon primaevus) x I Pantodonta Barylambdidae (including Archaeolambdidae) Archaeolambda planicanina x p Dinocerata Uintatheriidae Prodinoceratinae, new rank Prodinoceras martyr x p Mongolotherium efremovi x p Mongolotherium plantigradum x p Notoungulata Arctostylopidae Palaeostylops iturus x x Palaeostylops macrodon x x

ap, Paleocene affinities; I, biostratigraphically indeterminate for intercontinental correlation at the resolution required; E, Eocene (Sparnacian) affinities. bOne of us (McKenna) is preparing for publication elsewhere a review of the genus Phenacolophus, based in part upon additional remains of the type and other specimens, collected by the Russians in 1948 at Gashato.

COMMENTS ON CORRELATIVE subgroup, consisting of the Multituberculata, VALUE OF GASHATO AND Insectivora, and Anagalida, represent endemic NEMEGT MAMMALS holdovers from Cretaceous times, historically The mammalian assemblage from Gashato isolated from Europe by the Turgai Straits and the Nemegt Valley of Southern Mongolia (Schaffer, 1924, fig. 544; Kurten, 1966; D. E. can be subdivided into two major subgroups on Russell, 1968), from India by the Tethys Ocean, the basis of paleogeographic origin. The first and from North America by weak, roughly 1971 SZALAY AND MCKENNA: GASHATO FAUNA 279 concentric climatic belts centering around a order Anagalida, containing Zalambdalestidae, rotational paleopole situated with respect to the Pseudictopidae, Anagalidae, and Eurymylidae, continental masses relatively nearer northern constitutes a major radiation of several endemic Siberia than the present rotational pole (Irving, families descended from an insectivoran stock 1964; McElhinny and Wellman, 1969; Larsen, but sharing some features with lagomorphs. Mutschler, and Brinkworth, 1969). In late Members of the order are unified by dental Paleocene time, limited high latitude dispersal pattern and foot structure (where known), but in westward to Asia of the second major subgroup, their various lineages have diverged from their consisting of primitive uintatheres, barylamb- common ancestry sufficiently to warrant crea- dids, notoungulates, and the ancestors of Phena- tion of an order for the whole group. Khashana- colophus, took place. These same animals were gale, though a primitive anagalid with important somehow apparently prevented from entering links with the zalambdalestids, eurymylids, and Europe at the same time, but the reasons for that insectivorans, is not sufficiently known to be of are unknown and the question perplexing. correlative usefulness; its morphology is appro- Possibly the solution lies in an understanding of priate for either a late Paleocene or an early the altitude preferences of these early mammals: Eocene genus. Praolestes, Eurymylus, and Pseudic- those with populations adapted to higher ground tops are also ofno use as yet in correlation beyond in lower latitudes may have been preadapted for the boundaries of Mongolia. early dispersal across the Bering area, but were Immigrants to the Mongolian area during the prevented from reaching Europe westward by Paleocene were apparently few in number, the Turgai Straits as well as by altitude and suggesting a filter bridge. At least one mesony- latitude preferences. If a land connection from chid, another condylarth (arctocyonid or phena- the North American to the European crustal codontid), a barylambdid pantodont, a prodino- blocks existed at that time it was evidently a ceratine uintathere (or arctocyonine condylarth strong filter bridge, in contrast to Sparnacian ancestor of the prodinoceratines), and an arcto- time when little filter action is indicated, assum- stylopid notoungulate all are interpreted here to ing a land connection was present. Ifsuch a land have arrived prior to the Eocene, a majority and route existed in Sparnacian time it would also perhaps all immigrating to Asia from North have existed in the Paleocene, but would at that America. Thus Asian endemism began to be time have been a strong filter bridge because of broken down by sporadic arrivals of condylarths the relatively cooler and more varied Paleocene and condylarth derivatives from the northeast, climate (Dorf, 1959; Wolfe and Hopkins, 1967). across the Bering area, not by arrivals crossing The Bering route would have been an even the Turgai Straits from Europe. If any of the en- more effective filter in the Paleocene. Perhaps demic Mongolian forms crossed the Bering area the North Atlantic and Bering routes simply in the opposite direction, to colonize North filtered different genera in Paleocene time. America, we are forced to specify, ad hoc, that Gashato multituberculates are not useful for they would have been restricted to northern correlation beyond Mongolia because they are paleolatitudes and are therefore not known from best interpreted as relicts, descended from the American and southern Canadian Paleocene Cretaceous multituberculates of the same area. sites. The mesonychid, Pachyaena sp., from the The same can be said for the insectivorans, "middle bone-bearing horizon" (Gromova, which seem to be in situ differentiates.' The 1952, p. 71) ofthe Nemegt Valley, suggests early Eocene rather than late Paleocene age for one of iVan Valen (1966, p. 61) thought that Sarcodon weakly the Nemegt levels, if one assumes significant age suggested early Eocene age, but this idea was based on differences among the various Nemegt locali- incorrect views concerning the nature as well as the affinities of that genus. Van Valen (1967, p. 258 ff.) assigned a ties, but perhaps the animal is just an early provisional early Eocene age to the Gashato insectivorans occurrence in Asia of Pachyaena. Possibly Pachy- (and other taxa), referring apparently to figure 1 of Van aena arose in Asia from pre-existing mesonychids Valen and Sloan (1966) but not to the text (pp. 271-272) similar to Dissacus, such as were present at or figures 4 and 5 of the same paper, which had indicated Gashato and in the Paleocene of South China that in the authors' opinion Gashato was either late Paleo- cene or early Eocene in age. Hyracolestes or a close relative (Young and Chow, 1963). In North America and or descendant may have reached Europe bv Sparnacian Europe Pachyaena occurs only in the Eocene. time (Rich, In press). Phenacolophus, on the other hand, represents 280 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 an endemic differentiation from some arcto- The arctostylopids need no longer indicate an cyonid or phenacodontid condylarth, sugges- Eocene age for the Asian localities inasmuch as tive in several ways of Sirenia, Desmostylia, Arctostylops is now known to have been present in and Proboscidea. Presumably this differentiation the American late Paleocene. The original speci- had required time, but we have no evidence con- men of Arciostylops steini was collected from rocks cerning the rate ofevolution ofPhenacolophus. The no younger than early Wasatchian in any case. barylambdid pantodont, on the contrary, belongs to a family unknown before the late Paleocene in North America and unknown at SPARNACIAN FAUNAL any time in Europe. A peculiarity of the bary- REPLACEMENT lambdids is that they represent a number of By early Eocene (Sparnacian) time climates closely related but distinct lineages at the generic warmed (Dorf, 1959; Wolfe and Hopkins, 1967) level, yet intermediate steps in their phylogeny and a new wave of northern dispersal caused are unknown at present in the United States or extensive faunal overturn in the Northern Hemi- Mexico where they are abundant in late Paleo- sphere (Simpson, 1947; D. E. Russell, 1968). On cene deposits (Simons, 1960; Morris, 1966). the basis of paleontological evidence now in Presumably barylambdids originated in North hand, this dispersal was apparently directly America from Pantolambda or some closely re- between Europe and North America prior to the lated but still undescribed genus of Torrejonian final separation in the far north ofthose two land pantodonts. Inasmuch as they must also have masses, but fossil mammal-bearing true early occupied at least western Canada and Alaska Eocene sediments are not yet known from Asia during at least some part of the late Paleocene, other than from coastal China, and the available that area may well have been a true center of sample from there is too poorly known to allow evolution, various offshoots from a central much speculation about dispersal to or from lineage similar to Haplolambda having proceeded Europe of coastal forms across the Turgai from there to invade both Asia as far as Kwang- Straits in Sparnacian time. The possible differ- tungl and also areas to the south of Canada in ences in faunal composition between Southern the United States and Mexico, but apparently Mongolia and coastal China in early Eocene the family never reached Europe. time are at present unfortunately unknown. The The primitive Mongolian uintatheres Prodino- coastal early Eocene assemblage includes Cory- ceras and Mongolotherium are closely related both phodon, Homogalax, and Heptodon. the last two to each other and to the American late Paleo- genera being perissodactyls of American deriva- cene genus Bathyopsoides. The differences are tion potentially and probably actually ancestral minor and in part actually spurious; e.g., the to the Asian tapiroid2 radiation of later deposits plaster reconstructed horns of Probathyopsis (Radinsky, 1965). Perissodactyls deployed easily (Patterson, 1939) accepted as fact by Flerov throughout Asia by late Eocene time, and it is (1952b) when naming the essentially hornless difficult to imagine any Eocene fauna in the Mongolotherium as a new genus. Such differences Northern Hemisphere, especially an early Eo- as do actually exist among members of these cene one, lacking representatives of that order. three genera, insofar as they indicate taxonomic Coryphodon is likewise ubiquitous in early Eocene differences rather than sexual dimorphism or faunas. We prefer to postulate that the Gashato growth-stage differences, may represent species differences only. If this is true, the Mongolian 2Zdansky (1930) and Young (1944) have claimed that and Sinkiang occurrences of prodinoceratine palaeotheres were present in Shantung and Kwangtung in uintatheres could all be Paleocene in age. Uinta- the Eocene of China. Both occurrences have been referred theriine uintatheres were present in Asia by the to the otherwise European Lutetian genus Propalaeotherium, but that genus is now regarded as an hyracotheriine equid, early Eocene in the form of ?Probathyopsis (Chow not a palaeothere (Savage, Russell, and Louis, 1965, p. 1). and Tung, 1965, p. 371), although whether We agree that the Chinese species are hyracotheriine descended fromAsian Paleocene prodinoceratines differentiates, but question their reference to Propalaeother- or newly arrived from America we do not know. ium. The Chinese material is not yet well enough known to demonstrate special relationship to any European genus or lWe here assume that the undescribed Kwangtung to prove a crossing of the Turgai Straits. Chow (Tang and pantodont is more likely to be a small barylambdid Chow, 1964; 1965, p. 1342) now regards the Kwangtung (including the "archaeolambdids") than a pantolambdid. hyracotheriine occurrence as early Eocene in age. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 281 and Nemegt assemblages were present before the latest Paleocene in age. Romer (1966, p. 335) advent of Coryphodon and perissodactyls in Asia has proposed but not defined a "Gashatan rather than to attempt to claim ecological exclu- Asiatic Age" and an "Ulanbulakian Asiatic sion for which there is no independent evidence. Age"; if the term "Gashatan Asiatic Age" is to In summary, we believe that the Gashato be used, we suggest it be characterized by the fauna lived prior to an episode of increased dis- joint overlapping time ranges of Palaeostylops, persal that brought certain Sparnacian verte- Pseudictops, Prionessus, and Eurymylus. We refer brates to Asia via a northeastern, not a western Romer's "Ulanbulakian Asiatic Age" to the route. We therefore regard the Gashato fauna as "Gashatan." PALEOGENE NORTHERN DISPERSAL ROUTES AND THE GEOLOGICAL EVIDENCE

A REVOLUTION in geophysical interpretation of Funnell and Smith (1968) have calculated the our planet is currently sweeping geological rates of opening of various parts of the Atlantic thought and without question will also revolu- Ocean and have arrived at a center of rotation tionize and lend substance to paleogeographical of the North American continent away from interpretations by paleontologists. The three Europe (or vice versa) at latitude 880N., longi- subjects of "continental drift," "polar wander- tude 28°E. This is a different center of rotation ing," and "sea floor spreading" have now been from those proposed by Carey (1958) and Wil- meshed with profound new insight by geo- son (1963, fig. 5), and is not the same as any of physicists. Interested readers are referred to the centers of rotation of individual Atlantic recent issues of the Journal of Geophysical plates. Funnell and Smith's calculations, based Research for some ofthe more important articles upon a steady rate of spreading for the last 200 and lists of references. An excellent summary is million years, yield a figure of 67 per cent open- provided by Heirtzler et al. (1968). We attempt ing of the main part of the North Atlantic (south here to assess the implications of some of this of Greenland or Norway) at the end of the new geophysical work with regard to the calcu- Cretaceous. When extrapolated to late Paleo- lated position of the rotational pole at the begin- cene time this requires North America to be ning of the Tertiary and with regard to the rela- rotated back toward Europe by only an 11- tive positions of possible intercontinental dis- degree angle. But if the opening of the Atlantic persal routes in relation to that calculated pole has accelerated since the beginning of the Cre- position. We accept for the purposes ofargument taceous (Reyment, 1969) or the Norwegian and that Earth's field is primarily a dipole and that Greenland seas did not begin to open until about averaged secular variation of individual virtual 60 or 70 million years ago (Avery, Burton, and paleomagnetic pole positions should coincide Heirtzler, 1968; Vogt, Ostenso, and Johnson, with rotational pole positions (Irving, 1964, 1970), then a somewhat larger amount of move- pp. 45, 105). ment per unit of time is necessary. Ifthe opening McElhinny and Wellman (1969, p. 203) have of the Norwegian and Greenland seas took place recently updated Irving's (1964) calculation of mainly during the Tertiary, McElhinny and early Tertiary rotational pole positions by in- Wellman's (1969) early Tertiary rotational pole corporation of additional data from Scottish calculated from European data would more Tertiary igneous rocks (Raja, 1964; Smith, nearly coincide with the virtual geomagnetic 1966) and from Cretaceous and early Tertiary poles of Larsen et al., calculated from North andesites from Bulgaria (Vollstidt, Rother, and American data, but the data of Larsen et al. are Nozharov, 1968). A mean for 17 calculated posi- only suggestive concerning the position of the tions for the Eocene and Oligocene lies close to Paleocene rotational pole with relation to North the present position of the New Siberian Islands America because the sample of virtual poles is at latitude 77°N., longitude 150°E., with a small. 5-degree circle of 95 per cent confidence. This By means of a globe and a hemispherical lies close to the previously calculated Mesozoic- transparent plastic overlaywe have attempted to Tertiary polar-wander path for Asia (Irving, plot the approximate positions of the northern 1964, p. 137) and is on the same side of the continents at the beginning of the Eocene, Arctic Ocean but 2000 kilometers east of three oriented about a rotational pole in the vicinity of virtual geomagnetic pole positions determined the New Siberian Islands. North America was recently by Larsen, Mutschler, and Brinkworth first moved back toward Europe by the mini- (1969) from North American Paleocene lavas in mum amount required by Funnell and Smith Colorado. We accept that the rotational pole (fig. 2), and then by the large amount suggested was near the New Siberian Islands at the close by Avery et al. (fig. 3). According to the Funnell of the Paleocene. and Smith scheme, southeastern (not north- 282 1971 SZALAY AND MCKENNA: GASHATO FAUNA 283

FIG. 2. Attempted paleopolar projection of Holarctica for approximately late Paleo- cene time, incorporating only the concepts of Funnell and Smith (1968) and McElhinny and Wellman (1969). North America has been rotated back toward Europe 110 about a center of rotation at 880 N., 280 E. The late Paleocene rotational pole has been placed at 770N., 1500E., near the New Siberian Islands. No corrections are made for transform faults, fracture zones, or smaller crustal block movements in or north of the Norwegian and Greenland seas. A dry-land dispersal route across the Norwegian Sea is not suggested. Details of present coastlines are crudely depicted for ease of recognition. Iceland is omitted because it is not known to have existed in the Paleocene. eastern) Greenland and western Norway would transform fault zone (Spitsbergen fracture zone) still have been about 1000 kilometers from each is required. The Tertiary dextral movement other during Sparnacian time, suggesting that if along the same fracture zone under the rationale a North Atlantic dry-land dispersal route of Avery et al. would be close to 600 kilometers, existed, it lay north of the Norwegian Sea, cross- but this requires no more than about 1 cm./year ing the De Geer dextral transform fault zone separation of Greenland from Norway and the (Spitsbergen fracture zone) (Harland, 1961, Barents shelf, averaged over the last 55 million p. 127; Wilson, 1965, p. 344; Johnson and years. At the beginning of the Eocene Spits- Heezen, 1967; Ostenso, 1968; Harland, 1969; bergen and the Barents shelf could have been Vogt et al., 1970) from Greenland to a juxta- juxtaposed to northern Greenland and Elles- posed Spitsbergen and from there to the rest of mere Island if Avery et al. are correct. The Europe via an elevated Barents shelf. Under the European and North American crustal blocks Funnell and Smith scheme about 200 kilometers would have been in contact, not separated by a ofTertiary dextral movement along the De Geer spreading mid-ocean ridge. This is because the 284 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 mid-ocean ridge itselfwas offset sinistrally by the De Geer transform fault zone (Spitslbergen fracture zone) (see Wilson, 1965, for geometrical explanation). The part of the fault zone lying between the now more widely offset mid-ocean ridges is still active (Heezen and Ewing, 1961, fig. 10), as would be expected. It seems to consist of several closely spaced transform faults (Vogt et al., 1970, fig. 10a). The final phase of opening of the Norwegian and Greenland seas, connecting the Atlantic permanently with the Arctic Ocean, could have occurred at the end of Sparnacian time in the early Eocene and would in that case be the cause of observed dissimilari- ties at the generic level between terrestrial Cuisian and later faunas of Europe and North America. Subsequent Tertiary faunal similarities between Europe and North America resulted from dispersal via the Bering Route. A more southerly route for terrestrial organisms via Iceland and the Iceland-Faeroes aseis- mic ridge (Kurten, 1966) would have involved island-hopping at best, even assuming Iceland was above sea level (Johnson and Heezen, 1967). Such a route would not suffice, however, for the large scale faunal transfer that took place in the Sparnacian. That the Atlantic was already con- nected with the Norwegian Sea, athwart this postulated route, has been demonstrated by Saito, Burckle, and Horn (1967), who reported a medial Paleocene foraminiferal assemblage northeast of Iceland at latitude 660N., longi- FIG. 3. Attempted Sparnacian reassembly of the tude 0°. North American and European crustal blocks at Calculated paleolatitudes based upon a rota- Spitsbergen, Greenland, and Ellesmere Island by tional pole near the New Siberian Islands show subtracting subsequent motion along Wilson's (1965) shifted latitudes for various localities (table 2). De Geer transform fault zone (Spitsbergen fracture The Bering area would have been about 8 degrees zone) and opening Norwegian and Greenland Seas farther north than the Greenland-Barents shelf at a rate suggested by Avery et al. (1968) and Vogt route, and the latter would therefore have been et al. (1970). Iceland is omitted because it is not more favorably situated from a climatic stand- known to have existed at that time. Latitudes are point than it would have been had the rotational shown with respect to the rotational pole positions calculated by McElhinny and Wellmann (1969). The pole been where it is now. Although age deter- additional assumption is made that part of the Barents minations for Alaskan and Greenland early shelf was above sea level. The approximate edge of the Tertiary floras are not precise, Paleocene and Barents shelf is shown by a line -x-x-x-x. The epi- medial or late Eocene floras from Cook Inlet and continental Turgai Straits would have extended to the Gulf of Alaska (Wolfe, 1966; 1969) and Tethys. Details of coastlines are crudely depicted for ?Paleocene floras from east and western Green- ease of recognition. Large arrows indicate postulated land (Mathieson, 1932; Koch, 1963) consist of dry-land dispersal routes between European and leaves and wood of abundant broad-leaved ever- North American crustal blocks, and from North greens whose leaves had a high percentage of America to Asia via the Bering route. entire leaf margins. Such features are generally indicative of warm temperate to more tropical floras today. Clearly, by Sparnacian time, cli- 1971 SZALAY AND MCKENNA: GASHATO FAUNA 285 TABLE 2 mate had become favorable in both areas for the PRESENT AND CALCULATED EARLY EOCENE dispersal of terrestrial organisms, and Wolfe has PALEOLATITUDES FOR SOME SIGNIFICANT LOCALITIESa even suggested that in the (correlated) medial Eocene, extended periods of darkness could not Calculated have existed and that therefore Earth's axis of Locality Present Early Displace- rotation at that time may not have had so great Latitude Eocene ment Latitude an inclination as now. However, we know of no geophysical rationale for such a major axial Gashato, Mongolia 440 N. 520 N. 8°N. change that does not involve postulation of un- Kwangtung, China 230 N. 340 N. 11°N. known extraterrestrial forces. Bering Bridge 650 N. 740 N. 90 N. If, during the Sparnacian, the Bering Katalla Dist., Alaska 600 N. 620 N. 20 N. and Greenland-Barents shelf northern dispersal Bighorn Basin, 440 N. 380 N. 60S. routes became about equally possible for the Wyoming movement of terrestrial organisms from the Big Bend, Texas 300N. 220N. 8°S. standpoint of latitude and climate, and topo- Punta Prieta, Baja 290 N. 250 N. 40S California, Mexico graphy, narrow isthmuses, and other ecologically Spitsbergen 800 N. 660 N. 140S. restrictive factors were at that time not of much London 510N. 380N. 130S. greater importance in one area than in the other, Paris 490N. 360N. 130S. then the early Eocene Sparnacian fauna, especially ungulates, should have reached Asia in aBased primarily on the conclusions of McElhinny and sufficient strength to replace much ofthe endem- Wellman (1969) and secondarily upon those of Funnell and Smith ic Asian fauna still present in late Paleocene (1968). time at Gashato and the Nemegt Valley in Mongolia. SYSTEMATICS

WE DEAL HERE with only a part of the Gashato SARCODON MATTHEW AND GRANGER, 1925 fauna, based mainly on specimens in the Sarcodon MATTHEW AND GRANGER, 1925, P. 11 American Museum of Natural History. No Opisthopsalis MATTHEW, GRANGER, AND SIMPSON, attempt is made at this time to reevaluate multi- 1929, p. 8. tuberculates, pseudictopids, eurymylids, Phena- TYPE SPECIES: Sarcodon pygmaeus Matthew and colophus, or the notoungulates, all of which are Granger, 1925. potential subjects of additional research, and INCLUDED SPECIES: Type species only. some of which are currently under study by DISTRIBUTION: Type locality only, late Paleo- others. cene of southern Mongolia. DIAGNOSIS: In Hyracolestes and Deltatheridium ORDER INSECTIVORA the alveoli for Pl and P2 are constricted and SUPERFAMILY PALAEORYCTOIDEA small, characteristic of a short-faced animal, FAMILY DELTATHERIDIIDAE whereas in Sarcodon the alveoli for the premolars GREGORY AND SIMPSON, 1926 are well spaced, not constricted, somewhat like REVISED FAMILY DIAGNOSIS: Palaeoryctoids the spatial relationship of the premolars in mia- with I ?4/ > 2 C1/1 P4/4 M2/2. Last premolar some- cid carnivorans. It appears that the talonid of what molariform. P4 and molar trigonids high the first lower molar (the only homologous and shearing. M2 talonid elongate. molar preserved in all three genera) is relatively INCLUDED GENERA: Deltatheridium, Sarcodon wider and has an entoconid in Sarcodon, whereas (= Opisthopsalis), and Hyracolestes. the narrower M1 talonids of Hyracolestes and DISTRIBUTION: Cretaceous and Paleocene of Deltatheridium seem to lack an entoconid. southern Mongolia. Upper molars of Sarcodon are characterized by COMMENTS: It was recently recognized that a long, shearing postmetacrista, closely com- the dental formula of Deltatheridium has been pressed paracone and metacone, and a very misinterpreted by previous investigators (Mc- large, posterolingually offset hypocone with a Kenna, Mellett, and Szalay, In press). Van wide basin separating the apexes of the proto- Valen (1966, p. 50) has made a case for four cone and hypocone. upper incisors and for reduction in the number DISCUSSION: The genoholotype of Hyracolestes of lower incisors, but with regard to the cheek is clearly smaller than A.M.N.H. No. 21732 of teeth no one except Van Valen, to our know- Sarcodon, but small samples for each of these taxa ledge, has gone on any other assumption than suggest that this feature should be interpreted the original one, namely that three premolars with caution. and three molars were present in Deltatheridium. The greatest similarities between Sarcodon on Van Valen (ibid.) apparently miscounted the the one hand and Hyracolestes and Deltatheridium number of lower premolars. It has been tacitly on the other lie in the construction of P4's and in accepted by everyone else that P'/,were somehow the absence of the last lower molar. These are lost, that the single-rooted Pl/1 were P2/2, that accepted by us as indicative of family relation- the high penultimate premolars so characteristic ships among these genera. Several differences, of certain other Cretaceous therians were P4/4, listed under the diagnosis, indicate that Sarcodon and that the P4/4 were actually Ml/1. We have pygmaeus represents the more modified Paleo- approached the matter from a different set of cene genus and that Hyracolestes ermineus repre- assumptions, of which the most important are sents a more conservative, Deltatheridium-like the fundamental morphological similarity of the lineage. teeth themselves among Deltatheridium, Hyra- Van Valen (1966, p. 60) compared Sarcodon colestes, and Sarcodon, the recognition that the to Pararyctes in great detail and stated that same cheek teeth may be lost in all three genera, "Pararyctes is the closest genus to Sarcodon yet and that M3/3 is the tooth most likely to have been discovered." On page 61 he noted that "except lost in animals with prominent shearing modi- for Micropternodus (see below), the closest fications of P4/4-M2/2. approach to Sarcodon among other genera is by 286 1971 SZALAY AND MCKENNA: GASHATO FAUNA 287

I --l FIG. 4. Sarcodon Pygmaeus. Composite reconstruction of all available information concerning lower jaw (shown here as a right lower jaw).

4aaF

FIG. 5. Fragmentary left lower jaw of A.M.N.H. No. 21732, Sarcodon pygmaeus (holotype of Opisthopsalis vetus). Occlusal view. Scale in mm. and 0.5 mm. intervals.

Gypsonictops. .. ." Under Micropternodus (ibid., intermediate between ordinary palaeoryctids p. 61) Van Valen compared the North American and Micropternodus...." In his classification of genus to Sarcodon, suggesting strongly that the insectivorans, Van Valen (1967) placed Sarcodon features cited by him as resemblances are indica- with Micropternodus in the Micropternodontidae. tors of close affinity between the genera. On The similarity of the upper molars ofSarcodon, page 68 he noted that "Sarcodon appears to be but not the lower molars, to those of Micropter- 288 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

lsip-

FIG. 6. Fragmentary left lower jaw ofA.M.N.H. No. 21732, Sarcodonpygmaeus (holotype of Opisthopsalis vetus). Top, lingual view; bottom, buccal view. Scale in mm. and 0.5 mm. intervals.

nodus is the result of convergence. We agree with Sarcodon pygmaeus Matthew and Granger, 1925 Robinson (1969, p. 129) that Micropternodus is Table 3, Figures 4-13 probably a nyctitheriid we insectivore, but hold Sarcodon pygmaeus MATTHEW AND GRANGER, 1925, that Sarcodon is similar to Micropternodus partly p. 11. because nyctitheres originated from Cretaceous Opisthopsalis vetus MATTHEW, GRANGER, AND SIMP- palaeoryctoid stock via Batodon. SON, 1929, p. 8. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 289

FIG. 7. Left P4-M1 of A.M.N.H. No. 21732, Sarcodon pygmaeus (holotype of Opisthopsalis vetus). Top, buccal view; middle, lingual view; bottom, occlusal view.

TYPE: A.M.N.H. No. 20427, left upper molar, "Opisthopsalis vetus" so that a relatively accurate probably Ml. reconstruction could be made (fig. 4), with at HYPODIGM: Type and A.M.N.H. No. 21732, least the canine, the fourth premolar, and the badly crushed skull with premolars and molars, two molars in place. It was possible to indicate left horizontal ramus with P4-M1, and right the alveoli of the first three premolars in their horizontal ramus with canine and M2 (origi- correct positions. nally crushed into the skull) ; both specimens were No lower incisors are preserved. The canine, collected at Gashato. preserved on the right side only, is a slender, tall SPECIFIC DIAGNOSIS: Only known species of tooth. Judged from the alveoli, Pl was single- genus. rooted, P2 and P3 were double-rooted, and the DESCRIPTION: There is sufficient information roots of each of these were separated from those from the two horizontal rami of the type of of the tooth anterior to it by a small diastema. 290 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

W-W~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~....4

L _ _~~~~~~~~~~~~~~0

=_~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ _~~A FI.8.MNH o.272 Sacdonpgau_hltp f pshpai eu leftM2_npaebfrdiinlpeaato.Uprtohi otc ih is_prbalM2_cln0 m.itras

There are two mental foramina; the larger, nomenclature). The talonid is represented by a posterior foramen is under the anterior root of low shelfwith two broken facets, probably repre- P3, whereas the smaller foramen is under the senting the hypoconid (or hypoconulid) and the diastema between P1 and P2. The posterior entoconid. mental foramen is about halfway between the M1 is considerably fractured but the broken dorsal and ventral limits of the dentary, whereas enamel pieces are presumed to be retained in the anterior one is slightly more dorsal. essentially their original positions. The trigonid The left P4 is well preserved; it is a taller tooth is not very open lingually, and although the than M1. The protoconid is the tallest cusp; the paraconid and metaconid might have been metaconid is taller than the paraconid in appar- closer to each other, the three cusps are about ent (but perhaps not real because of possible equidistant. The angle between the protocristid breakage) contrast to P4 of Deltatheridium (Ml of and paracristid is about 50-55 degrees. The authors). The angle between the planes of the talonid is relatively wide transversely, and there protocristid and paracristid is approximately is clear indication of an entoconid. The cristid 85 degrees (see Szalay, 1969, pp. 198-203, for obliqua joins the protocristid approximately 1971 SZALAY AND MCKENNA: GASHATO FAUNA 291

FIG. 9. Damaged left M2 and ?M2 of A.M.N.H. No. 21732, Sarcodon pygmaeus (holotype of Opisthopsalis vetus). Top, occlusal view of ?M2; bottom, occlusal view of broken M2, with metaconid and most of protocristid missing. Scale in mm. and 0.5 mm. intervals.

halfway between the metaconid and protoconid. The hypoconulid appears to be in the middle of the posterior border of the talonid, but the exact position of the hypoconid cannot be determined. The left M2 is broken in half, and although great care was taken when it was excised from the mangled skull, the part bearing the metaconid was not found. The protoconid is slightly larger than the paraconid, and the paracristid forms a highly shearing V-shaped crest on a relatively straight, vertical plane. The trigonid fragment (figs. 9, 10) indicates a relatively large trigonid basin. The talonid, like the ultimate talonid in many mammals, is elongate. The 1mm. hypoconid is nearly worn away, but the hypo- - conulid is tall and pointed, and the entoconid is clearly defined but shorter and smaller than the hypoconulid. The right side of the muzzle of the crushed skull of "Opisthopsalis vetus," after it was cleaned, revealed remnants of the premolars and the first molar. Although the roots of pl-3 are preserved, virtually nothing certain can be said of these teeth, with the possible exception that P3 was three-rooted. The lingual half of the robust P4 is of particular interest. In addition to the strong protocone there is a faint but recognizable rem- FIG. 10. Damaged left M2 and ?M2 of A.M.N.H. nant of a hypocone (fig. 11), smaller than, but No. 21732, Sarcodon pygmaeus (holotype of Opisthopsalis similar to, the kind seen on the holotype of vetus). Top, occlusal view of ?M2; bottom, occlusal Sarcodon pygmaeus (figs. 12, 13). The buccal half view of broken M2, with metaconid and most of of P4 iS somewhat puzzling. The dominant cusp protocristid missing. is interpreted to be the paracone, but anterior 292 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 ______N______l 5_5 _ _e=s -l | |tE-S*sS|SS-I[),,.,.wa.st e!5*S_ jZl|l-fi-- s i1EX-fi:3N--IlX.-.'R-,__ sf .- i.> 4...2 s sb. R ...2 :! 5,,,^ _ ,,{_,:tSS>XE,.:

n- I .- -.11. ..

FIG. 11. Heavily damaged right maxillary dentition of A.M.N.H. No. 21732, Sarcodonpygmaeus (holotype of Opisthopsalis vetus). Top, approximately occlusal or ventral view; bottom, approximately lingual view. Scale in mm. and 0.5 mm. intervals.*.,2ti2-Fs-s...-_fkkl"' and posterior to that cusp no elements can be The upper cheek tooth in contact with the left homologized. M2 prior to their excision was probably the ulti- The badly eroded remains of the lingual half mate left upper molar, M2 (figs. 9, 10). The ofa molar posterior to P4 are the most conclusive anterobuccal and posterobuccal parts of this proof for the synonymy of "Opisthopsalis vetus" tooth are broken off, and the single, centrally with Sarcodonpygmaeus. Only the crumbling parts situated cusp (probably the paracone) is badly of the dentine remain, but it is quite clear that in worn. addition to the apex of the protocone the hypo- DISCUSSION: This taxon has been one of the cone was exactly like the characteristic structure most poorly prepared and studied of the seen on the type specimen ofSarcodon pygmaeus. Gashato mammals. New preparation of the 1971 SZALAY AND MCKENNA: GASHATO FAUNA 293

FIG. 12. A.M.N.H. No. 20427, damaged holotype of Sarcodon pygmaeus, left upper molar, probably Ml, occlusal view. Scale in mm. and 0.5 mm. intervals. holotype of " Opisthopsalis vetus" uncovered many HYRACOLESTES MATTHEW AND GRANGER, important details previously not seen; when 1925 Matthew, Granger, and Simpson (1929, p. 8) Hyracolestes MATTHEW AND GRANGER, 1925, p. 10. diagnosed "Opisthopsalis vetus," they were de- INCLUDED SPECIES: Type species only. ceived by the broken, separated right dentary DISTRIBUTION: Type locality only, Gashato, posterior to the alveoli of P4 and simply stated late Paleocene, southern Mongolia. that there were three molars in addition to the four premolars. Restudy of the mandible frag- ments reveals that there were only two molars posterior to P4. P4 and M1 are present on the left side (figs. 5, 6), whereas only part of the trigonid and the talonid of M2 are preserved. 44' '' Prior to preparation (fig. 8) the remains of M2 and the upper cheek tooth (figs. 9, 10) were in quasi-occlusion, or probably more correctly, in contact only. Although the buccal half of the right upper molar on the holotype of "Opisthopsalis vetus" is poorly preserved, it is adequate to show that the construction of the hypocone is identical to that of the holotype ofSarcodon pygmaeus (figs. 12, 13). It should be added here that Matthew, Granger, and Simpson (1929, p. 9) already astutely noted that "Opisthopsalis" may be congeneric with Sarcodon, although they mistakenly concluded that "the interest of the present specimen [A.M.N.H. No. 21732] demands its separate diagnosis." We cannot follow Van Valen (1966, p. 60) in endorsing the correctness of the figure of the 1mm. holotype of Sarcodon pygmaeus published by Matthew and Granger (1925). We found the FIG. 13. A.M.N.H. No. 20427, left upper molar, illustration to be inaccurate and had the type probably Ml, of holotype of Sarcodon pygnmaeus. refigured (figs. 12, 13). Occlusal view, damage restored. 294 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 TABLE 3 MEASUREMENTSa (IN MILLIMETERS) OF LOWER TEETH OF VARIOUS PLACENTALS FROM THE GASHATO FORMATION P3 P4 M1 M2 M3 L PW L AW PW L AW PW L AW PW L AW PW Hyracolestes ermineus (A.M.N.H. No. 20425) 1.80 0.95 2.35 1.30 1.35 2.40 1.35 1.20 Praolestes nanus (A.M.N.H. No. 21718) 1.30 0.70 1.45 - 0.25 1.7b 1.35 1.2b Sarcodon pygmaeus (A.M.N.H. No. 21732) 2.70 1.55 - 2.85 1.70 1.50 Khashanagale zofiae (A.M.N.H. No. 21751) - 2.45 1.90 1.80 2.30 1.90 1.60 2.10 1.60 1.30 ?Khashanagale, new species (A.M.N.H. No. 21762) - 1.15 0.90 aL, length; PW, posterior width; AW, anterior width. bApproximately. Other values rounded to nearest 0.05 millimeter.

DIAGNOSIS: Palaeoryctoids with M3/3 lost and which was apparently endemic in Asia until at morphology in several respects intermediate least Paleocene and probably until Oligocene between that of Deltatheridium and Sarcodon time. Deltatheridium constitutes the base of this (= Opisthopsalis), but more closely resembling radiation. Rich (In press) describes a tantalizing the former. P4 more elongate than in Sarcodon, French Sparnacian tooth from Avenay which, but with metaconid apparently higher than in except for larger size, is virtually identical with Deltatheridium (? due to wear). M1 talonid with M1 of Hyracolestes. Perhaps it is a European better formed basin than in Deltatheridium but direct descendant of Deltatheridium or perhaps it without entoconid (in contrast to Sarcodon). Pre- is a descendant of Hyracolestes that somehow molars anterior to P3 evidently small and crowd- reached Europe, but we believe that reference to ed and skull probably short-faced, as in Delta- the Miacidae is also possible. theridium. Size about two-thirds that of Sarcodon. In terms of characteristic adaptations which DIsCUSSION: Van Valen (1966, p. 86) referred set apart this interesting genus from almost all to Opisthopsalis, Hyracolestes, and Praolestes as other placentals the structure of the trigonids is erinaceoids, under a common heading. His key the most revealing. On P4 it is slightly larger and statements, in addition to various comparisons, more open lingually than on M1. The gently were: "As far as the single specimens known of curving prevallids support long carnassial edges Opisthopsalis and Hyracolestes, from the Gashato and a well-developed carnassial notch is present. of Mongolia, are preserved, there are almost no Although the upper teeth of Hyracolestes are not generic distinctions between them," and "... . pro- known, on the basis of the lower dentition we visional reference of Opisthopsalis, Hyracolestes, conclude that Hyracolestes was a small, carnivo- and Praolestes to the Erinaceoidea is indicated." rous mammal, as suggested by its original describ- Van Valen's fleeting survey misunderstood the ers, and that it was closely similar to Delta- significance as well as the relationships of these theridium of the Cretaceous Djadochta Forma- three distinct genera. tion. Insofar as the remains of Hyracolestes are known, they indicate a very unusual, puzzling Hyracolestes ermineus Matthew and Granger, mammal. It appears fairly certain to us that the 1925 teeth described are P3-M1, and the ultimate Table 3, Figures 14-18 tooth, inferred from its alveoli only, was M2 as in Hyracolestes ermineus MATTHEW AND GRANGER, 1925 Sarcodon. Based on the simple, narrow talonid of p. 10. M1, and on the absence of M3, it seems to us that TYPE: A.M.N.H. No. 20425, right mandible Sarcodon and Hyracolestes represent two distinct fragment with P3-M1, and alveoli for the roots lineages of a unique palaeoryctoid radiation, of C, P1, P2, and M2. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 295

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FIG. 14. A.M.N.H. No. 20425, holotype of Hyracolestes ermineus, right P3-M1, and alveoli for the roots of C, Pl, P2, and M2; occiusal view. Scale in mm. and 0.5 mm. intervals.

HYPODIGM: Type specimen only. recognized nor figured by the original describ- SPECIFIC DIAGNOSIS: Only known species of ers) probably housed a very small, vestigial Pl, the genus. whereas the remaining two alveoli probably held DESCRIPTION: For an appreciation of the un- a double-rooted P2. usual morphology and homologies of the teeth, Our interpretation of the two alveoli posterior the number and relative position of the alveoli to the last preserved tooth (interpreted here as are described. Only the posterior part of the M1) is that the anterior alveolus housed the root canine alveolus is preserved; it is sufficient, how- under the trigonid, whereas the posterior one ever, to indicate that the canine was large. There held the long, laterally constricted root of the are three discernible alveoli posterior to the talonid of an ultimate lower molar, M2. canine alveolus. The most anterior preserved The most anterior preserved tooth, interpret- tooth is interpreted here to be the third pre- ed here as P3, is simple-crowned with a tall molar. The tiny, anterior alveolus (neither protoconid, an anterobasal nubbin in place of a 296 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

FIG. 15. A.M.N.H. No. 20425, holotype of Hyracolestes ernmineus, right mandible fragment with P3-M1, and alveoli for the roots of C, Pl, P2, and M2. Top, medial view; bottom, lateral view. Scale in mm. and 0.5 mm. intervals. paraconid, and a single small cusp in the talonid stage. The protoconid is the tallest ofthe trigonid position. cusps and the paraconid is the lowest. The angle The tooth posterior to P3 can be designated between the planes of the protocristid and para- semimolariform (for definitions of premolari- cristid is about 85 degrees and there is a deep form, semimolariform, etc., see Szalay, 1969a, trigonid notch between paraconid and proto- p. 199) with a well-developed trigonid and a conid. The talonid is only represented by a talonid that has not quite reached the basined single, large cusp, structurally simpler than the C C

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._ 1971 SZALAY AND MCKENNA: GASHATO FAUNA 299

FIG. 19. A.M.N.H. No. 21718, holotype of Praolestes nanus, left mandible fragment with P3 M1, and alveoli for roots Of P2. Top, occiusal view; bottom medial view Scale in mm. and 0.5 mm intervals

same region in Sarcodon. The hypoflexid is exten- is large although it is smaller than the proto- sive and as a result the area anterobuccal to the conid. The angle between the planes of the talonid cusp is more extensive than the area on protocristid and paracristid is about 57 degrees. its opposite side which is homologous to the The anteroposteriorly elongate trigonid is wide talonid basin of tribosphenic lower teeth. open lingually. Although the posterolateral part On M1, as on P4, there is a deep notch on the of the talonid is chipped off, it is sufficiently well curving surface of the prevallid. The metaconid preserved to show that a large hypoconid was 300 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

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FIG. 20. A.M.N.H. No. 21718, holotype of Praolestes nanus, left mandible fragment with P3-M1, and alveoli for roots of P2; lateral view. Scale in mm. and 0.5 mm. intervals. present anterobuccal to the remaining talonid Mellett, and Szalay, In press) suggested that cusp. The hypoflexid is large, and the cristid Deltatheridium, Sarcodon, and Hyracolestes repre- obliqua joins the middle of the base of the tri- sent a natural group of palaeoryctoids and that gonid. If one assumes the posterior talonid cusp the Eocene and Oligocene didymoconids may be to be the hypoconulid, there is no trace of an (but see footnote p. 301) the only recognized entoconid on the lingually wide-open talonid. descendants of the earlier group. Except for Under P3, on the ventrolingual aspect of the possibly a single tooth from the Sparnacian of mandible fragment, there is a faint crest repre- France that is closely similar to M1 of Hyra- senting the posterior extension ofthe mandibular colestes but may represent merely an unrecog- symphysis. There is a single, large mental fora- nized miacid, no remains similar to those of any men under the anterior root of P3. of these peculiar animals have been found out- DISCUSSION: We have elsewhere (McKenna, side of Asia. The viverravine miacids may be

1mm. I aI FIG. 21. A.M.N.H. No. 21718, holotype ofPraolestes nanus, left mandible fragment with P3-M1, and alveoli for roots of P2; occlusal view. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 301

FIG. 22. A.M.N.H. No. 21718, holotype of Praolestes nanus, left mandible fragment with P3-Ml; lateral view. distantly related, but, if so, then via a pre- a tendency toward prismatic or unilaterally Djadochta common ancestor. hypsodont upper cheek teeth with crown pattern tending to be obliterated early in wear, a ten- ANAGALIDA, NEW ORDER dency toward procumbent incisors (variously We regard the mammalian families Zalamb- expressed), and a skeleton (particularly the foot), dalestidae, Pseudictopidae, Anagalidae, and where known, that is somewhat lagomorph-like. Eurymylidae as members of an endemic Cre- taceous and early Tertiary Asian radiation, whose closest living relatives are the Lago- morpha.1 The latter order also had an Asian FAMILY ZALAMBDALESTIDAE origin, probably from the Anagalida, but ceased GREGORY AND SIMPSON, 1926 to be endemic to Asia in the Eocene. Among the PRAOLESTES MATTHEW, GRANGER, AND principal characteristics of the order Anagalida SIMPSON, 1929 are the possession of molariform Praolestes MATTHEW, GRANGER, AND SIMPSON, 1929, posterior pre- p. 3. molars, anteroposteriorly compressed trigonids, TYPE SPECIES: Praolestes nanus. INCLUDED SPECIES: Type species only. 'Although we believe that the Didymoconidae may DISTRIBUTION: Type locality only, Gashato, eventually prove to be a member of the Anagalida, pos- late Paleocene, southern Mongolia. sibly a descendant of the Zalambdalestidae, the phylo- genetic and systematic position of this endemic Asian DIAGNOSIS: Small zalambdalestids in which P3 family should be decided on after the publication of paraconid is no longer a basal cusp but has a J. S. Mellett's researches on didymoconids. more elevated position and a metaconid is begin- 302 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

FIG. 23. A.M.N.H. No. 21718, holotype of Praolestes nanus, left mandible fragment with P3-Ml; medial view. ning to form on the posterolingual corner of the by recently collected specimens of Zalambdalestes. protoconid; P4 has a fully developed trigonid with high paraconid projecting anterolingually. Praolestes nanus Matthew, Granger, and Simpson, DISCUSSION: Van Valen (1967, p. 261) in his 1929 classification of insectivorans followed his earlier Table 3, Figures 19-23 views (1966, pp. 86, 87), formally placing Prao- Praolestes nanus MATTHEW, GRANGER, AND SIMPSON, lestes, "Opisthopsalis," and Hyracolestes in the Geo- 1929, p. 3. labidinae without a query or a discussion of the TYPE: A.M.N.H. No. 21718, left mandible problem. However, the premolars ofgeolabidines fragment with P3-M1, and alveoli for P2. are not so advanced as those of zalambdalestids, HYPODIGM: Type specimen only. especially in the development of the trigonid of SPECIFIC DIAGNOSIS: Only known species of P4. We ascribe the molar similarities to paral- the genus. lelism. DESCRIPTION: Because the most anterior pre- Kielan-Jaworowska (1 969b) has now de- served tooth is P3, the two alveoli on the anterior scribed unworn and undamaged lower dentitions part of the mandible fragment belonged to P2. of Zalambdalestes from the Cretaceous Djadochta P3 is almost completely erupted; the protoconid, Formation near Gashato, Mongolia, and mean- slightly curved posteriorly, is the dominant cusp. ingful comparisons with Praolestes can now be The paracristid, leading from the apex of the made. We regard Praolestes as a probable protoconid to the small but cuspate paraconid descendant of Zalambdalestes and the characteris- is curved like the edge of a scimitar sword. An tics noted in the generic diagnosis are regarded incipient metaconid is represented by a nubbin as advances beyond the features demonstrated on the lingual side of the crest which extends 1971 SZALAY AND MCKENNA: GASHATO FAUNA 303

1,1111111111 |,I'I FIG. 24. Stereoscopic photographs of A.M.N.H. No. 21751, holotype of Khashanagale zofiae, new genus and new species, posterior half of right horizontal ramus with M1 3, with M1 trigonid broken off; occlusal view. Scale in mm. and 0.5 mm. intervals. posteroventrally from the apex ofthe protoconid. with similar P4's. The protoconid is the tallest of This lingual half of the protocristid meets the the trigonid cusps; the metaconid is larger than cristid obliqua of the tiny talonid, the latter the paraconid. The angle between the planes of represented by a single cusp. the protocristid and paracristid of the trigonid is P4 has a well-developed trigonid with a pre- about 70 degrees. cingulid and has a broad, shelflike talonid M1 has an anteroposteriorly constricted tri- which has a tiny lingually shifted basin. The gonid with a strong precingulid, and a talonid talonid occluded with an enlarged P4 paracone which is slightly broader than the trigonid. The as in Zalambdalestes and many other mammals hypoconulid and entoconid are broken off; FIG. 25. Stereoscopic photographs of A.M.N.H. No. 21751, holotype of Khashanagale zofiae, new genus and new species, posterior half of right horizontal ramus with M1_3, with M1 trigonid broken off; lateral view. Scale as in figure 26. , k M r __#_ | ' - = 211111? ? EINJ G 1 _ r _ ^ _ ^ _ _| i _ _ [ i _ _ i ?jj _ 1 ?

_ S _ _ S _ _ w ? _ _ i g.':k 1,l______s | ? __ i ?

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_ a ?a-?5 _r ?_.g- iI;_.MlF X i j| _^=i _:N_E N _ w_ __w_ . __w-Z_ g__ S 'S1!!; _ -_|l_CF?EEf_r_ _EzlllllllllF||_^_ wFIG. 26. A.M.N.H.1No. 21751, holotyperof Shashanagale zofiae,_new genus and new species, posterior half of right horizontal ramus with M1_3, with M1 trigonid broken off; scale in mm. and 0.5 mm. intervals. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 305

3mm. I I I FIG. 27. A.M.N.H. No. 21751, holotype of Khashanagale zofiae, new genus and new species, posterior half of right horizontal ramus with M1 3, with M1 trigonid broken off. Left, occlusal and slightly buccal view of teeth; right, lateral view. therefore, the crucial relations of the hypo- young specimen, as indicated by the erupting P3, conulid and entoconid to each other cannot be is moderately deep, with two mental foramina. assessed. It is difficult to determine whether the The anterior one is under the anterior root of P2, protoconid or the metaconid was the tallest whereas the posterior foramen is under the trigonid cusp, because the tip of the protoconid incipient talonid of P3. is not present. The angle between the planes of the protocristid and paracristid of the trigonid is FAMILY ANAGALIDAE SIMPSON, 1931 approximately 40 degrees. KHASHANAGALE, NEW GENUS The mandible fragment, that of a relatively TYPE SPECIES: Khashanagale zofiae, new species. 306 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

FIG. 28. A.M.N.H. No. 21762, ?Khashanagale, new unnamed species, left dentary fragment with talonid of M3; occlusal view. Scale in 0.5 mm. intervals.

1mm. iI FIG. 29. A.M.N.H. No. 21762, ?Khashanagale, new unnamed species, left dentary fragment with talonid of M3; occlusal view.

INCLUDED SPECIES: Type species only. gonids, the incipiently bicolumnar molars, and DISTRIBUTION: Type locality only, Gashato, the construction of M3 suggest that Khashanagale late Paleocene, southern Mongolia. is an early relative of Anagale (see McKenna, ETYMOLOGY: Khashaat (xaumaam, i.e., Gash- 1963, for a review of the Anagalidae). The talon- ato) +Anagale. ids of Khashanagale are transversely narrower DIAGNOSIS: Primitive anagalids, distinct from than those of Anagale; this seems to indicate that Anagale in having transversely narrower talonids, anagalids were differentiated from a stock of and slightly less bicolumnar molars. The cusps very primitive placentals with relatively narrow on the lower molars are more distinct than those talonids (see also Zalambdalestes1 and didymo- ofAnagale. The ratio of length to posterior width conids). of the lower molars decreases from front to 'We take this opportunity to present long-needed illus- back. The numerical value of the ratios are 1.38, trations (figs. 31-35) of the original specimens of the im- 1.43, and 1.63 for M1, M2, and M3 respectively. portant Asiatic Cretaceous mammal Zalambdalestes. Clean- DISCUSSION: The anteroposteriorly narrow tri- ing of the specimens reported by Gregory and Simpson 1971 SZALAY AND MCKENNA: GASHATO FAUNA 307

1mm.m~

FIG. 30. Drawings of A.M.N.H. No. 21762, ?Khashanagale, new unnamed species, left dentary fragment with talonid of M3. Top, lateral view; bottom, medial view.

Van Valen (1966, p. 89) noted a number of Derivation of Pseudictops of the Gashato and similarities between Ptolemaia and Anagale. He Nemegt assemblages from an ancestry similar to clearly implied close, virtually family group primitive anagalids, with anteroposteriorly con- taxonomic relationships between Ptolemaia and stricted trigonids and narrow talonids, appears Anagale. At present, no special affinity between to be plausible at present (for similar views, see these genera appears probable to us, and we Van Valen, 1964).1 The characteristically nar- continue to regard Ptolemaia as a pantolestoid rowed talonid of M3 of Pseudictops, Eurymylus, insectivoran. anagalids, and lagomorphs appears to be a shared character, present probably in a common (1926) has revealed many important new details of the ancestor prior to the diversification of these dentition and the cranium. A.M.N.H. No. 21708, type of groups. Zalambdalestes lechei, is an extremely aged individual with One of the striking similarities of Anagale and cheek-tooth crowns nearly worn away. pl and p2 have Eurymylus is the manner in which the lower teeth dropped out and the alveoli have closed. The type of wear. In both genera, as in lagomorphs, the "Z. grangeri" is a somewhat younger individual of the same species, and the referred specimens in the Polish-Mongolian 1"Genus R" of Van Valen (1964, p. 486) appears to be collections (Kielan-Jaworowska, I969b) are younger still. a worn upper tooth of a leptictid near Myrmecoboides. Its All Djadochta Zalambdalestes can be regarded as a single relevance, in any way, to anagalid or lagomorph phylo- species, Z. lechei Gregory and Simpson, 1926. geny is highly questionable. 308 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

FiG. 31. A.M.N.H. No. 21708, part of the holotype of Zalambdalestes lechei, almost complete cranium, Djadochta Formation, late Cretaceous. Top, ventral view; bottom, dorsal view. Scale in mm. and 0.5 mm. intervals.

anterior part of the trigonid and the talonid of From a common ancestor which had certain the molar anterior to it form a basin into which characteristic predispositions of the masticatory the lingual half of the upper tooth occludes. apparatus, independent development of this 11111 liii] Il Il

FIG. 32. A.M.N.H. No. 21708, part of the holotype of Zalambdalestes lechei, partial left and right mandibles, Djadochta Formation, late Cretaceous; occlusal view. Scale in mm. and 0.5 mm. intervals.

FIG. 33. A.M.N.H. No. 21707, Zalambdalestes lechei, part ofright horizontal ramus with P3-M3, Djadochta Formation, late Cretaceous. Top, lateral, bottom, medial view. Scale in mm. and 0.5 mm. intervals. 310 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144

FIG. 34. A.M.N.H. No. 21709, Zalambdalestes lechei (holotype of "Z. grangeri"), partial palate with right cheek teeth, Djadochta Formation, late Cre- taceous, occlusal view. Scale in mm. and 0.5 mm. intervals. specialized wear pattern is possible. pock-marked as a result of somewhat poor preservation, possibly caused by etching by acidic ground water. Khashanagale zofiae, new species Ml, or what is left ofit, seems to have been the Table 3, Figures 24-27 largest of the three molars. M2 is slightly smaller TYPE: A.M.N.H. No. 21751, posterior half of than M1, and M3 is distinctly smaller than M2. right horizontal ramus with M1 3. The molar trigonids, preserved only on M2 and HYPODIGM: Type specimen only. M3, are approximately twice the height of the ETYMOLOGY: Named for our esteemed col- talonids and are somewhat columnar. The high- league, Dr. Zofia Kielan-Jaworowska. est cusp on the trigonids is the metaconid, but SPECIFIC DIAGNOSIS: Only known species of this may, at least in part, be caused by dispropor- the genus. tionally greater wear on the protoconid. The DESCRIPTION: A.M.N.H. No. 21751 is the paraconids are shelflike and close to the meta- posterior half of the horizontal ramus with conid; they form a functional unit with the broken remains of M1, and the relatively well talonid of the preceding tooth. A precingulid was preserved, but fractured M2 and M3. Broken present and extended farther bucally than in splinters of the posterior root of P4 are also Anagale. The trigonid notch is V-shaped, making present. The surfaces of the teeth are densely an angle of approximately 90 degrees between 1971 SZALAY AND MCKENNA: GASHATO FAUNA 311

FIG. 35. A.M.N.H. No. 21709, Zalambdalestes lechei (holotype of "Z. grangeri"), partial palate with right cheek teeth, Djadochta Formation, late Cretaceous, lateral view. Scale in 0.5 mm. intervals.

the slopes of the protoconid and metaconid on thick base on the ascending ramus. M2. The talonid notch is deep and V-shaped, with a rounded bottom; it is the outlet for the ?Khashanagale, new unnamed species small, lingually positioned remnant of the talon- Table 3, Figures 28-30 id basin. The talonid cusp apexes are obliterated A.M.N.H. No. 21762 is a left dentary frag- by wear, but the cusps themselves were becom- ment with the talonid of M3. Comparison of this ing subordinate components of what amounts to specimen with the type of Khashanagale zofiae, the enamel wall of the posterior column of the A.M.N.H. No. 21751, quickly reveals the great bicolumnar structure seen later in Anagale. similarity of the talonids of the last molars. As in What remains of the dentary is deep and the genoholotype of Khashanagale the mandible robust: the crista coronoidea arises from a very of the unnamed species was relatively deep. The 312 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 crista condyloidea in front ofthe deep masseteric (1966) and Szalay (1 969b; 1 969c). We refrain fossa is thick and well differentiated. This ani- from naming this species. mal, judged by its teeth and jaw depth, was about one-half the size of Khashanagale zofiae. ORDER DINOCERATA Although we consider it important to bring to FAMILY UINTATHERIIDAE FLOWER, 1876 light this new species from the Gashato Forma- SUBFAMILY PRODINOCERATINAE FLEROV, tion, we cannot justify naming it because of the 1952b, NEW RANK of the only known specimen. inadequacy We take this opportunity to make a minor ORDER CONDYLARTHRA adjustment in the taxonomy of uintatheres. SUPERFAMILY MESONYCHOIDEA Flerov proposed a new family, Prodinocera- FAMILY MESONYCHIDAE COPE, 1875 tidae in his first paper (1952b) on Mongolother- SUBFAMILY MESONYCHINAE COPE, 1875 ium from the Nemegt Valley. The Prodino- (=Mesonychidae Cope, 1875, p. 444; Mesonychinae ceratidae, with Prodinoceras as its type genus, also Wortman, 1901) included Mongolotherium, Bathyopsoides, and Pro- ?Dissacus sp. bathyopsis. Of particular significance here is the MATERIAL: A.M.N.H. No. 22145, frag- fact that Flerov included the last genus. Later mentary left P4. Wheeler (1961) employed a subfamily Bathyop- COMMENTS: A small mesonychid similar to sinae, a reduction in rank of Bathyopsidae Dissacus is present at Gashato, but has not been Osborn, 1898, for the genera Probathyopsis, Pro- identified by previous students. The specimen dinoceras, Bathyopsoides, Bathyopsis, and Mongolo- compares favorably with P4 of Dissacus nava- therium, but such usage, if adopted, would make jovius or D. saurognathus. The stylar area has been the uintathere subfamily Uintatheriinae diphy- broken away, which is no doubt why this tooth letic, as Uintatherium and Prouintatherium have has not been recognized previously. Elsewhere been shown by Dorr (1958) to be derived from in Asia mesonychine mesonychids ofcomparable Probathyopsis prior to the origin from the latter size are known only from the Paleocene of South genus of Bathyopsis. Bathyopsis, however, is the China (Chow and Young, 1963), but that probable ancestor of Tetheopsis and Eobasileus. material still awaits description. Dissacus-like Therefore, in order to avoid diphyly, Bathyopsis mesonychines are known in North America from and Probathyopsis are regarded here as primitive medial Paleocene to early Wasatchian (Sparna- members of the subfamily Uintatheriinae, thus cian) time and in Europe from the late Paleo- permitting use in modified form of Flerov's cene through medial Eocene time. Inasmuch as Prodinoceratidae for the mutually closely similar Dissacus was for a time a contemporary of Bathyopsoides, Prodinoceras, and Mongolotherium. Pachyaena, the presence of a Dissacus-like animal The Prodinoceratinae as thus visualized are uni- at Gashato is not evidence that the Gashato fied by the possession of a saggital crest rather assemblage is earlier than the Nemegt Valley than a flat skull roof. Horns were almost surely locality which has produced Pachyaena. absent or rudimentary, in spite of Patterson's For additional comments and details on (1939, fig. 109) depiction of them in the plaster Asiatic mesonychids see Szalay and Gould reconstruction of the skull of Bathyopsoides. SUMMARY

THE EARLIEST TERTIARY MAMMALIAN FAUNA action. Presumably this was the result of a more known from Asia occurs in southern Mongolia, equable climate. There is no evidence for a where it is found in late Paleocene sediments Greenland-Iceland-Faeroes dispersal route and approximately 55 million years old exposed at some evidence against it. Gashato and in the Nemegt Basin. Romer (1966) No attempt is made in the present paper to has proposed, but not defined, a "Gashatan reevaluate, except insofar as they bear on cor- Asiatic Age" for the Gashato fauna and we pro- relation, the Gashatan multituberculates, pseu- pose that the term be extended to the occurrence dictopids, eurymylids, Phenacolophus, or panto- of the same fauna, although to a different faunal donts, but the following taxonomic adjustments facies, in the Nemegt Basin, subsuming Romer's are made: (1966) "Ulanbulakian Asiatic Age." We supply 1. Opisthopsalis is synonymized with Sarcodon, a definition of the "Gashatan Asiatic Age": the and Sarcodon and Hyracolestes are added to the joint overlapping time ranges of Palaeostylops, insectivoran family Deltatheridiidae. Pseudictops, Prionessus, and Eurymylus. Additional 2. A new order, Anagalida, is proposed. The localities in Sinkiang and Kwangtung may also Anagalida includes the families Zalambdales- be Gashatan in age. tidae, Pseudictopidae, Anagalidae, and Eury- The Gashato fauna is made up of a mixture of mylidae. The Anagalidae are somewhat lago- endemic genera and a few genera that evidently morph-like and are believed to be related to reached Asia via the Bering route from North lagomorphs. America and beyond. There is no special simi- 3. Praolestes is referred to the Zalambdales- larity to Paleocene faunas of Europe, but this tidae. could be because of a double filtering action. 4. The Cretaceous genus Zalambdalestes is The most perplexing Gashatan mammals have known from a single species, Z. lechei. The type been the notoungulates, but recently Paleocene specimen ofZ. lechei is an extremely aged individ- notoungulates have been found in North Amer- ual with cheek-tooth crowns nearly worn away. ica and there is no evidence that notoungulates as pl and p2 have dropped out and the alveoli have such originated in Asia. At the beginning ofthe closed. The type specimen of "Z. grangeri" is a Eocene (Sparnacian), increased northern dis- somewhat younger individual ofthe same species persal brought about extensive, but still not and the referred specimens in the Polish collec- complete, faunal replacement in eastern Asia. tions are younger still. New illustrations of Analysis of geophysical data, as well as the American Museum specimens of Zalambdalestes faunal data, suggests that there is strong evidence are provided. for a dry-land dispersal route between the North 5. The Anagalidae are reported from the American and European crustal blocks via Paleocene for the first time and a new genus and Greenland and the Barents shelf as late as species, Khashanagale zofiae, is named. A second Sparnacian time in the Eocene, but not there- species of Khashanagale or of a closely related after. During Paleocene time, climate and other form is present at Gashato, but is not named. factors had a filtering effect on dispersal via both 6. A small Dissacus-like mesonychid is present the Bering and Greenland-Barents shelf routes, in the Gashato fauna at Gashato. but the former was closer to the rotational pole 7. In the classification of uintatheres, utiliza- position in the Paleocene and was a more effect- tion of Flerov's subfamily Prodinoceratinae is ive filter. During Sparnacian time, the Bering advocated in preference to Wheeler's subfamily area still acted as a filter, but the Greenland- Bathyopsinae. Barents shelf route now showed little filter

313 314 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 REFERENCES

AVERY, 0. E., G. D. BURTON, AND J. R. HEIRTZLER Mongolian paleontological expedition of 1968. An aeromagnetic survey of the Norwegian the Academy of Sciences of the U.S.S.R. Sea. Jour. Geophys. Res., vol. 73, no. 14, Trudy Paleont. Inst. Akad. Nauk, U.S.S.R., pp. 4583-4600, figs. 1-9. vol. 41, pp. 43-50, figs. 1-4, 1 pl. [In BERKEY, C. P., AND F. K. MORRIS Russian.] 1927. Geology of Mongolia, a reconnaissance 1952b. New Dinocerata from Mongolia. Dok. report based on the investigations of the Akad. Nauk, U.S.S.R., vol. 86, no. 5, years 1922-1923. New York, the American pp. 1029-1032, figs. 1-3. [In Russian.] Museum of Natural History, 475 pp. 1957a. A new coryphodont from Mongolia, and on BIRYUKOV, M. D., AND N. N. KOSTENKO evolution and distribution of Pantodonta. 1965. Concerning the "Obayly" fauna of the Vertebrata PalAsiatica, vol. 1, no. 2, pp. Zaysan Depression. Vestnik Akad. Nauk 73-81, figs. 1-3. Kazakhstan, vol. 21, no. 12, pp. 75-77. [In 1957b. Dinocerata of Mongolia. Trudy Paleont. Russian.] Inst. Akad. Nauk, U.S.S.R., vol. 67, CAREY, S. W. pp. 1-82, figs. 1-40, pls. 1-6. [In Russian.] 1958. The tectonic approach to continental drift. FLOWER, W. H. In Carey, S. W., Continental drift, a sym- 1876. Hunterian lectures on the relations of posium. Symp. Geol. Dept. Univ. Tas- extinct to existing Mammalia. Nature, vol. mania, no. 5, pp. 177-355, figs. 1-57. 13, pp. 307-308, 327-328, 350-352, 387- CHOW, M. 388, 409-410, 449-450, 487-488, 513-514; 1960. Prodinoceras and a summary of mammalian vol. 14, p. 11. fossils of Sinkiang. Vertebrata PalAsiatica, FUNNELL, B. M., AND A. G. SMITH vol. 4, no. 2, pp. 99-102, 1 fig. 1968. Opening of the Atlantic Ocean. Nature, CHOW, M., AND C. Li vol. 219, pp. 1328-1333, figs. 1-4. 1963. A fossil of Homogalax from the Eocene of GRADZIN'SKI, R.,J. KAZMIERCZAK, AND J. LEFELD Shantung. Sci. Sinica, vol. 12, no. 9, 1969. Geographical and geological data from the pp. 1411-1412. Polish-Mongolian paleontological expedi- 1965. Homogalax and Heptodon of Shantung. tions. Palaeont. Polonica, no. 19, 1968, pp. Vertebrata PalAsiatica, vol. 9, no. 1, pp. 33-82, figs. 1-35, pls. 5-7. 15-21, 2 figs., 1 pl. [Chinese, with English GREGORY, W. K., AND G. G. SIMPSON summary.] 1926. Cretaceous mammal skulls from Mongolia. CHOW, M., and Y. TUNG Amer. Mus. Novitates, no. 225, pp. 1-20, 1965. Notes on some new uintathere materials of figs. 1-19. China. Vertebrata PalAsiatica, vol. 6, no. GROMOVA, V. 4, pp. 368-374, 1 fig., 1 pl. [Chinese, with 1952. On the primitive carnivores from the English summary.] Paleogene of Mongolia and Kazakhstan. CHOW, M., AND C. C. YOUNG Trudy Paleont. Inst. Akad. Nauk, U.S.S.R., 1963. Cretaceous and Paleocene vertebrate hori- vol. 41, pp. 51-77, figs. 1-13, 2 pls. [In zons of North Kwangtung. Sci. Sinica, Russian.] Acad. Sinica, vol. 12, no. 9, p. 1411. HARLAND, W. B. COPE, E. D. 1961. An outline structural history of Spitsbergen. 1875. On the supposed Carnivora of the Eocene of In Raasch, G. 0. (ed.), Geology of the the Rocky Mountains. Proc. Acad. Nat. Sci. Arctic. Toronto, Univ. Toronto Press, vol. Philadelphia, vol. 27, pp. 444-448. 1, pp. 68-132, figs. 1-6. DORF, E. 1969. Contribution of Spitsbergen to understand- 1959. Climatic changes of the past and present. ing of tectonic evolution of North Atlantic Contrib. Mus. Paleont. Univ. Michigan, region. In Kay, M. (ed.), North Atlantic- vol. 13, no. 8, pp. 181-2 10, 10 figs., 1 pl. geology and continental drift. Mem. Amer. DORR, J. A., JR. Assoc. Petrol. Geol., no. 12, pp. 817-851, 1958. Prouintatherium, a new uintathere genus, figs. 1-13. earliest Eocene, Hoback Formation, Wyom- HEEZEN, B. C., AND M. EWING ing, and the phylogeny of the Dinocerata. 1961. The Mid-Oceanic Ridge and its extension Jour. Paleont., vol. 32, no. 3, pp. 506-516, through the Arctic Basin. In Raasch, G. 0. 1 fig., pls. 75-77. (ed.), Geology of the Arctic. Toronto, Univ. FLEROV, K. K. Toronto Press, vol. 1, pp. 622-642, figs. 1- 1952a. Pantodonts (Pantodonta) collected by the 13. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 315 HEIRTZLER, J. R., G. 0. DiCKSON, E. M. HERRON, McKENNA, M. C., J. S. MELLETT, AND F. S. SZALAY W. C. PITMAN, III, AND X. LE PICHON [In press.] Relationships of the Cretaceous mammal 1968. Marine magnetic anomalies, geomagnetic Deltatheridium. Jour. Paleont. field reversals, and motions of the ocean MATHIESEN, F. J. floor and continents. Jour. Geophys. Res., 1932. Notes on some fossil plants from East vol. 73, no. 6, pp. 2119-2136, figs. 1-11. Greenland. Meddel. Gr0nland, vol. 85, IRVING, E. no. 4, pp. 3-62, figs. 1-24, pls. 1-6. 1964. Paleomagnetism and its application to geo- MATTHEW, W. D. logical and geophysical problems. New 1928. The evolution of the mammals in the York, Wiley, pp. i-xviii, 1-399. Eocene. Proc. Zool. Soc. London, pt. 4, JEPSEN, G. L., AND M. 0. WOODBURNE 1927, pp. 947-985, figs. 1-16. 1969. Paleocene hyracothere from Polecat Bench MATTHEW, W. D., AND W. GRANGER Formation, Wyoming. Science, vol. 164, 1925. Fauna and correlation of the Gashato pp. 543-547, 1 fig. Formation of Mongolia. Amer. Mus. Novi- JOHNSON, G. L., AND B. C. HEEZEN tates, no. 189, pp. 1-12, figs. 1-14. 1967. Morphology and evolution of the Nor- MATTHEW, W. D., W. GRANGER, AND G. G. SIMPSON wegian-Greenland Sea. Deep-Sea Res., vol. 1928. Paleocene multituberculates from Mon- 14, pp. 755-771, figs. 1-13. golia. Amer. Mus. Novitates, no. 331, pp. 1- KIELAN-JAwOROwSKA, Z. 4, figs. 1-5. 1969a. Archaeolambdidae Flerov (Pantodonta) 1929. Additions to the fauna of the Gashato from the Paleocene of the Nemegt Basin, Formation of Mongolia. Ibid., no. 376, Gobi Desert. Palaeont. Polonica, no. 19, pp. 1-12, figs. 1-13. 1968, pp. 133-140, 1 fig., pls. 15, 16. MORRIS, W. J. 1969b. Preliminary data on the Upper Cretaceous 1966. Fossil mammals from Baja California: new eutherian mammals from Bayn Dzak, Gobi evidence on early Tertiary migrations. Desert. Ibid., pp. 171-191, figs. 1-4, Science, vol. 153, no. 3742, pp. 1376-1378, pls. 22-27. 1 fig. KIELAN-JAWOROWSKA, Z., AND N. DOVCHIN NovoZHILOV, N. I. 1969. Narrative of the Polish-Mongolian Paleont- 1954. Localities of mammals from the lower ological Expeditions 1963-1965. Palaeont. Eocene and upper Paleocene of Mongolia. Polonica, no. 19, 1968, pp. 7-30, 1 fig., Trudy Mongolsky Comm. Akad. Nauk, pls. 1-4. U.S.S.R., no. 59, pp. 33-46, figs. 1-6. pls. 1-5. [In Russian.] KOCH, B. E. OSBORN, H. F. 1963. Fossil plants from the lower Paleocene ofthe 1898. Evolution of the Amblyopda. Part I. Tali- Agatdalen (Angmartussut) area, central grada and Pantodonta. Bull. Amer. Mus. Nfigssuaq Peninsula, northwest Greenland. Nat. Hist., vol. 10, art. 11, pp. 169-218, Meddel. Gr0nland, vol. 172, no. 5, pp. 1- figs. 1-29. 120, figs. 1-27, pls. 1-55. OSTENSO, N. A. KURTAN, B. 1968. Geophysical studies of the Greenland Sea. 1966. Holarctic land connexions in the early Bull. Geol. Soc. Amer., vol. 79, no. 1, Tertiary. Comment. Biol., Soc. Sci. Fennica, pp. 107-131, figs. 1-21. vol. 29, no. 5, pp. 1-5, 1 fig. PATTERSON, B. LARSON, E. E., F. E. MUTSCHLER, AND G. L. BRINK- 1939. New Pantodonta and Dinocerata from the WORTH upper Paleocene of western Colorado. Geol. 1969. Paleocene virtual geomagnetic poles deter- Ser. Field Mus. Nat. Hist., vol. 6, no. 24, mined from volcanic rocks near Golden, pp. 351-384, figs. 100-111. Colorado. Earth Planetary Sci. Letts., vol. 1958. Affinities of the Patagonian fossil mammal 7, pp. 29-32, figs. 1-4. Aecrolestes. Breviora, no. 94, pp. 1-14, 1 fig. McELHINNY, M. W., AND P. WELLMAN PATTERSON, B., AND R. PASCUAL 1969. Polar wandering and sea-floor spreading in 1968. Evolution of mammals on southern con- the southern Indian Ocean. Earth Planet- tinents. V. The fossil mammal fauna of ary Sci. Letts., vol. 6, pp. 198-204, figs. 1-4. South America. Quart. Rev. Biol., vol. 43, McKENNA, M. C. no. 4, pp. 409-451, figs. 1-13, tables 1-12. 1963. New evidence against tupaioid affinities of RADINSKY, L. B. the mammalian family Anagalidae. Amer. 1965. Early Tertiary Tapiroidea of Asia. Bull. Mus. Novitates, no. 2158, pp. 1-16, figs. Amer. Mus. Nat. Hist., vol. 129 art. 2, 1-6. pp. 181-264, figs. 1-41, pls. 1-4. 316 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY VOL. 144 RAJA, P. K. S. land. Earth Planetary Sci. Letts., vol. 1, 1964. The palaeomagnetism of some Scottish pp. 341-347, figs. 1, 2. Tertiary dykes and their baked contacts. SULIMSKI, A. Geophys. Jour. Roy. Astron. Soc., vol. 9, 1969. Paleocene genus Pseudictops Matthew, Gran- p. 15. ger, and Simpson, 1929 (Mammalia) and REYMENT, R. A. its revision. Palaeont. Polonica, no. 19, 1969. Ammonite biostratigraphy, continental 1968, pp. 101-129, figs. 1-4, pls. 10-14. drift, and oscillatory transgressions. Nature, SZALAY, F. S. vol. 224, pp. 137-140, figs. 1-9. 1969a. Mixodectidae, Microsyopidae, and the RICH, T. H. insectivore-primate transition. Bull. Amer. 1971. Deltatheridia, Carnivora and Condylarthra Mus. Nat. Hist., vol. 140, art. 4, pp. 193- (Mammalia) of the early Eocene, Paris 330, figs. 1-28, pls. 17-57. Basin, France. Univ. California Publs. Geol. 1969b. The Hapalodectinae and a phylogeny of the Sci., vol. 88, pp. 1-72, figs. 1-18. Mesonychidae (Mammalia, Condylarthra). ROBINSON, P. Amer. Mus. Novitates, no. 2361, pp. 1-26, 1969. Nyctitheriidae (Mammalia, Insectivora) figs. 1-19. from the Bridger Formation of Wyoming. 1969c. Origin and evolution of function of the Univ. Wyoming Contrib. Geol., vol. 7, mesonychid condylarth feeding mechanism. no. 2, Summer, 1968, pp. 129-138, 2 pls. Evolution, vol. 23, no. 4, pp. 703-720, ROMER, A. S. figs. 1-7. 1966. Vertebrate Paleontology. 3rd ed. Chicago, SZALAY, F. S., and S. J. GOULD Univ. Chicago Press, pp. i-x, 1-468, figs. 1966. Asiatic Mesonychidae (Mammalia, Con- 1-443. dylarthra). Bull. Amer. Mus. Nat. Hist., RUSSELL, D. E. vol. 132, art. 2, pp. 127-174, figs. 1-12, 1968. Succession, en Europe, des faunes mam- pls. 9-2 1. maliennes au debut du Tertiaire. M6m. TANG, Hs., AND M. CHOW Bur. Rech. Geol. Min., no. 58, pp. 291-296, 1964. The vertebrate-bearing early Tertiary of South China: a review. Vertebrata Pal- 1 fig., 1 table. Asiatica, vol. 8, no. 2, pp. 119-133, 1 fig. SAITO, T., L. H. BURCKLE, AND D. R. HORN [In Chinese.] 1967. Palaeocene core from the Norwegian basin. 1965. The vertebrate-bearing early Tertiary of Nature, vol. 216, p. 357. South China: a review. Internat. Geol. Rev. SAVAGE, D. E., D. E. RUSSELL, AND P. LouIs vol. 7, no. 8, pp. 1338-1352, 1 fig. [In 1965. European Eocene Equidae (Perissodactyla). English.] Univ. California Publs. Geol. Sci., vol. 56, TROFIMOV, B. A. pp. i-vi, 1-94, figs. 1-42, 1 pl. 1952. On the genus Pseudictops-a peculiar in- SCHAFFER, F. X. sectivore from the lower Tertiary deposits 1924. Lehrbuch der Geologie. II. Teil. Grund- of Mongolia. Trudy Paleont. Inst. Akad. zuge der historischen Geologie (Geschichte Nauk, U.S.S.R., vol. 41, pp. 7-12, figs. 1-4. der Erde, Formationskunde. Leipzig und [In Russian.] Vienna, Franz Deuticks. pp. i-xii, 1-628, VAN VALEN, L. figs. 1-705. 1964. A possible origin for rabbits. Evolution, SIMONS, E. L. vol. 18, no. 3, pp. 484-491, figs. 1-3. 1960. The Paleocene Pantodonta. Trans. Amer. 1966. Deltatheridia, a new order of mammals. Phil. Soc., new ser., vol. 50, pt. 6, pp. 1-99, Bull. Amer. Mus. Nat. Hist., vol. 132, figs. 1-18. art. 1, pp. 1-126, figs. 1-17, pls. 1-8. SIMPSON, G. G. 1967. New Paleocene insectivores and insectivore 1931. A new insectivore from the Oligocene, Ulan classification. Ibid., vol. 135, art. 5, pp. 217- Gochu horizon, of Mongolia. Amer. Mus. 284, figs. 1-7, pls. 6, 7. Novitates, no. 505, pp. 1-22, figs. 1-5. VAN VALEN, L., AND R. E. SLOAN 1936. Census of Paleocene mammals. Ibid., no. 1966. The extinction of the multituberculates. 848, pp. 1-15. Syst. Zool., vol. 15, no. 4, pp. 261-278, 1947. Holarctic mammalian faunas and conti- figs. 1-5. nental relationships during the Cenozoic. VOGT, P. R., N. A. OSTENSO, AND G. L. JOHNSON Bull. Geol. Soc. Amer., vol. 58, pp. 613- 1970. Magnetic and bathymetric data bearing on 688, figs. 1-6. sea-floor spreading north of Iceland. Jour. SMITH, P. J. Geophys. Res., vol. 75, no. 5, pp. 903-920, 1966. Tertiary geomagnetic field reversal in Scot- figs. 1-13. 1971 SZALAY AND MCKENNA: GASHATO FAUNA 317

VOLLSTADT, H., K. ROTHER, AND P. NOZHAROV Eleventh Pacific Sci. Congr., Symp. no. 25. 1968. The palaeomagnetic stability and the WOOD, A. E. petrology of some Caenozoic and Cre- 1942. Notes on the Paleocene lagomorph, Eury- taceous andesites from Bulgaria. Earth mylus. Amer. Mus. Novitates, no. 1162, Planetary Sci. Letts., vol. 3 [1967], pp. 399- pp. 1-7, figs. 1-7. 408, figs. 1-9. 1957. What, if anything, is a rabbit? Evolution, WHEELER, W. vol. 11, no. 4, pp. 417-425, 1 fig. 1961. Revision of the uintatheres. Bull. Peabody YOUNG, C. C. Mus. Nat. Hist., no. 14, pp. 1-93, figs. 1-9, 1944. Note on the first Eocene mammal from pls. 1-14. South China. Amer. Mus. Novitates, no. WILSON, J. T. 1268, pp. 1-3, 1 fig. 1963. Hypothesis of Earth's behaviour. Nature, 1964. New fossil crocodiles from China. Verte- vol. 198, pp. 925-929, figs. 1-6. brata PalAsiatica, vol. 8, no. 2, pp. 189-208, 1965. A new class of faults and their bearing on figs. 1-6, 2 pls. continental drift. Ibid., vol. 207, pp. 343- Young, C. C., AND M. CHOW 347, figs. 1-10. 1962. Some reptilian fossils from the "Red Beds" WOLFE, J. A. of Kwangtung and Chekiang. Vertebrata 1966. Tertiary plants from the Cook Inlet region, PalAsiatica, vol. 6, no. 2, pp. 130-135, Alaska. U.S. Geol. Surv. Prof. Paper no. 2 figs., 1 pl. 398-B, pp. i-vi, 1-32, figs. 1-12, pls. 1-8. 1963. Cretaceous and Paleocene vertebrate hori- 1969. Paleogene floras from the Gulf of Alaska zons of north Kwangtung. Sci. Sinica, vol. region. U.S. Geol. Surv. Open File Rept., 12, no. 9, p. 1411. pp. i-ii, 1-111, figs. 1-8, pls. 1-6. ZDANSKY, 0. WOLFE, J. A., AND D. M. HoPKINS 1930. Die alttertiaren Saugetiere Chinas nebst 1967. Climatic changes recorded by Tertiary land stratigraphischen Bemerkungen. Paleont. floras in northwestern North America. In Sinica, ser. C, vol. 6, fasc. 2, pp. 5-87, Hakai, K. (ed.), Tertiary correlations and figs. 1-7, pls. 1-5. climatic changes in the Pacific. Tokyo,