ASIA

With the exception of Mongolia, Asia has been a virtual tabula rasa for mammals of Early Cretaceous age until re cently. New discoveries, many of which remain to be described, show that fossils from central and eastern Asia will play a key role in interpreting mammalian history during this pivotal interval. We have drawn from several of the useful summaries of these discoveries (Nessov, Sigogneau-Russell, and Russell, 1994; Wang et al., 1995; Nessov, 1997; Novikov et al., 1998; Averianov, 2000), together with original sources (the most important of which are cited in those works) and other information in providing the following account.

Uzbekistan and Russia

Most of the relatively recent advances in knowledge of early mammals from Middle Asia are occurrences of Late Cretaceous age (summarized below), with one exception: Bobolestes zhenge, from the Khodzhakul locality in the Khodzhakul Formation, Kizylkum Desert, Uzbekistan (figure 2.11). The age is believed to be late Albian, based on the shark fauna. Bobolestes is a rather primitive euther-ian and was first referred to the Pappotheriidae (Nessov, 1985a) before being placed in its own family (see Averi-anov, 2000).

The site of Shestakovo (Ilek Formation), in the Kemerovo region of Siberian Russia (figure 2.12), has thus far yielded two mammals: the eutriconodontan Gobicon-odon borissiaki (see Maschenko and Lopatin, 1998; Ali-fanov et al., 1999) and an as yet unidentified "symmetro-dontan." The site is notable in that it preserves articulated dinosaur remains; the fauna reportedly includes two species of Psittacosaurus, the protosuchian crocodilian Tagarosuchus, and a tritylodont; on the basis of the last two Novikov et al. (1998) suggested an earliest Cretaceous (Berriasian) age for the site. However, other workers (Ave-rianov and Skutschas, 2000a) indicated that Shestakovo is of Albian age. Given the occurrence of the same species of Gobiconodon at Hoovor, Mongolia, and the projected age of that site (see later), we believe that this latter estimate may be nearer to the mark. Tritylodontids were long thought to have become extinct in the Jurassic; in addition to the occurrence at Shestakovo (Tatarinov and Maschenko, 1999), an Early Cretaceous tritylodontid is now known from Japan (Setoguchi, Matsuoka, and Matsuda, 1999).

A second site in Russia, the Mogoito locality in the Murtoi Formation, Transbaikalia (figure 2.12), has thus

figure 2.11. Jurassic (asterisks, localities 1, 2,12) and Cretaceous (black diamond, locality 3, Early Cretaceous; gray diamonds, localities 4-11, Late Cretaceous) mammal sites of middle Asia and Russia (part). Localities or local faunas: 1, Kalmakerchin; 2, Tashkumyr (both Balabansay Formation; Callovian, Middle Jurassic, Kirghizia); 3, Khodzhakul (Khodzhakul Formation; late Albian, Uzbekistan); 4, Khodzhakulsay; 5, Sheikhdzheili; 6, Chelpyk (all Khod-zhakul Formation; early Cenomanian, Karakal-pakistan, Uzbekistan); 7, Ashikol (unnamed unit; ?early Turonian, Chim-kent District, Kazakhstan); 8, Dzhara-kuduk (late Turonian and Coniacian localities in the Bissekty Formation and Santonian, Aitym Formation; Uzbekistan); 9, Kansay (early Santonian, Khodzant District, Tajikistan); 10, Zhal-mauz Well (lower Bostobe Formation; Santonian, Kyzyl-Orda Province, Kazakhstan); 11, Grey Mesa (= Alymtau; Dar-basa Formation, early Campanian); 12, Peski Quarry (fissure filling; late Bathonian, Kolomensk District, Russia). (Not shown: Yantardakh; Khets Formation, Santonian, Siberia.)

figure 2.12. Late Jurassic (Mongolia) and Early Cretaceous (Russia,Mongolia,and China) mammal sites.White asterisk (locality 1), Late Jurassic; diamonds (localities 2-19), Early Cretaceous. Localities or local faunas: 1, Shar Teeg (Late Jurassic, Mongolia); 2, Shestakovo (Ilek Formation; Albian, Kemerovo District, Russia); 3,Mogoito (Murtoi Formation; ?Barremian-Aptian or Aptian-Albian,Transbaikalia, Russia); 4, Hoovor ("Hoovor Beds"; ?Aptian-Albian, Mongolia); 5, Oshih (Oshih Formation; ?Valanginian, Mongolia); 6, Khamaryn Us (Khukhtyk or Dzunbain Formation; ?Aptian-Albian, Mongolia); 7, Huang-Ni-Tan (Shengjinkou Formation; Early Cretaceous, Xinjiang, China); 8, Mazongshan (lower Xinmingbao Group; ?Barremian-Albian, Gansu, China); 9, Laolonghuoze; 10, Hangjin-Qi; 11, Yanhaizi; (all Eijinhoro Formation; ?Barremian, Inner Mongolia, China); 12, Elesitai (Bayan Gobi Formation; ?Aptian-Albian, Inner Mongolia, China); 13, Jianshangou; 14, Sihetun; 15, Lu-Jia-Tun (all Yixian Formation; middle Barremian, Liaoning, China); 16, Xindi; 17, Xinqiu (both Fuxin Formation; ?Aptian or Albian-Cenomanian, Liaoning, China); 18, Badaohao (Shahai Formation; ?Aptian, Liaoning,China); 19, Dawangzhangzi (Yixian Formation; middle Barremian, Liaoning, China).

figure 2.12. Late Jurassic (Mongolia) and Early Cretaceous (Russia,Mongolia,and China) mammal sites.White asterisk (locality 1), Late Jurassic; diamonds (localities 2-19), Early Cretaceous. Localities or local faunas: 1, Shar Teeg (Late Jurassic, Mongolia); 2, Shestakovo (Ilek Formation; Albian, Kemerovo District, Russia); 3,Mogoito (Murtoi Formation; ?Barremian-Aptian or Aptian-Albian,Transbaikalia, Russia); 4, Hoovor ("Hoovor Beds"; ?Aptian-Albian, Mongolia); 5, Oshih (Oshih Formation; ?Valanginian, Mongolia); 6, Khamaryn Us (Khukhtyk or Dzunbain Formation; ?Aptian-Albian, Mongolia); 7, Huang-Ni-Tan (Shengjinkou Formation; Early Cretaceous, Xinjiang, China); 8, Mazongshan (lower Xinmingbao Group; ?Barremian-Albian, Gansu, China); 9, Laolonghuoze; 10, Hangjin-Qi; 11, Yanhaizi; (all Eijinhoro Formation; ?Barremian, Inner Mongolia, China); 12, Elesitai (Bayan Gobi Formation; ?Aptian-Albian, Inner Mongolia, China); 13, Jianshangou; 14, Sihetun; 15, Lu-Jia-Tun (all Yixian Formation; middle Barremian, Liaoning, China); 16, Xindi; 17, Xinqiu (both Fuxin Formation; ?Aptian or Albian-Cenomanian, Liaoning, China); 18, Badaohao (Shahai Formation; ?Aptian, Liaoning,China); 19, Dawangzhangzi (Yixian Formation; middle Barremian, Liaoning, China).

far yielded an upper and a lower molar, first placed in the species Prokennalestes abramovi and later transferred to the new genus, Murtoilestes (Averianov and Skutschas, 2000a, 2001). The occurrence is a notable one because it is believed to be Barremian-Aptian and, hence, perhaps older than Hoovor, the source of Prokennalestes.

Mongolia

A useful, relatively recent summary on Mongolian vertebrate faunas and their age, relationships, and strati-graphic context is provided by Jerzykiewicz and Russell (1991). They pointed out that the fossil assemblages, as characterized by molluscs and vertebrates (Martinson, 1982), are analogous to the land-mammal ages of North America and can be used as the basis for Mongolian land-vertebrate ages. The only Early Cretaceous "age" relevant in the current context is the Khukhtekian, which has been characterized by the presence of harpymimid theropods and Iguanodon, as well as abundant Psittacosaurus (which is also common to older assemblages). The best repre sented Early Cretaceous mammal assemblage of Mongolia (figure 2.12), that of Hoovor (Trofimov 1978, 1980; Dashzeveg, 1979,1994;Dashzeveg and Kielan-Jaworowska, 1984; Kielan-Jaworowska, Dashzeveg, and Trofimov, 1987; Kielan-Jaworowska and Dashzeveg, 1989; Sigogneau-Russell et al., 1992), is referred to the Khukhtekian. Jerzykie-wicz and Russell (1991) considered the Khukhtekian to be Aptian-Albian in age, based on plant megafossils and elas-mobranchs, as well as on the absence of trionychid turtles, and this was corroborated by Shuvalov (2000). The section at Hoovor is more than 100 m thick, and the lacustrine and lacustrine-fluvial (deltaic) facies predominate. Shuvalov (2000) pointed out that the Aptian-Albian deposits in the region are more than 500 m thick. The beds that crop out at Hoovor have not been formally designated, and we refer to them for the purpose of this book informally as "Hoovor Beds."

The Aptian-Albian age of "Hoovor Beds" accords with a similar estimate, based on the shared presence of Gobi-conodon in both Hoovor and in the Cloverly Formation of

Montana (Jenkins and Schaff, 1988; Kielan-Jaworowska and Dashzeveg, 1998). It should be pointed out, however, that the age of the Cloverly itself is only loosely constrained and is based mainly on similarity of its vertebrate fauna to that of the Trinity Group, Texas, which has in-terbedded marine horizons (Jacobs et al., 1991; Jacobs and Winkler, 1998). Moreover, some elements of the Hoovor mammal assemblage, such as the eutriconodontan Gobi-conodon, are now being reported from units said to be Bar-remian (e.g., Cuenca-Bescos and Canudo, 1999) or even older (Maschenko and Lopatin, 1998; Novikov et al., 1998; Rougier et al., 2001). On the other hand, recent palyno-logical evidence suggests that at least one Khukhetian ver tebrate fauna is no older than than middle-late Albian (Hicks et al., 1999). Given the equivocal nature of the available data, an Aptian-Albian age for the Hoovor assemblage must be considered tentative.

The Hoovor fauna, discovered by Soviet-Mongolian Expeditions, includes some 17 mammalian taxa (table 2.11). It is of great interest because it contains some apparently primitive species, as well as early members of advanced groups and bizarrely specialized forms. Of the six or so multituberculates, most are comparable to "pla-giaulacidans" more characteristic of Late Jurassic and earliest Cretaceous faunas, while the uniquely derived Argin-baatar seems to fall between "plagiaulacidans" and the ta b l e 2.11. Early Cretaceous Mammals of Asia and Asiatic Part of Russia (see figure 2.12; locality numbers do not correspond between map and table). Localities: 1, Khodzhakul, Uzbekistan (Khodzhakul Formation, late Albian); 2, Shestakovo, Russia (Ilek Formation, ?Albian); 3, Mogoito, Russia (Murtoi Formation, ?Barremian-Aptian); 4, Hoovor, Mongolia ("Hoovor Beds," referred to also as Guchin Us Beds, ?Aptian-Albian); 5, Khamaryn Us, Mongolia (Khukhtyk or Dzunbain Formation, ?Aptian-Albian); 6, Elesitai, Inner Mongolia, China (Bayan Gobi Formation, ?Aptian-Albian); 7, Laolonghuoze; 8, Yanhaizi; 9, Hangjin-Qi, Inner Mongolia, China (all Eijinhoro Formation, ?Barremian); 10, Mazongshan, Gansu, China (Xinmingbao Group, Barremian-Albian); 11, Huang-Ni-Tan, Xinjiang, China (Shengjinkou Formation, Early Cretaceous); 12, Xinqiu; 13, Xindi, Liaoning, China (both Fuxin Formation, ?Aptian-Albian or Cenomanian); 14, Badaohao, Liaoning, China (Shahai Formation, ?Aptian); 15, Jianshangou; 16, Sihetun; 17, Lu-Jia-Tun; 18, Dawangzhangzi, Liaoning, China (all Yixian Formation, middle Barremian); 20, Oshih, Mongolia (Oshih Formation, ?Valanginian); 21, Kaseki-kabe, Ishikawa Prefecture, Japan (Kuwajima Formation, Hauterivian)

Mammalia incertae sedis (6, 7, 8, 11)

Family incertae sedis

Eutriconodonta

Gen. et sp. indet. (13)

"Amphilestidae"

Archaic "symmetrodontans"

Gen. et sp. indet. (5, 21)

Family incertae sedis

Gobiconodontidae

Gobiotheriodon infinitus (4)

Gobiconodon borrissiaki (2, 4)

Gen. et sp. indet. (14)

Gobiconodon hoburensis (4)

Stem Trechnotheria

Gobiconodon hopsoni (20)

Spalacotheriidae

Gobiconodon sp. nov. A (17)

Zhangheotherium quinquecuspidens (15)

Gobiconodon sp. nov. B (20)

Stem Cladotheria ("eupantotherians")

Hangjinia chowi (9)

Arguitheriidae

Repenomamus robustus (17)

Arguitherium cromptoni (4)

Gen. et sp. nov. (10)

Arguimuridae

Family incertae sedis

Arguimus khosbajari (4)

Jeholodens jenkinsi (16)

Stem Boreosphenida ("tribotherians")

Multituberculata

Aegialodontidae

?Albionbaataridae

Kielantherium gobiensis (4)

cf. Albionbaatar sp. (14)

Gen. et sp. indet. (14)

Arginbaataridae

Eutheria

Arginbaatar dmitrievae (4)

Family incertae sedis

Eobaataridae

Endotherium niomii (12)

Eobaatar magnus (4)

Eomaia scansoria (18)

Eobaatar minor (4)

Gen. et sp. indet. (4, 15)

Eobaatar sp. A (4)

Bobolestidae

Eobaatar sp. B (4)

Bobolestes zenge (1)

Monobaatar mimicus (4)

Kennalestidae

Sinobaatar lingyuanensis (18)

Murtoilestes abramovi (3)

Gen. et sp. indet. (21)

Prokennalestes minor (4)

?Plagiaulacidae

Prokennalestes trofimovi (4)

Gen. et sp. indet. (14)

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