A. burkei Dawson, 1964, and Khodzhentia vinogradovi ...... I am very grateful to Drs Donald RUSSELL and Vladimir GUSAROV for the help in preparation.
Bulletin du Museum national d'Histoire naturelle, Paris, 4' serie, 18, 1996 Section C, n° 4 : 629-662
Early Eocene Rodentia of Kyrgyzstan by Alexander A VERIANOV
Abstract. - Remains of the ctenodactyloid rodents Petrokozlovia cf. P. notos Shevyreva, 1972, Saykanomys cf. S. bohlini (Dawson, 1964) comb. nov., Advenimus cf. A. burkei Dawson, 1964, and Khodzhentia vinogradovi n.g. et n.sp (all Chapattimyidae), Alaymys ctenodactylus Averianov, 1993 and ?Adolomys sp. (Tamquammyidae) and Ctenodactyloidea indet. are described from the latest Early Eocene (late Ypresian, Cuisian) locality Andarak 2 in Kyrgyzstan. A review of other Eocene ctenodactyloid rodents is given. They consist of three families : Alagomyidae, Chapattimyidae (= Yuomyidae, = Advenimurinae) and Tamquammyidae (= Cocomyidae, = Orogomyidae). Probably the Ctenodactylidae originated in the Eocene. Ctenodactylidae and Baluchimyinae are monophyletic taxa, whereas Chapattimyidae is a clearly paraphyletic taxon. A paraphyletic status for the Tamquammyidae is also probable. The simultaneous evolution of diverse and differently adapted lineages of Glires in the humid environments of the coastal plains of South Asia (including the territory of Kyrgyzstan), resulted in the origin and further dispersal into more continental areas of such progressive groups as tamquammyid and ctenodactylid rodents, lagomorphs and highly derived mimotonids. Key-words. -
Rodentia, Eocene, Kyrgyzstan, cladistic analysis.
Description de rongeurs de !'Eocene inferieur terminal du Kirghizistan Resume. - Cet article decrit des echantillons de rongeurs de I 'Eocene inferieur terminal (Ypresien tardif, Cuisien) de la localite Andarak 2 du Kirghizistan; ii s'agit de Petrokozlovia cf. P. notos Shevyreva, 1972, Saykanomys cf. S. bohlini (Dawson, 1964) comb. nov., Advenimus cf. A. burkei Dawson, 1964, Khodzhentia vinogradovi n.g. et n.sp. (Chappatimyidae), Alaymys ctenodactylus Averianov, 1993 et ?Adolomys sp. (Tamquammyidae), ainsi que de Ctenodactyloidea indet. Suit une revue d'autres rongeurs ctenodactyloides eocenes appartenant a trois familles : Alagomyidae, Chapattimyidae (= Yuomyidae, = Advenimurinae) et Tamquammyidae (= Cocomyidae, = Orogomyidae). Les Ctenodactylidae et Jes Baluchimyinae sont probablement des taxons monophyletiques, tandis que Jes Chapattimyidae representent resolument un taxon paraphyletique. La nature paraphyletique des Tamquammyidae est elle aussi probable. L' evolution de diverses lignees de glires aux adaptations differentes, qui s'est produite dans l'environnement humide des plaines cotieres d'Asie du Sud (incluant le territoire du Kirghizistan) a eu pour resultat I' origine, et la dispersion ulterieure dans des milieux plus continentaux, de groupes aussi progressifs que Jes rongeurs tamquammyides et ctenodactylides, Jes lagomorphes et les formes hautement derivees que sont Jes mimotonides. Mots-cles. A. AvERIANov,
Rongeurs, Eocene, Kirghizistan, analyse cladistique.
Zoological Institute, Russian Academy of Sciences, Universitetskaya nab.I. 199034 St. Petersburg, Russia.
-630INTRODUCTION During the past decades great progress has been made in the study of Asian Paleogene mammals. The high number of species known from the mammal assemblages of China, Mongolia, Kazakhstan and Pakistan approximates the rich and diverse Paleogene assemblages from North America (RUSSELL & ZHAI 1987). However, the study of the evolution of different mammal groups and of the mammal fauna as a whole in the Paleogene of Asia is greatly confused due to the scarcity of reliable geochronological data. Most of the mammal-bearing localities in China, Mongolia, and Kazakhstan formed in continental deposits lacking remains of marine microfossils (Foraminifera, calcareous nannoplankton, or Radiolaria), upon which the detailed Paleogene time scale is based (HARLAND et al. 1990). The Eocene mammal assemblages from Pakistan and India accumulated in sediments of essentially freshwater or hypersaline basins and also cannot be correlated with the stratotypic Paleogene marine sections of Europe. Thus researchers on Paleogene mammals of Asia must determine the age of mammal assemblages by using the mammals themselves, that is, mostly the level of evolutionary development of the different mammalian taxa (index fossils, or widespread elements in the Paleogene faunas are too rare). Based on these "dates", researches study the evolution of the mammal faunas, which leads to circular conclusions. Using this "method", it is impossible to recognize heterochronies in the evolution of faunas, the time and place of origin for mammalian groups, the geographical and chronological pattern of their dispersal, the real dynamics of faunal turnover and its regional peculiarities, and other important problems. Undoubtedly, the study of faunal evolution should be carried out using age determinations from sources independent of this evolution. One of the rare cases meeting this requirement is the relatively diverse mammal fauna from the Andarak 2 locality in Kyrgyzstan. Quite abundant mammal remains from there were found deposited in marine coastal sediments yielding also numerous remains of other vertebrates; most important of these is the extremely rich fauna of chondrichthyan fishes (about thirty-five species), which can be compared directly with the sharks of Paniselian beds of Belgium (Uppermost Ypresian, Cuisian). The latter is approximately equivalent to the lower part of calcareous nannoplankton zone NP14, about 50 m.y. (AVERIANOV & UDOVICHENKO 1993). Hence the Andarak 2 locality is equivalent in age to the European Paleogene mammal unit MPlO (SCHMIDT-KITTLER 1987). As it now appears, further exploitation of this important locality will promote better dating of the Central Asiatic Paleogene mammal faunas and, finally, a better understanding of the evolution of these faunas and of individual mammalian groups. The geographical and geological settings of the Andarak 2 locality are given on Fig. 1. More detailed information, as well as a faunal list and a discussion of the geological age of this locality are given elsewhere (RESHETOV et al. 1978; RUSSELL & ZHAI 1987; AVERIANOV & UDOVICHENKO 1993; AVERIANOV 1994b). Among the mammals from the Andarak 2 locality are represented varied tapiroids, one species of the oldest amynodonts, a chalicothere, two taxa of diacodexid artiodactyls, a hyaenodontid and a large mesonychid are represented. But most abundant are remains of diverse Glires: ctenodactyloid rodents (Chapattimyidae and Tamquammyidae), the oldest lagomorphs (at least two taxa), and mimotonids. Only the following species from this fauna have been described:
-631the tapiroids Rhodopagus minutissimus Reshetov, 1979 and Pataecops microdon Reshetov, 1979, the tamquammyid rodent Alaymys ctenodactylus Averianov, 1993, the palaeoryctoid "insectivore" Sarcodon udovichenkoi Averianov, 1994a, the mimotonids Anatolmylus rozhdestvenskii Averianov, 1994b and Aktashmys montealbus Averianov, 1994b, and the lagomorph Valerilagus reshetovi Shevyreva, 1995.
69° 15' E
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