Alexander O. Averianov

Late Cretaceous relatives of rabbits, rodents, and other extant eutherian mammals

Extant eutherian mammals and their most recent common ancestor constitute the crown group Placentalia. This taxon, plus all extinct taxa that share a more recent common ancestor with placentals than they do with Metatheria (including marsupials), constitute Eutheria. The oldest well documented eutherian-dominated fauna in the world is Dzharakuduk, Uzbekistan. Among eutherians that it yields is Kulbeckia, an 85–90-Myr-old member of Zalambdalestidae (a family of Late Cretaceous Asian eutherians). This extends Zalambdalestidae back by some 10 million years from sites in the Gobi Desert, Mongolia. A phylogenetic analysis of well described Late Cretaceous eutherians strongly supports Zalambdalestidae, less strongly supports ‘Zhelestidae’ (a Late Cretaceous clade related to Tertiary ungulates), but does not support Asioryctitheria (a group of Late Cretaceous Asian eutherians). A second analysis incorporating placentals from clades that include rodents (Tribosphenomys), lagomorphs (Mimotona) and archaic ungulates (Protungulatum and Oxyprimus) strongly supports Zalambdalestidae in a clade with Glires (rabbits, rodents and extinct relatives) and less strongly ‘Zhelestidae’ within a clade that includes archaic ungulates (‘condylarths’). This argues that some Late Cretaceous eutherians belong within the crown group Placentalia. The ages of these taxa are in line with molecularly based estimates of 64–104 Myr ago (median 84 Myr ago) for the superordinal diversification of some placentals, but provide no support for a Late Cretaceous diversification of extant placental orders.

A new basal hadrosauroid dinosaur from the Late Cretaceous of Uzbekistan and the early radiation of duck-billed dinosaurs.

Levnesovia transoxiana gen. et sp. nov., from the Late Cretaceous (Middle–Late Turonian) of Uzbekistan, is the oldest well-documented taxon referable to Hadrosauroidea sensu Godefroit et al. It differs from a somewhat younger and closely related Bactrosaurus from Inner Mongolia (China) by a tall sagittal crest on the parietals and the absence of club-shaped dorsal neural spines in adult specimens. Levnesovia, Bactrosaurus and possibly Gilmoreosaurus represent the earliest radiation of Hadrosauroidea, which took place during the Cenomanian–Turonian and possibly in North America. The second, Santonian-age radiation of Hadrosauroidea included Aralosaurus, Hadrosauridae and lineages leading to Tanius (Campanian) and Telmatosaurus (Maastrichtian). Hadrosauridae appears to be monophyletic, but Hadrosaurinae and Lambeosaurinae originated in North America and Asia, respectively.

A Ceratopsian dinosaur Psittacosaurus sibiricus from the Early Cretaceous of West Siberia, Russia and its phylogenetic relationships

Synopsis Psittacosaurus sibiricus from the Aptian‐Albian Ilek Formation at Shestakovo, Kemerovo Province, West Siberia, is represented by two almost complete adult skeletons, several associated groups of bones and numerous isolated bones of individuals ranging from post‐hatchling to fully grown animals. Psittacosaurus sibiricus differs from nine other species of the genus by a unique combination of 32 diagnostic characters, six of which are autapomorphies of the species: small in‐fratemporal fenestra, anteroposteriorly short premaxilla, short medial process of postorbital, deep cleft for qaudratojugal on jugal, extending to the posterior side of jugal horn, angular with prominent tuber and 23 presacrals. Psittacosaurus sibiricus is the sister species of P. sinensis, with which it shares the prominent pyramidal laterally projecting jugal horn, but more derived than the latter in having more developed palpebral and postorbital horns. The three lateral foramina on the exoc‐cipital/opisthotic are interpreted as exits for cranial nerves X+XI, XII1+2 and XII3, in contrast with previous interpretations. Cranial nerve IX exits the brain cavity through the metotic fissure. Most Psittacosaurus localities are confined to lacustrine deposits and this animal undoubtedly inhabited areas around the great lakes widely distributed in Central Asia during the Early Cretaceous. The age of the Psittacosaurus biochron is estimated as Hauterivian‐Albian.

A new troodontid (Dinosauria: Theropoda) from the Cenomanian of Uzbekistan, with a review of troodontid records from the territories of the former Soviet Union

Abstract Based on a review of troodontid specimens from the territories of the former Soviet Union, including new discoveries from Uzbekistan, two dental morphotypes can be distinguished among Troodontidae from the Cretaceous of Asia: (1) unserrated teeth, present in Mei from Lujiatun (China; Early Cretaceous: Hauterivian-Barremian), an unnamed taxon from Hövöör (Mongolia; Early Cretaceous: Aptian-Albian), Urbacodon itemirensis, gen. et sp. nov. from Itemir and Urbacodon sp. from Dzharakuduk (Uzbekistan; Late Cretaceous: Cenomanian and Turonian, respectively), and Archaeornithoides from Bayn Dzak and Byronosaurus from Ukhaa Tolgod (Mongolia; Late Cretaceous: Campanian); and (2) serrated teeth, present in Sinornithoides from Huamuxiao (China; Early Cretaceous) and Sinornithoides-like taxa from Khamryn Us (Mongolia; Early Cretaceous: Aptian-Albian), Shestakovo (Russia; Early Cretaceous: Aptian-Albian), and Sheikhdzheili (Uzbekistan; Late Cretaceous: Cenomanian); Troodontidae indet. from Kansai (Tajikistan; Late Cretaceous: Santonian) and Alymtau (Kazakhstan; Late Cretaceous: Campanian), Saurornithoides (Mongolia and China; Late Cretaceous: Campanian-Maastrichtian), and Troodon from Kakanaut and Blagoveshchensk (Russia; Late Cretaceous: Maastrichtian).

New material of the Late Cretaceous deltatheroidan mammal Sulestes from Uzbekistan and phylogenetic reassessment of the metatherian-eutherian dichotomy

Sulestes karakshi Nessov, 1985b (= Deltatheroides kizylkumensis Nessov, 1993 = Marsasia aenigma Nessov, 1997) from the Late Cretaceous (Turonian) Bissekty local fauna, Kyzylkum Desert, Uzbekistan, is revised based on additional material from the type locality. It is characterized by an absence of palatal vacuities, double-rooted P1, an asymmetrical M3 with reduced metastylar lobe, an unreduced M4 and m4, obliquely oriented p1, anterior wall of the upper canine alveolus formed by premaxilla, and Meckelian groove on the dentary. PAUP analyses using a data matrix modified from Rougier et al. (1998, 2004) places Sulestes within Deltatheridiidae in an unresolved trichotomy with the Mongolian Campanian Deltatheridium and Deltatheroides. Oklatheridium from the Early Cretaceous of North America is sister taxon to these Late Cretaceous Asiatic deltatheridiidans. Deltatheridiidae is the sister group to other Metatheria including the crown clade Marsupialia. A Deltatheroides-like taxon from the Maastrichtian at Guriliin Tsav, Mongolia, is not related to the Stagodontidae but is sister taxon to other Boreometatheria. The North American Early Cretaceous Atokatheridium, Pappotherium, and Montanalestes are stem tribosphenic mammals, while Holoclemensia is at the base of the eutherian lineage.

Mammals from the Upper Cretaceous Aitym Formation, Kyzylkum Desert, Uzbekistan

The Upper Cretaceous (?Santonian) Aitym Formation in the central Kyzylkum Desert, Uzbekistan, produced remains of a cimolodontan multituberculate (Uzbekbaatar wardi), a spalacotheriid symmetrodont (cf. Shalbaatar sp.), a deltatheroidan (cf. Deltatherus sp.), possibly the asioryctithere aff. Daulestes sp., possibly two zalambdalestids (Kulbeckia sp. cf. K. kulbecke and aff. Kulbeckia sp.), two supposed lipotyphlans (Paranyctoides sp. cf. P. aralensis and Paranyctoides sp.), and zhelestid ungulatomorphs (cf. Aspanlestes sp., Parazhelestes sp. aff. P. minor, Parazhelestes sp. cf. P. robustus, and Eoungulatum sp. cf. E. kudukensis). The Aitym mammal fauna is most similar to the more diverse mammal fauna of the underlying Bissekty Formation (upper Turonian–Coniacian). Uzbekbaatar and Shalbaatar were most probably derived from North American immigrants. Paranyctoides and ‘Zhelestidae’ are of Middle Asian (a commonly and long used Soviet geographic region approximately extending from the Caspian Sea on the west to the Chinese border on the east, and from the Iranian and Afghan borders on the south to southern Kazakhstan on the north) origin and migrated to North America during the late Santonian–early Campanian. A dispersal route was present in Beringia during the entire Late Cretaceous, which may have worked as a cold filter, allowing intercontinental dispersals between Asia and western North America in both directions, especially during shorter, warm climatic phases. 2003 Published by Elsevier Ltd.

Mammalian Faunal Succession in the Cretaceous of the Kyzylkum Desert

Both metatherians and eutherians are known from the Early Cretaceous (Barremian, 125 mya; million years ago) of China, while eutherian-dominated mammalian faunas appeared in Asia at least by the earliest Late Cretaceous (Cenomanian, 95 mya). The approximately 99–93 my old (Cenomanian) Sheikhdzheili l.f. from western Uzbekistan is a small sample of only eutherians, including three zhelestids and a possible zalambdalestoid. The much better-known 90 my old (Turonian) Bissekty l.f. at Dzharakuduk in the central Uzbekistan includes 15 named and unnamed species, based on ongoing analyses. Of these, 12 are eutherians represented by at least the three groups—asioryctitheres, zalambdalestids, and zhelestids—plus an eutherian of uncertain position—Paranyctoides. Zalambdalestids and zhelestids have been argued to be related to the origin of the placental gliriforms (Euarchontoglires) and ferungulates (Laurasiatheria), respectively. Although there are four previously recognized metatherians, we believe three are referable to the deltatheroid Sulestes karakshi and the fourth, Sailestes quadrans, may belong to Paranyctoides. There is one multituberculate and one symmetrodont in the Bissekty l.f. While comparably aged (Turonian) localities in North America have somewhat similar non-therians, they have more metatherians and no eutherians. The next younger localities (early Campanian, ∼80 mya) in North America have both a zhelestid and Paranyctoides, suggesting dispersal of eutherians from Asia. At Dzharakuduk, the approximately 85 my old (late Turonian/Coniacian) Aitym l.f. is much less well known than the Bissekty l.f., but yields nearly identical taxa, with two non-therians, one metatherian, and six eutherians.

A new locality of Late Cretaceous snakes, mammals and other vertebrates in Africa (western Libya)

Abstract s sp. nov. (Reptilia sp. nov. (Reptilia, Serpentes, Simoliopheidae) is described from the Upper Cretaceous ‘unnamed’ beds of the Mizdah Formation (Santonian-Campanian) at Draa Ubari in western Libya. The accompanying fauna consists of an undetermined mammal represented by a caudal vertebra, of hybodontoid, ganopristid and lamnoid sharks, as well as dipnoans, lepisosteids, pycnodonts, enchodontids, turtles, crocodiles and ?dinosaurs.

The Late Cretaceous placental mammal Kulbeckia

Abstract Kulbeckia, a placental mammal from the late Turonian–Coniacian (Late Cretaceous) of Uzbekistan, was originally placed in the monotypic Kulbeckiidae. Important new material indicates that Kulbeckia is the basal most member of “Zalambdalestidae”, which also includes Zalambdalestes, Barunlestes, and the poorly known Alymlestes, all from the Late Cretaceous of Asia. Kulbeckia shares with other zalambdalestids: a narrow, somewhat elongated snout; procumbent, enlarged, and open-rooted medial lower incisor with enamel restricted to the more ventrolabial surface; and anteroposteriorly compressed and centrally pinched molar trigonids. Commensurate with its 10-million-year earlier age relative to other zalambdalestids, it is notable in its smaller size, probable retention of four lower incisors, bifurcated or two-rooted lower canine, relatively smaller or absent diastemata between anterior teeth, more lingually placed cristid obliqua, less reduced M3 and m3, and more dorsal and posterior placement of the angular process in adults. Kulbeckia kansaica (Tadjikistan) and Kulbeckia rara (Uzbekistan) are regarded as synonyms of Kulbeckia kulbecke, the only recognized species of Kulbeckia.

FERGANASAURUS VERZILINI, GEN. ET SP. NOV., A NEW NEOSAUROPOD (DINOSAURIA, SAURISCHIA, SAUROPODA) FROM THE MIDDLE JURASSIC OF FERGANA VALLEY, KIRGHIZIA

Abstract A partial sauropod skeleton from the Middle Jurassic (Callovian) Balabansai Formation in Kirghizia, comprising two dorsal and 16 caudal vertebrae, pelvis and limb bones is described and referred to Ferganasaurus verzilini, gen. et sp. nov. The manus is known only from drawings as original material has been lost; foot bones, except the astragalus, are unknown. Ferganasaurus forms an unresolved polytomy with neosauropods Jobaria, Diplodocoidea (Nemegtosauridae, Rebbachisauridae, Diplodocidae, and Dicraeosauridae), and Macronaria (Camarasaurus, Haplocanthosaurus and Titanosauriformes). The neosauropod characters of Ferganasaurus include five coossified sacral vertebra, metacarpal proximal ends subtriangular, composite proximal articular surface of metacarpus U-shaped, tibia with subcircular proximal end, astragalar ascending process extends to the posterior margin of the astragalus, and astragalus wedge-shaped in anterior view. Ferganasaurus is one of the oldest known neosauropods, and possesses two primitive characters unusual for a neosauropod (femur shaft with sigmoid curve, and fourth trochanter of the femur blade-like with acuminate apex).