Evgeny N. Maschenko

Early Cretaceous mammals of Western Siberia: 2. Tegotheriidae

New specimens of the tegotheriid docodont Sibirotherium rossicum Maschenko et al., 2003, including a maxillary fragment with two posterior teeth, an isolated upper molar, and mandibular fragments with teeth from the Early Cretaceous Shestakovo locality are described. The dental formula of Sibirotherium is I1 + ?C1P6M6?. The upper molars of Sibirotherium, with two main labial and three lingual cusps, are convergently similar to the molars of tribosphenic mammals. In the dentary, the symphysis is short and Meckel’s groove is reduced. Sibirotherium is similar in the structure of lower teeth to Tegotherium from the Upper Jurassic of Mongolia; it is the latest known representative of Docodonta.

Early Cretaceous Mammals of Western Siberia: 3. Zhangheotheriidae

New material of Kiyatherium cardiodens Maschenko, Lopatin et Voronkevich, 2002 from the Early Cretaceous Shestakovo 3 locality (Kemerovo Region, Western Siberia) suggest that this taxon belongs to symmetrodont mammals of the family Zhangheotheriidae. Kiyatherium has relatively long and narrow upper and lower molars, with large trigon and trigonid angles (triangularity is approximately as pronounced as in Tinodontidae); a wide and deep Meckel’s groove; a reduced and strongly posteriorly inclined coronoid process of the lower jaw; a very deep posterior mandibular incisure; a strong pterygoid crest; and a small pterygoid fossa. The evolutionary level of dental and mandibular morphology suggests that Kiatherium occupies a basal position in the family. The holotype of K. cardiodens shows replacement of the first molar, which is a unique case among Trechnotheria.

Morphology of a mammoth calf (Mammuthus primigenius) from Ol’chan (Oimiakon, Yakutia)

A partial corpse of a woolly mammoth calf (M. primigenius) found in 2004 in the Ol’chan mine (Oimiakon, Yakutia) is described. Based on DP3 and body size, the calf is considered to be 14–16 months of individual age. The specimen provides new data on the skeletal morphology and biological features of the woolly mammoth. The formation of mammoth skeleton, ossification of epiphyses, apophyses, and morphology of soft tissues are described for the first time based on multisection spiral X-ray computer tomography and virtual autopsy. Selective deposition of fat in the area of the withers and dorsal regions of the cervical constriction is established with certainty. The calf apparently died because of a deep cranial trauma.

A new genus of triconodont mammals from the Early Cretaceous of Western Siberia

were excludedfrom this group, the concept of the taxon Eutriconodonta [1], which corresponds to the infraclass Triconodonta sensu stricto [2], was established. The heterogeneity of this taxon is evident from some characters of this group, including the familiesAmphilestidae and Gobiconodontidae (Repenomamidae) [3, 4]. Phylogenetic analysis corroborated thatAmphilestidae and Gobiconodontidae are closer toancestors of therian mammals than Triconodontidae[5] and suggested the paraphyletic origin of Amphilestidae [5, 6], which is regarded as a key group for theunderstanding of dental evolution of Mesozoic mammals. Therefore, Mesozoic mammal groups with tricuspid teeth are frequently combined under the informal name “triconodont mammals” [5–7].In the present study, a new triconodont mammalfrom the Early Cretaceous Shestakovo 1 locality inWestern Siberia is described. The material was collected by E.N. Maschenko in 2009; it is housed in theBorissiak Paleontological Institute of the RussianAcademy of Sciences, Moscow (PIN).

Reassessment of Dolichopithecus (Kanagawapithecus) leptopostorbitalis, a colobine monkey from the Late Pliocene of Japan

In the original description of Dolichopithecus (Kanagawapithecus) leptopostorbitalis, Iwamoto, Hasegawa and Koizumi, 2005, a moderately large-sized colobine monkey from the Late Pliocene of central Japan, affinities to the European Dolichopithecus rather than to the Transbaikalian Parapresbytis were noted based on the similarities in cranial morphology. Computed tomography scans confirm the presence of the maxillary sinus in the holotype, whereas it is probably absent in specimens of the European Dolichopithecus ruscinensis, the type species of this genus. This feature is either present or absent homogeneously in any given genus of living anthropoids. Its presence or absence is unknown in Parapresbytis, but the distinct morphology of the maxillary incisors in this taxon suggests that this form had different feeding habits from the Japanese colobines. These findings suggest that the Japanese colobine should be referred to henceforth as Kanagawapithecus leptopostorbitalis. Kanagawapithecus shares many important facial and dental features with Dolichopithecus rather than with Parapresbytis, but this association depends largely on the limited availability of comparable materials for the latter. Among colobines, the presence of the maxillary sinus is recorded only in Libypithecus and Cercopithecoides. The maxillary sinus is absent in all modern Asian colobines, implying that Kanagawapithecus is an isolated form without any relationship to living forms. Nevertheless, such phylogenetic interpretations are largely dependent on the restricted fossil evidence from the Pliocene and Pleistocene of eastern Eurasia and will be reexamined when new findings are made.

Mandible and lower dentition of Parailurus baikalicus (Ailuridae, Carnivora) from Transbaikal area, Russia

Abstract. Although the modern lesser panda (Ailurus; Ailuridae; Carnivora; Mammalia) only lives in the temperate highland forests of the southern Himalayan region, its fossil remains of late Miocene to Pliocene age have been found widely across the Holoarctic region. Very few mandibles or lower teeth of these animals, however, have been identified. Here, we provide a detailed description of the mandible and lower dentition of a large-sized lesser panda, Parailurus baikalicus (Sotnikova, 2008), which has been discovered from the middle Pliocene of Udunga, Transbaikalia, Russia. In the Transbaikalian species, lower molars are low crowned and shows highly crenulated enamel pattern. The main cuspids of cheek teeth are heavily worn horizontally, suggesting a high specialization for leaf eating. The distinctive lower tooth morphology of P. baikalicus differs from those of other fossil lesser pandas discovered from Europe and North America and from those of modern species, suggesting that the morphology found in P. baikalicus is derived in the Ailuridae.

The first dinosaur egg from the Lower Cretaceous of Western Siberia, Russia

Abstract The Lower Cretaceous Ilek Formation in Western Siberia (Russia) has yielded various vertebrate fossils, including skeletal remains of dinosaurs. Here we report on a fragmentary theropod egg from the vertebrate locality Shestakovo 3 of the Ilek Formation in Kemerovo Province. We assign the specimen to the oogenus Prismatoolithus (oofamily Prismatoolithidae) as Prismatoolithus ilekensis oosp. nov., on the basis of the following unique combination of characters: ovoid-shaped egg; thin eggshell 300–330 μm thick; angustiprismatic morphotype; eggshell with three different layers; gradual transition between mammillary layer and prismatic layer; abrupt contact between prismatic layer and external layer; mammillary layer to prismatic layer to external layer thickness ratio is 1:3:0.6; prismatic layer with ill-defined squamatic texture; angusticanaliculate pore system; and smooth outer surface. Like other Early Creataceous Prismatoolithus, the egg of Prismatoolithus ilekensis oosp. nov. was laid by a small bodied theropod dinosaur (troodontid or primitive bird) and this taxonomic attribution is supported by results of our phylogenetic analysis. Prismatoolithus ilekensis oosp. nov. is the first Early Cretaceous ootaxon from Russia. urn:lsid:zoobank.org:act:734EAD40-86C3-488B-A61E-B5FF7378BC0E

New Data on Trunk Morphology in the Woolly Mammoth, Mammuthus primigenius (Blumenbach)

A well-preserved trunk (proboscis) of the woolly mammoth (Mammuthus primigenius) found in 2010 in the area of the Oiyagosskii Yar, about 30 km west of the mouth of the Kondratievo River (Yakutia) is described (mammoth named Yuka). The distal part of trunk has a transverse expansion. In the expanded condition, it changes the trunk cross section from oval to ellipsoidal. The expansion is laterally framed by skin folds with sites of muscles making the trunk cross diameter twice as great. Trunk expansion has been recorded in three mammoths: Yuka, Kolyma mammoth, and Kirgilyakh mammoth calf. Structural details of the trunk expansion of the Kirgilyakh mammoth calf and Yuka are almost completely identical. This morphological feature distinguishes trunk of M. primigenius from Loxodonta africana and Elephas maximus ones, the cross section of which remains oval throughout the trunk extent. The adaptive value of this unique trunk structure of the woolly mammoth in connection with cold climate conditions is discussed.

New data on the internal organs of a frozen Yukagir bison mummy (Bison priscus Bojanus, 1827), Yakutia, Russia

The paper presents the first morphological description of the internal organs of a frozen corpse of the steppe bison Bison priscus (Bojanus, 1827) from the Holocene of northern Yakutia. Necropsy revealed that most of the internal organs, including the brain, heart with the main vessels, and reproductive system were well preserved. It demonstrated that the anatomy of this bison was close to that of the genera Bos and Bison. Trauma or pathological changes in the organs were not detected. The cause of death of the bison remains unknown.

The first record of Deinotherium (Proboscidea, Mammalia) in the miocene of Adygea

The data on an isolated upper tooth (P4) of Deinotherium sp. from the Late Miocene beds of the Maikop 1 locality (Maikop, Republic of Adygea) are reported. This is the first record of Deinotherium from the Upper Miocene of Russia. The tooth crown of P4 is similar in size to D. proavum Eichwald, 1831 (= D. gigantissimum Stefanescu, 1892).