Browsing by Author "Wang, Yuan-qing."
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Item Biostratigraphy and diversity of Paleogene perissodactyls from the Erlian Basin of Inner Mongolia, China.(American Museum of Natural History., 2018-12-14) Bai, Bin, 1981-; Wang, Yuan-qing.; Li, Qian (Paleontologist); Wang, Hai-bing.; Mao, Fang-yuan.; Gong, Yan-xin.; Meng, Jin (Paleontologist)Extant perissodactyls (horses, rhinos, and tapirs) comprise a small portion of living mammals, but fossil perissodactyls were more diverse and commonly dominated Paleogene faunas. Unfortunately, the taxonomy and distribution of some Chinese Paleogene perissodactyls remain controversial and unclear, hampering the correlation of Asian paleofaunas with paleofaunas from other continents. Here we clarify the temporal and spatial distribution of Paleogene perissodactyl species from the Erlian Basin based on published specimens, archives, and our recent fieldwork. The strata of the Erlian Basin range nearly continuously from the late Paleocene to the early Oligocene, and almost all Eocene Asian Land Mammal Ages (ALMA) are based on corresponding faunas from the Erlian Basin. We revise the most complete section of deposits at Erden Obo (=Urtyn Obo) that range in age from the late Paleocene to the early Oligocene in the Erlian Basin, and correlate it with other type formations/faunas in the basin based mainly on the perissodactyl biostratigraphy and lithostratigraphy. Furthermore, we discuss perissodactyl faunal components and their diversity from the early Eocene to the early Oligocene in the Erlian Basin, as well as the correlation between middle Eocene ALMAs and North American Land Mammal Ages based on perissodactyl fossils. The general decrease in perissodactyl diversity from the middle Eocene to the late Eocene can probably be attributed to a global climatic cooling trend and related environmental changes. The diversity of perissodactyls declined distinctly during the Eocene-Oligocene Transition, when global average temperatures dropped considerably.Item Discovery of the first early Cenozoic euprimate (Mammalia) from Inner Mongolia ; American Museum novitates, no. 3571(New York, NY : American Museum of Natural History, 2007) Ni, Xijun.; Beard, K. Christopher.; Meng, Jin (Paleontologist); Wang, Yuan-qing.; Gebo, Daniel Lee, 1955-Although it is widely thought that euprimates originated in Asia, the fossil record of early euprimates remains sparse there. We describe herein a new omomyid euprimate, Baataromomys ulaanus, n. gen. et sp., based on an isolated right lower m2 from Bumbanian strata at Wulanboerhe in the Erlian Basin of Inner Mongolia, China. In terms of the size and proportions of m2, Baataromomys ulaanus is intermediate between Eurasian and North American species that are usually assigned to Teilhardina. Morphologically, m2 of Baataromomys differs from that of Teilhardina and North American small-bodied omomyids (including Anemorhysis, Tetonoides, Trogolemur, and Sphacorhysis) in having a smaller paraconid that is less fully connate with the metaconid, a lower entoconid, a weaker crest connecting the metaconid with the entoconid, and a weaker buccal cingulid. The new taxon is much smaller and lower crowned than Steinius, a genus commonly regarded as a basal omomyid. Despite the substantial difference in size, the m2s of Baataromomys and Steinius share some important features, including a very broad talonid basin and a relatively low hypoconid and cristid obliqua. Given its early occurrence and primitive anatomy, Baataromomys may eventually help to clarify the phylogenetic relationships among basalomomyids, but more complete specimens will be required to test this possibility. Baataromomys brandti from the basal Wasatchian zone Wa-0 in the northern Bighorn Basin, Wyoming, was previously allocated to Teilhardina. However, several dental features shared by B. brandti and B. ulaanus suggest that they are closely related. The co-occurrence of Baataromomys in Asia and North America indicates that small-bodied euprimates were able to dispersal across the Beringian region near the Paleocene-Eocene boundary.Item New craniodental materials of Litolophus gobiensis (Perissodactyla, "Eomoropidae") from Inner Mongolia, China, and phylogenetic analyses of Eocene chalicotheres. (American Museum novitates, no. 3688)(American Museum of Natural History., 2010) Bai, Bin, 1981-; Wang, Yuan-qing.; Meng, Jin (Paleontologist)We describe new craniodental specimens of Litolophus gobiensis recently unearthed from the type locality of the genus, and conduct phylogenetic analyses of Eocene chalicotheres based on a data matrix containing 21 taxa and 58 craniodental characters. Although the phylogenetic relationships of the Eocene chalicotheres are not well resolved in the strict component consensus tree, the 50% majority rule consensus shows that two post-earliest Eocene chalicothere lineages are present. The first lineage represents the main line of chalicothere evolution, including "Grangeria" anarsius, Eomoropus, and post-Eocene chalicotheres. The second lineage, consisting of Litolophus gobiensis and Grangeria canina, is the sister group and stem member to the main lineage. The derivative strict reduced consensus tree, with three unstable taxa pruned, supports some tree topologies of the 50% majority consensus. The taxonomy of some chalicothere taxa is revised based on the phylogenetic analyses, such as "Grangeria" anarsius being probably better referred to the genus Eomoropus as originally identified, E. ulterior being the sister taxon to E. amarorum, and Lophiodon being excluded from the Ancylopoda but allied with the Ceratomorpha.Item A new Eocene rodent from the lower Arshanto Formation in the Nuhetingboerhe (Camp Margetts) area, Inner Mongolia ; American Museum novitates, no. 3569(New York, NY : American Museum of Natural History, 2007) Meng, Jin (Paleontologist); Li, Chuan-Kuei.; Ni, Xijun.; Wang, Yuan-qing.; Beard, K. Christopher.A new miniscule rodent represented by isolated cheek teeth is reported from the lower part of the late early Eocene Arshanto Formation, Nuhetingboerhe (Camp Margetts) area, Inner Mongolia. A new family, based on the new genus and species, is proposed. The new taxon resembles alagomyids but differs from early rodents in having a partial buccal cingulum, a distinct metaconule that merges posteriorly with the postcingulum, a transversely oriented trigon basin that widely separates the paracone and metacone, a prominent hypoconulid on lower molars, and in lacking the hypocone and protocristid. It differs from alagomyids in having a greater length/width ratio of upper cheek teeth, a neomorphic cusp termed as the preprotoconule, a preprotoconule crista that projects anteriorly, an anteroconid on dp4, an oblique cristid obliqua bearing a distinct mesoconid, and the hypoconid more posteriorly extended (or hypoconulid less posteriorly extended) on m3. The dental morphology of the new taxon is derivable from analagomyid dental pattern and is intermediate between alagomyids and rodents of modern aspect; it casts new light on the evolution of dentition of early rodents.Item New material of Alagomyidae (Mammalia, Glires) from the late Paleocene Subeng locality, Inner Mongolia ; American Museum novitates, no. 3597(New York, NY : American Museum of Natural History, 2007) Meng, Jin (Paleontologist); Ni, Xijun.; Li, Chuan-Kuei; Beard, K. Christopher.; Gebo, Daniel Lee, 1955-; Wang, Yuan-qing.; Wang, Hongjiang.Newly discovered specimens of alagomyids, mostly isolated teeth collected by screenwashing at the Gashatan (late Paleocene) Subeng locality in Inner Mongolia, document considerable intraspecific variation in Tribosphenomys minutus that has not been appreciated previously because of limited sample sizes. P4s of Tribosphenomys are described for the first time, which helps to clarify the posterior premolar identification of alagomyids. Some of the alagomyid specimens are referred to Tribosphenomys cf. T. secundus and Neimengomys qii gen. and sp. nov. Based on the new data, Tribosphenomys borealis from the Bumban Member of the Naran Bulak Formation, Mongolia, is considered to be a junior synonym of Alagomys inopinatus, and T. tertius from the Zhigden Member of the Naran Bulak Formation is regarded as a junior synonymof T. minutus. Alagomyidae, consisting of Tribosphenomys, Alagomys and Neimengomys, is maintained as a valid family. The presence of a diversity of alagomyids and other recently obtained fossils and stratigraphic evidence from the Erlian Basin suggest that the Gashatan and Bumbanian of Asia are probably correlative to the late Tiffanian-early Wasachian of North America. The faunal turnover during the Gashatan and Bumbanian in Asia is probably related to the late Paleocene-early Eocene global warming, but current evidence is insufficient to link any specific event with the Paleocene-Eocene Thermal Maximum.Item New material of Eocene Helaletidae (Perissodactyla, Tapiroidea) from the Irdin Manha Formation of the Erlian Basin, Inner Mongolia, China, and comments on related localities of the Huheboerhe area. (American Museum novitates, no. 3878)(American Museum of Natural History., 2017-04-14) Bai, Bin, 1981-; Wang, Yuan-qing.; Mao, Fang-yuan.; Meng, Jin (Paleontologist)Perissodactyls first appeared at the beginning of the early Eocene and reached their highest diversity, dominating contemporaneous mammalian faunas in species richness during the middle Eocene. Tapiroidea is an important perissodactyl group that includes earliest-Eocene forms, such as Orientolophus as well as extant taxa (such as Tapirus), that preserves numerous plesiomorphic characters. Because tapiroids were widely distributed in North America and Asia in the middle Eocene, they have played an important role in biostratigraphically defining middle Eocene North American Land Mammal Ages (NALMA) and Asian Land Mammal Ages (ALMA), respectively, as well as in biostratigraphic correlation between the two continents. Here we report a new cranial specimen of middle Eocene helaletid Paracolodon fissus and a maxilla of Desmatotherium mongoliense from the middle Eocene Irdin Manha Formation of the Erlian Basin, Inner Mongolia, China. Paracolodon fissus was previously assigned to Desmatotherium, Helaletes, or Colodon, whereas D. mongoliense was assigned to Helaletes or Irdinolophus by different authors. Based on the new material described in this report, we are able to clarify the affinities and phylogenetic position of these species according to morphological comparison and phylogenetic analyses. We maintain the genus Paracolodon for P. inceptus and P. fissus from Asia and reassign mongoliense to Desmatotherium. Fossils of perissodactyls and other groups from the Irdin Manha Formation favor correlation of the Irdinmanhan ALMA with the early and middle Uintan NALMA (Ui1-Ui2). Through our field investigation, we also clarified that the localities "7 miles southwest" and "10 miles southwest" of Camp Margetts, originally used by the American Museum of Natural History's Central Asiatic Expedition (CAE), correspond to the localities currently known as Huheboerhe and Changanboerhe, respectively.Item A new species of Forstercooperia (Perissodactyla, Paraceratheriidae) from northern China with a systematic revision of forstercooperiines. (American Museum novitates, no. 3897)(American Museum of Natural History., 2018-03-21) Wang, Hai-Bing.; Bai, Bin, 1981-; Meng, Jin (Paleontologist); Wang, Yuan-qing.Forstercooperiines are a group of large, primitive rhinocerotoids that are commonly regarded as ancestral to later giant rhinos. However, the type genus of forstercooperiines, the Middle Eocene Forstercooperia, is one of the most poorly known rhinocerotoids, and is represented only by fragmentary material. Here we name a new species, Forstercooperia ulanshirehensis, based on five specimens, including a well-preserved cranium and a pair of complete mandibles. This new material was collected from the Ulan Shireh Formation in the western part of the Erlian Basin and the Irdin Manha Formation in the eastern part of the Erlian Basin, northern China. These specimens provide the most complete craniodental remains of Forstercooperia sensu stricto (excluding Pappaceras), and on this basis the species-level taxonomy of forstercooperiines is thoroughly revised and six species of two genera are considered as valid. Specimens previously assigned to "Forstercooperia minuta" are reassigned to different species based on the revised diagnoses. All equivocal specimens that were thought to have an affinity with Forstercooperiinae are briefly discussed. Based on a new character matrix, phylogenetic analyses fully resolve the relationships of early rhinocerotoids, including the recovery of Forstercooperia and Pappaceras as sister groups. The occurrence of Forstercooperia ulanshirehensis in the eastern and western Erlian Basin is indicative of age correlation between the lower part of the Ulan Shireh Formation and the Irdin Manha Formation.Item A new species of Gomphos (Glires, Mammalia) from the Eocene of the Erlian Basin, Nei Mongol, China. (American Museum novitates, no. 3670)(New York, NY : American Museum of Natural History., 2009) Meng, Jin (Paleontologist); Kraatz, Brian P.; Wang, Yuan-qing.; Ni, Xijun.; Gebo, Daniel Lee, 1955-; Beard, K. Christopher.Dental and postcranial specimens of Gomphos shevyrevae, sp. nov., from the lower part of the Irdin Manha Formation at the Huheboerhe locality, Erlian Basin, Nei Mongol (Inner Mongolia), are described. The new species differs from G. elkema and G. ellae in having more robust teeth with inflated cusps and stronger lophs and a calcaneus with extra articulation for the astragalus and navicular. The new species is stratigraphically well constrained and probably represents the youngest known species of the genus, extending its geological record into the Middle Eocene. It also shows that mimotonids coexisted for millions of years as a side branch of duplicidentates with the earliest stem lagomorphs, including Dawsonolagus.Item New stratigraphic data from the Erlian Basin : implications for the division, correlation, and definition of Paleogene lithological units in Nei Mongol (Inner Mongolia) ; American Museum novitates, no. 3570(New York, NY : American Museum of Natural History, 2007) Meng, Jin (Paleontologist); Wang, Yuan-qing.; Ni, Xijun.; Beard, K. Christopher.; Sun, Chengkai.; Li, Qian (Paleontologist); Jin, Xun (Paleontologist); Bai, Bin, 1981-Newly measured stratigraphic sections are reported for Paleogene rocks in the Nuhetingboerhe-Huheboerhe (Camp Margetts) area of Nei Mongol (Inner Mongolia), China. The composite sequence in this region is 82.4 m thick, encompassing three lithological units separated by important depositional hiatuses. In stratigraphic order, these rock units correspond to the Nomogen, Arshanto and Irdin Manha formations. The sequence contains faunas from four Asian land-mammal "ages", the Gashatan, Bumbanian, Arshantan, and Irdinmanhan, which together span the interval from late in the late Paleocene to early in the middle Eocene. Comparisons with localities and sections documented since the time of the Central Asiatic Expeditions (CAE) show that the so-called Houldjin gravels of the CAE from this area are mostly Irdin Manha Formation and that the "Irdin Manha beds" of the CAE belong to the Arshanto and/or Nomogen formations. These findings reveal that previous concepts of the Irdin Manha and Arshanto faunas from the Camp Margetts area probably include fossils of different ages, so that the corresponding Asian land-mammal "ages" based on these faunas are problematic and need systematic revision. The Nomogen, Arshanto, and Irdin Manha formations are redefined.Item Osteology of the Middle Eocene ceratomorph Hyrachyus modestus (Mammalia, Perissodactyla). (Bulletin of the American Museum of Natural History, no. 413)(American Museum of Natural History., 2017-06-09) Bai, Bin, 1981-; Meng, Jin (Paleontologist); Wang, Yuan-qing.; Wang, Hai-Bing.; Holbrook, Luke.The middle Eocene ceratomorph Hyrachyus has been considered a pivotal genus in ceratomorph evolution, either as a transitional form from tapiroids to rhinocerotoids, giving rise to all later rhinocerotoids, or else as the sister taxon to other rhinocerotoids. Thus, Hyrachyus has been commonly chosen as an outgroup in phylogenetic analyses of rhinocerotoids. However, little has been published on the osteology of Hyrachyus, even though well-preserved craniodental and postcranial specimens of this taxon have been in collections for decades. Here, we describe and illustrate the cranial and postcranial osteology of Hyrachyus modestus, based mainly on the exceptionally preserved specimens housed at the American Museum of Natural History, specifically AMNH FM 12664. Our bone-by-bone description provides detailed information on the osteological morphology of Hyrachyus, which should be useful for phylogenetic analyses of both rhinocerotoids and perissodactyls in general, because it provides one of the more complete and best-preserved examples of the skeleton of an earlier Eocene perissodactyl....