Browsing by Author "Gebo, Daniel Lee, 1955-"
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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 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 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.