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Rochester, NY, United States

Korth W.W.,Rochester Institute of Vertebrate Paleontology | De Blieux D.D.,Utah Geological Survey
Journal of Vertebrate Paleontology | Year: 2010

Four species of rodents (two heteromyids and two cricetids) and one lagomorph are identified from the late Tertiary Sevier River Formation of Utah. The heteromyids include a new genus and species of heteromyine, Metaliomys sevierensis, which is intermediate in morphology between the Clarendonian and early Hemphillian Diprionomys Kellogg and the extant genera Liomys and Heteromys. A single specimen is referred to Diprionomys sp., cf. D. minimus (Kellogg). The cricetid Paronychomys lemredfieldi Jacobs is known from the Hemphillian of Arizona. The second cricetid is referred to a new genus Basirepomys. Peromyscus pliocenicus Wilson from the Hemphillian of California is designated as the type species of the new genus, to which the new species B. robertsi from Utah is referred. Basirepomys is viewed as intermediate between Peromyscus and the basal neotomyine Repomys May from the late Hemphillian and Blancan. The only lagomorph in the fauna is Hypolagus vetus (Kellogg). Four of the taxa recognized from the Sevier River Formation (Diprionomys, Paronychomys lemredfieldi, Basirepomys, and Hypolagus vetus) are elsewhere known from the Hemphillian of North America. However, it is not possible at this time to determine whether the fauna is early or late Hemphillian. © 2010 by the Society of Vertebrate Paleontology.

Emry R.J.,Smithsonian Institution | Korth W.W.,Rochester Institute of Vertebrate Paleontology
Proceedings of the Biological Society of Washington | Year: 2013

Two species of the eomyid rodent Paradjidaumo are recognized from the Chadronian (latest Eocene) White River Formation in the Flagstaff Rim area of Wyoming: P. hansonorum from early Chadronian levels and P. nanus, new species, from higher levels representing the middle Chadronian.

Korth W.W.,Rochester Institute of Vertebrate Paleontology | Evander R.L.,American Museum of Natural History
Annals of Carnegie Museum | Year: 2016

Twenty-one species of small mammals are recognized from the Observation Quarry fauna including four new species: The lipotyphlans Lanthanotherium observatum (Erinaceidae), Antesorex wilsoni (Soricidae), and Scalopoides hutchisoni (Talpidae), and the rodent Mioheteromys subterior (Heteromyidae). Due to more complete material, emended diagnoses are provided for the plesiosoricid Plesiosorex greeni Martin and Lim, 2004, and cricetid rodent Copemys lindsayi Sutton and Korth, 1995. Of the 21 species recognized, seven are unique to this faunal assemblage, six are restricted to the Hemingfordian, seven are known elsewhere only from the Barstovian or later, and one is known from both the Hemingfordian and Barstovian. The small mammals suggest that the Observation Quarry contains a transitional Hemingfordian-Barstovian fauna with a greater number of species from the latter, supporting an early Barstovian age.

Rybczynski N.,Canadian Museum of Nature | Ross E.M.,Carleton University | Korth W.W.,Rochester Institute of Vertebrate Paleontology
PLoS ONE | Year: 2010

The extant beaver, Castor, has played an important role shaping landscapes and ecosystems in Eurasia and North America, yet the origins and early evolution of this lineage remain poorly understood. Here we use a g eometric morphometric approach to help re-evaluate the phylogenetic affinities of a fossil skull from the Late Miocene of China. This specimen was originally considered Sinocastor, and later transferred to Castor. The aim of this study was to determine whether this form is an early member of Castor, or if it represents a lineage outside of Castor. The specimen was compared to 38 specimens of modern Castor (both C. canadensis and C. fiber) as well as fossil specimens of C. fiber (Pleistocene), C. californicus (Pliocene) and the early castorids Steneofiber eseri (early Miocene). The results show that the specimen falls outside the Castor morphospace and that compared to Castor, Sinocastor possesses a: 1) narrower post-orbital constriction, 2) anteroposteriorly shortened basioccipital depression, 3) shortened incisive foramen, 4) more post eriorly located palatine for a men, 5) longer rostrum, and 6) longer braincase. Also the specimen shows a much shallower basiocciptal depression than what is seen in living Castor, as well as prominently rooted molars. We conclude that Sinocastor is a valid genus. Given the prevalence of apparently primitive traits, Sinocastor might be a near relative of the lineage that gave rise to Castor, implying a possible Asiatic origin for Castor. © 2010 Rybczynski et al.

Korth W.W.,Rochester Institute of Vertebrate Paleontology
Annals of Carnegie Museum | Year: 2015

Twenty species of rodents are recognized from the early Whitneyan Cedar Pass Fauna of South Dakota. Two new species are recognized, the sciurid Douglassciurus bjorki (including specimens originally referred to Cedromus wilsoni Korth and Emry, 1991, from the late Whitneyan Blue Ash Fauna) and the cricetid Paciculus cedrus. Due to a more complete record at Cedar Pass, the florentiamyid Hitonkala martintau Korth, 2008, is allocated to the genus Kirkomys Wahlert, 1984 as a new combination, Kirkomys martintau (Korth, 2008). The new sample of this species also allows for a description of the complete cranium of Kirkomys previously only known from a single partial skull. Among the genera of rodents identified from Cedar Pass, two earlier occurring genera have their last occurrence and six later occurring genera have their first occurrence. Thirteen genera that extend into the Arikareean present in the later Whitneyan Blue Ash Fauna are lacking in the Cedar Pass Fauna. Only one genus of rodent is limited to the Whitneyan, Disallomys Korth, 2009a. This demonstrates that the age represented by the fauna at Cedar Pass is transitional between the Orellan and later Whitneyan horizons. The proportions of rodents (relative number of specimens and species) also differ between the Cedar Pass and the Blue Ash faunas, again, indicating an earlier age for the Cedar Pass Fauna.

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