Rochester Institute of Vertebrate Paleontology

Rochester, NY, United States

Rochester Institute of Vertebrate Paleontology

Rochester, NY, United States

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Rybczynski N.,Canadian Museum of Nature | Ross E.M.,Carleton University | Samuels J.X.,John Day Fossil Beds National Monument | 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 | 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.


Korth W.W.,Rochester Institute of Vertebrate Paleontology | Samuels J.X.,National Park Service
Annals of Carnegie Museum | Year: 2015

The John Day Formation of Oregon is one of the richest and best studied assemblages in North America. Including seven members and spanning about 20 million years, there are over 150 vertebrate species known from the John Day Formation. The rodent faunas of John Day have not been as well studied as larger mammals, with many families having received little attention in the last hundred years. Here, twenty one species of rodents are described, based on new discoveries and previously unpublished specimens from the John Day Formation. The new material includes four new genera and species; the eutypomyid Allotypomys pictus, the anchitheriomyine castorid Microtheriomys brevirhinus, the eomyid Proapeomys condoni, the heteromyid Bursagnathus aterosseus; and six new species: the sciurine sciurid Miosciurus covensis, the eomyids Apeomys whistleri and Neoadjidaumo arctozophus, the heteromyids Proheteromys latidens and Trogomys oregonensis, and the sicistine dipodid Plesiosminthus fremdi. The problematical eomyid species, "Florentiamys" lulli Wood, 1936a, is referred questionably as a new combination, ?Proapeomys lulli (Wood, 1936a). Emended diagnoses of Miosciurus ballovianus (Cope, 1881) and Proheteromys thorpei Wood, 1935b, are offered based upon substantially more complete material than was previously known for either. Biostratigraphic ranges of the newly described rodents allow more direct comparison with other contemporaneous faunas from North America. These new rodents also allow better reconstruction of past ecosystems and are vital for understanding how faunas have changed through time in the region.


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.


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.


Emry R.J.,Smithsonian Institution | Korth W.W.,Rochester Institute of Vertebrate Paleontology
Journal of Vertebrate Paleontology | Year: 2012

The White River Formation at Flagstaff Rim in central Wyoming is a key sequence for understanding the biochronology and chronostratigraphy of the Chadronian North American Land Mammal Age. The lower part of this section represents early Chadronian time, an interval whose fauna has not been well known. From these early Chadronian levels 15 species of rodents are discussed and/or described. Of these, three are new species, all belonging to the Eomyidae: Namatomys erythrus, Metanoiamys paradoxus, Cristadjidaumo skinneri. These rodent assemblages add substantially to our knowledge of early Chadronian faunas, and show successional changes in the rodent taxa from the earliest Chadronian through middle Chadronian. © 2012 by the Society of Vertebrate Paleontology.


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.


Korth W.W.,Rochester Institute of Vertebrate Paleontology
Annals of Carnegie Museum | Year: 2013

Four species of mylagaulid rodents are described from the Tesuque Formation, Espanola Basin of New Mexico: Alphagaulus vetus (Matthew, 1924), Ceratogaulus robustus, new species, Notogaulus minor, new genus and species, and Notogauhis major, new species. Ceratogaulus robustus is distinguished from other species of the genus by its much heavier dentary and relatively wider premolar. Notogaulus is separable from other mylagaulines in its unique features of its cranium (ovate rugose areas on the nasals; shape, thickness, and porosity of bone on the postorbital processes), and relatively primitive dental morphology (no preferred separation of the branches of the parafossette on P4). The recognition of a distinct genus of mylagaulid from New Mexico demonstrates that by the middle Miocene (Barstovian) derived mylagaulines had evolved regionally into distinct genera.


Korth W.W.,Rochester Institute of Vertebrate Paleontology
Annals of Carnegie Museum | Year: 2011

The species of Eumys Leidy, 1856, are reviewed. Six species are recognized and emended diagnoses are presented for the genus and all species. The enigmatic species, Coloradoeumys galbreathi Martin, 1980, is considered a new junior synonym of Eumys elegans Leidy, 1856; Coloradoeumys Martin, 1980, therefore becomes a new subjective synonym of Eumys Leidy, 1856. Additional specimens of Eumys cricetodontoides White, 1954, and Eumys parvidens Wood, 1937, are recognized and described. A new species, Eumys euryodus, from the Whitneyan of Nebraska is described. Size and proportional measurements of the molars, along with features of the occlusal morphology, are the major factors used to distinguish the species of Eumys.


Korth W.W.,Rochester Institute of Vertebrate Paleontology
Annals of Carnegie Museum | Year: 2011

Specimens previously identified as the Hemphillian cricetid Basirepomys pliocenicus (Wilson, 1937) (=Peromyscus pliocenicus Wilson, 1937) by Korth and De Blieux (2010) have been re-examined, and several distinct species are here recognized. Specimens from the early Hemphillian Rome fauna of Oregon are referred to a new, more primitive species of Basirepomys Korth and De Blieux, 2010, here named Basirepomys romensis, new species, which differs from other species of the genus in having lower-crowned cheek teeth and incomplete alternation of cusps on some molars. Specimens from the early Hemphillian Juniper Creek and Little Valley faunas of Oregon are referable to Paronychomys Jacobs, 1977, rather than Basirepomys, and represent a new species, Paronychomys shotwelli, which is distinguished from other species of the genus by its larger size and relatively longer lower third molar. A specimen previously referred to Peromyscus pliocenicus from the early Hemphillian of Kansas is referable to Paronychomys sp. Specimens identified as Peromyscus cf. pliocenicus from the late Hemphillian of California represent a new genus and species, Miotomodon mayi, which is distinguished from Basirepomys and Paronychomys by its higher-crowned cheek teeth, position of the ascending ramus on the mandible, and morphology of the mesoloph (-id) on the molars. Miotomodon is a probable ancestor for both Repomys May, 1981, and the Recent Neotomodon Merriam, 1898.

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