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Evolution of the aeluroid Carnivora. Significance of auditory structure in the nimravid cat Dinictis. American Museum novitates ; no. 2886

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dc.contributor.author Hunt, Robert M., Jr., 1941- en_US
dc.date.accessioned 2005-10-06T18:10:00Z
dc.date.available 2005-10-06T18:10:00Z
dc.date.issued 1987 en_US
dc.identifier.uri http://hdl.handle.net/2246/5217
dc.description 74 p. : ill. ; 26 cm. en_US
dc.description Includes bibliographical references (p. 71-74). en_US
dc.description.abstract Evolutionary lineages among living and extinct Carnivora can be identified by a diagnostic pattern of ontogenetic elements forming the auditory bulla enclosing the middle ear, best observed in newborn and juvenile animals. However, in the fossil record, the delicate unfused bulla parts of very young carnivorans are rarely preserved. Thus bulla composition in extinct lineages is difficult to determine unless juveniles with well-preserved auditory bullae can be found. Discovery in 1981 of an intact cranium of a juvenile aeluroid carnivoran (Dinictis) from the White River Group (Oligocene) in northwestern Nebraska has resulted in an improved understanding of bulla structure in Nimravidae, extinct catlike carnivorans of the Oligocene and Miocene of the northern continents. Bulla structure indicates that nimravids are not close relatives of the living cats (Felidae), nor are they ancestral to them. Analysis of the auditory region supports the view of Piveteau (1931) and Teilhard (1945) that two major radiations (nimravids, felids) of catlike mammals have occurred on the northern continents during the last 35 to 40 million years. The auditory bulla of Dinictis is formed by three ontogenetic elements: (1) a small bony rostral entotympanic with septate lateral margin confined to the anterointernal comer of the auditory region; (2) a bony planar ectotympanic with highly produced styliform process developed to close the anteroexternal bulla wall; (3) a caudal entotympanic divided into ossified dorsal and cartilaginous ventral parts, forming the anterointernal, medial, and posterior walls and ventral floor of the bulla. These elements join during ontogeny to produce a single chambered bulla lacking a true septum bullae. However, the anterointernal bulla wall of Dinictis contains a small vertically oriented partition formed by entotympanic elements here named the proseptum, a structure previously mistaken for the septum bullae of felids. Nimravid auditory bullae are derivable from an aeluroid morphotype bulla formed by three ontogenetic elements: a ventrally concave septate rostral entotympanic, a crescentic nearly planar ectotympanic, and a single small probably L-shaped caudal entotympanic without inflected ventral edge, the latter element intervening between ectotympanic and rostral entotympanic. Intervention of the caudal entotympanic between ectotympanic and rostral entotympanic is termed the athictic condition, and occurs in nimravids and Nandinia. In viverrids, herpestids, and hyaenids, a thictic condition is achieved by fusion of ectotympanic with rostral entotympanic, excluding the caudal entotympanic from the space between them. In felids, this ectotympanic-rostral entotympanic contact is delayed into later ontogeny, resulting in the bradynothictic condition. Thictic and bradynothictic bullae of viverrids, herpestids, hyaenids, and felids can be derived from the athictic morphotype bulla. The African aeluroid Nandinia binotata is the only living carnivoran in which the structure of the auditory region closely approaches the projected aeluroid morphotype; the bulla of Nandinia is representative of a primitive state from which all living and fossil aeluroid bullae can be derived. en_US
dc.format.extent 21006390 bytes
dc.format.mimetype application/pdf
dc.language eng en_US
dc.language.iso en_US
dc.publisher New York, N.Y. : American Museum of Natural History en_US
dc.relation.ispartofseries American Museum novitates ; no. 2886 en_US
dc.subject.lcc QL1 .A436 no.2886, 1987 en_US
dc.subject.lcsh Dinictis. en_US
dc.subject.lcsh Aeluroidea -- Evolution. en_US
dc.subject.lcsh Ear -- Anatomy. en_US
dc.subject.lcsh Auditory pathways. en_US
dc.subject.lcsh Carnivora, Fossil -- Nebraska. en_US
dc.subject.lcsh Mammals, Fossil -- Nebraska. en_US
dc.subject.lcsh Paleontology -- Oligocene -- Nebraska. en_US
dc.subject.lcsh Paleontology -- Nebraska. en_US
dc.subject.lcsh Paleontology -- White River Group. en_US
dc.subject.lcsh Carnivora -- Phylogeny. en_US
dc.title Evolution of the aeluroid Carnivora. Significance of auditory structure in the nimravid cat Dinictis. American Museum novitates ; no. 2886 en_US
dc.title.alternative Significance of auditory structure in the nimravid cat Dinictis en_US
dc.title.alternative Aeluroid Carnivora en_US
dc.type text en_US


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  • American Museum Novitates
    Novitates (Latin for "new acquaintances"), published continuously and numbered consecutively since 1921, are short papers that contain descriptions of new forms and reports in zoology, paleontology, and geology. New numbers are published at irregular intervals.

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