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Ontogeny and Diversity of the Oldest Capybaras (Rodentia: Hydrochoeridae; Late Miocene of Argentina)
Cecilia M. Deschamps, A. Itatí Olivares, Emma Carolina Vieytes and María Guiomar Vucetich
Journal of Vertebrate Paleontology
Vol. 27, No. 3 (Sep. 12, 2007), pp. 683-692
Stable URL: http://www.jstor.org/stable/30126368
Page Count: 10
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According to our previous model for interpreting the fossil record of capybaras the cheek teeth grow in width and length throughout life; flexids (especially h.s.i. and h.t.i.) deepen allometrically resulting in diverse occlusal morphologies during ontogeny; in the more derived species the 'onset' of flexid development is pre-displaced, and the relative depth and development rate of the flexids increase. Consequently, we interpreted the different occlusal morphologies found in the fossil record as different ontogenetic stages, leading to a drastic diminution of latest MiocenePliocene taxonomic diversity. The analysis of the geologically oldest capybaras, which are from the Arroyo Chasicö Formation (Chasicoan SALMA, late Miocene), is added. This study suggests a single species occurs in this formation that cannot be separated at the genus level from Huayquerian species. In the Arroyo Chasicó species, which is older and theoretically more primitive than that of the Huayquerian, the flexids are shallower as predicted. The analysis supports our model of capybara dental ontogeny and evolution and encourages revision of the whole family according to this model.
Journal of Vertebrate Paleontology © 2007 The Society of Vertebrate Paleontology