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Mastication in the hyrax and its relevance to ungulate dental evolution

Published online by Cambridge University Press:  08 February 2016

Christine M. Janis
Christine M. Janis*
Affiliation:
Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts 02138
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Abstract

The hyrax, a living primitive subungulate, makes an ideal model in terms of its molar morphology for early lophodont ungulates. Cine fluoroscopic studies of mastication show that the proposed Phase II in jaw movement, experimentally demonstrated in primates, but surmised in ungulates only from molar wear facets, does in fact exist in this animal, but does not appear to be an important component of the masticatory cycle. Comparison of tooth wear in early Tertiary ungulates with contemporaneous primates shows that, whereas primates enlarge the Phase II wear facets on the molars as they move into more herbivorous niches, the same is not true for ungulates, and in fact Phase II may be lost altogether in grazing forms. It is concluded that “grinding” in herbivorous ungulates is a process fundamentally different from that described for herbivorous primates.

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Type
Research Article
Information
Paleobiology , Volume 5 , Issue 1 , Winter 1979 , pp. 50 - 59
Copyright
Copyright © The Paleontological Society 

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References

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