An evaluation of jaw suspension in sharks. American Museum novitates ; no. 2706

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New York, N.Y. : American Museum of Natural History
"Evidence and opinions on the nature and diversity of elasmobranch jaw suspension are discussed and the phylogenetic implications of some of these differences are considered. The hyomandibula is attached to the mandibular joint in all living elasmobranchs, and all are therefore hyostylic with respect to the hyomandibula. Amphistyly is a subset or condition of hyostyly rather than an alternative mode of jaw support. Living osteichthyans and perhaps acanthodians are similarly hyostylic, and there is no reason to suppose that this condition is anything but a primitive gnathostome character. Some elasmobranchs have an orbital process which has a consistent relationship to nerves and vessels within the orbit. It is possible to use this relationship systematically to define a group of 'orbitostylic' sharks in a novel way. The orbital process does not seem to correspond to the 'basal articulation' of acanthodians and osteichthyans"--P. [1].
17 p. : ill. ; 26 cm.
Includes bibliographical references (p. 15-17)