Aspidorhynchiformes

Article By:

Cavender, Ted M. Museum of Zoology, University of Michigan, Ann Arbor, Michigan.

Last reviewed:October 2019

DOI:https://doi.org/10.1036/1097-8542.055800

A small order of specialized holostean fishes which are first recorded from Middle Jurassic deposits of Europe. Later records indicate that they were a very successful group in terms of geographic range, and probably had a worldwide distribution in the warm seas of the Cretaceous Period. The order contains one family, Aspidorhynchidae, and two genera, Aspidorhynchus and Belonostomus. These fishes, some of which reached a length of over 3 ft (0.9 m), are characterized by a ganoid scale covering with much deepened scales along the flank, by an elongate fusiform body and head with long slender snout, and by an externally symmetrical tail. All the fins are small, and fringing fulcra are reduced or absent. The dorsal and anal fins are positioned opposite one another far back on the body, and the pelvic fins are inserted closer to the anal than to the pectorals (see illustration). The vertebral column shows a fair amount of ossification with thin ringlike or half centra. See also: Holostei

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