Anatomical and systematic review of the Pachycormidae, a family of mesozoic fossil fishes.

Abstract

A detailed account of the anatomy of Pachycormus macropterus (Blainville) 1818, the type species of the type genus of the family Pacbycormidae is given, with special reference to the neurocranium, visceral arch skeleton and pectoral girdle. The genera and species ascribed to the family Pachycormidae by various authors are reviewed with the result that: - three genera, Leedsichthys (Woodward) 1889, Eugnathides Gregory, 1923, and Ohmdenia Hauff 1953, are removed; three other genera, Asthenocormus (Wagner) 1863, Prosauropsis Sauvage 1895, and Orthocormus Weitzel, 1930 are found to be ill founded and their species redistributed within the family; and the number of species in several of the remaining genera is reduced. A revised diagnosis of the family is given and a list of characters drawn up, on the basis of which the Pachycormidae sensu stricto is considered to be monophyletic; the interrelationships of the genera within the family are considered. Finally the relationships of the pachycormids to other major groups of fishes are reviewed and a new systematic position assigned