Anatomical revision of the fossil shark Hybodus fraasi (Chondrichthyes, Elasmobranchii). American Museum novitates ; no. 2857

Abstract

The skeletal anatomy of Hybodus fraasi, an Upper Jurassic hybodontid shark from Solnhofen, has been reinvestigated. Its cranial anatomy is very similar to that of H. basanus, a Lower Cretaceous species, and both taxa share certain features not so far identified in Lower Jurassic hybodontids. Previous interpretation of the pectoral fin morphology is shown to be incorrect, and instead the pectorals of H. fraasi conform to a pattern that is apparently conservative for hybodontids. Dermal denticles from various regions of the body, together with special lateral line scales and teeth, are subjected to SEM investigation. The shagreen consists only of nongrowing denticles"--P. [1].