Cranial morphology of the fossil elasmobranch Synechodus dubrisiensis. American Museum novitates ; no. 2804

Abstract

"The neurocranium of Synechodus dubrisiensis, a late Cretaceous elasmobranch, is described for the first time. Several similarities in the ethmoidal and otico-occipital regions of Synechodus and Recent elasmobranchs contrast sharply with conditions found in other fossil sharks, including Hybodus. The neurocrania of Synechodus and Hybodus are profoundly different. Similarities between Synechodus and various groups of Recent elasmobranchs suggest two alternative hypotheses of relationship. In one, Synechodus is a sister taxon to all Recent sharks and rays. In the other, Synechodus would be closely allied to galeomorphs (orectolobids, chiloscyllids, and galeoids) and to Heterodontus. Synechodus and Heterodontus are most parsimoniously regarded as successive sister-groups to galeomorphs"--P. [1].