New information on the Devonian shark Mcmurdodus, based on material from western Queensland, Australia

Abstract

Histological structure of the type and newly collected teeth of the shark Mcmurdodus whitei TURNER &YOUNG, 1987, from a Devonian (?late Emsian-early Eifelian) limestone outcrop in the Cravens Peak Beds of western Queensland, was determined by immersion in anise oil, thin sectioning, and acid etching of fractured surfaces. The morphology and vascularization of the teeth are comparable to those of modern hexanchiform and echinorhinid squaliform sharks, being most similar to those of Echinorhinus. Amultilayered enameloid layer is not discernible in Mcmurdodus teeth, but a parallel-fibred layer is possibly present. Prismatic calcified cartilage, presumed to be from M. whitei, appears identical to that of all elasmobranchs. Scales and spines and distinctive ringlike elements occur in the same horizon, the latter comparable with elements that encircle the lateral line in Echinorhinus, and which are found in no other Recent elasmobranchs.