New data on the soft tissues and external morphology of the antiarch Bothriolepis canadensis (Whiteaves 1880), from the Upper Devonian of Miguasha, Quebec.

Abstract

The euantiarch Bothriolepis canadensis from the Late Devonian of Miguasha is revisited on the basis of some new material which yields additional information about its internal anatomy and overall external morphology. New evidence for soft tissue preservation in this species is provided by the discovery of blood vessel imprints beneath the plates of the thoracic armour in several specimens. The pattern of some of these blood vessel imprints, in the anterior part of thoracic armour raises the question of their possible relations to the presumed paired pharyngeal diverticles, or “lungs”, previously described in this species. The nature of the more or less metameric grooves on the internal surface of the dorsal plates of the thoracic armour is discussed, and it is suggested that they may have housed lymphatic vessels. A new reconstruction of the armour of B. canadensis is proposed, on the basis of two specimens which have not been subjected to dorsoventral flattening. The overall morphology of B. canadensis appears thus to be in better agreement with Patten’s than with Stensio’s reconstruction; i.e., with a rather deep thoracic armour and more tilted skull roof.