First Report of Peripheral Nerves in Bone from Triceratops horridus Occipital Condyle

Abstract

Peripheral nerves in vertebrate systems have been studied for centuries. Nerve anatomy, including the connective tissues that cushion nerves, are well described in the literature. The outer connective tissues, known as the epineurium and perineurium, include a double layer of collagen fibers that form a double helical wrapping that is visible with polarized light microscopy and by other contrast methods. This wrapping is a diagnostic characteristic of nerve tissues. Decades of research into dinosaur bones have produced interesting endocasts of probable brain morphology, but no soft and flexible nerve tissues have been reported from dinosaur remains. In this study we provide evidence of nerve fragments, characterized by a double helical wrapping of collagen fibers, from a Triceratops condyle collected at the Hell Creek Formation, MT. Based on comparison with nerves from an avian model we conclude that these are fragments of nerves that once resided in vivo in Triceratops.