Tag: Joseph N. Keating

Joe is a PhD student at the School of Earth Sciences at the University of Bristol, UK. Joe studies the evolution of the vertebrate skeleton. In particular, he hopes to better understand the microscopic structure of the skeleton in primitive vertebrates and, using this information, to determine how growth of the skeleton has evolved through time. Joe’s PhD is supervised by Philip Donoghue of the University of Bristol and Zerina Johanson of the Natural History Museum, London. Joe completed an undergraduate degree in geology with palaeobiology at the University of Leicester, UK.

Contact Details:

Joseph N. Keating, Department of Earth Sciences, University of Bristol, Queen’s Road, Bristol, BS8 1RJ, UK.

Fossil Focus: Heterostraci

Fossil Focus
by Joseph N. Keating*1 Introduction: The Heterostraci (which means ‘different shield’) make up an extinct group of jawless fish that lived during the early to middle Palaeozoic era, approximately 440 million to 359 million years ago. They were exceptionally diverse, with over 300 species currently described from marine and freshwater sediments of North America, Europe and Siberia­­­. Heterostracans are characterized by their external armour of distinct plates, which are composed mainly of bone and dentine (a hard-tissue component of teeth in vertebrates). Most heterostracans can be classified into two major groups, the cyathaspids and the pteraspids, which differ with respect to the structure, number and arrangement of their armoured plates. Heterostracan fossils are rarely found as comp