Imperial College London

Dr. Martin D. Brazeau

Faculty of Natural SciencesDepartment of Life Sciences (Silwood Park)

Senior Lecturer



+44 (0)20 7594 2254m.brazeau




W2.2KennedySilwood Park






BibTex format

author = {Castiello, M and Brazeau, MD},
doi = {10.1111/pala.12345},
journal = {Palaeontology},
pages = {369--389},
title = {Neurocranial anatomy of the petalichthyid placoderm Shearsbyaspis oepiki Young revealed by X-ray computed microtomography},
url = {},
volume = {61},
year = {2018}

RIS format (EndNote, RefMan)

AB - Stemgroup gnathostomes reveal the sequence of character acquisition in the origin of modern jawed vertebrates. The petalichthyids are placodermgrade stemgroup gnathostomes known from both isolated skeletal material and rarer articulated specimens of one genus. They are of particular interest because of anatomical resemblances with osteostracans, the jawless sister group of jawed vertebrates. Because of this, they have become central to debates on the relationships of placoderms and the primitive cranial architecture of gnathostomes. However, among petalichthyids, only the braincase of Macropetalichthys has been studied in detail, and the diversity of neurocranial morphology in this group remains poorly documented. Using Xray computed microtomography, we investigated the endocranial morphology of Shearsbyaspis oepiki Young, a threedimensionally preserved petalichthyid from the Early Devonian of TaemasWee Jasper, Australia. We generated virtual reconstructions of the external endocranial surfaces, orbital walls and cranial endocavity, including canals for major nerves and blood vessels. The neurocranium of Shearsbyaspis resembles that of Macropetalichthys, particularly in the morphology of the brain cavity, nerves and blood vessels. Many characters, including the morphology of the pituitary vein canal and the course of the trigeminal nerve, recall the morphology of osteostracans. Additionally, the presence of a parasphenoid in Shearsbyaspis (previously not known with confidence outside of arthrodires and osteichthyans) raises some questions about current proposals of placoderm paraphyly. Our detailed description of this specimen adds to the known morphological diversity of petalichthyids, and invites critical reappraisal of the phylogenetic relationships of placoderms.
AU - Castiello,M
AU - Brazeau,MD
DO - 10.1111/pala.12345
EP - 389
PY - 2018///
SN - 0031-0239
SP - 369
TI - Neurocranial anatomy of the petalichthyid placoderm Shearsbyaspis oepiki Young revealed by X-ray computed microtomography
T2 - Palaeontology
UR -
UR -
UR -
VL - 61
ER -