The hyoid arch and braincase anatomy of Acanthodes support chondrichthyan affinity of ‘acanthodians’
File(s)
Published version
Author(s)
Brazeau, MD
de Winter, V
Type
Journal Article
Abstract
Solving the evolutionary relationships of the acanthodians is one of the key problems in reconstructing ancestral anatomical conditions for the jawed vertebrates (gnathostomes). Current debate concerns whether acanthodians are an assemblage of stem chondrichthyans, or a more generalized grade encom- passing some early stem osteichthyans. The skull anatomy of Acanthodes bronni has been pivotal in these debates, owing to tension between chondrichthyan- and osteichthyan-like models of reconstruction. We use computed tomography scanning and traditional palaeontological techniques to resolve the long- standing debate about the anatomy of the jaw suspension. We establish the correct length of the hyomandibula and show that it attaches to a process on the ventrolateral angle of the braincase below the jugular vein groove. This condition corresponds precisely to that in chondrichthyans. This character represents an unambiguously optimized synapomorphy with chondrichthyans given current gnathostome phylogenies, corroborating the growing consensus of the chondrichthyan affinity of acanthodians.
Date Issued
2015-12-22
Date Acceptance
2015-11-13
Citation
Proceedings of the Royal Society B: Biological Sciences
ISSN
0962-8452
Publisher
Royal Society, The
Start Page
1
End Page
6
Journal / Book Title
Proceedings of the Royal Society B: Biological Sciences
Volume
282
Issue
1821
Copyright Statement
© 2015 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
Publication Status
Accepted