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The structure of the sarcopterygian Onychodus jandemarrai n. sp. from Gogo, Western Australia: with a functional interpretation of the skeleton

Published online by Cambridge University Press:  26 July 2007

Mahala Andrews ,
John Long ,
Per Ahlberg ,
Richard Barwick  and
Ken Campbell
Mahala Andrews
Affiliation:
formerly at National Museum of Scotland, Edinburgh, UK
John Long
Affiliation:
Western Australian Museum, Francis Street, Perth, Western Australia, now at the National Museum of Victoria, Melbourne, Victoria, Australia. e-mail: jlong@museum.vic.gov.au
Per Ahlberg
Affiliation:
Natural History Museum, Cromwell Road, London, UK, now at Department of Evolutionary Organismal Biology, University of Uppsala, Sweden. e-mail: Per.Ahlberg@ebc.uu.se
Richard Barwick
Affiliation:
Department of Earth and Marine Sciences, Australian National University, Canberra, ACT, Australia. e-mail: richard.barwick@anu.edu.au
Ken Campbell
Affiliation:
Department of Earth and Marine Sciences, Australian National University, Canberra, ACT, Australia. e-mail: ken.campbell@anu.edu.au
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Abstract

A description of the head, mandible, pectoral girdle, humerus, medial fins and their supports, and the dissociated vertebral column has been prepared for Onychodus jandemarrai n. sp. from the Gogo Formation (Frasnian) of Western Australia. This is the most completely known species of the genus. The feature influencing most of the head morphology is the retractable parasymphysial tusk whorls. Their presence has caused a reorganisation of the braincase, palate (including the loss of the vomers), and lateral displacement of the nasal capsules. The extensive mandibular articulation is in cartilage, and the mandibular symphysis is weak. This makes for a kinetic skull. There is a single submandibular on each side. The vertebral column is poorly ossified, consisting of intercentra which have no ventral contact, and pleurocentra. The neural arches have no longitudinal ligament, have unequal sides, and asymmetrical placing of the dorsal and ventral nerve root foramina. Each arch has an anterior surface that often attaches to the next anterior arch. The caudal fin is almost diphycercal; all the medial fins have strong support structures. An attempt is made to discuss the functional morphology of many features of the skeleton.

Keywords

AnatomyDevonianOnychodontidaeSarcopterygiansskeletal functions
Type
Research Article
Information
Earth and Environmental Science Transactions of The Royal Society of Edinburgh , Volume 96 , Issue 3 , September 2005 , pp. 197 - 307
Copyright
Royal Society of Edinburgh 2005

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