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Anatomical study of two previously undescribed specimens of Clevosaurus hudsoni (Lepidosauria: Rhynchocephalia) from Cromhall Quarry, UK, aided by computed tomography, yields additional information on the skeleton and hitherto undescribed bones

Anatomical study of two previously undescribed specimens of Clevosaurus hudsoni (Lepidosauria: Rhynchocephalia) from Cromhall Quarry, UK, aided by computed tomography, yields additional information on the skeleton and hitherto undescribed bones
Anatomical study of two previously undescribed specimens of Clevosaurus hudsoni (Lepidosauria: Rhynchocephalia) from Cromhall Quarry, UK, aided by computed tomography, yields additional information on the skeleton and hitherto undescribed bones

We investigate two well-preserved and previously undescribed specimens of Clevosaurus hudsoni from a Late Triassic fissure deposit at Cromhall Quarry, SW Britain. For the first time computed tomography (CT) scans of British Triassic fissure specimens have been successfully digitally segmented. Visualisation software was used to isolate bone from matrix and to separate individual bones from each other, revealing hidden cranial and postcranial elements. The CT data, together with stereoscopic microscope analysis, have enabled a full evaluation of the specimens including previously poorly known or undescribed elements of the type species of the clevosaur clade. We present detailed descriptions of the cervical vertebrae including the atlas-axis complex. Little studied bones such as the gastralia and epipodials are detailed here and a gap in the lower temporal bar is confirmed. Sclerotic ossicles are presented for the first time for C. hudsoni. A fully fused scapulocoracoid and unfused astragalus and calcaneum provide new insights into clevosaur ontogeny. The CT scans provide key information on post mortem movement and taphonomy of the specimen, revealing fragmentation of part of the skull by the right arm, which has been thrust into the right side of the skull displacing both cranial and jaw bones.

anatomy, Bristol fissure, Clevosaurus, computed tomography, rhynchocephalian, sphenodontian, Triassic
0024-4082
163-195
O'Brien, Aileen
f49eddeb-5a61-4bdd-ab38-38597ebabc80
Whiteside, David I.
868b161c-24f9-4222-a195-f4e03c13012c
Marshall, John E.A.
cba178e3-91aa-49a2-b2ce-4b8d9d870b06
O'Brien, Aileen
f49eddeb-5a61-4bdd-ab38-38597ebabc80
Whiteside, David I.
868b161c-24f9-4222-a195-f4e03c13012c
Marshall, John E.A.
cba178e3-91aa-49a2-b2ce-4b8d9d870b06

O'Brien, Aileen, Whiteside, David I. and Marshall, John E.A. (2018) Anatomical study of two previously undescribed specimens of Clevosaurus hudsoni (Lepidosauria: Rhynchocephalia) from Cromhall Quarry, UK, aided by computed tomography, yields additional information on the skeleton and hitherto undescribed bones. Zoological Journal of the Linnean Society, 183 (1), 163-195. (doi:10.1093/zoolinnean/zlx087).

Record type: Article

Abstract

We investigate two well-preserved and previously undescribed specimens of Clevosaurus hudsoni from a Late Triassic fissure deposit at Cromhall Quarry, SW Britain. For the first time computed tomography (CT) scans of British Triassic fissure specimens have been successfully digitally segmented. Visualisation software was used to isolate bone from matrix and to separate individual bones from each other, revealing hidden cranial and postcranial elements. The CT data, together with stereoscopic microscope analysis, have enabled a full evaluation of the specimens including previously poorly known or undescribed elements of the type species of the clevosaur clade. We present detailed descriptions of the cervical vertebrae including the atlas-axis complex. Little studied bones such as the gastralia and epipodials are detailed here and a gap in the lower temporal bar is confirmed. Sclerotic ossicles are presented for the first time for C. hudsoni. A fully fused scapulocoracoid and unfused astragalus and calcaneum provide new insights into clevosaur ontogeny. The CT scans provide key information on post mortem movement and taphonomy of the specimen, revealing fragmentation of part of the skull by the right arm, which has been thrust into the right side of the skull displacing both cranial and jaw bones.

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More information

e-pub ahead of print date: 15 December 2017
Published date: 8 May 2018
Keywords: anatomy, Bristol fissure, Clevosaurus, computed tomography, rhynchocephalian, sphenodontian, Triassic

Identifiers

Local EPrints ID: 421252
URI: http://eprints.soton.ac.uk/id/eprint/421252
ISSN: 0024-4082
PURE UUID: 9e0d6d5d-fcb3-42e9-bfd1-890f52535699
ORCID for John E.A. Marshall: ORCID iD orcid.org/0000-0002-9242-3646

Catalogue record

Date deposited: 29 May 2018 16:30
Last modified: 28 Apr 2022 01:33

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Contributors

Author: Aileen O'Brien
Author: David I. Whiteside

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