Evolution and development of the synarcual in early vertebrates
The synarcual is a structure incorporating the anterior vertebrae of the axial skeleton and occurs in vertebrate taxa such as the fossil group Placodermi and the Chondrichthyes (Holocephali, Batoidea). Although the synarcual varies morphologically in these groups, it represents the first indication,...
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| Format: | Journal Article |
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Springer-Verlag
2012
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| Online Access: | http://hdl.handle.net/20.500.11937/14979 |
| _version_ | 1848748768705380352 |
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| author | Johanson, Z. Trinajstic, Kate Carr, R. Ritchie, A. |
| author_facet | Johanson, Z. Trinajstic, Kate Carr, R. Ritchie, A. |
| author_sort | Johanson, Z. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The synarcual is a structure incorporating the anterior vertebrae of the axial skeleton and occurs in vertebrate taxa such as the fossil group Placodermi and the Chondrichthyes (Holocephali, Batoidea). Although the synarcual varies morphologically in these groups, it represents the first indication, phylogenetically, of a differentiation of the vertebral column into separate regions. Among the placoderms, the synarcual of Cowralepis mclachlani Ritchie, 2005 (Arthrodira) shows substantial changes during ontogeny to produce an elongate, spool-shaped structure with a well-developed dorsal keel. Because the placoderm synarcual is covered in perichondral bone, the ontogenetic history of this Cowralepis specimen is preserved as it developed anteroposteriorly, dorsally and ventrally. As well, in the placoderm Materpiscis attenboroughi Long et al., 2008 (Ptyctodontida), incomplete fusion at the posterior synarcual margin indicates that both neural and haemal arch vertebral elements are added to the synarcual. A survey of placoderm synarcuals shows that taxa such as Materpiscis and Cowralepis are particularly informative because perichondral ossification occurs prior to synarcual fusion such that individual vertebral elements can be identified. In other placoderm synarcuals (e.g. Nefudina qalibahensis Lelièvre et al., 1995; Rhenanida), cartilaginous vertebral elements fuse prior to perichondral ossification so that individual elements are more difficult to recognize. This ontogenetic development in placoderms can be compared to synarcual development in Recent chondrichthyans; the incorporation of neural and haemal elements is more similar to the holocephalans, but differs from the batoid chondrichthyans. |
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| format | Journal Article |
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| institution | Curtin University Malaysia |
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| last_indexed | 2025-11-14T07:10:18Z |
| publishDate | 2012 |
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| spelling | curtin-20.500.11937-149792017-09-13T16:06:24Z Evolution and development of the synarcual in early vertebrates Johanson, Z. Trinajstic, Kate Carr, R. Ritchie, A. Synarcual Placodermi Vertebral fusion Vertebral column Chondrichthyes Holocephali Batoidea The synarcual is a structure incorporating the anterior vertebrae of the axial skeleton and occurs in vertebrate taxa such as the fossil group Placodermi and the Chondrichthyes (Holocephali, Batoidea). Although the synarcual varies morphologically in these groups, it represents the first indication, phylogenetically, of a differentiation of the vertebral column into separate regions. Among the placoderms, the synarcual of Cowralepis mclachlani Ritchie, 2005 (Arthrodira) shows substantial changes during ontogeny to produce an elongate, spool-shaped structure with a well-developed dorsal keel. Because the placoderm synarcual is covered in perichondral bone, the ontogenetic history of this Cowralepis specimen is preserved as it developed anteroposteriorly, dorsally and ventrally. As well, in the placoderm Materpiscis attenboroughi Long et al., 2008 (Ptyctodontida), incomplete fusion at the posterior synarcual margin indicates that both neural and haemal arch vertebral elements are added to the synarcual. A survey of placoderm synarcuals shows that taxa such as Materpiscis and Cowralepis are particularly informative because perichondral ossification occurs prior to synarcual fusion such that individual vertebral elements can be identified. In other placoderm synarcuals (e.g. Nefudina qalibahensis Lelièvre et al., 1995; Rhenanida), cartilaginous vertebral elements fuse prior to perichondral ossification so that individual elements are more difficult to recognize. This ontogenetic development in placoderms can be compared to synarcual development in Recent chondrichthyans; the incorporation of neural and haemal elements is more similar to the holocephalans, but differs from the batoid chondrichthyans. 2012 Journal Article http://hdl.handle.net/20.500.11937/14979 10.1007/s00435-012-0169-9 Springer-Verlag restricted |
| spellingShingle | Synarcual Placodermi Vertebral fusion Vertebral column Chondrichthyes Holocephali Batoidea Johanson, Z. Trinajstic, Kate Carr, R. Ritchie, A. Evolution and development of the synarcual in early vertebrates |
| title | Evolution and development of the synarcual in early vertebrates |
| title_full | Evolution and development of the synarcual in early vertebrates |
| title_fullStr | Evolution and development of the synarcual in early vertebrates |
| title_full_unstemmed | Evolution and development of the synarcual in early vertebrates |
| title_short | Evolution and development of the synarcual in early vertebrates |
| title_sort | evolution and development of the synarcual in early vertebrates |
| topic | Synarcual Placodermi Vertebral fusion Vertebral column Chondrichthyes Holocephali Batoidea |
| url | http://hdl.handle.net/20.500.11937/14979 |