PRIMITIVE JAW STRUCTURE IN AN ARTICULATED BRACHYTHORACID ARTHRODIRE (PLACODERM FISH; EARLY DEVONIAN) FROM SOUTHEASTERN AUSTRALIA

A unique ‘buchanosteid’ arthrodire specimen from Emsian limestones at Burrinjuck represents the complete articulated remains of the head and cheek, and most of the trunk armor bones from a single fish, together with well-ossified braincase and jaw cartilages. The structure of the toothplates and jaw...

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Bibliographic Details
Published in:Journal of vertebrate paleontology 2001-12, Vol.21 (4), p.670-678
Main Authors: YOUNG, G. C, LELIÈVRE, H, GOUJET, D
Format: Article
Language:English
Subjects:
Armor
Bone plates
Bones
Cartilage
Geology
Jaw
Phylogenetics
Taxa
Vertebrate paleontology
Zoology
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Description
Summary:A unique ‘buchanosteid’ arthrodire specimen from Emsian limestones at Burrinjuck represents the complete articulated remains of the head and cheek, and most of the trunk armor bones from a single fish, together with well-ossified braincase and jaw cartilages. The structure of the toothplates and jaws are described, and compared with primitive brachythoracid material from Saudi Arabia of similar age. Both the palatoquadrate and meckelian cartilages are well preserved, and perichondrally ossified as single elements. As previously described in some phlyctaeniids, the dermal gnathal elements carry crowded denticles similar to the normal tubercular ornament, enlarged along anterior and lateral margins. Six characters concerning gnathal plates of brachythoracids, which have been used in phylogenetic analysis, are discussed and reformulated.
ISSN:0272-4634
1937-2809
DOI:10.1671/0272-4634%282001%29021%5B0670%3APJSIAA%5D2.0.CO%3B2