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Article: Two new specimens of Anthracosaurus (Amphibia: Anthracosauria) from the Northumberland Coal Measures

Publication: Palaeontology
Volume: 30
Part: 1
Publication Date: March 1987
Page(s): 15 26
Author(s): J. A. Clack
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How to Cite

CLACK, J. A. 1987. Two new specimens of Anthracosaurus (Amphibia: Anthracosauria) from the Northumberland Coal Measures. Palaeontology30, 1, 15–26.

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Two specimens from the Low Main Seam at Newsham, Northumberland are attributed to the genus Anthracosaurus. The first is a skull table (Hancock Museum specimen G 13.78) previously attributed to 'Eogyrinus' (= Pholiderpeton, Clack 1987). This skull table was used in the past to demonstrate the presence of a 'kinetic line' between the embolomere skull table and cheek. The holotype of A. russelli lacks such a kinetic line, but the apparent paradox can be resolved if the 'kinetic line' was not mobile in the later embolomere families Eogyrinidae and Anthracosauridae, but acted as a butt joint to resist vertical forces.The second specimen (Hancock Museum specimen G 24.39) is an isolated right jugal. It shows an unusually excavated orbital margin, which leaves the bone very narrow below it. This unique character is confirmed as present in the holotype of A. russelli. Incorporation of this jugal into new reconstructions shows the skull to be higher and narrower than formerly appreciated, and without any conspicuous 'lateral flare' in the suspensorial region.Characters of the skull table including dermal ornament are used to construct a cladogram of the embolomeres, including the isolated skull table pertaining to Pteroplax.
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