. Chordate morphology. Morphology (Animals); Chordata. inter- temporal. supratemporal _ tabular C Figure 4-23 Fossil amphibians, branchiosaurs, and Eugynnus. A, B, dorsal and ventral views of Amphibamus, o branchiosaur; C, dorsal view of Bronchiosourus, D, E, dorsal and ventral o Eugynnus; F, lateral view of skull ond or Eugynnus; G, medial v,ew of mandible of Eugyrinus. (After Gregory, 1950, and Wotson, 1940) pair of palatines. The vomer and palatine each had a large tooth or tusk affixed to them. The posterior part of the palatine was probably separated as the ectopterygoid. T
. Chordate morphology. Morphology (Animals); Chordata. inter- temporal. supratemporal _ tabular C Figure 4-23 Fossil amphibians, branchiosaurs, and Eugynnus. A, B, dorsal and ventral views of Amphibamus, o branchiosaur; C, dorsal view of Bronchiosourus, D, E, dorsal and ventral o Eugynnus; F, lateral view of skull ond or Eugynnus; G, medial v,ew of mandible of Eugyrinus. (After Gregory, 1950, and Wotson, 1940) pair of palatines. The vomer and palatine each had a large tooth or tusk affixed to them. The posterior part of the palatine was probably separated as the ectopterygoid. The pterygoids were triradiate (three-pronged) and there were large interpterygoid fontanelles. A small epipterygoid ex- tended up from the palatoquadrate, near its attachment to the basipterygoid process, and passed between the Vi and V2 branches of the trigeminal nerve. The endocranium had slight exoccipital and basiocci- pital perichondral ossifications. These bones contributed to the single occipital condyle. The exoccipital was perforated by a hypoglossal foramen and formed the posterior margin of the vagus foramen. There was no supraoccipital; the postparietal and tabular had slight flanges extending down over the occipital surface. The otic capsule was ossified, probably from prootic and opisthotic centers. The mandible was quite primitive in its cover of dermal bones. It was like that of the branchiosaur but had two small splenials along the ventral inner margin. The artic- ular region appears to have been ossified from the supra- angular. There was a foramen for the internal mandibular branch of the facial nerve (chordi tympani) just below the articular area. The branchial skeleton is not known. Along with the Seymouriamorpha, Eugynnus is classed as an anthracosaur. The anthracosaurs, or coal lizards, are presumed to be on the direct line of evolution to the reptile. The anthracosaur usually described is Palaeogyrmus (Figure 4-24). Only the skull of this Pennsylvanian f
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