ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
This study is based on serial sections of the occipital and otic regions of a therocephalian from the Tapinocephalus zone. The occipital region as preserved consists of the basioccipitals and exoccipitals. The basioccipital is long and slender and is separated from the more anterior basisphenoid by an unossified zone. The exoccipitals are large and contain a part of the jugular foramen and two foramina for cranial nerve XII.The otic bones are fused together to form a periotic. The most striking feature of the inner ear is the medioventral position of the vestibule. Passing back into the periotic from the vestibule is a deep recessus scala tympani. This recess opens anteriorly into a ventral fenestra in the vestibule, the fenestra rotunda. These structures are similar to those of Dimetrodon and the gorgonopsian.The anterior part of the periotic is projected ventrally to form a basicranial process. This probably arose by intramembranous ossification. The unossified zone between the basioccipital and basisphenoid may represent a persistent basicranial fenestra.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1050630104
