Stenolaemate bryozoans from the Graham Formation, Pennsylvanian (Virgilian) at Lost Creek Lake, Texas, USA

Palaeontologia Electronica

article

Andrej Ernst¹  Anna Lene Claussen²  Barbara Seuss²  Patrick N. Wyse Jackson³ 

[1] Universität Hamburg;Friedrich-Alexander University Erlangen-Nürnberg;Trinity College

关键词: Finis Shale;    cyclothem;    North American Midcontinent;    morphology;    taxonomy;    ecology;   

DOI  :  10.26879/1174

学科分类：社会科学、人文和艺术（综合）

来源: Palaeontologia Electronica

【 摘 要 】

An exceptionally well-preserved bryozoan fauna has been described from the Finis Shale Member, Graham Formation, Pennsylvanian (Virgilian) at Lost Creek Lake, Texas, USA. Nineteen bryozoan species (four cystoporates, one trepostome, two rhabdomesine cryptostomes, and 12 fenestrates) have been identified in two profiles which cut the most vertical range, at the level of the outcrop-base, of the Finis Shale. Two species are new: a trepostome Dyscritella felixi n. sp. and a fenestrate Laxifenestella texana n. sp. The fauna was studied on a combined basis of external and internal morphology, using a SEM and thin sections, respectively. Bryozoans from the Finis Shale Member exhibit a variety of growth forms from encrusting unilaminar, erect ramose, erect reticulate robust, and erect reticulate delicate, to erect pinnate morphologies. The erect growth forms clearly dominate, and bryozoans become more robust in the upper level of the profiles. The distribution pattern of bryozoan growth forms indicates gradual shallowing in the profiles supporting the assumption of a transgressive-regressive cycle in the Finis Shale. Bryozoan richness, abundance, and α-diversity increase toward the top of the profiles. Palaeobiogeographic relations of the Finis Shale bryozoans are mostly restricted to the American realm, with some connections to the Pennsylvanian of Europe.

【 授权许可】

CC BY|CC BY-NC-SA