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Busch, R.E., Jr., 1983

Techniques for the recognition of articulate brachiopods in thin section, with examples from the Mankomen Group (Permian), Alaska

Bibliographic Reference

Busch, R.E., Jr., 1983, Techniques for the recognition of articulate brachiopods in thin section, with examples from the Mankomen Group (Permian), Alaska: University of California, Davis, Ph.D. dissertation, 428 p., illust., maps.

Abstract

This study presents (1) a new thin section terminology for articulate brachiopods and ways to recognize a thin section of unknown orientation; (2) methods for recognizing an articulate brachiopod to genus or species level; and (3) the skeletal petrography of 14 species of 14 genera of articulates from the Pennsylvanian (Atokan) to Permian (Wolfcampian to Wordian) Mankomen Group, Alaska Range, east-central Alaska. (1) All orientations of thin sections of brachiopods except tangential sections are redefined in terms of their relationship to the plane of bilateral symmetry or a radial element, a plane normal to the exterior surface of the shell at the plane of section, and the relative degree of measurement error introduced by the orientation. (2) Thin-section identification of an articulate is conditional on a priori knowledge of the gross morphology and skeletal architecture of both valves. Diagnostic aspects of the morphology may include: relative size; details of shape including lateral profile, relative curvature, and type and degree of development of folding, plication, or costation; and macro- and micro-ornament. Aspects of the skeletal architecture include details of: the valve geometry (profile, thickness, and curvature geometries); the number and types of calcareous shell layers and their geometries; details of fabrics and fabric elements; punctation; external ornament; and internalia. (3) Species described are: Rhipidomella sp. indet. (Orthida); Leurosina? sp. indet. (Strophomenida, Chonetidina, Rugosochonetinae); Chonetinetes sp. indet. (Chonetinellinae); Liosotella? sp indet. (Productidina, Productacea, Paucispiniferidae); Calliprotonia sp. indet. (Echinoconchidae); Reticulatia sp. indet. (Dictyoclostidae); Yakovlevia sp. indet. (Linoproductidae); Stenoscisma spitzbergiana (Stepanov) (Rhynchonellida, Stenoscismatacea); Rhynchopora kochi Dunbar (?Rhynchonellida, Rhynchoporacea); Cleiothyridina sp. indet. (Spiriferida, Athyrididina); Neospirifer sp. indet. (Spiriferidina, Spiriferacea, Spiriferidae); Spiriferella keilhavii (von Buch) (Brachythyrididae); Martinia sp. indet. (Reticulariacea, Martiniidae); and Spiriferellina sp. indet. (Spiriferinida, Spiriferinidina, Spiriferinacea, ?Reticulariinidae).

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