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.
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).
Theses and Dissertations