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Taxonomy from fossilworks.org. Synonyms: Lingula mytiloides Meek and Worthen 1873 and Lingula umbonata White 1884. From Lutz-Garihan 1979, p. 458: "Shell small, ovate, very light colored, preserved mostly as external or internal molds of undetermined valves. Posterior margins smoothly rounding into lateral margins; greatest width at mid-length or slightly toward anterior. Convexity of valve greatest along antero-posterior line at mid-width, and at apex, convexity then decreases laterally so that cross-section is almost an upside-down V. Surface marked by closely spaced growth lines. Interior of valve not seen.” Identified by oilshale using Lutz-Garihan 1979. References: Shumard, B. F. and Swallow, G.C. (1858) Descriptions of new fossils from the Coal Measures of Missouri and Kansas. Academy of Science of St. Louis Transactions 1:198-227. Yancey, T. E. (1978) Brachiopods and mollusca of the Lower Permian Arcturus Group, Nevada and Utah, Part 1: brachiopods, scaphopods, rostroconchs, and bivalves. Bulletins of American Paleontology 74(303):257-367 Lutz-Garihan, A.B. (1979) Brachiopods from the Upper Mississippian Bear Gulch Limestone of Montana. Compte Rendu, Neuvième Congrès International de Stratigraphie et de Géologie du Carbonifère. Vol. 5: 457–467.

Together with Bryozoa and other Brachiopods. Taxonomy from Fossilworks.org, From Lutz-Garihan 1979, p. 463: “ Shell small; pedicle valve with moderately well-developed ears, convexity unknown because of deformation of shells, but umbo extends somewhat beyond hinge; greatest width at mid-length of valve; ornamentation of pedicle valve consists of rugae and growth lines, some rugae enlarged as nodes occasionally, and in some specimens, some costae develop at about half the distance from posterior but are somewhat irregular; relatively thick spines along hinge and irregularly across valve. Brachial valve gently concave, with ears: surface ornamentation has a wavy appearance because of sometimes irregular growth lines and rugae; some rugae interrupted by nodes; costae irregularly developed an some brachial valves; but not extending completely to posterior; spines probably absent, some brachial valves convex at center of hinge on exterior for a minute part of length, giving appearance of a node at this position. No interior structures seen.” Identified by oilshale using Lutz-Garihan 1979. References: Girty, G. (1911) THE FAUNA OF THE MOOREFIELD SHALE OF ARKANSAS. DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY. BULLETIN 439. 1-145 Lutz-Garihan, A.B. (1979) Brachiopods from the Upper Mississippian Bear Gulch Limestone of Montana. Compte Rendu, Neuvième Congrès International de Stratigraphie et de Géologie du Carbonifère. Vol. 5: 457–467pp. Link: Browse Collections - College of Humanities and Sciences / UM Paleontology Center - University Of Montana (umt.edu)

Taxonomy according to Mickle et al., 2009. The University of Montana, UM Paleontology Center website (Browse Collections - College of Humanities and Sciences / UM Paleontology Center - University Of Montana (umt.edu)) lists "Yogoniscus gulo" as an old taxon on some specimens (but not on all specimens) of Beagiascus pulcherrimus. Obviously, confusion has occurred. Diagnosis from Mickle et al., p. 639: “A lower actinopterygian fish defined by the following combination of characters: elongate fusiform body, narrow in cross section; premaxillae narrowly sutured in midline; nasal notched anteriorly and posteriorly; posterodorsal process of antorbital forms base of posterior nasal notch; frontal with a sinuous sagittal suture; crescent-shaped dermosphenotic; large dermopterotic with a wide posterior plate, laterally spurred, anteromedial process situated within a notch in the frontal; three large suborbitals situated within curve of preoperculum, small fourth suborbital overlapping large suborbital, suborbital between posteroventral infraorbital and maxilla; four infraorbitals – narrow infraorbital ventral to orbit, crescent-shaped posteroventral infraorbital, an intervening element, and T-shaped posterodorsal infraorbital, tapered anterior end of posterodorsal infraorbital comes in contact with tapered posterior end of nasal; mosaic of several small bones in curve of posterodorsal infraorbital for spiracular bone; long maxillary plate; two rows of pointed, posteriorly inclined teeth down length of maxilla; prominent posteroventral process of maxilla; anteriorly inclined hatchet shaped preoperculum; one row of 5 or 6 anteopercular bones along anterior margin of operculum – ventral-most anteopercular bone wider and longer than the others; rectangular, anteriorly inclined operculum with transverse ganoine ridges; rhombic suboperculum with vertical ganoine ridges; total of 14 or 15 branchiostegal rays – five above mandibular corner, 9 or 10 at and below mandibular corner, first branchiostegal twice as high as second; anterior and posterior extrascapular rows sharing median extrascapular (anterior row – three lateral bones, posterior-single bone bearing supratemporal commissure); unsutured postspiracular; one row of rhombic postcleithral scales; narrow ventrolateral flank scales; f ank scales finely pectinated; fan-like pectoral fin; triangular pelvic fin, triangular dorsal and anal fins with posterior edges tapering off gradually; heterocercal caudal fin deeply forked, accessory flap on epicaudal lobe; all fins bear long, stout, overlapping fringing fulcra on leading edges; precaudal ridge scales continuous between the anal and caudal, and dorsal and caudal fins. Meristic, morphometric, and cranial measurements are presented in Tables 9 to 12.” Line drawing from Mickle et al., 2009, p. 642: ID by oilshale using Mickle et al., 2009. Reference: Mickle, K. E., Lund, R. and Grogan. E. D. (2009): Three new palaeoniscoid fishes from the Bear Gulch limestone (Serpukhovian, Mississippian) of Montana (USA) and the relationships of lower actinopterygians. Geodiversitas 31(3):623-668. DOI: 10.5252/g2009n3a6

Taxonomy from Fossilworks.org.Can also be found in Mazon Creek. References: F. R. Schram (1979): Worms of the Mississippian Bear Gulch Limestone of central Montana, USA. Transactions of the San Diego Society of Natural History. Volume 19, No 9, pp 107-120

Taxonomy from Lund & Poplin 2002. Diagnosis for P. hibbardi from Lund & Melton 1982, p. 486: "Tarrasioid fishes ranging in length to 136 mm; the maximum head length/total length ratio is 0.155; maximum body height total/length ratio is 0.172; the total length/snout-vent length ratio is 1.746. There are 27 to 29 precaudal vertebral arches and 68 to 73 precaudal scale rows. There are 28 to 31 scale rows above the lateral line at the anal notch and 50 to 54 rows below the lateral line. There are 27 to 28 caudal vertebral arches, disappearing at the downturn of the tail, and 78 to 81 caudal scale rows. There are approximately 4 jointed, unbranched fin rays to each vertebral arch." Line drawing from Lund & Melton 1982, p. 489: Identified by oilshale using Lund & Melton 1982. References: R. Lund and W. G. Melton Jr. 1982. A new actinopterygian fish from the Mississippian Bear Gulch limestone of Montana. Palaeontology 25(3):485-498. R. Lund and C. Poplin 2002. Cladistic analysis of the relationships of the Tarrasiids (Lower Carboniferous Actinopterygians). Journal of Vertebrate Paleontology 22:480-486.

Taxonomy from Factor & Feldman 1985. Diagnosis from Factor & Feldman 1985 p. 339: "Malacostracan with thinly sclerotized carapace; prominent anteriorly directed mid-dorsal spine; antero-dorsal and antero-ventral spines present. Ventral margins of abdominal pleura triangular, smooth. Third abdominal segment with strong dorsal flexure." Line drawing from Factor & Feldman 1985, p. 342: Bar represents 1 cm. Identified by oilshale References: Schram, F., Horner, J. (1979) Crustacea of the Mississippian Bear Gulch Limestone of Central Montana. Journal of Paleontology Vol. 52, No. 2 (Mar., 1978), pp. 394-406. Factor D. F. and Feldmann R. M. (1985): Systematics and Paleoecology of Malacostracan Arthropods in the Bear Gulch Limestone (Namurian) of central Montana. Carnegie Museum of Natural History. 54, 319-356. Jenner, R. A., Hof, C. and Schram, F. R. (1998): Palaeo- and archaeostomatopods (Hoplocarida, Crustacea) from the Bear Gulch Limestone, Mississippian (Namurian), of central Montana. Contributions to Zoology 67 (3) 155-185.