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Female, head disarticulated and displaced. The fish is embedded in a mass of filamentous algae. Alternative combination: Physonemus falcatus. "The genus Physonemus was originally erected for P. arcuatus by McCoy (1848) to receive elegant forwardly-curved, well omamented Paleozoic fin spines of unknown affìnities ... The Paleozoic fin spine Physonemus falcatus St. John and Worthen 1883, from the Valmeyeran St. Louis Limestone of St. Louis, Missouri, has been found on sexually mature males of a small, highly sexually dimorphic chondrichthyan from the Chesterian Bear Gulch Limestone of Montana" (Lund 1985, p.1). Diagnosis from Lund 1985, p.3: “Small sharks, maximum known size 145 mm fork length, with forwardly-curved spines, inclined at mean angle of 14.5 degrees to the horizontal. Neither spine nor first dorsal fin present on juveniles below 124 mm length, nor on females. Males with elongate rostrum, denticles covering dorsum of rostrum, cranium and dista] portion of dorsal rod, females with short rostrum and devoid of denticles. Teeth delicate, cladodont, tooth whorls of larger, non-cladodont teeth external to jaws. Pectoral fin with five prearticular basals, a metapterygium bearing six radials, and an axis of seven elements with only one radial. Pelvic girdle supports 8—10 radials; clasper of male consisting of 6—8 axials and a three-part mixopterygium. Second dorsal fin of 12—14 well spaced radials followed by a triangular basal plate, l9—21 distal radials. Axial skeleton of 44 precaudal segments, 18 preural caudals and 16—18 ural caudals. Caudal fin deeply forked, equilobate, with no radials between dorsal and ventral lobes.” Line drawing from Lund 1985, p. 13: References: St. John, O. H. and Worthen, A. H. (1875). Descriptions of fossil fishes. Geological Survey of Illinois 6:245—488. St. John, O. H. and Worthen, A. H. (1883). Descriptions of fossil fishes; a partial revision of the Cochliodonts and Psammodonts. Geological Survey of Illinois 7:55—264. Lund, Richard (1985). The morphology of Falcatus falcatus (St. John and Worthen), a Mississippian stethacanthid chondrichthyan from the Bear Gulch Limestone of Montana, Journal of Vertebrate Paleontology, 5:1-19, DOI: 10.1080/02724634.1985.10011842.

Taxonomy from Lund 2000. Diagnosis for the genus Discoserra from Lund 2000, p. 180: "Teeth of the premaxilla, maxilla and dentary long, thin, and styliform. Posterior end of maxilla does not extend back to level of anterior margin of orbit. Parietals excluded from contact in dorsal midline by postrostral 2, which contacts supraoccipital. No transverse supratemporal commissure in supraoccipital. Two rows of paired bones over orbit. One to three interopercular bones; two to three small postspiraculars and a presupracleithrum. Branchiostegals very variable in size, number and shape. Dorsal ridge scales with small, forwardly facing hooks; two to three small anal fin hooks. Origin of anterior edge of dorsal fin set well below dorsal margin of ridge scales. All fins with well spaced rays; pelvic fin reduced, caudal fin rounded." Line drawing from Lund 2000, p. 183: Identified by oilshale using Lund 2000. References: R. Lund (2000) The new Actinopterygian order Guildayichthyiformes from the Lower Carboniferous of Montana (USA). Geodiversitas 22(2):171-206

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 Factor & Feldmann 1985. Diagnosis from Factor & Feldmann 1985, p. 331: "Palaeostomatopod with five carinae on posterior surface of carapace and six carinae on abdominal tergites. Terminal spike more than half the length of telson; telson serrate in region of caudal furcae. Uropodal protopod serrate distally; endopod a small spine-like projection; exopod styliform, serrate along distal third of outer margin." Line drawing from Factor & Feldmann 1985, p. 332: The bar represents 1 cm. Identified by oilshale. References: Ronald A. Jenner; Cees H.J. Hof; Frederick R. Schram (1998): Palaeo- and Archaeostomatopods (Hoplocarida: Crustacea) from the Bear Gulch Limestone, Mississippian (Namurian), of central Montana. Contributions to Zoology, 67 (3) 155-186. FREDERICK R. SCHRAM (2007): PALEOZOIC PROTO-MANTIS SHRIMP REVISITED. Journal of Paleontology, September 2007, v. 81, p. 895-916. Haug et al. (2010): Evolution of mantis shrimps (Stomatopoda, Malacostraca) in the light of new Mesozoic fossils. BMC Evolutionary Biology 2010, 10:290. Schram (1969): Some Middle Pennsylvanian Hoplocarida (Crustacea) and their phylogenetic significance. Fieldiana, Geology, Vol.12, No.14 Link (04.2013) Factor, D. F., and Feldmann, R. M. (1985) Systematics and paleoecology of malacostracan arthropods in the Bear Gulch Limestone (Namurian) of Central Montana. Annals of Carnegie Museum 54, p. 319-356.

Probably Lingula species A in Lutz-Garihan 1985. Taxonomy from Fossilworks.org. References: 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, 5: 457-467.

Allenypterus montanus was first described by Melton as a Dorypterid; in 1977 this fish was recognized by Lund as a Coelacanth. Taken from "Fossil Fishes of Bear Gulch" by Lund, Richard, and Grogan, E.D., 2005, Bear Gulch web site, www.sju.edu/research/bear_gulch, 1/11/2016 (last update from 2/1/2006): Allenypterus montanus is a coelacanth of relatively primitive skull osteology but with a unique, teardrop-shaped body form. They range in size from about 25 mm (1 inch) to 150 mm (6 1/4 inches) in length. Like other coelacanths, Allenypterus had a complete covering of thin, rounded, overlapping scales, and webbed fins with few, widely spaced rays. No teeth, thick lips, and a very small gape of the mouth show that this fish was a suction feeder on small prey. The body is very high relative to length. The paired fins are large with delicate webbing. The paired fins, second dorsal and anal fins are supported on long muscular lobes by segmental bony axes that are covered with fine rounded scales. There is a long, continuous dorsal lobe of the webbed caudal fin. The combination of all these fins, webs, and lobes indicates a superb maneuverer in weedy, sheltered environments but a fish that could not outswim any predator. It is noteworthy that the belly was armored, suggesting that Allenypterus may have swam and fed on and close to the bottom. The body form of Allenypterus is unique among known coelacanths — all others differ subtly only in proportions. The skull of Allenypterus is among the most primitive coelacanth skulls known. Line drawing from Lund & Lund 1985, p.242: References: Melton, W. G. 1969. A new dorypterid fish from central Montana. Northwest Science 43:196-206 Glickman W. L. 1977: Allenypterus montanus (Crossopterygii: Coelacanthiformes) from the Bear Gulch Limestone of Montana. Adelphy University, 1977. Lund, R. & Lund, W. 1984: New genera and species of coelacanths from the Bear Gulch Limestone (Lower Carboniferous) of Montana (U.S.A.) Geobios, Volume 17, issue 2, p. 237-244. Lund, R., and W.L. Lund, 1985. "Coelacanths from the Bear Gulch Limestone (Namurian) of Montana and the evolution of the Coelacanthiformes." Bull. Carnegie Mus. Nat. Hist. 25: 1-74. Lund, W. L., R. Lund and G. Klein, 1985. "Coelacanth feeding mechanisms and the ecology of the Bear Gulch coelacanths." Compte Rendu, Neuvième Congrès International de Stratigraphie et de Géologie du Carbonifère, 5: 492-500. Friedman, M. & Coates, M. 2006: A newly recognized fossil coelacanth highlights the early morphological diversification of the clade Proc. R. Soc. B (2006) 273, 245–250. Hagadorn, J.: Bear Gulch: An Exceptional Upper Carboniferous Plattenkalk

Taxonomy from Fossilworks.org. Kalops diophrys is distinguished from its larger sister species, Kalops monophrys, by fewer caudal fin rays, a different number of supraorbital bone rows, and the development of its ganoine ridging at a smaller size. The cranial osteology most closely resembles that of the poorly known Palaeoniscus and "Elonichthys" serratus. The snout structure is closest to the Tarrasiiformes. Diagnosis from Poplin & Lund 2002, p. 1020: "Total length ranging from 50 to 96 mm; in the midline, postrostral meeting the frontal at mid-orbitalevel; two rows of supraorbitals; presence of a bone, probable spiracula lateral to the dermosphenotic; dermopterotic with a spur posterolateral to the anterior extrascapular row; six infraorbitals, and about 12 suborbital bones; anterior limb of the preopercle not as high as the maxillary posterior plate; presence of a small postspiracular behind the dermohyal; opercle tall, two and a half as high as long; ten to 12 branchiostegal rays; two rows of extrascapulars: anterior one with five paired and one median ossicles, posterior one with one paired bone carrying the supratemporal commissure; supracleithrum not as high as the opercle; scales of the lateral line hexagonal; three to six predorsal scutes, not reaching the skull; pectoral fin fan shaped; dorsal fin long based, spanning about 21 scale rows; anal fin without fulcra; scaled lobe of the caudal fin at 30 degrees to the body axis." Line drawing from Poplin & Lund 2002, p. 1022: Identified by oilshale using Poplin & Lund 2002. References: Poplin, C., & R. Lund. 2002. "Two Carboniferous fine-eyed paleoniscoids (Pisces, Actinopterygii) from Bear Gulch (USA)." Journal of Paleontology 76: 1014-1028.

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.