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Showing results for tags 'bear gulch'.
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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
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From the album: Invertebrates
Reticycloceras sp. Early Carboniferous Serpukhovian Heath Shale Formation Bear Gulch Montana USA -
Janvier, P. & Lund, R. 1983 – Hardistiella montaniensis from the Lower Carboniferous of Montana with remarks on the affinity of the lampreys. J. Vert. Paleont. 2, 407-413. Janvier, P. & Lund, R. 1986 – A second lamprey from the Lower Carboniferous of Bear Gulch Montana. Geobios 19, 647-652. Robert S. Sansom, Sarah E. Gabbott, and Mark A. Purnell Decay of vertebrate characters in hagfish and lamprey (Cyclostomata) and the implications for the vertebrate fossil record Proc. R. Soc. B. 2011 278 1709 1150-1157 Janvier, P., Lund, R. & Grogan, E. Further consideration of the earliest known lamprey Hardistiella montanensis, Janvier and Lund, 1983, from the Carboniferous of the Bear Gulch, Montana, U.S.A. J. Vertebrate Paleontology 24, 742-743 (2004).
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From the album: Vertebrates
Palaeoniscidae indet. "Bigeye" Early Carboniferous Serpukhovian Heath Shale Formation Bear Gulch Fergus County Montana USA -
Taken from Lund, Richard, and Grogan, E.D., 2005, Bear Gulch web site, www.sju.edu/research/bear_gulch, 14/11/2016, page last updated 2/1/2006: "Heteropetalus elegantulus is an elegantly slim little euchondrocephalan with many different tooth shapes along its jaws. It ranges to only about 4 inches in length. Skull, jaws, and dentition place it close to Debeerius. It is common in the weedier shallow water areas. There are no scales, except for a small patch at the rear of the dorsal fin of males. Lateral line canals of the head are supported by rather large highly modified scales. Heteropetalus has an almost eel-like body, a protocercal tail, rounded and very flexible pectoral fins midway up the sides of the body, and a single long flexible undulatory dorsal fin (preceded by a small fin spine). All these features indicate a maneuverer in weedy or reef-like environments as well as along the bottom. Mature males have a distinctly strengthened, hooked and denticulated posterior end of the dorsal fin; the dorsal fin of males was significantly higher than that of females. This dorsal fin dimorphism is similar to that seen in the Gouramies, modern bony tropical fish available in any pet store. They have a very small mouth, with the teeth crowded to the front of the jaws, and a variety of plucking, nipping, and crunching teeth. The jaw suspension itself is rather flexible to give it a certain amount of both lateral and fore-and-aft motion. The bright yellow spots in the dorsal view of a head are the inner ears, and the yellow is from iron oxide particles that were bio-concentrated during the life of this fish. H. elegantulus was originally described as a petalodont, but subsequent discoveries proved it to be otherwise; it is closely related to Debeerius ellefseni." This fish is clearly a male as shown by the claspers. References: Lund, R. (1977). A new petalodont (Chondrichthyes, Bradyodonti) from the Upper Mississippian of Montana. Annals of Carnegie Museum, 46 (19): 129-155. Grogan E.D. & Lund, R. (2000). Debeerius ellefseni (Fam. Nov., Gen. Nov., Spec. Nov.), an autodiastylic chondrichthyan from the Mississippian Bear Gulch Limestone of Montana (USA), the relationships of the Chondrichthyes, and comments on gnathostome evolution. Journal of Morphology, 243 (3): 219-245.
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- bear gulch
- carboniferous
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Picture of the recent Pyrosoma atlanticum provided by Show_ryu - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=15193539 Lit.: CUOMO, C., ROSBACH, S. and BARTHOLOMEW, P. (2015): INVERTEBRATES OF THE UPPER MISSISSIPPIAN BEAR GULCH LIMESTONE – A TALE OF JELLIES AND TUNICATES ? 2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015), Paper No. 327-5
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Taxonomy from Fossilworks.org Diagnosis from Lund & Poplin 2000, p. 429: "Aesopichthyidae up to 9 cm long, with a subterminal mouth; single median rostropostrostral remote from the rim of the mouth; premaxillae small and loose, not meeting in the midline, resulting in a median rostral notch; vertically oriented pillar-shaped antorbital; three infraorbitals, the first is below and posterior to the orbit, the third is T-shaped and contacts the nasal anterodorsally; suborbitals thin, one large and occasionally up to three; dermosphenotic small, triangular; two paired extrascapulars; tear-drop shaped maxilla; mandible with short, anterior, toothed portion, a coronoid process and greatly overlapped by maxilla; a single row of marginal teeth on the premaxilla, maxilla and dentary; preoperculum, high, nearly vertical with a long quadratojugal line; operculum shorter anteroposteriorly than suboperculum, vertical to long axis of the fish; seven to eight branchiostegal rays; characteristic ornamentation of the dermal skull with heavy transverse ganoine ridges on the rostropostrostral, prominent, thick and posteriorly pointed tubercles on the skull roof, but significant ganoine absent from suborbitals, preoperculum and dermohyal; first infraorbital and extrascapulars fringed with sharp posterior spikes; pectoral fin with well spaced, unbranched, entirely articulated rays; dorsal fin with contiguous and entirely articulated rays except the seven posterior ones which are separated, unarticulated and borne by a short scaled lobe; caudal fin equilobate and deeply cleft with webbed rays; 12 to 14 median scutes continuous from skull to dorsal fin, and small scutes between dorsal and caudal fins. For meristics and morphometrics see Table 1." Line drawing from Lund & Poplin 2000, p. 439: Identified by oilshale using Lund & Poplin 2000. References: Lund R. & Poplin C. 2000. — Two new deep-bodied Actinopterygians from Bear Gulch, (Montana, USA, Lower Carboniferous). Journal of Vertebrate Paleontology 20: 428-449. Fossil Fishes of Bear Gulch
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- aesopichthys
- bear gulch
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Taxonomy from Fossilworks.org. Diagnosis from Lund & Lund 1984, p. 239: " Marine rhabdodermatids having large dentary, precoronoid and ectopterygoid teeth. The preorbital region is higher and more rounded than in other rhabdodermatids, the cheek bones deeply overlap each other and the operculum. The operculum articulates with the tabular and the posterior margin of the tabular is level with the posterior margin of the skull. Tubercular ornamentation is sparse on the anterior skull-roof and preorbital region, dense on the very thin cheek bones of large individuals. Dense vermiform ornamentation is found on operculum and angular behind the angular pit line; sparse linear ridges on skull-roof posterior to intracranial joint. The first dorsal fin plate has ventral processes indicating fusion from supraneural elements. The second dorsal fin is anteroposteriorly elongated and bears a posterior articulation for the fin axis, and the anal plate, which rarely ossifies, is a simple rod in the ventral body wall, anterior to the first hemal spine. Pelvic plates are very broad anteriorly, with 3 major and one minor anterior lateral process. The size ranges from 79 mm to 219 mm in standard length. Elliptical caudal fin and cylindrical body form." Line drawing from Lund & Lund 1984, p 239: Identified by oilshale using Lund & Lund 1984. References: Lund, R., Lund, W. (1984) New genera and species of coelacanths from the Bear Gulch Limestone (Lower Carboniferous) of Montana (USA). Geobios, 17, fasc 2:237-244. Lund, R., Lund, W. (1985) Coelacanths from the Bear Gulch Limestone (Namurian) of Montana and the evolution of the Coelacanthiformes. Bull. Carnegie Mus. Nat. Hist. 25, pp 1-74. Link: Fossil Fishes of Bear Gulch
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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.
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Lit.: EDWIN K. MAUGHAN and ALBERT E. ROBERTS (1967): Big Snowy and Amsden Groups and the Mississippian-Pennsylvanian Boundary in Montana. GEOLOGICAL SURVEY PROFESSIONAL PAPER 554 7 B Lutz-Garihan, A.B. (1979). Brachiopods from the Upper Mississippian Bear Gulch Limestone of Montana. Neuvieme Congres International de Stratigraphie et de Geologie du Carbonifere. Compte Rendu Vol. 5: 457-467 pp. EDIT: Subperiod is Mississippian and Epoch is Late.
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Taxonomy from Fossilworks.org. Diagnosis from Lund & Poplin 1997, p. 467: "Wendyichthys with the following characters: dermosphenotic small, lateral to the anterior part of the frontal and with a slight variable contact with the nasal; thin sclerotic boues; two suborbitals not in contact with each other nor with the surrounding bones, occasionally with one additional anamestic element; maxilla with a sharp posteroventral angle; one row of marginal teeth; operculum in tight contact with suboperculum; 12—13 branchiostegal rays; presence of an extralateral gular on each side of the median gular; six to eight ridge scales midway between the skull and the dorsal fin; three to four ridge scales immediate in front of dorsal fin origin. For meristics and morphometrics see Table 1." Line drawing from Lund & Poplin 1997, p. 472: Identified by oilshale using Lund & Poplin 1997. References: Lund R. & Poplin C. 1997. — The Rhadinichthyids (Palaeoniscoid, Actinopterygians) from the Bear Gulch Limestone of Montana (USA, Lower Carboniferous). Journal of Vertebrate Paleontology 17: 466-486.
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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.
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- bear gulch
- carboniferous
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Taken from Lund, Richard, and Grogan, E.D., 2005, Bear Gulch web site, www.sju.edu/research/bear_gulch, 14/11/2016, page last updated 2/1/2006: "Heteropetalus elegantulus is an elegantly slim little euchondrocephalan with many different tooth shapes along its jaws. It ranges to only about 4 inches in length. Skull, jaws, and dentition place it close to Debeerius. It is common in the weedier shallow water areas. http://people.sju.edu/~egrogan/BearGulch/images_fish_art/Hetelegantulus_duo.jpg Male (top) and female (bottom). There are no scales, except for a small patch at the rear of the dorsal fin of males. Lateral line canals of the head are supported by rather large highly modified scales. Heteropetalus has an almost eel-like body, a protocercal tail, rounded and very flexible pectoral fins midway up the sides of the body, and a single long flexible undulatory dorsal fin (preceded by a small fin spine). All these features indicate a maneuverer in weedy or reef-like environments as well as along the bottom. Mature males have a distinctly strengthened, hooked and denticulated posterior end of the dorsal fin; the dorsal fin of males was significantly higher than that of females. This dorsal fin dimorphism is similar to that seen in the Gouramies, modern bony tropical fish available in any pet store. http://people.sju.edu/~egrogan/BearGulch/fossils_fish/Helegantulus_head_640.jpg Dorsal view of Heteropetalus elegantulus head They have a very small mouth, with the teeth crowded to the front of the jaws, and a variety of plucking, nipping, and crunching teeth. The jaw suspension itself is rather flexible to give it a certain amount of both lateral and fore-and-aft motion. The bright yellow spots in the dorsal view of a head are the inner ears, and the yellow is from iron oxide particles that were bio-concentrated during the life of this fish. H. elegantulus was originally described as a petalodont, but subsequent discoveries proved it to be otherwise; it is closely related to Debeerius ellefseni." Lit.: Lund, R. 1977 - A new petalodont (Chondrichthyes, Bradyodonti) from the Upper Mississippian of Montana. Annals of Carnegie Museum, 46 (19): 129-155. Grogan E.D. & Lund, R. (2000): Debeerius ellefseni (Fam. Nov., Gen. Nov., Spec. Nov.), an autodiastylic chondrichthyan from the Mississippian Bear Gulch Limestone of Montana (USA), the relationships of the Chondrichthyes, and comments on gnathostome evolution. Journal of Morphology, 243 (3): 219-245.
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References: UM Paleotology center: http://hs.umt.edu/paleo/collections/browse.php?id=25460
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The dark spot in the living chamber is either thought to be an ink sac or a beak and radula. References: Doguzhaeva, L., Mapes, R. and Mutvei, H. (2007):Beaks and radula of Early Carboniferous goniatites. Lethaia 30(4):305 - 313
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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.
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Taxonomy from Factor & Feldman 1985. Diagnosis from Factor & Feldman 1985, p. 328: "Bivalved phyllocarid. Elongate telson with medial longitudinal carina, longer than pretelson segment, dorsally flexed at posterior end. Uropods reduced, blade-like, pretelson segment elongate. Fifth abdominal segment with circular notch in antero-ventral corner of pleuron. Line drawing from Factor & Feldman 1985, p. 328; Line bar represents 1 cm. Identified by oilshale using Factor & Feldman 1985. References: Frederick R. Schram & John Horner (1978). "Crustacea of the Mississippian Bear Gulch Limestone of Central Montana". Journal of Paleontology 52 (2): 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. Annals of Carnegie Museum 54, p. 319-356.
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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
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Kalops monophrys is known by over 125 specimens from the Bear Gulch Limestone. K. monophrys is distinguished from its smaller sister species, Kalops diophrys, by having more caudal fin rays, a different number of supraorbital bone rows, and the development of its ganoine ridging at a larger size. The cranial osteology of Kalops most closely resembles that of the poorly known Palaeoniscus and "Elonichthys" serratus. The snout structure is closest to that of the Tarrasiiformes. Diagnosis from Poplin & Lund 2002, p. 1014: "Total length ranging from 44 to 116 mm; postrostral meeting the frontal in the midline anteriorly to mid-orbit level; ovoid antorbital; one row of supraorbitals; about five infraorbitals and five suborbitals; anterior extremity of the preopercle as high as the posterior plate of the maxillary; about 15 branchiostegal rays; one pair of extrascapulars; supracleithrum higher than opercle; from eight up to 17 predorsal median scutes, continuous between skull and dorsal fin; dorsal fin spanning 14 scale rows; anal fin with fulcra; scaled lobe of the caudal fin at 25 degrees to the body axis." Line drawing from Poplin & Lund 2002, p. 1017: Identified by oilshale using Poplin & Lung 2002. References: Poplin, C., & R. Lund (2002) "Two Carboniferous fine-eyed paleoniscoids (Pisces, Actinopterygii) from Bear Gulch (USA)." Journal of Paleontology 76: 1014-1028.
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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.
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Lit.: MOORE, R., McKENZIE, S. and LIEBERMAN, B. (2007): A CARBONIFEROUS SYNZIPHOSURINE (XIPHOSURA) FROM THE BEAR GULCH LIMESTONE, MONTANA, USA. Palaeontology, Vol. 50, Part 4, 2007, pp. 1013–1019. Schram, F. (1979): Limulines of the Mississippian Bear Gulch limestone of central Montana, USA. Transactions of the San Diego Society of Natural History 19:67-74 (1979)
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References: Lund, R. 1982 - Harpagofututor volsellorhinus new genus and species (Chondrichthyes, Chondrenchelyiformes) from the Namurian Bear Gulch Limestone, Chondrenchelys problematica Traquair (Visean), and their sexual dimorphism. Journal of Paleontology, 56 (4): 938-958. Lund, R. & Grogan, E.D. 1997 - Soft tissue pigments of the Upper Mississippian chondrenchelyid, Harpagofututor volsellorhinus (Chondrichthyes, Holocephali) from the Bear Gulch Limestone, Montana, USA. Journal of Paleontology, 71 (2): 337-342.
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A modern Ratfish, Bischoff Island, British Columbia, Canada (from Wikipedia: Clark Anderson/Aquaimages) Lit.: Grogan, E. Lund, R. 2002: The geological and biological environment of the Bear Gulch Limestone (Mississippian of Montana, USA) and a model for its deposition. Geodiversitas 2002, 24 (2): 296-315 Lund, R. 1977 - Echinochimaera meltoni new genus and species (Chimaeriformes), from the Mississippian of Montana. Annals of Carnegie Museum, 46 (13): 195-221. Hagadorn, J.: Bear Gulch: An exceptional Upper Carboniferous Plattenkalk
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- bear gulch
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Paraconularia subulata (Hall 1858) together with Aviculopecten sp., a bivalve mollusc. References: Babcock, L. E., and R. M. Feldmann (1986): Devonian and Mississippian conulariids of North America. part B. Paraconularia, Reticulaconularia, New Genus, and organisms rejected from Conulariida. Annals of Carnegie Museum 55: 411-479.
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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.
