Edited by oilshale
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By oilshale (edited)
Coelacanth
Kingdom: Animalia
Eon: Phanerozoic
Era: Paleozoic
Period: Carboniferous
Sub Period: Mississippian
Epoch: Late
International Age: Serpukhovian
Big Snowy Group
Heath Formation
Bear Gulch Bed
Acquired by: Purchase/Trade
Length: 21 cm
Bear Gulch
Fergus County
Montana
United States
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.
Edited by oilshale
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