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Three new palaeoniscoid fishes from the Bear Gulch Limestone (Serpukhovian, Mississippian) of Montana (USA) and the relationships of lower actinopterygians

Kathryn E. MICKLE, Richard LUND, Eileen D. GROGAN, Kathryn E. MICKLE, Richard LUND & Eileen D. GROGAN

en Geodiversitas 31 (3) - Pages 623-668

Published on 30 September 2009

Three new palaeoniscoid fishes (Osteichthyes, Actinopterygii), representing two new genera, Lineagruan judithi n. gen., n. sp., L. snowyi n. gen., n. sp., Beagiascus pulcherrimus n. gen., n. sp., are described from the Bear Gulch Limestone Member of the Heath Formation (Serpukhovian) of Montana, a 318 million year old lagerstätte. Morphological, morphometric, and meristic data were analyzed and compared to data for other Paleozoic actinopterygians. Differences among the species were noted in character complexes that may have played a role in feeding or propulsive regimes and fine-scale niche partitioning. A matrix of 111 characters and 40 taxa was constructed using relatively complete taxa ranging from the Devonian to the Recent. Cladistic analysis using Hennig86 and Winclada resulted in two trees. Branch-and-bound treatment generated one tree, in which the palaeoniscoids were paraphyletic. In all instances, the relationships of the three new species were consistent. It is noted that a number of the palaeoniscoid clades proposed by the current cladistic analysis have also been generated in earlier analyses of Bear Gulch fishes and other independent analyses. This recurring pattern implies some robustness to these associations in spite of variations between the matrices generating them.
Keywords :
Bear Gulch Limestone, Palaeoniscoids, lower actinopterygians, Carboniferous, Mississippian, USA, phylogeny, new species, new genera
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