Meeting Abstract

7.5  Saturday, Jan. 4 09:00  Ecomorphotypes and habitats in a Mississippian Bay LUND, R.*; GREENFEST-ALLEN, E.; GROGAN, E. D.; Carnegie Museum; Penn Center for Bioinformatics, University of Pennsylvania; Saint Joseph’s University rdicklund3@gmail.com

The 323 million year old Bear Gulch Lens of the Bear Gulch Member, Heath Formation, of Montana, USA is recognized for the preservation of its fauna in terms of quality and diversity. Here we capitalize on these factors and 40+ years of data collection to evaluate the relationship between functional morphology and ecology in these Upper Mississippian marine fishes. The vertebrate members of the bay fauna were scored for thirteen morphological characters demonstrated or inferred to be of functional significance in habitat utilization among extant fishes. Based on similarities in character coding, taxa were grouped into 16 ecomorphotypes, only one of which contained both osteichthyan and chondrichthyan taxa. Of the remainder, nine were comprised exclusively of chondrichthyans, one of coelacanths, one of Acanthodes, and four of actinopterygians. Chondrichthyans span a spectrum of grossly different feeding, propulsive, and sexually dimorphic adaptations, and the chondrichthyan ecomorphotypes showed strong distributional trends in relation to bay habitats. Neritic fusiform actinopterygians occupied one ecomorphotype, which was subdivided on the basis of feeding specializations. Uniquely specialized actinopterygians occupied the remaining ecomorphotypes. Actinopterygians display few ecologically sensitive morphological deviations from a fusiform body plan and generalized feeding mechanism, and the relative distribution of actinopterygian ecomorphotypes varied little across the bay habitats. Factors that could have contributed to the disparity of actinopterygian versus chondrichthyan responses to adaptive diversification are discussed.