Morphology and Evolution of Fossil and Living Gars (Actinopterygii: Lepisosteiformes), Part 2

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0075460Bemis and Grande Among the earliest lineages of vertebrate animals with living survivors today are several groups of primitive fishes including the sturgeons, bowfins, paddlefishes, and gars. Dr. William Bemis at University of Massachusetts-Amherst and his colleague at the Field Museum, Dr. Lance Grande, have been conducting detailed morphological and anatomical studies of all the living species of these fishes as well as of fossil material housed in the world's major museums. Their goal in this project is to integrate knowledge of the living species of gars with the wealth of fossil material known for the group, to describe morphological changes through time, assess migration routes and biogeographic ranges, and help determine the precise pattern of early vertebrate evolutionary diversification. Although all the living gars are limited to North and Central America, fossils have been described from Europe, Africa, Asia, and South America, from time horizons extending back through the Mesozoic. Many of these fossils are extremely well preserved, providing details of morphology and anatomy that make possible quite fine-scale comparison with living forms. In addition, the integration of fossil species with living taxa in an overall genealogical or phylogenetic framework and classification will help understand the environmental setting in which early fish evolution took place, for example whether marine lineages diversified less than freshwater lineages. Because fossil taxa typically will lack data for some features or characters observable from living species, the investigators will also explore theoretical issues concerning the effects of missing data on algorithms used to reconstruct phylogenetic trees