DISSERTATION RESEARCH: New Data from the Integument and Osteoderms for Amniote Phylogeny

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A grant has been awarded to Dr. Maureen O'Leary and Mr. Robert Hill at SUNY at Stony Brook to investigate the anatomy of the skin in amniotes, a large group of animals including modern birds, reptiles, and mammals. New information about the skin will be used to discover the evolutionary relationships of these animals. Information about the skin is available in both living and extinct forms because some amniotes have bones in the skin, called osteoderms, which are commonly found as fossils. The anatomy of different types of amniote skin, and all types of osteoderms, will be described and cataloged using digital photography, illustrations, and microscopic thin-sections. The new data will be combined with data from existing analyses on the skulls, skeletons, and soft tissues of amniotes to provide a more comprehensive picture of the evolution of these animals. The reconstruction of soft tissue features such as skin in dinosaurs and other extinct species depends largely on what is known about their genealogical relationships. It is therefore crucial to resolve any competing hypotheses before accurate reconstructions of extinct amniotes can be made. In recent years the evolutionary relationships between major groups of amniotes have been a point of considerable debate. The relationships of turtles are particularly controversial; turtles have been hypothesized to be the closest relatives of a number of extinct groups, and even modern crocodiles. The most remarkable feature of the turtle - its shell - may be a uniquely evolved structure, or may have formed from the fusion of bones in the skin of the turtle's ancestor. This study will be the first in which information about the skin is used to unravel the genealogical relationships of amniotes, contributing to a broader understanding of amniote evolution in general, and the origin of turtles in particular.