Collaborative Research: The Late Devonian Tetrapodomorph Tiktaalik roseae

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ABSTRACT Project Title: Collaborative Research: The Late Devonian Tetrapodomorph Tiktaalik roseae PI: Edward B. Daeschler, Associate Curator of Vertebrate Zoology, Academy of Natural Sciences of Philadelphia, 1900 Benjamin Franklin Parkway, Philadelphia, PA 19103 PI: Neil H. Shubin, Robert R. Bensley Distinguished Professor, Department of Organismal Biology and Anatomy, 1027 East 57th Street, University of Chicago, Chicago, IL 60637 Tiktaalik roseae is a fossil fish from the Late Devonian Period (385-362 million-years-ago) that was discovered in 2004 on Ellesmere Island, Nunavut, Canada. This species is the finned animal that is most closely related to tetrapods (limbed vertebrates). As an intermediate form, T. roseae helps us to recognize the sequence of morphological changes across the fish-to-tetrapod transition and can teach us about the forces that were driving these important evolutionary changes. T. roseae was first described in 2006 and has provoked a great deal of interest among evolutionary biologists. To date, however, the only published reports on this species have been short papers in Nature. With continued study and documentation of the abundant and well-preserved material of T. roseae, we will fill the need for a detailed investigation of this important fossil at the cusp of the fish-to-tetrapod transition. A primary contribution of this research will be a detailed publication on a wide range of topics about T. roseae. The core of this publication will be a thorough morphological description including extensive figures of many of the 50+ specimens. We will also investigate the internal structure of bones in the fins for the first time, further document the ancient environment where T. roseae lived, and produce new studies of the evolutionary tree across the fish-to-tetrapod transition. The other major contribution of this project will take advantage of the quality of T. roseae fossils to assess the functional anatomy of the fins and skull. Evaluation of the hypothesis that the fins were capable of body support will involve detailed analysis of joint structure and the relative motions possible between bones, fin rays, and scales of the front fin and shoulder. The second set of analyses will explore the relationship between skull architecture and different stresses and strains in the skull related to movement, breathing and feeding. At the conclusion of this study, all T. roseae specimens are to be returned to the Government of Nunavut, and so the timely publication of these data via print and websites is of particular importance. The discovery and description of T. roseae has received considerable attention from educational organizations and media internationally; as a textbook transitional fossil it has become a powerful tool in the communication of evolution to the general public. The PIs have a record of public lectures and development of web-based educational resources. We will make use of this research project to further communicate the results of the work, as well as the scientific process, to a broad audience and thereby help people get a better grasp of how evolution works.