9306294 Bolt This research involves an investigation of morphological variation in protoanthracosaur tetrapods from Paleozoic sites in Delta, Iowa, and Goreville, Illinois. New fossil materials will be prepared, specimens will be described, and new specimens will be named and illustrated. The preparation and description of this material will increase by approximately 25% the number of known Mississippian tetrapod genera. %%% The morphology and relationships of the earliest tetrapods are poorly understood at present largely because there are few well preserved and well prepared specimens available for study. Furthermore, some of the best represented early tetrapod groups are highly derived morphologically. The Delta fossils are the oldest terrestrial vetebrates ever found in the United States and among the oldest in the world, as no more than a dozen localities are known to be of equal or greater age. Both the Delta and Goreville sites have produced exceptionally well preserved species of terrestrial animals. The age, exceptional preservation, diversity and abundance of specimens at both sites provide an extraordinary opportunity to learn about early terrestrial vertebrates and morphological diversification among vertebrate lineages.