63 GAIA Nº 15, LISBOA/LISBON, DEZEMBRO/DECEMBER 1998, pp. 63-74 (ISSN: 0871-5424) artigos/papers New Mexico Museum of Natural History and Science. 1801 Mountain Road NW, ALBUQUERQUE, NM 87104. USA Department of Earth and Planetary Sciences, University of New Mexico. ALBUQUERQUE, NM 87131. USA Theropods are among the first dinosaurs, and their body fossils occur in Upper Triassic sediments in North and South America, Greenland, Europe, and India, with footprints known from North America,