The Middle to Late Jurassic Terrestrial Vertebrate Faunal Transition in Northwestern China: A Paleontologic, Stratigraphic, and Geochronologic Study

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The late Middle through early late Jurassic (Callovian through Oxfordian) is one of the most poorly known intervals in the terrestrial vertebrate fossil record. The Shishuqou Formation of the Xinjiang Autonomous Region of northwestern China preserves a rich sequence of fossils spanning this period. This is an important time in the history of modern terrestrial vertebrates because many group (mammals, birds, crocodilians, squamates, frogs, salamanders) were just beginning to diversify and the single supercontient of Pangea with its cosmopolitan fauna was just beginning to divide. Furthermore, several groups of dinosaurs that would diversify and dominate the Cretaceous (i.e., sauropods, ornithopods, stegosaurs, ankylosaurs, and coelurosaurs) first appeared and radiated during Middle and Late Jurassic. Thus, fossils from the Shishugou Formation can contribute to an understanding of the most basic relationships and early evolution within the major groups of modern tetrapods and dinosaurs and the beginning of modern faunal provinciality. The four year project proposed here combines palentological studies of the fossils with stratigraphic, peleoenvironmental, and geochronological studies of the sediments and volcanic deposits to document the fauna and establish a calibrated stratigraphic framework for faunal change within the formation.Support is requested for 1) further field work to collect more vertebrate fossils, including a program of screenwashing for microvertabates; 2) field work establishing the stratigraphic and palenivornment distributions of taxa in the formation and any correlations between them 3) museum studies documenting these in the and related fossils and laboratory studies dating the tuffs and bentonites and determining their geochemical composition. These separate lines of research will be synthesized into a calibrated model for fanual and environmental change in the formation that is integrated with existing regional tectonics and paleoclimatic interpretations.