Proceeding of the Seventh Annual Meeting of the Chinese Society of Vertebrate Paleontology

The Jehol Biota of western Liaoning Province is represented by four vertebrate complexes: the lower Yixian Fm. Confuciusornis-Sinosauropteryx-Zhangheotherium Complex; the middle Yixian Fm. Monjurosuchus-Hyphalosaurus-Liaoxiornis C mplex; the upper Yixian Fm. Lycoptera muroii-Manchurochelys manchouensis Complex, and the Jiufotang Fm. Cathayornis-Chaoyangia-Psittacosaurus Complex. These assemblages are all determined to be Early Cretaceous in age and are correlated to the Mesozoic Geologic Time Scale of Gradstein et al. on the basis of 40Ar/39Ar dates from extrusive basalts and tuffs interbedded with the fossiliferous units. Age assignments for the vertebrate fossils are recognized as middle Barremian, late Barremian, and Aptian stages. The stratigraphic range represented by the Yixian and Jiufotang formations spans the late Valanginian through Barremian and Aptian stages. Introduction* Ever since the distinguished geologist A. W. Grabau erected the nomenclature of the Jehol System (Grabau, 1923) and Jehol Biota (Grabau, 1928) in the 1920’s, the sedimentary units comprising the Jehol Group and the fauna contained therein have constituted a focal point fo