Geology and Paleontology of Psittacosaurus from Amphoe Khon Sawan, Changwat Chaiyaphum

Abstract

According to Buffetaut, Sattayarak and Suteethorn (1989), new species of Ceratopsians, Psittacosaurus was collected from Ban Dong bang Noi in Changwat Chaiyaphum, within conglomerates bed of Khok Kruat Formation in Khorat Group. To determine biostratigraphic position and paleo-environments are the purpose of this study. Lithostratigraphy of study area can be divided into 2 successions; Lower and Upper successions. Upper succession composes mostly of reddish-brown sandstone and conglomerate with calcareous nodule, fine to medium grained sandstones. Conglomerate contains granule to small pebbles of calcareous nodule, sub-rounded to rounded pebbles up to 1 cm., sand lens in conglomerates shows small ripple cross-bedded, therefore lithofacies is transition from clast-supported through sand matrix-supported which horizontally stratification. Lower succession composes mostly of purple sandstone, varies in grained size. The sandstone succession contains of sandstone which interbedded between cross-bedded sand and parallel laminated sand at the lower part and shows small ripple-cross bed interbedded with parallel lamination at the upper part. The total thickness is 25 m. The results from lithostratigraphic column and lithofacies, paleoenvironments can be reconstructed. The lower sandstone succession are deposit on point bar in meandering river system and continued accumulated in the upper succession. Conglomerates are transported by high-velocity current and deposited in point bar. Biostatigraphic position can be fixed on top of Upper successions within conglomerates bed which accumulate in point bar of meandering river.