Dinosaur footprint assemblage from the Lower Cretaceous Khok Kruat Formation,Khorat Group,northeastern Thailand  

作　　者：Shohei Kozu Apsorn Sardsud Doungrutai Saesaengseerung Cherdchan Pothichaiya Sachiko Agematsu Katsuo Sashida 

机构地区：[1]Graduate School of Life and Environmental Sciences,University of Tsukuba,Ibaraki 305-8572,Japan [2]Department of Mineral Resources,Ministry of Natural Resources and Environment,Thailand

出　　处：《Geoscience Frontiers》2017年第6期1479-1493,共15页地学前缘（英文版）

摘　　要：The Khok Kruat Formation is the upper part of the Khorat Group,which consists of upper Lower Cretaceous non-marine sedimentary rocks in northeastern Thailand.Many dinosaur footprints have been known from the upper Lower Cretaceous(Aptian-Albian)Khok Kruat Formation at the Huai Dam Chum(Tha Uthen)site,northeastern Thailand.Approximately 600 tracks occur in thin mudstone layer of the northern part of the outcrop at the Huai Dam Chum track site.Two types of footprints,small-sized theropod and crocodylomorph are imprinted with mud cracks and ripple marks on the thin mud layer.Most of footprints are referred to cf.Asianopodus,and are imprinted by small-sized theropoda,probably ornithomimosauria.Theropod tracks are mainly separated into two groups,Group A and Group B.From ichnological viewpoints,the small-sized theropod track assemblage indicates the herd behaviour and its idiosyncratic group composition.In particular,the histogram of size-frequency measurements of Group A shows the anomalous bimodal distribution.We consider that there are two hypotheses;the first one is due to the male-female difference,and the second is a result of the different growing stage.The Khok Kruat Formation is the upper part of the Khorat Group,which consists of upper Lower Cretaceous non-marine sedimentary rocks in northeastern Thailand.Many dinosaur footprints have been known from the upper Lower Cretaceous(Aptian-Albian)Khok Kruat Formation at the Huai Dam Chum(Tha Uthen)site,northeastern Thailand.Approximately 600 tracks occur in thin mudstone layer of the northern part of the outcrop at the Huai Dam Chum track site.Two types of footprints,small-sized theropod and crocodylomorph are imprinted with mud cracks and ripple marks on the thin mud layer.Most of footprints are referred to cf.Asianopodus,and are imprinted by small-sized theropoda,probably ornithomimosauria.Theropod tracks are mainly separated into two groups,Group A and Group B.From ichnological viewpoints,the small-sized theropod track assemblage indicates the herd behaviour and its idiosyncratic group composition.In particular,the histogram of size-frequency measurements of Group A shows the anomalous bimodal distribution.We consider that there are two hypotheses;the first one is due to the male-female difference,and the second is a result of the different growing stage.

关 键 词：DINOSAUR FOOTPRINT ASSEMBLAGE Cretaceous Khorat GROUP Khok Kruat FORMATION Thailand 

分 类 号：P534.53[天文地球—古生物学与地层学] Q915[天文地球—地质学]