【摘要】 大山铺恐龙动物群产于中侏罗统下沙溪庙组中,该组为一套陆源碎屑沉积,以紫红色泥岩为主,夹有多层浅灰绿色中一微粒砂岩和粉砂岩,属河流相和湖泊相交替沉积。恐龙动物群赋存于微粒长石岩屑砂岩中,砂岩富含云母片,杂基填隙,浪成沙纹层理和微波状层理发育,并具中一大型板状交错层理,属低能湖滨浅滩沉积。当时恐龙生活于水,草丰茂的湖滨平原上,因食富砷植物引起中毒并导致恐龙大批死亡,遗体埋藏于湖滨浅滩中。异常死亡和原地埋藏于低能浅滩,这是造成本区恐龙化石的数量丰富和保存完整的根本原因。更多还原

【Abstract】 The dinosaur fauna at Dashanpu is found in lower Shaximiao Formationof middle Jurassic, which consists of a suite of terrigenous clastic sediments.composed mainly by purple mudstone with greyish--green, medium--to micro-grained sandstone and siltstone intercalation. The compositional and texturalmaturity of sandstone is not high. The characteristics of paleontology andpetrology show that the lower Shaximiao Formation belongs to alternatedeposits of fluvial and lacustrine facies. The dinosaur fauna occurs in micro--grained feldspatholithic sandstone,which is rich in mica fragments, matrix interstitial. Wave--ripple crossbedding, micro--wavy bedding and medium--to large--scale tabular crossbedding are clearly seen. Petrological characteristics indicate that it belongsto lake--shore shallow--bank deposit under lower energy condition. At that time, the dinosaurs lived on a lake--shore plain with profusewater and grass. The reason for leading them to a mass death is supposed tobe poisoning by plants with abundant arsenic the dinosaurs ate. Their remainswere buried in the lake--shore shallow--bank. The abnormal death and theburial in situ in shallow--bank of low energy are the main factors to providea great deal of well preserved dinosaur fossils in this region.更多还原