中国肯氏兽-山西鳄组合带的新发现之三:山西临县的主龙型类

近几十年,华北的二马营组上部地层以产出中国肯氏兽-山西鳄四足动物化石组合而闻名.最近在山西临县白道峪于上覆的铜川组一段发现了中国肯氏兽.本文描述了同一地点同一层位产出的主龙型类化石,包括一具山西鳄的部分骨架以及一些可以归入suchian的主龙类.它们是铜川组一段首次记述的主龙型类.最有鉴定特征的suchian材料包括一个大的髂骨以及一个小的、形状很奇特的、可能是跟骨的骨骼.髂骨可能可以归入一个奇异的波波龙类(poposauroid).因为中国肯氏兽与山西鳄同时出现在白道峪,表明中国肯氏兽-山西鳄组合可以向上延伸到铜川组一段.髂骨与跟骨大小悬殊,可能代表两个从未在中国肯氏兽-山西鳄组合报道过的物种.白道峪发现了特化的波波龙类,支持了波波龙类在中三叠世大量分化的观点.

New discoveries from the Sinokannemeyeria-Shansisuchus Assemblage Zone: 3.Archosauriformes from Linxian,Shanxi, China

The tetrapod assemblage from the Middle Triassic upper part of the Ermaying Formation of northern China has been known for two decades as the Sinokannemeyeria-Shansisuchus Assemblage because of the characteristic presence of the dicynodont therapsid Sinokannemeyeria and the erythrosuchid archosauriform Shansisuchus.Recently a Sinokannemeyeria species has been described from Member I of the Tongchuan Formation,which overlies the Ermaying,near Baidaoyu,Linxian,Shanxi Province.Here we document archosauriform specimens from the Baidaoyu site,including a partial Shansisuchus skeleton and some additional bones from probable suchian archosaurs,which constitute the first archosauriform material known from Member I of the Tongchuan.The most intriguing archosauriform specimens are a large ilium probably attributable to an unusual poposauroid,and a small,strangely shaped element that appears to represent a highly autapomorphic suchian calcaneum.Given the presence of both Sinokannemeyeria and Shansisuchus at Baidaoyu,the stratigraphic range of the Sinokannemeyeria-Shansisuchus Assemblage can be considered to extend upward into the Tongchuan Formation,although with possible changes in faunal composition.The occurrence of a poposauroid ilium at the Baidaoyu locality adds to the evidence that poposauroids diversified extensively during the Middle Triassic.