新疆吉木萨尔大龙口剖面锅底坑组新发现的兽头类和迟滞鳄类（英文）

Therocephalian(Therapsida) and chroniosuchian(Reptiliomorpha) from the Permo-Triassic transitional Guodikeng Formation of the Dalongkou Section,Jimsar,Xinjiang,China

锅底坑组是重要的二叠—三叠系过渡序列,本组在新疆吉木萨尔大龙口出露广泛,产出吉木萨尔兽以及水龙兽两类二齿兽类。本文报道了在大龙口剖面首次发现的兽头类和迟滞鳄类,这也是此二类群在锅底坑组的首次报道。新发现的兽头类被命名为付氏大龙口兽(Dalongkoua fuae)。其鉴定特征包括上颌骨犬后齿齿槽外边缘向背向凹入;切齿有圆形和匙形;切齿和犬齿有微弱的锯齿;齿骨冠状突有显著的收肌窝;反折翼近三角形,有两个平滑的凹陷。锅底坑组目前有3~4属二齿兽类、1属兽头类和1属迟滞鳄类,这一发现增加了其多样性。这些类群都在二叠纪末的大灭绝中幸存下来,直到中晚三叠世才消失。

The Guodikeng Formation encompasses the terrestrial Permo-Triassic transition sequence in China. This formation crops out in the Dalongkou section, Jimsar, Xinjiang where remains of the dicynodonts Jirnusaria and Lystrosaurus were found. We are describing here a therocephalian and a chroniosuchian from the Dalongkou section, which are the first records of these groups for the Guodikeng Formation. Diagnostic characters of the new therocephalian, Dalongkouafuae gen. and sp. nov., include maxillary ventral margin strongly concave in lateral view; incisors spatulated and rounded; incisors and canines with faint serrations; coronoid process of the dentary with a marked external adductor fossa; triangular reflected lamina of the angular with two smooth concavities. Chroniosuchians are represented by several postcranial elements and the vertebral morphology is similar tO Bystrowiana and Bystrowiella. These remains are interpreted as representing a Bystrowianidae indeterminate. The new findings increase the diversity of the Guodikeng Formation that is now represented by three or four dicynodonts, one therocephalian and one chroniosuchian. All these groups survived the massive P-T extinction but disappear from the fossil record in the Middle to Upper Triassic.