陕甘宁盆地二马营组的假鳄类

在陕甘宁盆地东北缘二马营组发现的两种假鳄类,经鉴定均属Euparkeridae。其中之一与Euparkeria较相近;根据肩胛骨、肱骨和骨质背板等的显著不同,定名为侨家梁哈拉寨鳄(Halazhaisuchus qiaoensis),新属、新种。依据骨髂形态,另一标本归入世鲁番鳄属(Turfanosuchus),取名沙圪堵吐鲁番鳄(Turfanosuchus shageduensis)、新种。

TWO PSEUDOSUCHIAN REPTILES FROM SHAN-GAN-NING BASIN

During the field work of 1977 many vertebrate fossils were discovered from the Er-Ma-Ying Formation of the northeastern district, Shan-Gan-Ning Basin by a field team of IVPP. Among these collections there are two specimens, with partial postcranial skeletons, of Pseudosuchian. According to their characteristic features, they are attribu table to two different genera of Euparkeridge. Genus Halazhaisuchus gen, nov. Generic diagnosis—as for the species. Halazhaisuchus qiaoensis sp. nov. Type V6027, 13 vertebrae; a pair of scapulae; left coracoid; a pair of humeri; right radius and ulna; several proximal portions of ribs. Locality and Horizon Fugu, Shansi; Lower Er-Ma-Ying Formation. Diagnosis Submedium-sized pseudosuchian. Pectoral girdle well-developed. Scapular exceptionally elongated and strongly expanded at both ends; ratio of it to humerus over 115; and oval muscle-attachment area above glenoid with obviously projected ridge. Coracoid very large, forming two thirds of glenoid. Humerus strong, terminating in triangularly expanded apex proximally in consequence of well-developed detopectoral crest at uppermost quarter, Radius and ulna slender, and ulna with well-developed olecranon process. Vertebrae little amphicoelous, with elongated centra and low vertebral spine developing good expansions at tops (only posterior cervical and anterior dorsal regions); presacral vertebrae with intercentra. Cervical and anterior dorsal ribs tri-headed. On either side of midline running a row of dorsal scutes, over-lapping and leaf-like in outline; posterior end of scutes grooved ventrally; in cervical and anterior dorsal regions scutes of both side sutured together firmly. Remarks The new form is considered to be closely related to Euparkeria from Cynognathus Zone in south Africa in the light of the characters mentioned above. They share a number of common characters, including some primitive ones such as the presence of intercentra and the large coracoid, etc; which lead us to classify the new form in Euparkeridae. In the new form, however, the exceptionally elongated scapular and the ratio of it to humerus, the position of the deltopectoral crest of the humerus, olecranon process of the ulna and the absence of the lateral seutes are very different from those seen in Euparkeria. It therefore reasonale that the specimen V6027 necessititates the creation of a new genus and a species, Halazhaisuchus qiaoensis. Genus Turfanosuchus Young, 1973 Turfanosuchus shageduensis sp. nov. Type V6028, right mandibular ramus ; 6 cervical vertebrae; right scapular, coracoid, humerus, redius, ulna, femur, tibia, and fibula. Locality and Horizon Zhun-Ge-Er-Qi, Inner Mongolia; Lower Er-Ma-Ying Formation. Diagnisis Submedium-sized pseudosuchian. Narrow and elongated mandibular curved upward, anteroirly. Scapular narrow, expanding upward and forward, dorsally. Fore-limb/hind-over 73; humerus strong, with separation of inner condyle from outer one distally and arc-expanded apex proximally because of large deltopectoral crest developed close to upper end; femur strongly sigmoid, with large fourth trochanter consisting of triangular ridge; tibia shorter and stronger; and fibula unusually slender. Vertebrae with slightly elongated centra, without intereentra and dorsal scutes. Remarks In view of the facts that the characteristic features of the specimen V6028, the lack of intercentra and dorsal scute, narrow and elongated mandibular curved upward anteriorly, the arc-expansion of humerus at proximal end, femur stwisted, submedium-sized body as well are closely comparable to those shown in Turfanosuchus, it reasonablly belongs to the genus. There is, however, a number of differences between the new specimen and the sole species, T. dabanensis (see comparison below), therefore for the new specimen V6028 Turfanosuchus shageduensis is erected.