Pittman Michael, Pei Rui, Tan Qingwei, Xu Xing
Vertebrate Palaeontology Laboratory, Department of Earth Sciences, The University of Hong Kong , Pokfulam , Hong Kong, China.
Long Hao Institute of Geology and Paleontology , Hohhot, Nei Mongol , China.
PeerJ. 2015 Dec 7;3:e1480. doi: 10.7717/peerj.1480. eCollection 2015.
The first dromaeosaurid theropod from the Lower Cretaceous Bayan Gobi Formation is identified based on an incompletely preserved partially-articulated left leg, increasing the known diversity of its understudied ecosystem. The leg belongs to specimen IVPP V22530 and includes a typical deinonychosaurian pedal phalanx II-2 with a distinct constriction between the enlarged proximal end and the distal condyle as well as a typical deinonychosaurian enlarged pedal phalanx II-3. It possesses a symmetric metatarsus and a slender and long MT V that together suggest it is a dromaeosaurid. Two anatomical traits suggest the leg is microraptorine-like, but a more precise taxonomic referral was not possible: metatarsals II, III and IV are closely appressed distally and the ventral margin of the medial ligament pit of phalanx II-2 is close to the centre of the rounded distal condyle. This taxonomic status invites future efforts to discover additional specimens at the study locality because-whether it is a microraptorine or a close relative-this animal is expected to make important contributions to our understanding of dromaeosaurid evolution and biology. IVPP V22530 also comprises of an isolated dromaeosaurid manual ungual, a proximal portion of a right theropod anterior dorsal rib and an indeterminate bone mass that includes a collection of ribs. Neither the rib fragment nor the bone mass can be confidently referred to Dromaeosauridae, although they may very well belong to the same individual to whom the left leg belongs.
基于一具保存不完整但部分关联的左腿化石，首次确定了来自下白垩统巴音戈壁组的驰龙科兽脚亚目恐龙，这增加了对该研究较少的生态系统中已知的物种多样性。这条腿属于标本IVPP V22530，包括一根典型的恐爪龙类第二趾第二跖骨，在扩大的近端和远端髁之间有明显的收缩，以及一根典型的恐爪龙类扩大的第二趾第三跖骨。它具有对称的跗跖骨和细长的第五跖骨，共同表明它是驰龙科恐龙。两个解剖特征表明这条腿类似小盗龙类，但无法进行更精确的分类归属：第二、第三和第四跖骨在远端紧密贴合，第二趾第二跖骨内侧韧带窝的腹缘靠近圆形远端髁的中心。这种分类地位促使未来在研究地点努力发现更多标本，因为——无论它是小盗龙类还是近亲——这种动物预计将对我们理解驰龙科的进化和生物学做出重要贡献。IVPP V22530还包括一块孤立的驰龙科手部爪骨、一根右兽脚亚目恐龙前背肋骨的近端部分以及一块不确定的骨块，其中包括一组肋骨。尽管肋骨碎片和骨块很可能属于与左腿相同的个体，但它们都不能确定地归属于驰龙科。
