A New Troodontid Dinosaur from the Lower Cretaceous Yixian Formation of Liaoning Province,China

A new troodontid dinosaur, Daliansaurus liaoningensis gen. et sp. nov., is erected based on a nearly complete specimen from the Lower Cretaceous Yixian Formation of Beipiao City, Liaoning Province, China. This well preserved skeleton provides important new details of the anatomy for Liaoning troodontids, and gives new insight into their phylogenetic relationships and evolution. Daliansaurus is distinguished from other troodontids by an enlarged ungual on pedal digit IV, which is approximately the same size as the sickle-shaped second ungual, and is differentiated from other Liaoning troodontids by a number of characters of the skull, manus, pelvis, and hindlimb. A phylogenetic analysis recovers Daliansaurus within a subclade of Liaoning troodontids that also includes Sinovenator, Sinusonasus, and MeL We erect a name for this group--Sinovenatorinae--and argue that it reflects a localized radiation of small-bodied troodontids in the Early Cretaceous of eastern Asia, similar to previously recognized radiations of Liaoning dromaeosaurids and avialans. As more Liaoning theropods are discovered, it is becoming apparent that small, feathered paravians were particularly diverse during the Early Cretaceous, and future work is needed to clarify how this diversity arose, which species coexisted, and how these numerous species partitioned niches.

New Material of Zhenyuanopterus(Pterosauria) from the Early Cretaceous Yixian Formation of Western Liaoning

A new partial specimen of Zhenyuanopterus from the Lower Cretaceous Yixian Formation of Beipiao city, Liaoning Province is described. This specimen is slightly larger than half the size of the holotype. Although it is not complete, it provides new information on Zhenyuanopterus both in taxonomy and ontogeny： the total number of the caudal vertebrae is 15; the forelimb is more robust than the hindlimb; the growth rate of the humerus and femur is constant, and their ratio is about 1. Compared with the holotype, the scapula and coracoid grow faster than the humerus and the femur. The scapula and coracoid may slow their growth rate after a certain ontogenetic stage. The pectoral girdle, robust forelimb and weak hindlimb of the new material（XHPM1088） together with data from the holotype of Zhenyuanopterus indicate that this taxon spent less time on land than in the sky or other ecological niches such as forests and cliffs.