New Material Of Yabeinosaurus From The Early Cretaceous Jiufotang Formation Of Western Liaoning

As the first lizard of the Early Cretaceous Jehol Biota,Yabeinosaurus has a large body plan with a snout-pelvic length over 300 mm.In the last two decades,this taxon is well known with many fossils and paleontological studies.However,it is still limited in mature morphology.Here,this study described a nearly complete large skeleton in morphology and discussed the species taxonomy of Yabeinosaurus.This fossil was obtained from the Early Cretaceous Jiufotang Formation of Xiaotaizi,Jianchang,western Liaoning Province.It well exhibits the mature morphology.An unusual feature is revealed by the new specimen,well distinct from the two species of Yabeinosaurus(Y.robustus and Y.bicuspidens).The mandibular angular process is triangular in new specimen;while it is hook-like in Y.robustus and finger-like in Y.bicuspidens.This feature further obscures the difference between the two species.Caudal autotomy is firstly well described in Yabeinosaurus,such as caudal autotomy firstly positioned on the 6th caudal vertebra;the autotomy is consistent with the transverse process;autotomic plane is slightly posteriorly positioned on the process.Meanwhile,the caudal regeneration is also preserved,and shorter than the original tail,as in the extant lizards.In addition,the validity of the co-existing Indrasaurus is questioned in lacking more valuable diagnostic features.