New Discovery And Significance Of Early Cretaceous Pterosaur Tracks In The Wuerhe Region Of Xinjiang China

In 2019,the largest group of pterosaur tracks in China were found at the Huangyangquan Reservoir tracksite in Wuerhe District,Karamay City,Xinjiang Uygur Autonomous Region.These tracks consist of three shapes,which constitute two morphological types: one is the trackways and isolated tracks made by a walking progression,and the other is the scratch representing the swim traces.Based on the morphology,stratigraphy,footprint paleoecology,sedimentology,and biokinetics multidisciplinary research methods,taking the pterosaur tracks and invertebrate traces as the research object which were found in the lower belt of the lower Cretaceous Tugulu Group in Huangyangquan reservoir,and based on previous research data,with detailed field survey,regional geological data collection,current research progress,by means of field observation,field data measurement and color 3D imaging,a systematic paleontology study of pterosaur tracks in the area has been carried out,and a detailed description and systematic classification of the tracks have been completed,the palaeoecology and palaeoclimate of Early Cretaceous in Wuerhe District have been discussed,the palaeocommunity features have been improved,and the palaeosedimentary environment of Tugulu group in this region has been reconstructed.Specific achievements include:(1)Wuerhe pterosaur tracks are associated with abundant invertebrate traces that would indicate the inland lakeshore basin settings,which is consistent with the evolution of the habitat of pterosaurs in the Cretaceous;(2)197 pterosaur tracks were described and compared in the Huangyangquan area,and assigned them to Pteraichnus saltwashensis.The size of these tracks varied greatly(the length of the maus ranged from 2.5 cm to 12.3 cm),indicating the difference in population size;(3)A group of special pterosaur tracks are described.These parallel scratches are consistent with the swimming tracks of pterosaurs discovered before,indicating the behavior of pterosaurs in shallow water;(4)The bone fossils of Dsungaripterus has been found in the same layer of the tracks,and combined with the size and shape of the tracks,all evidence indicates that the trackmaker of the Huangyangquan P.saltwashensis is most probably Dsungaripteridae.Because of the influence of the COVID-19 and the limit of time,in this dissertation,the study of pterosaur tracks in this area is still not perfect.In the future,it may be possible to gradually broaden the research field and direction of pterosaur tracks from the analysis of geometric morphometry,size and frequency structure,etc.,to make it better for palaeoecology,palaeoenvironment and the improvement of palaeontological community.