First deciphering of large pterosaur footprints and their trackmaker in the Junggar Basin, China

Abstract

Pterosaur footprints are important trace fossils for understanding the ecological habits of pterosaurs, and they are extremely rare worldwide. Within the Lower Cretaceous of the Junggar Basin of Xinjiang, hundreds of large pterosaur footprints have been unearthed. These imprints underwent a meticulous examination encompassing their dimensions, length-to-width ratio, proportions of digital and metatarsal parts, and divarication between digits of the manus imprints. A new ichnospecies, Pteraichnus junggarensis isp. nov., has been proposed based on these detailed analyses. By comparing these footprints with the anatomical characteristics of local larger pterosaur pedal bone fossils, it is suggested that the large-sized P. junggarensis footprints were produced by Dsungaripterus weii. The successful correlation between pterosaur fossils and their footprints within the Wuerho Pterosaur Fauna marks a momentous stride in deducing trackmakers based on their footprints. Moreover, estimates of pterosaur pes length and hip height were, for the first time, derived from a comprehensive scrutiny of 54 non-pterodactyloid and pterodactyloid specimens. A salient discovery was the markedly reduced ratio of hip height to pes length in non-pterodactyloid pterosaurs in comparison to their pterodactyloid counterparts. By employing fitted linear equations grounded on footprint dimensions, it is posited that the hip height for Noripterus complicidens ranges from 0.10 to 0.20 m, while for D. weii, it ranges from 0.28 to 0.46 m. Additionally, based on the ratio of stride length to hip height in the trackways, it is inferred that the trackmakers exhibited a typical walking gait, with speeds of 0.33 and 0.25 m/s, respectively.