Early Jurassic theropod elongate tracks with metatarsal marks from Yunnan, China

Abstract

ABSTRACT Elongate tracks with metatarsal marks are a rare type of dinosaur track that have been identified in various locations around the world. These tracks have been attributed to both theropods and ornithischians, and the mechanism of their formation has remained elusive. In this study, we describe well-preserved elongate tracks with metatarsal marks from two adjacent track sites in the Lower Jurassic Fengjiahe Formation in Yunnan Province, China. These tracks occur together with ‘normal’ tridactyl tracks that lack a metatarsal mark. The tracks were produced by theropod dinosaurs and are consistent with the classic Lower Jurassic Eubrontes-Grallator-Kayentapus assemblage found in the United States. We propose that these elongate tracks are formed by deep penetrations of the foot in soft substrate, where sediment collapses above parts of the descending foot, leaving a shallow surface track that preserves a metatarsal mark. Our findings provide new insights into the locomotion and behaviour of Early Jurassic theropod dinosaurs and highlight the importance of Yunnan Province in the study of dinosaur tracks in China.