Newly discovered Middle Jurassic dinosaur tracks in the Baladeh region and faunal changes in northern Iran

Abstract

During the Triassic–Jurassic period, the West Asian region was situated in the coastal area of Northern Tethys and served as a key paleobiogeographic link between European and Asian faunal evolution. However, the Early Mesozoic tetrapod record from this region is relatively limited in contrast to Iran, which is situated in south-eastern West Asia and predominantly characterized by track records. This study presents new tracksites discovered in the early Middle Jurassic of the Baladeh region, southern margin of the North-Central zone Alborz Mountains in northern Iran. These sites are characterized by the dominance of basal ornithischian tracks, Anomoepus, alongside Brontopodus-like sauropod trackways and the occurrence of tiny tetrapod swimming track. The inclusion of various herbivores of the Middle Jurassic Baladeh ichnofauna was possibly influenced by the change in climate and vegetal resources, as well as by the contemporaneous ornithischian radiation center in southwest China. Testing this hypothesis will require the discovery of additional fossil evidence from the Middle East and Eastern Asia.