The first dinosaurs in Iberia: a new dinosaur tracksite from the Sinemurian (Lower Jurassic) of Portugal

Abstract

ABSTRACT Dinosaur fossils from the Lower Jurassic are very scarce in the Iberian Peninsula, which lacks a dinosaur track record. This study reports a new ichnosite from this age, at the Alvaiázere Municipality (Lusitanian Basin, Portugal) with several well-defined dinosaur and other archosaurs tracks. Seventeen tracks were identified at the top sedimentary surface of a fine-grained dolostone bed belonging to the Coimbra Formation (Sinemurian, Lower Jurassic). Therefore, the tracksite could have an age of ~196 to 194 Ma, based in the stratigraphic position of the tracksite in the Coimbra Formation succession. The ichnological comparison allows us to ascribe these tracks to Moyenisauropus and Batrachopus ichnogenera. The dinosaur tracks are assigned to the new ichnospecies Moyenisauropus lusitanicus isp. nov. The trackmaker could be a basal thyreophoran dinosaur related to Emausaurus or Scelidosaurus, and the presence of a manus-pes pair track set verifies that these tracks were made by a quadrupedal gait. The crocodylomorph trackmaker could be a teleosaurid. The analysed bioturbated fine-grained dolostone bed was deposited in very shallow subtidal to intertidal, carbonate lagoonal (?) environment. The evidence provided here indicates the presence of crocodylomorphs and thyreophoran dinosaurs in a tropical coastal wetland carbonate system developed during the Early Jurassic in the Lusitanian Basin (Atlantic western margin of Iberia).