The dinosaur tracksite from the lower Barremian of Areia do Mastro Formation (Cabo Espichel, Portugal): implications for dinosaur behavior

Abstract

We described a dinosaur tracksite found in the uppermost part of the Areia do Mastro Formation (lowermost Barremian, Lower Cretaceous), located at 1.5 km north of Cabo Espichel (Sesimbra, Portugal). The studied tracks are distributed in a heavily trampled limestone bed which crops out alongside the rocky beach. The studied trampled surface is highly dinoturbated, 541 tracks assigned to sauropods, ornithopods and theropods were identified. The majority of footprints (336) were produced by the herbivores. The dinoturbated level is a micritic nodular limestone, deposited in a very shallow subtidal to intertidal lagoon environment. Due to the intense bioturbation and limited exposed area, it is difficult to clearly define trackways, but the tracks can provide information about the producers and their behaviours. It is inferred that dinosaurs crossed this area at different times; the herbivores (sauropods and ornithopods) may possibly used the coastal area as passage between feeding spots, while carnivores frequented the area to hunt in groups or individually.