First Jurassic to earliest Cretaceous dinosaur footprints for Bolivia at the Castellón formation (Tacurú Group), Tarija

Abstract

Bolivia has an outstanding tetrapod ichnological record from the uppermost Cretaceous deposits plus a newTriassic locality recently reported. Here, we report a new ichnosite, the first for the Jurassic to earliestCretaceous in the Castellón Formation (Tarija, Bolivia) bearing about 350 dinosaur tracks. With the exceptionof few tridactyl tracks, all exhibit sauropod characteristics. The exposed set consists of three mediumgauge,subparallel large quadrupedal trackways, with one trackway oriented in opposite direction to the other two.The best preserved trackway shows large pedes of about 95 cm and 75 cm in length and width, respectively.The trackmaker was about 3.80 m in height at the hip and walked at a speed under 5 km/h. Availableevidence suggests that the producer of the more detailed trackway may be a member of non-NeosauropodaEusauropoda, even if a titanosauriform producer cannot be discarded. Dozens of small-sized sauropodtracks, less than 15 cm in pes diameter, appear associated with two of the trackways. The distribution ofthese trackways provides elements to test gregariousness among trackmakers if a possible synchronism isaccepted. Wanderings recognisable on the sediment surface suggest that they may collectively represent anichnological example of herd behaviour.