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 new Triassic locality recently reported. Here, we report a new ichnosite, the first for the Jurassic to earliest Cretaceous in the Castellón Formation (Tarija, Bolivia) bearing about 350 dinosaur tracks. With the exception of 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. Available evidence suggests that the producer of the more detailed trackway may be a member of non-Neosauropoda Eusauropoda, even if a titanosauriform producer cannot be discarded. Dozens of small-sized sauropod tracks, less than 15 cm in pes diameter, appear associated with two of the trackways. The distribution of these trackways provides elements to test gregariousness among trackmakers if a possible synchronism is accepted. Wanderings recognisable on the sediment surface suggest that they may collectively represent an ichnological example of herd behaviour.

KEYWORDS:

• Sauropod tracks
• ichnites
• palaeoecology
• dinosaur behaviour
• Jurassic

Acknowledgments

Paolo Citton is deeply acknowledged for a lot of work and comments provided in the making of this paper. Ignacio Díaz-Martínez is warmly thanked for discussion about ichnotaxonomy of sauropod tracks. Jens N. Lallensack, Ismar de Souza Carvalho, two anonymous reviewers and the Editor in Chief are acknowledged for their comments and suggestions that contributed improving the manuscript. Dr. Víctor Ramos provided some references concerning the age.

Disclosure statement

No potential conflict of interest was reported by the author(s).