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

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).

KEYWORDS:

• Ornithischian tracks
• dinosaurs
• crocodylomorphs
• Coimbra Formation
• Sinemurian
• Lusitanian Basin

Acknowledgments

We would like to thank to all the CPGP team members which have participated in the fieldwork. This research was mainly founded by Centro Português de Geo-História e Pré-História and by national funds through the Fundação para a Ciência e Tecnologia (FCT), under the projects UID/Multi/00073/2020 (Centro de Geociências, Univ. Coimbra) and projects UIDB/04292/2020 & UIDP/04292/2020 (MARE – Marine and Environmental Sciences Centre) and LA/P/0069/2020 (ARNET); Ciência Viva – Agência Nacional para a Cultura Científica e Tecnológica, which has financially supported the field work through the program “Ocupação Científica dos Jovens nas Férias” (Scientific Occupation of Youngsters During Holidays), involving students of secondary schools, who we would like to thank for their collaboration; Lara Börjesson; Luís Pereira and Pedro Gomes. We also would like to thank to Paula Cassiano from the Alvaiázere Municipality and to the Mayor João Paulo Guerreiro of the Alvaiázere Municipality, has shown of the new ichnosite and our research. We would also like to thank to Andrea Baucon for construction of the false-colour depth map, to Margarida salvador for the English revision, to Gareth Dyke (Editor) and the two reviewers, Jens N. Lallensack and Paige dePolo for their suggestions for improvements to the original manuscript. We would like to make a special thanks to Mr. Acácio Gonçalves, the owner of the tracksite, and to his son, António Gonçalves, who authorized the field research work.

Disclosure statement

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

Additional information

Funding

The work was supported by the Fundação para a Ciência e a Tecnologia [UID/Multi/00073/2020]; Centro Português de Geo-História e Pré-História .