The Presence of Ankylosaur Tracks in the Guará Formation (Brazil) and Remarks on the Spatial and Temporal Distribution of Late Jurassic Dinosaurs

ABSTRACT

The Guará Formation (Paraná Basin, southern Brazil) is an Upper Jurassic unit that yielded a dinosaur ichnoassemblage composed of theropod, ornithopod, and sauropod tracks. A new set of footprints is described herein and its major features are heteropody, paraxony, and both manual and pedal tetradactyly, among others. Using ichnological, osteological, and stratigraphic approaches, we interpret these tracks as produced by an ankylosaur dinosaur. The record of these armored dinosaurs in South America is scarce and restricted to the Cretaceous units of Argentina, Bolivia, and Brazil. Therefore, the presence of these tracks in the Guará Formation provides the oldest evidence of ankylosaurs in western Gondwana and the first uncontroversial record of this group in Brazil. In addition, a comparison between the Guará Formation fossil record and other Kimmeridgian–Tithonian dinosaur-bearing units worldwide indicates that more efforts are needed to better understand the geographical distribution of Late Jurassic dinosaurs.

KEYWORDS:

• Ankylosauria
• South America
• Gondwana
• Paraná Basin
• Kimmeridgian–Tithonian

Acknowledgments

The authors thank to Dr. Abdelouahed Lagnaoui (Chouaïb Doukkali University, Morocco) and Hendrik Klein (Saurierwelt Paläontologisches Museum, Germany) for the invitation to contribute to the ICCI Special Volume. We also thank Dr. Martin G. Lockley (UCD, USA), Dr. Spencer G. Lucas (NMMNHS, USA), Dr. Fabio M. Petti (MUSE, Italy), and Hendrik Klein for their useful comments that improved this article. We are grateful to Novella Razzollini (Institut Català de Paleontologia Miquel Crusafont, Spain) for sharing bibliography, Dr. Felipe Pinheiro (Unipampa, Brazil) for the field work support, Voltaire Paes (UFRGS, Brazil) for the artistic work in Figure 3, and Catherine Fitzpatrick (FURG, Brazil) for the language review of the manuscript. Dr. Marcelo Fernandes (UFSCar, Brazil) and Agustín Martinelli (UFRGS, Brazil) provided an important discussion that greatly improved the earlier drafts of the manuscript.

Additional information

Funding

This work was financed by the CNPq (Process Number 140581/2014–6) and CAPES (Process Number AEX 10791/14–0) aided to HF and PD–D, respectively.