New Data on Therangospodus oncalensis from the Berriasian Fuentesalvo Tracksite (Villar del Río, Soria, Spain): An Example of Gregarious Behaviour in Theropod Dinosaurs

Abstract

Therangospodus oncalensis is a Berriasian theropod ichnotaxon from the Cameros Basin (Soria Province, Spain). We discovered new trackways assigned to this ichnotaxon during cleaning and conservation works at the type locality (Fuentesalvo), enabling us to describe it more precisely. Therangospodus oncalensis was made by a medium-sized theropod dinosaur and is characterized by a single tapering pad on each toe, a rounded heel impression and a narrow trackway. In addition to having similar morphometric characteristics, most of the trackways at the Fuentesalvo site show comparable size and biometric features. This indicates that, in terms of size and age, a homogeneous population of a single theropod species could have produced these tracks. Moreover, the similar orientation (lying within a range of only 15°) and estimated speed suggested by most of the trackways, lend weight to the hypothesis that the trackmaker of Therangospodus oncalensis was able, at least at times, to move in structured packs displaying gregarious behaviour. Furthermore, this is the first structured pack of theropods to be described.

Keywords:

• Therangospodus
• Earliest Cretaceous
• gregariousness
• Soria
• Cameros Basin
• Spain

ACKNOWLEDGEMENTS

The Mesozoic and Quaternary Vertebrate Group of the University of Zaragoza (“Aragosaurus group,” http://www.aragosaurus.com) is supported by the Ministerio de Educación y Ciencia and the ERDF (“CGL2004-0393/BTE”), as well as the Gobierno de Aragon (Financiación de Grupos Consolidados, 2005–2006) and Paleoymás, S.L. The studies at the ichnological sites of Tierras Altas in the province of Soria were carried out with the permission and due to the interest of the Junta de Castilla y León, the Diputación Provincial de Soria, the Mancomunidad de Tierras Altas, and the Ayuntamiento de Villar del Río, who support and promote the conservation and knowledge of these sites (http://www.rutadelasicnitas.com/). Drs. Martin Lockley and Vanda dos Santos and a third anonymous reviewer made suggestions that improved the original manuscript. Thanks to Eva Barcelona for her help during the first mapping in the field. The technical team of Paleoymás helped us in the field (Alfredo Morós, Javi Rubio, Cristobal Rubio, Sergio Rasal and Alberto Pablo) and with figures and data processing (Dani Castilla and Dani Ibáñez). Rupert Glasgow and Andy Rindsberg corrected the English text.