First record of a giant bird (Ornithuromorpha) from the uppermost Maastrichtian of the Southern Pyrenees, northeast Spain

ABSTRACT

Throughout the evolutionary history of Avialae, several members of this clade have evolved into giant forms, in different time periods and ecological contexts. In Europe, the first birds that show this condition, the Gargantuaviidae, occur during the Late Cretaceous (late Campanian–early Maastrichtian), but it is during the Paleogene when more groups evolve large forms. However, until now, there was no record of any giant bird during the late Maastrichtian of Europe, close to the K/Pg boundary. Here we describe a cervical vertebra (MPZ 2019/264) from Beranuy (Huesca, NE Spain), which is the first fossil evidence of a giant bird from the late Maastrichtian of Europe, within Chron C29r. The vertebra displays some features, such as a well-marked heterocoelous articulation, lateral pneumatic foramina, ventral carotid processes, and a low neural spine, that support its inclusion within the clade Ornithuromorpha. This phylogenetic assignment is supported by two cladistic analyses. The vertebra is clearly different from the one assigned to Gargantuavis, meaning that it belonged to a distinct taxon. Although the kinship between these two taxa of giant birds is still unclear, this finding demonstrates that large-sized birds were part of the ecological communities of the Ibero-Armorican island from the late Campanian to the Late Maastrichtian, being present during the last hundreds of thousands of years prior to the K/Pg extinction event.

ACKNOWLEDGMENTS

This research forms part of the project CGL2017-85038-P, subsidized by the Spanish Ministry of Science and Innovation, the European Regional Development Fund, the Government of Aragón (Grupo Aragosaurus: Recursos geológicos y Paleoambientes), the project PTDC/CTA-PAL/31656/2017, subsidized by the Fundação para a Ciência e a Tecnologia, and the project UIDB/04035/2020, subsidized by GeoBioTec. M.P-P is supported by a PhD grant from the Spanish Ministry of Education, Culture and Sport (Grant Number FPU 16/03064). M.M-A and E.P-P are supported by postdoctoral grants funded by the Fundação para a Ciência e a Tecnologia, Portugal (Grant numbers SFRH/BPD/113130/2015, SFRH/BPD/116759/2016, PTDC/CTA-PAL/31656/2017).

The Government of Aragón (Dirección General de Patrimonio Cultural) funded the fieldwork campaign during which MPZ 2019/264 was found (DGA Exp231_08-2009). We thank E. Buffetaut and M. Ezcurra for granting access, respectively, to the Cruzy vertebra (MC-MN 478) at the Musée de l’Association Culturelle, Archéologique et Paléontologique de l’Ouest Biterrois, (Cruzy, Hérault, France) and to the holotype of Patagopteryx (MACN-N-03) at the Museo Argentino de Ciencias Naturales (Buenos Aires, Argentina). We want to acknowledge Paleoymás for the preparation of the fossil, the technician B. Notario (CENIEH) for her help with the CT-scanning, and I. Pérez for her help with the photography of MPZ 2019/264. R. Glasgow reviewed the text in English. We thank E. Buffetaut and an anonymous reviewer for their valuable comments on the original manuscript, that have helped to improve the text. We also thank L. Zanno for her editorial work.