A new small-bodied ankylosaurian dinosaur from the Upper Cretaceous of North Patagonia (Río Negro Province, Argentina)

RIGUETTI, FACUNDO; PEREDA-SUBERBIOLA, XABIER; PONCE, DENIS; SALGADO, LEONARDO; APESTEGUÍA, SEBASTIÁN; ROZADILLA, SEBASTIÁN; ARBOUR, VICTORIA

JOURNAL OF SYSTEMATIC PALAEONTOLOGY

CAMBRIDGE UNIV PRESS

Año: 2022 vol. 20

1477-2019

The most representative ankylosaurian remains from Argentina have been found in sediments of the Allen Formation(Campanian–Maastrichtian) in Salitral Moreno, Rıo Negro Province. Several authors have discussed the identity andhistory of these remains. In this study, we review all published material along with some new remains in order tosummarize all the knowledge about these ankylosaurs. Previously published material includes a tooth, dorsal and anteriorcaudal vertebrae, a femur and several osteoderms. The new remains include synsacral and caudal elements, a partial femurand osteoderms. The anatomy of the tooth, the synsacrum, the mid-caudal vertebra, the femur and the osteoderms, andthe histology of the post-cervical osteoderms, support a nodosaurid identification, as proposed in previous descriptions ofthe Salitral Moreno material. Patagopelta cristata gen. et sp. nov. is a new nodosaurid ankylosaur characterized by thepresence of unique cervical half-ring and femoral anatomies, including high-crested lateral osteoderms in the half rings anda strongly developed muscular crest in the anterior surface of the femur. The 2 m body length estimated for Patagopeltais very small for an ankylosaur, comparable with the dwarf nodosaurid Struthiosaurus. We recovered Patagopelta withinNodosaurinae, related to nodosaurids from the ‘mid’-Cretaceous of North America, contrasting the previous topologies thatrelated this material with Panoplosaurini (Late Cretaceous North American nodosaurids). These results support apalaeobiogeographical context in which the nodosaurids from Salitral Moreno, Argentina, are part of the allochthonousfauna that migrated into South America during the late Campanian as part of the First American Biotic Interchange.