FOSSIL VERTEBRATES FROM THE LATE CRETACEOUS (CAMPANIAN) CERRO FORTALEZA FORMATION, SANTA CRUZ PROVINCE, ARGENTINA

, F.L. AGNOLÍN; G. ALVAREZ-HERRERA; M. ARANCIAGA ROLANDO; M. MOTTA; S. ROZADILLA; L. VERDIQUIO; J. D. ANGELO; S. MINER; A. MORENO; G. MUÑOZ; M. P. ISASI; F. E. NOVAS

PUBLICACION ESPECIAL - ASOCIACION PALEONTOLOGICA ARGENTINA

ASOCIACIÓN PALEONTOLÓGICA ARGENTINA

Lugar: caba; Año: 2021

0328-347X

The Cerro Fortaleza Formation is a stratigraphical unit that outcrops near the Cerro Fortaleza, at northwestern Santa Cruzprovince. Up to the date this unit yielded fossil remains of dinosaurs, including the sauropod Puertasaurus reuili, theornithopod Talenkauen santacrucensis, and the theropods Orkoraptor burkei and Austrocheirus isasii. Several field trips to thearea resulted in the discovery of lamniform sharks, lepisosteiform fishes, the dipnoan Atlantoceratodus iheringi, chelid andmeiolaniid chelonians, peirosaurid crocodyliforms, mosasaurid lepidosauromorphs, and abundant dinosaur remains (allhoused at the paleontological collections of the Museo Padre Molina, Santa Cruz province, Argentina). The later include apartially articulated tail of a small-sized titanosauriform with procoelous and amphiplatyan vertebrae, and another, probablymore derived form with procoelous caudals. Isolated sauropod teeth indicate the presence of a derived lithostrotian and theenigmatic Clasmodosaurus spatula. Among theropods, diverse abelisaurid and megaraptorid remains were found. A partialulna, manual claw and metatarsal IV belonging to the holotype of Austrocheirus isasii were also found. The morphology ofthe new elements does not comfortably fit with abelisaurid or megaraptoran theropods. The fossil vertebrate content ofthe Cerro Fortaleza Formation indicates close biological ties with faunistic remains previously reported from the MataAmarilla Formation (Cenomanian), but shows several differences with the overlying Chorrillo Formation (Maastrichtian).This may indicate that a strong faunistic change among vertebrates probably occurred at the Campanian/Maastrichtianboundary in the Patagonian Austral Basin.