Late Cretaceous Dinosaurs of West Antarctica's James Ross Basin

Late Cretaceous dinosaurs from the James Ross Basin, West Antarctica

Authors:

1. Marcelo A. Reguero (a,c,d)
2. Claudia P. Tambussi (a,d)
3. Rodolfo A. Coria (b, d)
4. Sergio A. Marenssi (c,d)

Affiliations:

a. División Paleontología de Vertebrados, Museo de La Plata, Paseo del Bosque s/n, B1900FWA, La Plata, Argentina

b. Universidad Nacional de Río Negro, Sede Alto Valle – Subsecretaría de Cultura de Neuquén – Museo Carmen Funes, Av. Córdoba 55 (8318), Plaza Huincul, Neuquén, Argentina

c. Instituto Antártico Argentino, Cerrito 1248, C1010AAZ Ciudad Autónoma de Buenos Aires, Argentina

d. Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Rivadavia 1917, C1033AAJ Ciudad Autónoma de Buenos Aires, Argentina

Abstract:

The fossil record of terrestrial vertebrates from the Late Cretaceous of Antarctica is currently composed of non-avian and avian dinosaurs from the marine sediments of the James Ross Basin, Antarctic Peninsula (West Antarctica). Although two dinosaurian formational assemblages (Late Campanian/Early Maastrichtian and Late Maastrichtian) are known, the record is still scattered, and evolutionary scenarios are tentative. Ten non-avian dinosaurs have been reported from Coniacian to Maastrichtian deposits, along with possible sauropod footprints of Early Maastrichtian age from Snow Hill Island. Five avian dinosaurs have been recorded or described exclusively from the Maastrichtian. The presence of an advanced titanosaur with characteristic procoelous mid-caudal vertebrae in Snow Hill Island Formation at Santa Marta Cove implies that the group achieved a global distribution by the Late Campanian. The Late Campanian/Early Maastrichtian non-avian dinosaur (ankylosaurs, ornithopods and dromaeosaurid theropods) clades probably attained a near-cosmopolitan distribution before the Late Cretaceous, and some aspects of this hallmark ‘Gondwanan’ fauna may therefore reflect climate-driven provinciality, not vicariant evolution driven by continental fragmentation. Antarctic Late Cretaceous avian dinosaurs are rare. They are restricted to the Maastrichtian and consist of a cariamid?, gaviids, a charadriiform and the basal Anseriformes Vegavis, and provide the first strong evidence for a basal radiation of birds known to exist in the Cretaceous.