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A dromaeosaur from the Maastrichtian of James Ross Island and the Late Cretaceous Antarctic dinosaur fauna

January 1, 2007

The recovery of material of a small theropod from the Early Maastrichtian, Cape Lamb Member of the Snow
Hill Island Formation is an unusual occurrence from primarily marine sediments. The pedal morphology of the
specimen that includes a Metatarsal II with a lateral expansion caudal to Metatarsal III, a third metatarsal that is
proximally narrow and distally wide, a Metatarsal III with a distal end that is incipiently ginglymoidal and a second
pedal digit with sickle-like ungual are all diagnostic of a theropod that belongs to the family of predatory dinosaurs, the
Dromaeosauridae. Yet this Antarctic dromaeosaur retains plesiomorphic features in its ankle and foot morphology. As
new dromaeosaur species are being recovered from the mid-Cretaceous of South America and the retention of primitive
characters in the Antarctic dromaeosaur, a new biogeographic hypothesis on dromaeosaur distribution has been
generated. Gondwanan dromaeosaurs are not North America immigrants into South America and Antarctica; rather
they are the relicts of a cosmopolitan dromaeosaur distribution, which has been separated by the vicariant break up of
Pangea and created an endemic clade of dromaeosaurs in Gondwana.

Publication Year 2007
Title A dromaeosaur from the Maastrichtian of James Ross Island and the Late Cretaceous Antarctic dinosaur fauna
DOI 10.3133/ofr20071047SRP083
Authors Judd A. Case, James E. Martin, Marcelo Reguero
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2007-1047-SRP-083
Index ID ofr20071047SRP083
Record Source USGS Publications Warehouse