Describer

Currie & Varricchio, 2004

Time

Cretaceous Late Campanian Maastrichtian

Classification

Saurischia Theropoda Tetanurae Coelurosauria Dromaeosauridae

Diet

Carnivore

Fossilsite

Horseshoe Canyon Formation, Alberta, Canada

Info

Genus - Typespecies - Skull

Currie, P.J. and Varricchio, D.J. (2004)A New Dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada In: Feathered Dragons: Studies on the Transition from Dinosaurs to Birds, (eds. by Currie, P.J., Koppelhus, E.B., Shugar, M.A. and Wright, J.L. pp. 112-132

Abstract: The discovery of a new dromaeosaurid in the Horseshoe Canyon Formation (uppermost Campanian-lowermost Maastrichtian, Upper Cretaceous) increases the known diversity of this interesting group of theropods, considered by many as the closest non-avian theropod relatives of Archaeopteryx and other derived birds. The new animal, known from a partial skull, is relatively small. It differs from the contemporary Bambiraptor, Saurornitholestes, and Velociraptor in having a short, deep face. The teeth are more strongly inclined toward the throat than they are in most other dromaeosaurids, and are all almost the same size. Phylogenetic analysis suggests that the new dromaeosaurid may represent an independent lineage having origins back in the early Cretaceous.\\\\\\\"

Etymology: \\\\\\\"Atroci\\\\\\\" is a Latin word meaning savage, whereas \\\\\\\"raptor\\\\\\\" is Latin for robber. The species is named after Wayne Marshall of East Coulee, Alberta, who discovered the type specimen.

Holotype: TMP 95.166.1, a partial skull that includes premaxillae, the right maxilla, the right dentary, portions of the left dentary, teeth, and numerous bone fragments.

Locality and age: The holotype was recovered from strata about 5 m above the Daly Coal Seam #7 (Gibson 1977) in the Horseshoe Canyon Formation (upper Campanian or lower Maastrichtian, Upper Cretaceous) at UTM 12U 372,125E,5,708,055 N, which is about 5 km west of the Royal Tyrell Museum of Paleontology in Drumheller, Alberta.

Diagnosis: Small velociraptorine, dromaeosaurid theropod that differs from Saurornitholestes and Velociraptor in having a shorter, deeper face. Subnarial body of premaxilla is taller than its anteroposterior length as in Deinonychus and possibly Dromaeosaurus.

Internarial and maxillary processes of premaxilla subparallel and oriented more dorsally than posteriorly. Larger maxillary fenestra than in any other velociraptorines. Maxillary fenestra is directly above the promaxillary fenestra, rather than well behind it as in all other dromaeosaurids. Maxillary teeth more strongly inclined toward the throat than in all other dromaeosaurids except Bambiraptor and Deinonychus. Maxillary dentition is essentially isodont.\\\\\\\"