Friday, December 20, 2013

[Paleontology • 2013] Acheroraptor temertyorum • A New dromaeosaurid (Dinosauria: Theropoda) with Asian Affinities from the latest Cretaceous of North America


Acheroraptor temertyorum, the new Hell Creek dromaeosaurid. Closely related to the Asian genus Velociraptor, this theropod approached Deinonychus in size and lived alongside Tyrannosaurus and Triceratops. "I worked closely with Dr. David Evans to restore the life appearance of the animal," here shown pissing off a Tyrannosaurus for beating it to the carcass of a Triceratops, and also snacking on a scavenging mammal.

Evans, Larson and Currie (2013) DOI: 10.1007/s00114-013-1107-5

Abstract
Dromaeosaurids from the Maastrichtian of North America have a poor fossil record and are known largely from isolated teeth, which have typically been referred to taxa based on more complete material from earlier Campanian strata. An almost complete maxilla with well-preserved dentition and an associated dentary from the Hell Creek Formation of Montana are used to establish a new dromaeosaurid taxon in the latest Maastrichtian, immediately prior to the end-Cretaceous extinction event. Acheroraptor temertyorum gen. et sp. nov. is differentiated from other dromaeosaurids on the basis of a hypertrophied postantral wall that projects posteriorly into the antorbital fenestra, a maxillary fenestra positioned low in the antorbital fossa and directly posterior to the promaxillary fenestra, and distinctive dentition with marked apicobasal ridges. The new material allows a dromaeosaurid from the Maastrichtian of North America to be placed within a phylogenetic framework for the first time. Phylogenetic analysis suggests Acheroraptor is a velociraptorine that is more closely related to Asian dromaeosaurids, including Tsaagan and Velociraptor, than it is to Dromaeosaurus, Saurornitholestes, or any other taxon from North America. As part of the Lancian Tyrannosaurus–Triceratops fauna, A. temertyorum is the latest occurring dromaeosaurid. Its relationships and occurrence suggest a complex historical biogeographic scenario that involved multiple, bi-directional faunal interchanges between Asia and North America during the Late Cretaceous.

Keywords: Dromaeosauridae, Theropoda, Cretaceous, Biogeography


Acheroraptor

Evans, D. C., D. Larson, and P. J. Currie. 2013. A New dromaeosaurid (Dinosauria: Theropoda) with Asian Affinities from the latest Cretaceous of North America. Naturwissenschaften. 100 (11): 1041-1049. doi: dx.doi.org/10.1007/s00114-013-1107-5 



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