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[dinosaur] Tyrannosauroid metatarsus from Campanian Merchantville Formation of Delaware (free pdf)

Ben Creisler

A new paper in open access:

Chase D. Brownsteinâ (2017)Â
A tyrannosauroid metatarsus from the Merchantville formation of Delaware increases the diversity of non-tyrannosaurid tyrannosauroids on Appalachia.Â
PeerJ 5:e4123
doi: https://doi.org/10.7717/peerj.4123

During the Late Cretaceous, the continent of North America was divided into two sections: Laramidia in the west and Appalachia in the east. Although the sediments of Appalachia recorded only a sparse fossil record of dinosaurs, the dinosaur faunas of this landmass were different in composition from those of Laramidia. Represented by at least two taxa (Appalachiosaurus montgomeriensis and Dryptosaurus aquilunguis), partial and fragmentary skeletons, and isolated bones, the non-tyrannosaurid tyrannosauroids of the landmass have attracted some attention. Unfortunately, these eastern tyrants are poorly known compared to their western contemporaries. Here, one specimen, the partial metatarsus of a tyrannosauroid from the Campanian Merchantville Formation of Delaware, is described in detail. The specimen can be distinguished from A. montgomeriensis and D. aquilunguis by several morphological features. As such, the specimen represents a potentially previously unrecognized taxon of tyrannosauroid from Appalachia, increasing the diversity of the clade on the landmass. Phylogenetic analysis and the morphology of the bones suggest the Merchantville specimen is a tyrannosauroid of âintermediateâ grade, thus supporting the notion that Appalachia was a refugium for relict dinosaur clades.

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