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Eotrachodon, new basal hadrosaurid from Late Cretaceous of Alabama (Appalachia)

Ben Creisler

A new paper:

Albert Prieto-Marquez, Gregory M. Erickson & Jun A. Ebersole (2016)
A primitive hadrosaurid from southeastern North America and the origin
and early evolution of ‘duck-billed’ dinosaurs.
Journal of Vertebrate Paleontology (advance online publication)

Eotrachodon orientalis gen. et sp. nov. (latest Santonian of Alabama,
southeastern U.S.A.) is one of the oldest and most basal hadrosaurid
dinosaurs and the only hadrosaurid from Appalachia (present day
eastern North America) with a preserved skull. This taxon possesses a
relatively derived narial structure that was until now regarded as
synapomorphic for saurolophine (solid-crested or crestless)
hadrosaurids. Maximum parsimony analysis places E. orientalis as the
sister taxon to Saurolophidae (Saurolophinae + Lambeosaurinae).
Character optimization on the phylogeny indicates that the
saurolophine-like circumnarial structure evolved by the Santonian
following the split between saurolophines and lambeosaurines but prior
to the major hadrosaurid radiation. Statistical dispersal-vicariance
analysis posits an Appalachian ancestral area for Hadrosauridae and
subsequent dispersal of their ancestors into Laramidia (present-day
western North America) during the Cenomanian.