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Theropod dinosaur fossil found in Washington state



Ben Creisler
bcreisler@gmail.com

New in PLoS ONE:

Brandon R. Peecook  & Christian A. Sidor  (2015)
The First Dinosaur from Washington State and a Review of Pacific Coast
Dinosaurs from North America.
PLoS ONE 10(5): e0127792
doi:10.1371/journal.pone.0127792
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0127792

We describe the first diagnostic dinosaur fossil from Washington
State. The specimen, which consists of a proximal left femur, was
recovered from the shallow marine rocks of the Upper Cretaceous
(Campanian) Cedar District Formation (Nanaimo Group) and is
interpreted as pertaining to a large theropod on the basis of its
hollow medullary cavity and proximally placed fourth trochanter. The
Washington theropod represents one of the northernmost occurrences of
a Mesozoic dinosaur on the west coast of the United States and one of
only a handful from the Pacific coast of Laramidia during the
Cretaceous. Its isolated nature and preservation in marine rocks
suggest that the element was washed in from a nearby fluvial system.
If the femur pertains to a tyrannosauroid, which seems likely given
its size and the widespread occurrence of the group across Laramidia
during Late Cretaceous times, then it would represent an earlier
occurrence of large body size than previously recognized (complete
femur length estimated at 1.2 meters). Uncertainty surrounding the
latitude of deposition of the Nanaimo Group (i.e., the Baja-British
Columbia hypothesis) precludes assigning the Washington theropod to
either of the putative northern or southern biogeographic provinces of
Laramidia.

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News:

http://phys.org/news/2015-05-paleontologists-dinosaur-fossil-washington-state.html