First dinosaur fossil in Washington State found

Paleontologists have unearthed the first dinosaur fossil from Washington State which is approximately 80 million years old.

The fossil from the Late Cretaceous period was discovered while collecting ammonite fossils (a nautilus-like creature) from a marine rock unit along the shores of Sucia Island State Park in the San Juan Islands.

The fossil is the partial left femur of a theropod dinosaur, the group of two-legged, carnivorous dinosaurs that includes Velociraptor, Tyrannosaurus rex and modern birds. It is 16.7 inches long and 8.7 inches wide but would have been over three-feet-long when complete.

"This specimen, though fragmentary, gets Washington into the dinosaur club. It preserves enough anatomy that we were able compare it to other dinosaurs and be confident of its identification," said Christian Sidor from the Burke Museum of Natural History and Culture at the University of Washington.

Although incomplete, the authors believe it is a theropod dinosaur femur due to the hollow middle cavity of the bone where marrow was present - unique to theropods during this time period.

Sidor and colleague Brandon Peecook compared the fossil to other specimens and were able to calculate and estimate that the complete femur would have been over a meter in length (1.17m) - slightly smaller than T. rex.

The paper appeared in the open-access journal PLOS ONE.