In 2012, a team of paleontologists were scouring the rocky shores of what is today the small island of Sucia, located within Puget Sound, between Washington State and Vancouver Island. On the hunt for prehistoric shells, they inadvertently stumbled upon the bone of a creature never known to have ranged that far north - a dinosaur.
Initially, scientists from the University of Washington's Burke Museum were unaware of the significance of their find. It took years to chip away rock encasing the bone, and even then, it was difficult to determine what part of the animal the bone represented and to whom it might have belonged. But after extensive comparisons, they were convinced the bone came from a dinosaur, making it the first dino fossil every to be found in the state of Washington. Their research was just published online in the journal PLOS ONE.
"For a long time, we thought very little of the specimen," says Christian Sidor, the study's co-author and Burke Museum Curator of Vertebrate Paleontology. "We didn't think we could identify it, other than as a large piece of bone. Then we found a critical piece of anatomy."
The bone turned out to be a portion of a left femur (thigh bone), belonging to a theropod - a group of two-legged dinosaurs that included the largest terrestrial carnivores ever to have walked the planet. The dinosaur in question is most likely a tyrannosaur, based on its size, its hollow medullary cavity, certain morphological features, and the fact that the genus was common to the region during the Late Cretaceous (between 100 and 65 million years ago). But none had ever been found that far north.
"The fossil won't win a beauty contest," Sidor says. "But fortunately it preserves enough anatomy that we were able to compare it to other dinosaurs and be confident of its identification."
Hard for you to imagine a tyrannosaur roaming the Washington coast? That's because today, the region is a very different place than it was 80 million years ago when this particular tyrannosaur was alive.
The Late Cretaceous was a period of great dinosaur diversity, especially in North America. But during this time, the continent was divided into two large landmasses by a shallow, inland sea than ran north and south, similar to today's Rocky Mountains, though situated further west. The majority of dinosaur remains come from the eastern edge of the western landmass, known as Laramidia.
But few specimens have emerged from the northern area of Laramidia. Tectonic activity and modern development have limited the amount of fossils in the region, making this recent find that much more exciting, and important.
For now, the specimen resides among collections housed within the Burke Museum. Scientists continue to examine the important find and hope it will provide a better understanding of dinosaur distribution in the Pacific Northwest.
