Seattle Scientists Unearth Washington's First Ever Dinosaur Fossil

May 20, 2015

  Washington State has its first dinosaur.

Researchers at the Burke Museum say they excavated a weathered, 80 million year old thighbone from a beach on Sucia Island in the San Juans. It is the first verified dinosaur fossil ever found in Washington.

And how is it that Washington has never produced a dinosaur bone before? Well, to find fossils you need rocks of the right age close to the surface. But most of Western Washington was underwater for much of the dinosaur era. In other parts of the state, the rock that’s exposed is too old, or the right kind of rock isn’t exposed.

The first dinosaur fossil described from Washington State.
Credit Courtesy of PLOS ONE (modified by Burke Museum)

So researchers weren’t expecting anything like this in April of 2012 as they scoured Sucia Island for Ammonite fossils – little squidlike invertebrates that lived in ancient oceans. But they noticed an object poking out of the ground that didn’t seem to fit.

“The average person walking around on the beach would not be able to recognize it, probably,” said Christian Sidor, curator of vertebrate paleontology at the Burke Museum. “It was just a slightly discolored, rock-looking object on the beach surface.”

A Closer Look 

The silhouette of a typical tyrannosaur-like theropod.

They could tell it was bone by the color and texture, and they called their colleagues at the Burke to have a look. Sidor says he knew it was a fossil from a big animal, but figured it was probably a marine reptile of some kind – nothing all that special. Sidor put it in a long queue of fossils to be analyzed, and proceeded to not think much of it.

“I really discounted this fossil for a long time,” he said.

The fossil is pretty beat up, with few clues as to its former owner. But eventually Sidor got around to taking a closer look, and inside the bone he found a cavity, a hallmark of a group of dinosaurs called therapods, which are two-legged meat-eaters that included velociraptor and Tyrannosaurus Rex. Then, flipping the bone over, he saw a telltale ridge along its top where muscle once attached.

“That is what gave it away,” Sidor said.

Washington had just become the 37th state to join the dinosaur club.

One Frightening Washingtonian

The fossil itself is about a foot-and-a-half long. Triangular and jagged, it looks a bit like a colossal tooth. Sidor says it was likely the top of a four-foot thighbone, which in turn means the dinosaur itself was probably about 35 feet long.

“We know that it’s a large carnivorous dinosaur related to something like T. Rex,” Sidor said.

Not a bad first dinosaur to unearth. Judging by the type of rock it was found in paleontologists believe it likely died near the ocean and eventually tumbled into the water.

The find helps fill in the fairly sketchy picture of dinosaur life on the west coast. The vast majority of in-tact discoveries come from interior west states such as Montana or Wyoming. But get closer to the Pacific Ocean, and the record thins out quite a bit. California has a few dinosaur fossils. Oregon has one, Sidor says, though it’s not a published find. There are a handful in British Columbia. And now the west coast’s fossil record has a new entrant – one that will soon be on public display at the Burke Museum.

Sidor and his collaborators describe their find in the journal, PLOS ONE