By sheer happen chance a few months ago, I was reading one of the entries for the Seattle PI’s Ask The Burke columns from a few years ago and stumbled across an article about how a giant sloth was discovered under the Sea-Tac Airport! The very true story is that when parts of Sea-Tac were being built in 1961, most of a giant sloth fossil was discovered in a peat bog. Initially misidentified as an ice age bison, two-thirds of a giant sloth fossil was eventually discovered after being preserved in almost perfect condition.

This fossil eventually became known at Meg, named after the scientific name for the giant sloth, megalonyx, and eventually found a home at the Burke Museum in Seattle. Thanks to casts from another Megalonyx specimen and some manufacturing, the rest of the fossil was recreated, almost 12,700 years after the creature had died. While other fossils of this giant animal had been found in North America (including the first one identified by the third president, Thomas Jefferson), this fossil seems to be the first of this animal found in the Pacific Northwest!

It’s a scientific fact that giant animals like mammoths and mastodons once roamed the earth, with fossils providing important evidence. And there have been a few fossils of these large animals found here in the Northwest! Meg, the giant sloth fossil, is just one of these fossils and there are a few more that have been discovered. Here are some of the fossils and their related animals that have been found in the northwest:

Giant Ground Sloth

As mentioned, Meg the Megalonyx fossil was found under part of what is now Sea-Tac Airport. While it might seem absurd now, giant sloths used to roam North and South America. According to the San Diego Zoo, the Megalonyx Jeffersoni was roughly 10 feet tall, was roughly the size of a bison, and weighed around 2,205 pounds (1,000kgs). The Megalonyx also seemed to prefer forests along rivers and/or lakes and like all giant ground sloths, had large jaws, short snouts, and powerfully clawed limbs.

While it is a little terrifying to think of a 10-foot tall sloth just roaming around, we can thank one giant sloth species for avocados! Lestodons were prehistoric giant sloths that lived in the grassy plains of South America and while their diet primarily consisted of grass and foliage, they sometimes ate the early avocado, pit and all! Lestodons lived much earlier than the megalonyx sloths, as they became extinct roughly 30,000 years ago while the megalonyx sloths died off roughly 11,000 years ago.

Want to learn more about giant sloths that once roamed north and south America? Here are some cool articles and resources:

Baleen Whale

In the summer of 1993, a few amateur fossil hunters found the bones of what is now known as the world’s oldest known fossil of a toothless whale on the Olympic Peninsula. This whale, like modern humpbacks and gray whales, had baleen structures that the whales used to sift food from the ocean.

There was another toothless whale fossil found in Oregon during the 1970s but it hadn’t been thoroughly studied until recently. Some researchers think this whale, which lived around 32-33 million years ago, would have had a suction feeder and could vacuum up its prey. However, this theory is controversial and there are other researchers with some doubts.

Rodents and Beavers

In 2015, researchers announced that they had discovered several new prehistoric rodent species at the John Day Fossil Beds National Monument in Oregon. This area in Oregon is known for its fossils, colorful rock formations, and preservations of evolution and past ecosystems and this new discovery brought ten prehistoric species to light. One such fossil was 23 million years old but looks very similar to the modern pocket mouse! Many of the fossils found in this discovery were ancestors or relatives to modern-day species, including a tiny, prehistoric beaver.


There have actually been a few mammoth tusks uncovered in Washington state over the last few years. One was a broken tusk found near Ridgefield, Washington in 2010 and probably belonged to a Columbian mammoth from 15,000 years ago. And another tusk was found in Seattle four years later; it was measured at 8.5 feet long and was buried 25-30 feet below the street. Thanks to construction, the tusk was found and the company and landowner worked with Seattle’s Burke Museum to excavate and preserve the tusk. The Burke Museum even has a playlist on YouTube about the excavation process!

Tusks haven’t been the only mammoth fossils found in the state, as a partial skull was found near Sequim, Washington in early 2016. All of these fossils tell us more about the Columbian mammoths (Mammuthus columbi) that once roamed the west coast of North America, from Alaska to Mexico. The Columbian mammoth is actually the Washington state symbol and was one of the largest land mammals in North America!

Fossils can be these really amazing insights to the life that once lived on earth. If you want to learn more about fossils, megafauna, and so much more, here are some more resources:

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