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Earth Notes: Jurassic Bonebed

A painting of a large furry creature with an open mouth and beaver-like teeth, in an unearthly pink landscape with four smaller creatures hurrying toward a burrow in a bank, and two dinosaur-like creatures fighting in the distance.
Glen Canyon National Recreation Area
Artist Brian Engh depicts the Tritylodont Stronghold in this painting, showing life related to rare fossils discovered in Glen Canyon National Recreation Area.

The shrinking shoreline of Lake Powell has revealed a wonder: an extraordinary collection of fossil bones from the Early Jurassic period. They offer a glimpse into the life of a now-extinct creature called a tritylodontid, which once lived almost everywhere on the globe 180 million years ago.

The discovery occurred by chance. The fossils had been submerged beneath water until drought shrank the reservoir. Scientists stumbled across them while documenting nearby fossil tracks.

There isn’t another bonebed like it anywhere in the Navajo sandstone. It’s rare to find fossil tracks and bones together, and even rarer to find tritylodontids. They were beaver-sized creatures with broad, flat tails, and probably gave birth to live young, even though they’re not considered mammals.

They might have lived in burrows in the vast sand dunes that covered this area during the Early Jurassic. They would have been lured to a marshy spot between the dunes, where their bones were later found.

Scientists had to scramble to recover the fossils before snowmelt raised Lake Powell’s level and submerged the site again. They cut out big blocks of stone, wrapped them in burlap, and shipped them by houseboat across the reservoir. They’re now at the St. George Dinosaur Discovery Site in Utah, where paleontologists will make scans and study the find. Eventually, the fossils will find a home at the Prehistoric Museum in Price, Utah, where visitors can marvel at this rare glimpse into the past.

This Earth Note was produced by KNAU and the Sustainable Communities Program at Northern Arizona University. I’m Melissa Sevigny.

Melissa joined KNAU's team in 2015 to report on science, health, and the environment. Her work has appeared nationally on NPR and been featured on Science Friday. She grew up in Tucson, Arizona, where she fell in love with the ecology and geology of the Sonoran desert.
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