Oldest known T. Rex relative found in Utah

Lythronax argestes, shown in this artist’s reconstruction, lived roughly 80 million years ago, about 10 million years before the first T. rex.

Lukas Panzarin

Guest post by Erin Wayman

The earliest known relative of Tyrannosaurus rex has been unearthed. While working in southern Utah, paleontologists discovered fossils of a carnivorous dinosaur dating to roughly 80 million years ago. The researchers say the animal — named Lythronax argestes, or the gore king of the southwest — was an early member of the tyrannosaur family.

The approximately 8-meter-long dinosaur lived in Utah when western North America was an island, cut off from the rest of the continent by a sea. Mark Loewen of the Natural History Museum of Utah in Salt Lake City and colleagues say the tyrannosaur family probably originated on this landmass. When sea levels dropped several million years later, tyrannosaurids migrated more widely across North America and into Asia, the team proposes November 6 in PLOS ONE.


Lythronax argestes, the earliest known member of the tyrannosaur family, lived roughly 80 million years ago in what is now Utah. Mark Loewen

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