Idaho isn’t known for turning up many dinosaur fossils—which makes the recent discovery of three brand new T. rex cousins uncovered there all the more rare.
The dinos were found by researchers from Montana State University in the Wayan Foundation of Caribou-Targhee National Forest. According to the study, which is published in Historical Biology: An International Journal of Paleobiology, the team primarily found at least three new kinds of theropods—carnivorous dinosaurs that ran about on their hind legs and had grasping hands, like Tyrannosaurus rex.
While the family of one of the theropods is as of yet indeterminate, two of these three new dinos date back to around 95 million years ago, and fall into the small- to mid-sized range of their specific family—Tyrannosauroidea. Based on their fragmentary fossil evidence (mostly teeth), they were able to estimate that the larger tyrannosauroid they discovered was the size of a horse, while the smaller was similar in size to a Labrador retriever.
Vertebra samples collected by the team.
Limited evidence means tough work
Of course, such conclusions weren’t the easiest to reach, given the limited evidence.
“The challenge is identifying the animals based on the fragmentary specimens we find,” said MSU doctoral student L.J. Krumenacker, who has been searching Idaho for dinosaur fossils for 10 years, in an MSU statement.
“I put my best effort into it. It’s possible I could discover some identifications are wrong if we find more complete remains later. But I’d be thrilled because then we’d have an even better understanding. I’d really like to find more.”
This Idahoan cache wasn’t just new kinds of tyrannosauroids, though. They also discovered two fossilized eggs belonging to oviraptosaurs (“egg snatchers”)—the first evidence of their ever having lived in the area. Further, these oviraptosaurs are now the largest dinos known to have lived in Idaho.
These four discoveries show that Idaho had a much more diverse presence of dinosaurs than previously known—but there’s more, as these dinos are some of only a few fossils found dating to the middle Cretaceous period.
“We don’t really have many dinosaurs from this time period,” said MSU paleontology professor David J. Varricchio. “This new evidence is really filling in the time, temporal and spatial gap.”
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Pictured is L.J. Krumenacker, a part of the team behind the discovery. Images credit of: Montana State University
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