Paleontologists at Montana State University recently discovered fossil
evidence in Idaho that denotes new types of dinosaurs from the Late
Cretaceous Period.
The fossil evidence of the unidentified dinosaurs—which dates back to 95 million years ago—includes a pair of fossilized eggs from a large dinosaur called oviraptorosaur, teeth from a relative of the Tyrannosaurus rex, a small tyrannosauroid, teeth from a raptor and from an unidentified carnivorous dinosaur, and vertebrae from a smaller carnivorous dinosaur.
L.J. Krumenacker, paleontologist and MSU Earth sciences graduate student, was part of the team of paleontologists who discovered the fossils.
“The main problem is dinosaurs of this age are very rare from North America, so there is not much to compare them to that has been found so far,” Krumenacker said.
More fossils are needed to completely classify the dinosaurs and determine familial relationships, appearance and behavioral habits such as diet.
“Part of the challenge in unraveling the evolutionary history of a particular lineage of animals is dealing with a fragmentary fossil record,” said Jordon Bright, a UA geosciences graduate student. “Finds like this fill in a lot of blank spaces and unanswered questions.”
Though evidence is only based on isolated teeth, bones and eggs, Krumenacker said he has some ideas about what these dinosaurs could have been. He believes the tyrannosauroid-like dinosaur could have been similar to various species from the genus Megaraptor, and the eggs could have been laid by an oviraptorosaur, or “egg thief lizard.”
“The [tyrannosauroid] is the largest definite predator we know of in the formation and may have been the top carnivore,” Krumenacker said.
While people most commonly think of dinosaurs as towering beasts, there exists great diversity in size when it comes to the prehistoric animals.
“There are smaller species of [tyrannosauroid] dinosaurs, as this [new discovery] points out, that were the size of horses and dogs,” Bright said. “From an evolutionary point of view, this allows us to ask broader questions about how these dinosaurs evolved, without being locked into the idea that ‘bigger is better.’”
Though this is a step in the right direction, there is still a lot to do in terms of finding and classifying the fossils.
Krumenacker said the next steps are to keep looking for fossils, explaining that “there is a huge backlog of specimens from the Robinson Bonebed that still need [to be] removed from the rock in the laboratory.”
More specimens will be described and studied as more fossils are found within the bonebed in Idaho.

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