Scientists in Utah have uncovered evidence of a new species of plant-eating dinosaur that used to be a popular snack for prehistoric crocodiles.
Clint Boyd, of the South Dakota School of Mines and Technology, discovered evidence of the new species in a collection of small bits of fossil bones found in the western state.
While examining the tiny bones for skull fragments with teeth in them, he found a bone with what looked like enamel in it, only it wasn't a piece of a skull; it was the end of a femur.
“A thigh bone, which actually has a crocodile tooth stuck in it and broken off," Boyd says. "And then, as we started looking on the other bones, we started finding marks that are known to be diagnostic for crocodilian feeding traits.”
Boyd and his team realized they had evidence that these ancient reptiles, known as crocodyliforms, attacked their prey in a manner very much like modern crocodiles.
They determined that what the crocodyliforms were eating was a previously-unrecognized small bipedal dinosaur species. The fossil bones belonged to baby dinosaurs who were 1 to 2-meters long.
Boyd says the finding shows that the popular image of dinosaurs as the dominant species needs to be revised.
“Little baby dinosaurs, they are normally having to worry about the theropod dinosaurs, velociraptors, T. rex, things like that," Boyd says. "So this kind of adds a new dimension to going and getting water. You also had your dominant riverine carnivores, the crocodilians, attacking these herbivores as well, so they kind of had it coming from all sides.”
Based on the teeth marks on the fossils, and the fact that there are many bone fragments, the paleontologists believe the crocodilians were not much bigger than their prey.
The newly identified dinosaur species has not yet been named.