New York: Crocodile-like beasts may have munched on young dinosaurs some 75 million years ago, scientists say.
Scientists who analysed bite marks on dinosaur bones suggested the rivalry between the reptiles started early in life.
Bites from living crocodylians such as alligators and crocodiles are often seen on the bones of their prey and scavenged bodies. Scientists can use these to identify bite marks on fossils from crocodyliforms, the reptiles to which modern crocodylians belong, LiveScience reported.
Now, scientists have unearthed fossils in the Grand Staircase-Escalante National Monument in southern Utah which provide direct evidence of a small crocodyliform biting juvenile dinosaurs.
"This area is very hot and arid in the summer and cold in the winter. Most of the area is dominated by massive, cliff-forming rock outcrops," said researcher Clint Boyd, a vertebrate paleontologist at the South Dakota School of Mines and Technology.
Back when the reptiles were alive, their environment was warm and wet, dominated by rivers and floodplains and lush with bushes and trees.
Dinosaurs in the area included duck-billed hadrosaurs, horned ceratopsians such as Triceratops and predatory relatives of T rex. The area also holds an especially diverse assembly of crocodyliforms, including the gigantic alligatoroid Deinosuchus riograndensis.
Scientists uncovered 75-million-year-old fossils of three members of a kind of small, two-legged herbivorous dinosaur known as a hypsilophodontid.
On the right thighbone of one, the researchers found a conical tooth embedded that was just 2.5 millimetres wide (a little less than one-tenth of an inch), and similarly tiny puncture marks were seen on a left shoulder bone.
"I was very surprised to find such clear feeding traces on such small bones," Boyd told the website.
"It shows the importance of carefully evaluating all the fossils collected from an area, and not assuming that some fossils won`t be important just because they are very small or not completely preserved," Boyd added.
Researchers could not determine how large the crocodyliform that made the marks was. However, the dinosaurs in question probably weighed about 13 to 21 kg; and living crocodylians 3 to 6 feet long are known to take down prey that big.
"Usually people tend to focus on the dangers that big, adult dinosaurs were having to deal with, but this study shows that even though dinosaurs were the dominant animals during the Cretaceous, they still had to worry about predators as soon as they were born," Boyd said.
The study was published in the journal PLOS ONE.