The fossil remains of small dinosaurs that burrowed into the ground have been found by scientists in Montana, US.
The 95-million-year-old bones are from an adult and two juveniles and were unearthed in a chamber at the end of a 2.1m-long sediment-filled tunnel.
The researchers say the discovery is the first definitive evidence that some dinosaurs dug dens and cared for their young in such structures.
The Montana dinosaurs have not been seen by palaeontologists before and have been given the scientific name Oryctodromeus cubicularis, meaning "digging runner of the lair".
And from Montana State:
The 95-million-year-old bones of an adult Oryctodromeus cubicularis and two juveniles were found jumbled together in a burrow about 15 miles from Lima, Montana State University paleontologist David Varricchio said in an online paper published March 21 by the British scientific journal, Proceedings of the Royal Society B. Co-authors were Yoshihiro Katsura, a former MSU graduate student, and Anthony Martin from Emory University in Atlanta.
"The presence of an adult and two juveniles within a denning chamber represents some of the best evidence for dinosaur parental care," Varricchio said. "The burrow likely protected the adult and young Oryctodromeus from predators and harsh environmental conditions. Burrowing behavior may have allowed other dinosaurs to survive in extreme environments such as polar regions and deserts and questions some end-Cretaceous extinction hypotheses."
H/T to Afarensis.