Living Under Your Feet

Hypsilophodontids are small, quick moving herbivorous creatures known worldwide from the Middle Jurassic to the Cretaceous. One species in particular, however, is of interest to us this week and is actually of interest to a great many other scientists as well. There is no extravagantly unique bone structure or defensive adaptation that sets this dinosaur apart from all other dinosaurs and makes it so worthy of extra attention. In fact, what sets Oryctodromeus cubicularis apart from other Hypsilophodontids is the living conditions in which it has been discovered. Unearthed originally in Montana, Oryctodromeus (which translates to "digging runner") has also been unearthed with its home intact and, in three instances, with the dinosaurs still at home. These "homes" were underground burrows, making Oryctodromeus the first dinosaur to be unearthed with evidence of burrowing behaviors. Three individuals in the burrow, identifiable as skeletons in advanced imaging, were found in a burrow that was lined with sand; thus the burrows are preserved as sandstone cores embedded in, typically, mud or clay based stone.Oryctodromeus skeletons were identified in the burrow by comparing their characters with the known characters of the species which are based off of many different excavations and a lot of identified and associated material of many different individuals. Small animals, about 6.8 feet (2.1m) long and approximately 70lbs (32kg), Oryctodromeus adults had basic digging tools for hands. Adaptations in the Montana specimens (named Blackleaf specimens for their location of discovery) have shown jaw, forelimb, and pelvic adaptations that would have aided in soil removal from the burrows. All of these, and more, will be discussed further in the coming week.

©Mark Hallet (via National Geographic, May 2008)