Oryctodromeus

Oryctodromeus was a small herbivorous ornithopod dinosaur that lived during the mid-Cretaceous period in what is now Montana, North America. It measured roughly two metres in length and weighed around twenty to thirty kilograms, making it about the size of a modern retriever dog. The skeleton displays clear anatomical adaptations for digging, such as strong forelimbs and a fused hip girdle capable of anchoring powerful burrowing muscles. Remarkably, the original fossils were found within an infilled underground den containing one adult and two juveniles, providing direct evidence of burrowing habits and parental care in dinosaurs. Oryctodromeus likely fed on low-growing ferns, roots, and shrubs, darting quickly on its hind legs when above ground and retreating into subterranean chambers to escape harsh weather and larger predatory theropods.

Fossils were discovered preserved inside an underground burrow alongside two juveniles of the same species.

Where and when

Oryctodromeus lived in the Late Cretaceous, from 95 to 93.5 million years ago (Cenomanian age). Its remains come from United States, in the Blackleaf Formation.

The numbers

Length 2.1 m. Mass about 24 kg. Hip height about 0.7 m. That is 1.2 human-lengths, or 0.19 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Oryctodromeus with a bus Place on the timeline