Orodromeus

Orodromeus is a small, gracile herbivorous dinosaur from the Late Cretaceous Two Medicine Formation of Montana. 5 metres in length, it was an agile biped with elongated shins and a stiffened tail, built for bursts of speed to evade predators like dromaeosaurs and tyrannosaurs. Its skull possessed closely packed, ridged teeth that efficiently processed tough vegetation. Orodromeus has an interesting history: fossil clutches of eggs and embryos found nearby were originally thought to belong to this small plant-eater, but further preparation revealed they were actually laid by the predatory troodontid Troodon. Closely related to burrow-nesting dinosaurs like Oryctodromeus, Orodromeus was an active and abundant member of its upland ecosystem.

Nesting sites initially attributed to Orodromeus were later discovered to actually belong to the theropod Troodon.

Where and when

Orodromeus lived in the Late Cretaceous, from 76.5 to 74.5 million years ago (Campanian age). Its remains come from United States, in the Two Medicine Formation.

The numbers

Length 2.3 m (estimates run from 2 to 2.5 m). Mass about 26 kg. Hip height about 0.7 m. That is 1.4 human-lengths, or 0.21 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Orodromeus with a bus Place on the timeline