Open Paleo

Orodromeus

Horner & Weishampel, 1988 OR-o-DROHM-ee-us

From Greek 'oros' (mountain) and 'dromeus' (runner); meaning 'Mountain Runner', referring to the Egg Mountain site where it was discovered and its cursorial habits.

83.6–72.2 million years ago Campanian, Late Cretaceous
Late Cretaceous stages

Orodromeus is a genus of herbivorous orodromine thescelosaurid dinosaur from the Late Cretaceous of North America. Only one species is known, the type species Orodromeus makelai.

Diagnosis

  1. Palpebral anchored to the postorbital part of the posterior margin of orbit
  2. Lateral boss on the jugal
  3. Maxillary and dentary teeth broadly triangular in lateral view, often as wide as they are high
  4. Rounded apical ridge subequally dividing anterior and posterior region of the crown
  5. Anterior and posterior edges of crown bear five to six uniformly-sized denticles in adult
  6. Radiale, intermedium, and ulnare plus one distal carpal form unfused wrist

Species

Orodromeus makelai Horner & Weishampel, 1988

Type species

Named for Robert Makela, who discovered the fossil remains during excavations at Egg Mountain, Montana.

Holotype
MOR 294 , Museum of the Rockies
Material
Virtually complete skull and skeleton, lacking the tail
Horizon
upper Two Medicine Formation, Campanian, Late Cretaceous , 83.6–72.2 million years ago
Locality
Egg Mountain site, Willow Creek Anticline, Montana, United States

References

  1. Horner, J. R.; Weishampel, D. B. (1988). A comparative embryological study of two ornithischian dinosaurs. Nature 332(6161): 256-257. Springer Science and Business Media LLC. doi:10.1038/332256a0

    Gives the horizon as the "Upper Two Medicine Formation, Upper Cretaceous (? Late Campanian)".

    horner1988a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.

    Source of the mass and hip height estimates, and the appearance features.

    jones2026a