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American Dinosaur Egg Orodromeus makelai

Most dinosaur eggs are found in China or Patagonia. This is a direct cast replica of an American dinosaur egg found at “Egg Mountain” in Montana. The last two photos on the right show shell detail. The egg is somewhat flattened.

The remains of Orodromeus eggs were discovered by Robert Makela during the excavation in Teton County, Montana, of the Egg Mountain brooding colony of a much larger relative, Maiasaura. The type species, Orodromeus makelai, was named and shortly described by Jack Horner and David B. Weishampel in 1988. The generic name is derived from Greek ὄρος, oros, "mountain", in reference to the Egg Mountain site, and δρομεύς, dromeus, "runner", referring to the cursorial habits of the animal. The specific name honoured the late Makela.

The holotype specimen, MOR 294, was found in a layer of the Two Medicine Formation, dating from the Campanian stage, about 75 million years ago. It consists of a partial skeleton with skull. The paratypes are MOR 249, a clutch of nineteen eggs, some with embryo; PP 22412, a set of hind limbs; MOR 331, a partial skeleton; MOR 248, a skeleton with skull; and MOR 403, a braincase.

Orodromeus was a small fast bipedal herbivore that probably coexisted with dinosaurs such as Daspletosaurus and Einiosaurus. Its length was estimated by Horner & Weishampel at 2.5 meters, (8.2 feet).