| Orodromeus | |
|---|---|
.png) | |
| Orodromeus makelai | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | †Ornithischia |
| Family: | †Thescelosauridae |
| Subfamily: | †Orodrominae |
| Genus: | †Orodromeus Horner &Weishampel,1988 |
| Species: | †O. makelai |
| Binomial name | |
| †Orodromeus makelai Horner & Weishampel, 1988 | |
Orodromeus (meaning "Mountain Runner") is agenus ofherbivorousorodrominethescelosauriddinosaur from theLate Cretaceous ofNorth America. Only one species is known, thetype speciesOrodromeus makelai.
The remains ofOrodromeus were discovered byRobert Makela during the excavation inTeton County,Montana, of theEgg Mountain brooding colony of a much larger relative,Maiasaura. Thetype species,Orodromeus makelai andOrodromeus niedae, were named and shortly described byJack Horner andDavid B. Weishampel in1988. 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. Thespecific name honoured the late Makela.[1]
Theholotype specimen, MOR 294, was found in a layer of theTwo Medicine Formation, dating from theCampanian stage, about 75million years ago. It consists of a partial skeleton with skull. Theparatypes are MOR 246, aclutch of nineteeneggs, some withembryos; PP 22412, a set ofhindlimbs; MOR 331, a partial skeleton; MOR 248, a skeleton with skull; and MOR 403, a braincase.[1] A full publisheddescription is still lacking, though an unpublished thesis onOrodromeus exists.[2] However, MOR 246 and other eggs from Egg Mountain are now considered to belong to atroodontid[3] which may beStenonychosaurus.[4]
Orodromeus was a small fastbipedal herbivore that probably coexisted with dinosaurs such asDaspletosaurus andEiniosaurus. Its length was estimated by Horner & Weishampel at 2.5 metres.[1]
Orodromeus is distinguished by apalpebral that is at its back attached to thepostorbital; a boss on thejugal; a non-fused wrist; and triangularmaxillary anddentary teeth with a superficial flatocclusion.[1]
Orodromeus was by Horner & Weishampel assigned to theHypsilophodontidae, as the youngest known member.[1] Today these are seen as an unnatural,paraphyletic, group, andOrodromeus is simply considered to be a basal member of theEuornithopoda.Brownet al. (2013[5]) put it in the familyThescelosauridae and named a new subfamily (Orodrominae) after it.
Because of the advanced development of the bones and teeth of the embryos, Horner concluded that the young ofOrodromeus wereprecocial.
It has been speculated that this animal may haveburrowed much like its relativeOryctodromeus, based upon the packing of their bones in situations where they typically would have been scattered.[6]
Mallon et al. (2013) examined herbivorecoexistence on the island continent ofLaramidia, during the Late Cretaceous. It was concluded that smallornithischians likeOrodromeus were generally restricted to feeding on vegetation at, or below the height of 1 meter.[7]
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