|Reconstruction of the type species, Orodromeus makelai|
Brown et al, 2013
Horner & Weishampel, 1988
Orodromines were a mostly North American based group with fossils from Canada and United States only. Albertadromeus, as its name suggests, is only from the upper (later) part of the Oldman Formation in the Belly River Group of Alberta, Canada. Orodromeus, the type genus, was widespread through Montana. Its holotype was found at the Egg Mountain in the Two Medicine Formation. Oryctodromeus fossils were found in the Lima Peaks section of the Blackleaf Formation, also from Montana. Zephyrosaurus, the most widespread genus, lived in southern Montana and northern Wyoming. Its holotypes locality is the Wolf Creek Canyon, which is a sandstone in the Cloverly Formation.
Orodromines are widespread throughout time starting in the Aptian and ending in the Campanian. The earliest fossils are of Zephyrosaurus and are from the Aptian (113 Ma). After a 13 million year gap in the fossil record, fossils of a less common Oryctodromeus date to about 95 Ma in the Cenomanian. The next chronological fossils are from 76.5 Ma and belong to Albertadromeus. The latest fossils in the fossil record belonging to Orodromines are from the type genus, Orodromeus and date to 75 Ma.
Previously, all genera in Orodrominae (except Albertadromeus, which was named along with Orodrominae) were classified in the now unnatural group Hypsilophodontidae. They are all now simply considered to be basal members of Euornithopoda. The cladogram below is based on a phylogenetic analysis by Brown et al., 2013.
Albertadromeus is an extinct genus of orodromine parksosaurid dinosaur known from the upper part of the Late Cretaceous Oldman Formation (middle Campanian stage) of Alberta, Canada. It contains a single species, Albertadromeus syntarsus.Averostra
Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.Avetheropoda
Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.Cerapoda
Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.Dinosauriformes
Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.Haya griva
Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.Jingshanosaurus
Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.Koreanosaurus
Koreanosaurus (meaning "Korean lizard") is a genus of ornithopod dinosaur. One species has been described, Koreanosaurus boseongensis.Neornithischia
Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having a thicker layer of asymmetrical enamel on the inside of their lower teeth. The teeth wore unevenly with chewing and developed sharp ridges that allowed neornithischians to break down tougher plant food than other dinosaurs. Neornithischians include a variety of basal forms historically known as "hypsilophodonts", including the Parksosauridae; in addition, there are derived forms classified in the groups Marginocephalia and Ornithopoda. The former includes clades Pachycephalosauria and Ceratopsia, while the latter typically includes Hypsilophodon and the more derived Iguanodontia.Neotheropoda
Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.Orionides
Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.Orodromeus
Orodromeus (meaning "Mountain Runner") is a genus of herbivorous parksosaurid dinosaur from the Late Cretaceous of North America.Oryctodromeus
Oryctodromeus (meaning "digging runner") was a genus of small parksosaurid dinosaur. Fossils are known from the middle Cretaceous Blackleaf Formation of southwestern Montana and the Wayan Formation of southeastern Idaho, USA, both of the Cenomanian stage, roughly 95 million years ago. A member of the small, presumably fast-running herbivorous family Parksosauridae, Oryctodromeus is the first dinosaur published that shows evidence of burrowing behavior.Parksosauridae
Parksosauridae is a clade or family of small ornithischians which have previously been generally allied to hypsilophodontids. Parksosauridae is often considered a synonym of Thescelosauridae, but the two groups cannot be synonyms because Parksosauridae is defined as a stem, while Thescelosauridae is defined as a node.Thescelosaurinae
Thescelosaurinae is a subfamily of ornithischian dinosaurs from the Early Cretaceous of Asia and the Late Cretaceous of North America.Unaysauridae
Unaysauridae is a family of basal sauropodomorphs from the Late Triassic of India and Brazil.Xixiposaurus
Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.Yueosaurus
Yueosaurus is an extinct genus of basal ornithopod dinosaur known from Zhejiang Province, China.Zephyrosaurus
Zephyrosaurus (meaning "westward wind lizard") is a genus of orodromine ornithischian dinosaur. It is based on a partial skull and postcranial fragments discovered in the Aptian-Albian-age Lower Cretaceous Cloverly Formation of Carbon County, Montana, USA. New remains are under description, and tracks from Maryland and Virginia, also in the USA, have been attributed to animals similar to Zephyrosarus.