Leaellynasaura is a genus of small herbivorous ornithischian dinosaurs from the Albian stage of the Early Cretaceous, first discovered in Dinosaur Cove, Australia. The only known species is Leaellynasaura amicagraphica. It was described in 1989, and named after Leaellyn Rich, the daughter of the Australian palaeontologist couple Tom Rich and Patricia Vickers-Rich who discovered it. The specific name, amicagraphica, translates to "friend writing" and honours both the Friends of the Museum of Victoria and the National Geographic Society for their support of Australian paleontology.
Hypsilophodontidae is a traditionally used family of ornithopod dinosaurs, generally considered invalid today. It historically included many small bodied bipedal neornithischian taxa from around the world, and spanning from the Middle Jurassic until the Late Cretaceous. This inclusive status was supported by some phylogenetic analyses from the 1990s and mid 2000s, although there have also been many finding that the family is an unnatural grouping which should only include the type genus, Hypsilophodon, with the other genera being within clades like Thescelosauridae and Elasmaria. A 2014 analysis by Norman recovered a grouping of Hypsilophodon, Rhabdodontidae and Tenontosaurus, which he referred to as Hypsilophodontia. All other analyses from around the same time have instead found these latter taxa to be within Iguanodontia.
Thescelosaurus was a genus of small neornithischian dinosaur that appeared at the very end of the Late Cretaceous period in North America. It was a member of the last dinosaurian fauna before the Cretaceous–Paleogene extinction event around 66 million years ago. The preservation and completeness of many of its specimens indicate that it may have preferred to live near streams.
Parksosaurus is a genus of neornithischian dinosaur from the early Maastrichtian-age Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada. It is based on most of a partially articulated skeleton and partial skull, showing it to have been a small, bipedal, herbivorous dinosaur. It is one of the few described non-hadrosaurid ornithopods from the end of the Cretaceous in North America, existing around 70 million years ago.
Neornithischia is a clade of the dinosaur order Ornithischia. It is 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.
Changchunsaurus is an extinct genus of small herbivorous dinosaur from Early Cretaceous deposits of Gongzhuling, Jilin, China. It is the first named dinosaur genus from Jilin.
Jeholosaurus is a genus of neornithischian dinosaur from the Early Cretaceous Period. It is thought to have been a herbivorous small ornithopod.
Nanosaurus is the name given to a genus of neornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic-age. Its fossils are known from the Morrison Formation of the south-western United States. The type and only species, Nanosaurus agilis, was described and named by Othniel Charles Marsh in 1877. The taxon has a complicated taxonomic history, largely the work of Marsh and Peter M. Galton, involving the genera Laosaurus, Hallopus, Drinker, Othnielia, and Othnielosaurus, the latter three now being considered to be synonyms of Nanosaurus. It had historically been classified as a hypsilophodont or fabrosaur, types of generalized small bipedal herbivore, but more recent research has abandoned these groupings as paraphyletic and Nanosaurus is today considered a basal member of Neornithischia.
The Wonthaggi Formation is an informal geological formation in Victoria, Australia whose strata date back to the Early Cretaceous. It is part of the Strzelecki Group within the Gippsland Basin. Dinosaur remains are among the fossils that have been recovered from the formation. It is partially equivalent to the Eumeralla Formation.
The Eumeralla Formation is a geological formation in Victoria, Australia whose strata date back to the Early Cretaceous. It is Aptian to Albian in age. Dinosaur remains are among the fossils that have been recovered from the formation, particularly from the Dinosaur Cove locality.
Thescelosauridae is a clade of neornithischians from the Cretaceous of Asia, North America and possibly South America. The group was originally used as a name by Charles M. Sternberg in 1937, but was not formally defined until 2013, where it was used by Brown and colleagues as the group uniting Thescelosaurus and Orodromeus, based on their phylogenetic results. During a phylogenetic revision of neornithischians by Clint Boyd in 2015, the authorship of Thescelosauridae was given to Brown and colleagues, which meant that the similar name Parksosauridae, informally defined in 2002 by Buchholz, would have had priority over Thescelosauridae. The two clades had slightly different definitions, with Parksosauridae referring to all animals closer to Parksosaurus than Hypsilophodon, but they contained the same taxa so Boyd used Parksosauridae under the assumption it had priority. However, in formalizing the clade following the regulations of the PhyloCode, Madzia, Boyd, and colleagues identified in 2021 that Sternberg was the proper authority for Thescelosauridae, giving it priority over Parksosauridae. As well, they gave Thescelosauridae the definition of the largest clade containing Thescelosaurus neglectus but not Iguanodon bernissartensis, as long as Hypsilophodon foxii was not in the group, modifying previous definitions for Thescelosauridae in order to maintain its modern use, so that the clade was not applied if Thescelosaurus fell within Hypsilophodontidae, a family that has not been recently used but may be revived if the systematic position of Hypsilophodon was solidified at some point in the future. Madzia et al. identified the analysis of Madzia et al. in 2018 as the reference analysis for the name Thescelosauridae, an analysis based on a revised version of the 2015 Boyd analysis.
Albalophosaurus is a genus of ceratopsian ornithischian dinosaur. It was described in 2009 from remains found in 1997 by Yoshinori Kobayashi from the Kuwajima Formation of central Japan, outcropping in Hakusan in the Ishikawa Prefecture. The holotype, SBEI 176, consists of cranial bones from an incomplete, disarticulated skull and left lower jaw thought to belong to a single individual. The type species is named A. yamaguchiorum. The generic name is derived from Latin albus, "white", and Greek λόϕος (lophos), "crest", a reference to the snow-covered crest of Mount Hakusan. The specific name honours Ichio Yamaguchi and Mikiko Yamaguchi, who discovered and prepared many fossils from the site.
Koreanosaurus is a genus of orodromine neornithischian dinosaur. One species has been described, Koreanosaurus boseongensis.
Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.
Thescelosaurinae is a subfamily of thescelosaurid dinosaurs from the Early Cretaceous of Asia and the Late Cretaceous of North America.
Yueosaurus is an extinct genus of basal neornithischian dinosaur known from Zhejiang Province, China.
Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts".
Albertadromeus is an extinct genus of orodromine thescelosaurid dinosaur known from the upper part of the Late Cretaceous Oldman Formation of Alberta, Canada. It contains a single species, Albertadromeus syntarsus.
Diluvicursor is a genus of small ornithischian from the Lower Albian of Australia. It is known from one species, the type species D. pickeringi. The two known specimens, a vertebra and a partial juvenile postcranium discovered in 2005 from the Eumeralla Formation, are known, and they were named in early 2018.
