Ornithopoda is a clade of ornithischian dinosaurs, called ornithopods, that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, dominating the North American land. Their major evolutionary advantage was the progressive development of a chewing apparatus that became the most sophisticated ever developed by a non-avian dinosaur, rivaling that of modern mammals such as the domestic cow. They reached their apex of diversity and ecological dominance in the hadrosaurids, before they were wiped out by the Cretaceous–Paleogene extinction event along with all other non-avian dinosaurs. Members are known from all seven continents, though they are generally rare in the Southern Hemisphere.
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 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.
Notohypsilophodon is a genus of ornithopod dinosaur from the Late Cretaceous of Argentina. It was described as the only "hypsilophodont" known from South America, although this assessment is not universally supported, and Gasparinisaura is now believed to have been a basal euornithopod as well.
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.
Limaysaurus is a genus represented by a single species of rebbachisaurid sauropod dinosaurs, which lived during the mid-Cretaceous period, about 99.6 to 97 million years ago, in the Cenomanian, in what is now South America.
Anabisetia is a genus of ornithopod dinosaur from the Late Cretaceous Period of Patagonia, South America. It was a small bipedal herbivore, around 2 metres long.
Fukuisaurus is a genus of herbivorous ornithopod dinosaur that lived during the Early Cretaceous in what is now Japan. The type species is F. tetoriensis, which was named and described in 2003.
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.
Talenkauen is a genus of basal iguanodont dinosaur from the Campanian or Maastrichtian age of the Late Cretaceous Cerro Fortaleza Formation, formerly known as the Pari Aike Formation of Patagonian Lake Viedma, in the Austral Basin of Santa Cruz, Argentina. It is based on MPM-10001A, a partial articulated skeleton missing the rear part of the skull, the tail, and the hands. The type and only species is Talenkauen santacrucensis.
Jeholosaurus is a genus of neornithischian dinosaur from the Early Cretaceous Period. It is thought to have been a herbivorous small ornithopod.
Loncosaurus is an extinct genus of ornithopod dinosaur from the Upper Cretaceous of Provincia de Santa Cruz, Argentina. The type species is Loncosaurus argentinus, described by the famous Argentinian paleontologist Florentino Ameghino, but is considered a dubious name. Details on this animal are often contradictory, befitting a genus that was long confused for a theropod.
Antarctopelta is a genus of ankylosaurian dinosaur, a group of large, quadrupedal herbivores, that lived during the Campanian stage of the Late Cretaceous period on what is now James Ross Island, Antarctica. Antarctopelta is the only known ankylosaur from Antarctica and a member of Parankylosauria. The only described specimen was found in 1986, the first dinosaur to be found on the continent, by Argentine geologists Eduardo Olivero and Robert Scasso. The fossils were later described in 2006 by paleontologists Leonardo Salgado and Zulma Gasparini, who named the type species A. oliveroi after Olivero.
The Anacleto Formation is a geologic formation with outcrops in the Argentine Patagonian provinces of Mendoza, Río Negro, and Neuquén. It is the youngest formation within the Neuquén Group and belongs to the Río Colorado Subgroup. Formerly that subgroup was treated as a formation, and the Anacleto Formation was known as the Anacleto Member.
Heterodontosauridae is a family of ornithischian dinosaurs that were likely among the most basal (primitive) members of the group. Their phylogenetic placement is uncertain but they are most commonly found to be primitive, outside of the group Genasauria. Although their fossils are relatively rare and their group small in numbers, they have been found on all continents except Australia and Antarctica, with a range spanning the Early Jurassic to the Early Cretaceous.
Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.
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".
Trinisaura is a genus of ornithopod dinosaur that lived during the late Campanian stage of the Upper Cretaceous, around 73 to 72 million years ago in what is now James Ross Island off the coast of northern Antarctica near Patagonia. It is known from a single, incomplete postcranial skeleton that includes several vertebrae, a partial pelvis, and nearly complete right hindlimb. The fossils were collected in 2008 by paleontologists Juan Moly and Rodolfo Coria from the sandstone of the Snow Hill Island Formation. It remained undescribed in the collections of the Museo de La Plata until its description by Coria and colleagues in 2013, being the basis of the novel genus and species Trinisaura santamartaensis. The genus name is to commemorate the efforts of Argentine geologist Trinidad "Trini" Diaz and the Latin root -sauros, meaning "lizard". The species name is after Santa Marta Cove, where the fossils were collected.
Morrosaurus is an extinct genus of herbivorous elasmarian dinosaur that lived in the late Cretaceous in Antarctica. The only known species is the type Morrosaurus antarcticus.
Teratopodus is an ichnogenus of titanosaurian sauropod footprint. It includes a single species, T. malarguensis, known from prints found in the Late Cretaceous Anacleto Formation of Argentina. The Teratopodus tracks represent some of the best sauropod pes tracks currently known from South America.
