Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 245 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is a subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs, having evolved from earlier theropods during the Late Jurassic epoch, and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs—birds—and the extinct non-avian dinosaurs, which are all dinosaurs other than birds.
Iguanodon, named in 1825, is a genus of iguanodontian dinosaur. While many species found worldwide have been classified in the genus Iguanodon, dating from the Late Jurassic to Early Cretaceous, taxonomic revision in the early 21st century has defined Iguanodon to be based on one well-substantiated species: I. bernissartensis, which lived during the Barremian to early Aptian ages of the Early Cretaceous in Belgium, Germany, England, and Spain, between about 126 and 122 million years ago. Iguanodon was a large, bulky herbivore, measuring up to 9–11 metres (30–36 ft) in length and 4.5 metric tons in body mass. Distinctive features include large thumb spikes, which were possibly used for defense against predators, combined with long prehensile fifth fingers able to forage for food.
Gideon Algernon Mantell MRCS FRS was a British obstetrician, geologist and palaeontologist. His attempts to reconstruct the structure and life of Iguanodon began the scientific study of dinosaurs: in 1822 he was responsible for the discovery of the first fossil teeth, and later much of the skeleton, of Iguanodon. Mantell's work on the Cretaceous of southern England was also important.
Hypsilophodon is a neornithischian dinosaur genus from the Early Cretaceous period of England. It has traditionally been considered an early member of the group Ornithopoda, but recent research has put this into question.
Hylaeosaurus is a herbivorous ankylosaurian dinosaur that lived about 136 million years ago, in the late Valanginian stage of the early Cretaceous period of England. It was found in the Grinstead Clay Formation.
Pachycephalosauria is a clade of ornithischian dinosaurs. Along with Ceratopsia, it makes up the clade Marginocephalia. With the exception of two species, most pachycephalosaurs lived during the Late Cretaceous Period, dating between about 85.8 and 65.5 million years ago. They are exclusive to the Northern Hemisphere, all of them being found in North America and Asia. They were all bipedal, herbivorous/omnivorous animals with thick skulls. Skulls can be domed, flat, or wedge-shaped depending on the species, and are all heavily ossified. The domes were often surrounded by nodes and/or spikes. Partial skeletons have been found of several pachycephalosaur species, but to date no complete skeletons have been discovered. Often isolated skull fragments are the only bones that are found.
Pelorosaurus is a genus of titanosauriform sauropod dinosaur. Remains referred to Pelorosaurus date from the Early Cretaceous period, about 140-125 million years ago, and have been found in England and Portugal. Thomas Holtz estimated its length at 24 meters.
Regnosaurus is a genus of herbivorous stegosaurian dinosaur that lived during the Early Cretaceous Period in what is now England. It was one of the first stegosaurs disvovered.
Cumnoria is a genus of herbivorous iguanodontian dinosaur. It was a basal iguanodontian that lived during the Late Jurassic period in what is now Oxfordshire, United Kingdom.
Ornithopsis was a medium-sized Early Cretaceous sauropod dinosaur, from England. The type species, which is the only species seen as valid today, is O. hulkei.
Mantellisaurus is a genus of iguanodontian dinosaur that lived in the Barremian and early Aptian ages of the Early Cretaceous Period of Europe. Its remains are known from Belgium (Bernissart), England, Spain and Germany. The type and only species is M. atherfieldensis. Formerly known as Iguanodon atherfieldensis, the new genus Mantellisaurus was erected for the species by Gregory Paul in 2007. According to Paul, Mantellisaurus was more lightly built than Iguanodon and more closely related to Ouranosaurus, making Iguanodon in its traditional sense paraphyletic. It is known from many complete and almost complete skeletons. The genus name honours Gideon Mantell, the discoverer of Iguanodon.
Mary Ann Mantell was a British fossil collector and the wife of the British paleontologist Gideon Mantell. She is credited – although this is disputed – with the discovery of the first fossils of Iguanodon and provided several pen and ink sketches of the fossils for her husband's scientific description of the Iguanodon.
Philip Reese Bjork is an American geologist and paleontologist known for his work in unearthing dinosaur species in America.
Paleontology or palaeontology is the study of prehistoric life forms on Earth through the examination of plant and animal fossils. This includes the study of body fossils, tracks (ichnites), burrows, cast-off parts, fossilised feces (coprolites), palynomorphs and chemical residues. Because humans have encountered fossils for millennia, paleontology has a long history both before and after becoming formalized as a science. This article records significant discoveries and events related to paleontology that occurred or were published in the year 1825.
Sir Richard Owen was an English biologist, comparative anatomist and paleontologist. Owen is generally considered to have been an outstanding naturalist with a remarkable gift for interpreting fossils.
Hypselospinus is a genus of iguanodontian dinosaur which was first described as a species of Iguanodon by Richard Lydekker in 1889, the specific name honouring William Henry Fitton.
Barilium is a genus of iguanodontian dinosaur which was first described as a species of Iguanodon by Richard Lydekker in 1888, the specific epithet honouring the discoverer Charles Dawson.
Ankylopollexia is an extinct clade of ornithischian dinosaurs that lived from the Late Jurassic to the Late Cretaceous. It is a derived clade of iguanodontian ornithopods and contains the subgroup Styracosterna. The name stems from the Greek word, “ankylos”, mistakenly taken to mean stiff, fused, and the Latin word, “pollex”, meaning thumb. Originally described in 1986 by Sereno, a most likely synapomorphic feature of a conical thumb spine defines the clade.
