Marginocephalia is a clade of ornithischian dinosaurs that is characterized by a bony shelf or margin at the back of the skull. These fringes were likely used for display. There are two clades included in Marginocephalia: the thick-skulled Pachycephalosauria and the horned Ceratopsia. All members of Marginocephalia were primarily herbivores. They basally used gastroliths to aid in digestion of tough plant matter until they convergently evolved tooth batteries in Neoceratopsia and Pachycephalosauria. Marginocephalia first evolved in the Jurassic Period and became more common in the Cretaceous. They are basally small facultative quadrupeds while derived members of the group are large obligate quadrupeds. Primitive marginocephalians are found in Asia, but the group migrated upwards into North America.
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 66 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.
Stegoceras is a genus of pachycephalosaurid (dome-headed) dinosaur that lived in what is now North America during the Late Cretaceous period, about 77.5 to 74 million years ago (mya). The first specimens from Alberta, Canada, were described in 1902, and the type species Stegoceras validum was based on these remains. The generic name means "horn roof", and the specific name means "strong". Several other species have been placed in the genus over the years, but these have since been moved to other genera or deemed junior synonyms. Currently only S. validum and S. novomexicanum, named in 2011 from fossils found in New Mexico, remain. The validity of the latter species has also been debated.
Tianchisaurus, also invalidly called Tianchiasaurus and "Jurassosaurus", is a genus of ankylosaurian dinosaur from the Late Jurassic (Oxfordian–Kimmeridgian)-aged Toutunhe Formation of China. If it actually belongs to the family Ankylosauridae as proposed by Dong Zhiming, it would be the second earliest member of that family, being slightly younger than Spicomellus. Unlike other ankylosaurids, it lacked a bony club at the tip of its tail.
Archaeoceratops, meaning "ancient horned face", is a genus of basal neoceratopsian dinosaur from the Early Cretaceous of north central China. It appears to have been bipedal and quite small, reaching 0.9 m (3.0 ft) in length and 10 kg (22 lb) in body mass. It had a comparatively large head but no horns, possessing only a small bony frill projecting from the back of its head.
Xiaosaurus, is a genus of small herbivorous dinosaur from the middle Jurassic, approximately 169 to 163.5 mya. Xiaosaurus lived in what is now the Sichuan Basin of China.
Tylocephale is a genus of pachycephalosaurid dinosaur, a group of dome-headed, herbivorous ornithischians, that lived during the Late Campanian stage of the Late Cretaceous in what is now Mongolia. It is known from a partial skull and associated mandible that were unearthed in 1971 by a Polish-Mongolian Expedition to the Barun Goyot Formation of the Gobi Desert. The specimen was described in 1974 by Polish paleontologists Teresa Maryańska and Halszka Osmólska as a new genus and species.
Tsintaosaurus is a genus of hadrosaurid dinosaur from China. It was about 8.3 metres (27 ft) long and weighed 2.5 tonnes. The type species is Tsintaosaurus spinorhinus, first described by Chinese paleontologist C. C. Young in 1958.
Tanius is a genus of hadrosauroid dinosaur. It lived in the Late Cretaceous of China. The type species, named and described in 1929 by Carl Wiman, is Tanius sinensis. The generic name honours the Chinese paleontologist Tan Xichou. The specific epithet refers to China. In 2010 Gregory S. Paul estimated the length of Tanius at 7 metres (23 ft) and its weight at 2 metric tons.
Sinosaurus is an extinct genus of theropod dinosaur which lived during the Early Jurassic Period. It was a bipedal carnivore approximately 5.5 metres (18 ft) in length and 300 kilograms (660 lb) in body mass. Fossils of the animal were found at the Lufeng Formation, in the Yunnan Province of China.
Stenopelix is a genus of small marginocephalian dinosaur, possibly a basal ceratopsian, from the Early Cretaceous of Germany. It lived in the late Berriasian Stage of the Cretaceous period, approximately 140 myr ago. The genus is based on a partial skeleton lacking the skull, and its classification is based on characteristics of the hips.
Gongbusaurus is a genus of ornithischian, perhaps ornithopod, dinosaur that lived between about 160 and 157 million years ago, in the Late Jurassic period. A small herbivore, it is very poorly known. Two species have been assigned to it, but as the original name is based on teeth, there is no concrete evidence to connect the two species. Its fossils have been found in China.
Yinlong is a genus of basal ceratopsian dinosaur from the Late Jurassic Period of central Asia. It was a small, primarily bipedal herbivore.
Nanyangosaurus is a genus of herbivorous ornithischian dinosaur belonging to Hadrosauroidea that lived in the Late Cretaceous of present-day Henan Province, China.
Alaskacephale is an extinct genus of pachycephalosaurid, a group of dome-headed, herbivorous ornithischian dinosaurs, that lived during the Campanian stage of the Late Cretaceous period in what is now northern Alaska. The genus is one of the few known Arctic dinosaurs and was found in the Prince Creek Formation, which preserves a menagerie of fossils. The only known specimen, a squamosal bone, was found in 1999 and later described in 2005. However, Alaskacephale was not formally named until the next year.
Dong Zhiming is a Chinese vertebrate paleontologist formerly employed at the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. He began working at the IVPP in 1962, studying under Yang Zhongjian, who was director at the time. He has described fossil remains of many dinosaurs. He investigated and described the Shaximiao Formation; an important contribution to science since they are composed of Middle Jurassic beds which do not commonly yield fossils.
Cerapoda is a clade of the dinosaur clade Ornithischia, that includes pachycephalosaurs, ceratopsians and ornithopods
This timeline of pachycephalosaur research is a chronological listing of events in the history of paleontology focused on the pachycephalosaurs, a group of dome-skulled herbivorous marginocephalian dinosaurs. One of the first major events related to the history of pachycephalosaur research actually regards the discovery of an unrelated dinosaur called Troodon, reported from the western United States by Joseph Leidy in 1856. The type specimen of Troodon was simply an unusual tooth, but the close resemblance between Troodon teeth and pachycephalosaur teeth would cause taxonomic confusion for over a century. This was resolved by Phil Currie in 1987, who realized that Troodon belonged to a group of bird-like carnivores then known as saurornithoidids, but since renamed Troodontidae after Troodon itself. The first scientifically documented true pachycephalosaur remains were discovered in Early Cretaceous rocks from England and named Stenopelix not long after Troodon was named in America. Other notable early finds include the well-known pachycephalosaur Stegoceras validum.
Sinocephale is a genus of pachycephalosaurid dinosaur that lived in Inner Mongolia, China during the Cretaceous period. The only species, Sinocephale bexelli, was originally named as a species of the genus Troodon in 1953, and later transferred to the genus Stegoceras. After decades of being considered dubious, it was re-evaluated in 2021 and recognized as a valid taxon, being given a unique generic name. The original holotype was lost, with modern research conducted using rediscovered plaster casts. Scant material makes for limited knowledge of its life appearance, but it is distinguished by an embayment on the back of the domed skull, which would give it a heart shape as seen from above. It is potentially the oldest known pachycephalosaurid and falls within the subset of the family called Pachycephalosaurinae, related to animals such as Pachycephalosaurus and Prenocephale. The geologic context of the species has been historically unclear but it is currently thought to originate in rocks belonging to the Ulansuhai Formation.
The Jiangjunding Formation is a geological formation in Shandong, China whose strata date back to the Campanian-Maastrichtian stages of the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the group.
