Centrosaurines Temporal range: Late Cretaceous, | |
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Centrosaurus "nasicornus" skeleton, Palaeontological Museum Munich | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Clade: | Dinosauria |
Clade: | † Ornithischia |
Clade: | † Ceratopsia |
Family: | † Ceratopsidae |
Subfamily: | † Centrosaurinae Lambe, 1915 |
Type species | |
† Centrosaurus apertus Lambe, 1904 | |
Subgroups | |
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Synonyms | |
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Centrosaurinae (from the Greek, meaning "pointed lizards") is a subfamily of ceratopsid, a group of large quadrupedal ornithischian dinosaur. Centrosaurine fossil remains are known primarily from the northern region of Laramidia (modern day Alberta, Montana, and Alaska) but isolated taxa have been found in China and Utah as well. [3]
Defining features of centrosaurines include a large nasal horn, short supratemporal horns, and an ornamented frill projecting from the back of the skull. [4] With the exception of Centrosaurus apertus , all adult centrosaurines have spike-like ornaments midway up the skull. [5] Morphometric analysis shows that centrosaurines differ from other ceratopsian groups in skull, snout, and frill shapes. [6] There is evidence to suggest that male centrosaurines had an extended period of adolescence, and sexual ornamentation did not appear until adulthood. [4]
Centrosaurinae was named by paleontologist Lawrence Lambe in 1915, with Centrosaurus as the type genus. The centrosaurines are further divided into three tribes: the Nasutoceratopsini, the Centrosaurini, and the Pachyrhinosaurini by Ryan et al (2016). [7] Nasutoceratopsins are defined as centrosaurines closer to Nasutoceratops titusi than to Centrosaurus apertus and centrosaurins are defined as centrosaurines (more specifically eucentrosaurans) closer to Centrosaurus apertus than to Pachyrhinosaurus canadensis . Until 2016, the only division used was Pachyrhinosaurini, which is defined as centrosaurines closer to Pachyrhinosaurus canadensis than to Centrosaurus apertus.
The classification of centrosaurines and the relationships among the various species is complicated by a wide degree of variation between individuals and growth stages. Some features that have traditionally been used to classify these dinosaurs, like the number and arrangement of frill ornaments or spikes, have been discovered to be more variable than previously thought. For example, the cladogram presented below follows a 2016 phylogenetic analysis by Chiba et al. (2017). [8] These authors treated the species Rubeosaurus ovatus as distinct from Styracosaurus albertensis, and recovered several distinct clades within Centrosaurini, which together formed a sister group to the Pachyrhinosaurini:
Centrosaurinae |
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However, subsequent studies have cast doubt on the usefulness of minor variations in frill spike arrangement for classifying centrosaurines. In particular, large sample sizes of the species Centrosaurus apertus and Styracosaurus albertensis have shown a higher than predicted amount of variation. In 2020, Holmes et al. explored what the effect of recognizing such diversity would have on centrosaur classification. They used the same data as Chiba et al.'s 2017 study, but treated Rubeosaurus as a synonym of Styracosaurus, dropping it from their taxon list. The resulting cladogram (below) found Centrosaurini as a polytomy, a grouping with no discernable sister group relationships within it. The authors concluded that this meant the variation present within these species made it difficult to find any real resolution among them, and may even provide support for the hypothesis that centrosaurines evolved primarily via anagenesis (a single lineage changing through time) rather than cladogenesis (multiple branching lineages with shared common ancestors). [9]
Centrosaurinae |
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Centrosaurine fossils have mostly been found in Western North America (Alberta, Montana, and Alaska). [3] In the United States, two taxa, Diabloceratops and Machairoceratops , have been found as far south as Utah. Yehuecauhceratops, a nasutoceratopsin from Coahuila, Mexico, is the southernmost occurrence of a centrosaurine in North America. [3] No centrosaurine fossils had been uncovered outside Western North America until the 2010 discovery of Sinoceratops in the Shandong Province of China. [10] However, some authors question the placement of Sinoceratops within Centrosaurinae. All other Late Cretaceous dinosaur groups from North America have also been found in Asia, so the initial absence of Asian centrosaurines had been surprising. [10] The current evidence suggests that Centrosaurinae originated in Laramidia 90-80 million years ago, [3] with the discovery of the oldest known centrosaurine, Menefeeceratops further proving this. [11] [1] This means Sinoceratops would have migrated to China from North America. [7] Some hypothesize that centrosaurines originated in southern Laramidia and later radiated north. [12]
Compared to their sister group, Chasmosaurinae, centrosaurines are relatively small. The primitive Sinoceratops is an exception, with an estimated skull length of 180 centimetres (71 in). [10] By contrast, the skull length of Albertoceratops was more typical for this group at only 67 centimetres (26 in). [5] In general, centrosaurines were about the size of a rhinoceros with body lengths ranging from 2.5–8 metres (8.2–26.2 ft). [13]
Possible neonate sized centrosaurine fossils have been documented in the scientific literature. [14] Research indicates that centrosaurines did not achieve fully developed mating signals until nearly fully grown. [15] [4] Scott D. Sampson found commonality between the slow growth of mating signals in centrosaurines and the extended adolescence of animals whose social structures are ranked hierarchies founded on age-related differences. [15] In these sorts of groups, young males are typically sexually mature for several years before actually beginning to breed, when their mating signals are most fully developed. [16] Females, by contrast, do not have such an extended adolescence. [16]
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: CS1 maint: multiple names: authors list (link)Ceratopsidae is a family of ceratopsian dinosaurs including Triceratops, Centrosaurus, and Styracosaurus. All known species were quadrupedal herbivores from the Upper Cretaceous. All but one species are known from western North America, which formed the island continent of Laramidia during most of the Late Cretaceous. Ceratopsids are characterized by beaks, rows of shearing teeth in the back of the jaw, elaborate nasal horns, and a thin parietal-squamosal shelf that extends back and up into a frill. The group is divided into two subfamilies—Chasmosaurinae and Centrosaurinae. The chasmosaurines are generally characterized by long, triangular frills and well-developed brow horns. The centrosaurines had well-developed nasal horns or nasal bosses, shorter and more rectangular frills, and elaborate spines on the back of the frill.
Styracosaurus is an extinct genus of herbivorous ceratopsian dinosaur from the Late Cretaceous of North America. It had four to six long parietal spikes extending from its neck frill, a smaller jugal horn on each of its cheeks, and a single horn protruding from its nose, which may have been up to 60 centimeters long and 15 centimeters wide. The function or functions of the horns and frills have been debated for many years.
Einiosaurus is a genus of herbivorous centrosaurine ceratopsian dinosaur from the Upper Cretaceous of northwestern Montana. The name means 'bison lizard', in a combination of Blackfeet Indian eini and Latinized Ancient Greek sauros; the specific name (procurvicornis) means 'with a forward-curving horn' in Latin. Einiosaurus is medium-sized with an estimated body length at 4.5 metres (15 ft).
Achelousaurus is a genus of centrosaurine ceratopsid dinosaur that lived during the Late Cretaceous Period of what is now North America, about 74.2 million years ago. The first fossils of Achelousaurus were collected in Montana in 1987, by a team led by Jack Horner, with more finds made in 1989. In 1994, Achelousaurus horneri was described and named by Scott D. Sampson; the generic name means "Achelous lizard", in reference to the Greek deity Achelous, and the specific name refers to Horner. The genus is known from a few specimens consisting mainly of skull material from individuals, ranging from juveniles to adults.
Centrosaurus is a genus of centrosaurine ceratopsian dinosaur from Campanian age of Late Cretaceous Canada. Their remains have been found in the Dinosaur Park Formation, dating from 76.5 to 75.5 million years ago.
Monoclonius is an extinct genus of herbivorous ceratopsian dinosaur found in the Late Cretaceous layers of the Judith River Formation in Montana, United States, and the uppermost rock layers of the Dinosaur Park Formation in Alberta, Canada dated to between 75 and 74.6 million years ago.
Brachyceratops is a dubious genus of ceratopsian dinosaur known only from partial juvenile specimens dating to the late Cretaceous Period of Montana, United States.
Medusaceratops is an extinct genus of centrosaurine ceratopsian dinosaur known from the Late Cretaceous Judith River Formation of Montana, northern United States. It contains a single species, Medusaceratops lokii.
Agujaceratops is a genus of horned dinosaur from the Late Cretaceous (Campanian) of west Texas. It is a chasmosaurine (long-frilled) ceratopsian. Two species are known, Agujaceratops mariscalensis, and A. mavericus.
Diabloceratops is an extinct genus of centrosaurine ceratopsian dinosaur that lived approximately 81.4-81 million years ago during the latter part of the Cretaceous Period in what is now Utah, in the United States. Diabloceratops was a medium-sized, moderately built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 4.5 metres (15 ft) in length and 1.3 metric tons in body mass. At the time of its discovery, it was the oldest-known ceratopsid, and first centrosaurine known from latitudes south of the U.S. state of Montana. The generic name Diabloceratops means "devil-horned face," coming from Diablo, Spanish for "devil," and ceratops, Latinized Greek for "horned face." The specific name honors Jeffrey Eaton, a paleontologist at Weber State University and long time friend of the lead author Jim Kirkland. Eaton had a big role in establishing the Grand Staircase-Escalante National Monument where the specimen was found. The type species, Diabloceratops eatoni, was named and described in 2010 by James Ian Kirkland and Donald DeBlieux.
Sinoceratops is an extinct genus of ceratopsian dinosaur that lived approximately 73 million years ago during the latter part of the Cretaceous Period in what is now Shandong province in China. It was named in 2010 by Xu Xing et al. for three skulls from Zhucheng, China. The name of its type species Sinoceratops zhuchengensis means "Chinese horned face from Zhucheng", after the location of its discovery.
Kosmoceratops is a genus of ceratopsid dinosaur that lived in North America about 76–75.9 million years ago during the Late Cretaceous period. Specimens were discovered in Utah in the Kaiparowits Formation of the Grand Staircase–Escalante National Monument in 2006 and 2007, including an adult skull and postcranial skeleton and partial subadults. In 2010, the adult was made the holotype of the new genus and species Kosmoceratops richardsoni; the generic name means "ornate horned face", and the specific name honors Scott Richardson, who found the specimens. The find was part of a spate of ceratopsian discoveries in the early 21st century, and Kosmoceratops was considered significant due to its elaborate skull ornamentation.
Pachyrhinosaurini is a tribe of centrosaurine dinosaurs. The clade existed during the Late Cretaceous, about 83.6 to 68.5 million years ago, evolving during the early Campanian, and becoming extinct in the Maastrichtian. The tribe contains five genera: Styracosaurus, Stellasaurus, Einiosaurus, Achelousaurus, and Pachyrhinosaurus. Pachyrhinosaurus and Achelousaurus form the clade of pachyrhinosaurins called the Pachyrostra ("thick-snouts"), characterized primarily by their nasal bosses.
Nasutoceratops is genus of ceratopsid dinosaur that lived in North America during the Late Cretaceous period, about 76.0–75.5 million years ago. The first known specimens were discovered in Utah in the Kaiparowits Formation of the Grand Staircase–Escalante National Monument (GSENM) from 2006 onwards, including a subadult skull with a partial postcranial skeleton and rare skin impressions and two partial skulls. In 2013, the subadult was made the holotype of the new genus and species Nasutoceratops titusi; the generic name means "large-nosed horned face", and the specific name honors the paleotologist Alan L. Titus for his work at the GSENM. The dinosaur was noted for its large nose in news reports, and later featured in Jurassic World films.
Coronosaurus is a genus of centrosaurine ceratopsian dinosaurs which lived in the Late Cretaceous, in the middle Campanian stage. Its remains, two bone beds, were discovered by Phillip J. Currie in the Oldman Formation of Alberta, Canada, and its type and only species, Coronosaurus brinkmani, was first described in 2005, as a new species within the genus Centrosaurus. Later studies questioned the presence of a direct relationship, and in 2012 it was named as a separate genus. Coronosaurus means "crowned lizard", coming from "corona", Latin for crown, and "sauros", Greek for lizard; this name refers to the unique, crown-like shape of the horns on the top of its frill.
This timeline of ceratopsian research is a chronological listing of events in the history of paleontology focused on the ceratopsians, a group of herbivorous marginocephalian dinosaurs that evolved parrot-like beaks, bony frills, and, later, spectacular horns. The first scientifically documented ceratopsian fossils were described by Edward Drinker Cope starting in the 1870s; however, the remains were poorly preserved and their true nature was not recognized. Over the next several decades, Cope named several such genera and species. Cope's hated rival, Othniel Charles Marsh, also described ceratopsian remains. In 1887, Marsh mistook a Triceratops horn for one belonging to a new species of prehistoric Bison. Marsh also named the eponymous genus Ceratops in 1888. The next year, he named the most famous ceratopsian, Triceratops horridus. It was the discovery of Triceratops that illuminated the ceratopsian body plan, and he formally named the Ceratopsia in 1890.
Wendiceratops is a genus of herbivorous centrosaurine ceratopsian dinosaur from the Late Cretaceous of Canada.
Yehuecauhceratops is a genus of horned centrosaurine ceratopsid dinosaur from the Late Cretaceous of Coahuila, Mexico. It contains a single species, Y. mudei, described from two partial specimens by Rivera-Sylva et al. in 2016 and formally named by Rivera-Sylva et al. in 2017. It was a small centrosaurine with a body length of 3 metres (9.8 ft), making it smaller than Agujaceratops and Coahuilaceratops, the other two ceratopsids in its environment; the three may have been ecologically segregated. A ridge bearing a single roughened projection near the bottom of the squamosal bone, which probably supported a small horn, allows Yehuecauhceratops to be distinguished from other centrosaurines. Its affinities to nasutoceratopsin centrosaurines, such as Avaceratops and Nasutoceratops, are supported by various morphological similarities to the former.
Stellasaurus is a genus of centrosaurine ceratopsid dinosaur that lived in Montana during the Late Cretaceous. The type and only species is Stellasaurus ancellae. Its remains have been found in the Late Campanian age Two Medicine Formation, the same geological unit which its relatives Rubeosaurus, Einiosaurus, and Achelousaurus were discovered in.