Pentaceratops Temporal range: Late Cretaceous, 76–73 Ma |
|
---|---|
Type skull of Pentaceratops sternbergii, AMNH 6325 | |
Scientific classification | |
Phylum: | Chordata |
Class: | Reptilia |
Superorder: | Dinosauria |
Order: | †Ornithischia |
Suborder: | †Ceratopsia |
Family: | †Ceratopsidae |
Subfamily: | †Chasmosaurinae |
Genus: | †Pentaceratops Osborn, 1923 |
Species: | †P. sternbergii |
Binomial name | |
Pentaceratops sternbergii Osborn, 1923 |
Pentaceratops is a genus of ceratopsid dinosaur from the late Cretaceous Period of what is now North America. The appearance of Pentaceratops sternbergii in the fossil record marks the end of the Judithian land vertebrate age and the start of the Kirtlandian.[1] Its name means "five-horned face", derived from the Greek penta (πέντα, meaning 'five'), ceras (κέρας, 'horn') and -ops (ωψ, 'face'),[2] in reference to its two long epijugal bones, spikes which protrude out sidewards from under its eyes, in addition to the three more obvious horns.
Pentaceratops lived around 75-73 million years ago, its remains having been mostly found in the Kirtland Formation[1] in the San Juan Basin in New Mexico. Other dinosaurs which shared its time period include Parasaurolophus cyrtocristatus, the pachycephalosaur Sphaerotholus, the armored dinosaur Nodocephalosaurus and the tyrannosauroid Bistahieversor.
It was about 8 m (27 ft) long, and has been estimated to have weighed around 5,500 kg (13,000 lb).
Contents |
The first examples were collected by C. H. Sternberg in the San Juan Basin in New Mexico and described by Henry Fairfield Osborn in 1923, who obligingly gave it the specific name sternbergii after its discoverer. The frill of Pentaceratops is larger than that of Triceratops, with two large holes (fenestrae) in it. In 1930, Carl Wiman described a second species of Pentaceratops, P. fenestratus, but this was later determined to be the same species as the original finds. Further material discovered in Colorado has been identified as Pentaceratops in 2006.[3]
Pentaceratops has the distinction of having produced the largest known skull for a land vertebrate. That skull and its associated skeleton are on display at the Sam Noble Oklahoma Museum of Natural History.[4] The skeleton was found in New Mexico in 1941, and has since been reclassified as Titanoceratops.[5]
Within the Ceratopsia, Pentaceratops belonged to the subfamily Ceratopsinae and appears to be most closely related to Anchiceratops and the earlier genus Chasmosaurus. It may have been a close relative to the ancestor of Torosaurus, which lived a few million years later, right at the end of the Cretaceous period, when all ceratopsians died out.
Pentaceratops, like all ceratopsians, was an herbivore. During the Cretaceous, flowering plants were "geographically limited on the landscape", and so it is likely that this dinosaur fed on the predominant plants of the era: ferns, cycads and conifers. It would have used its sharp ceratopsian beak to bite off the leaves or needles.
Thomas M. Lehman has observed that Pentaceratops is the only known Judithian ceratopsian from New Mexico.[6] Large herbivores like the ceratopsians living in North America during the Late Cretaceous had "remarkably small geographic ranges" despite their large body size and high mobility.[6] This restricted distribution strongly contrasts with modern mammalian faunas whose large herbivores' ranges "typical[ly] ... span much of a continent."[6] Pentaceratops along with Kritosaurus and Parasaurolophus formed the dominant fauna of southern North America.[7] This region was characterized by lower taxonomic diversity in communities where lambeosaurine were less common and centrosaurs were completely lacking.[7]