Pentaceratops

Pentaceratops Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Holotype skull of P. sternbergii, AMNH 6325
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Ceratopsia
Family:	†Ceratopsidae
Subfamily:	†Chasmosaurinae
Genus:	†Pentaceratops Osborn, 1923
Type species
†Pentaceratops sternbergii Osborn, 1923

Pentaceratops ("five-horned face") is a

Pentaceratops was about 5.5–6 meters (18–20 ft) long, and has been estimated to have weighed around 2.5 metric tons (2.8 short tons). It had a short nose horn, two long brow horns, and long horns on the jugal bones. Its skull had a very long frill with triangular hornlets on the edge.

Discoveries and species

The first specimens were collected by Charles Hazelius Sternberg in the San Juan Basin in New Mexico. Sternberg worked in commission for the Swedish Uppsala University. In 1921 he recovered a skull and a rump, specimens PMU R.200 and PMU R.286, at the Meyers Creek near the Kimbetoh Wash in a layer of the Kirtland Formation. He sent these fossils to paleontologist Carl Wiman. In 1922 Sternberg decided to work independently and began a dig north of Tsaya Trading Post, in the Fossil Forest of San Juan County. Here he discovered a complete skeleton, which he sold to the American Museum of Natural History. The museum then sent out a team headed by Charles Mook and Peter Kaisen to assist Sternberg in securing this specimen; subsequent digging by Sternberg in 1923 brought the total of AMNH specimens to four. The rump of the main specimen was discarded by the museum because it had insufficient value as a display.

The species was named and described by Henry Fairfield Osborn in 1923, as Pentaceratops sternbergii. The generic name means "five-horned face", derived from the Greek penta (πέντα, meaning five), keras (κέρας, horn) and -ops (ὤψ, face),^[4] 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 as with Triceratops. Osborn obligingly gave it the specific name sternbergii to honor its discoverer.^[5] The name had been suggested to Osborn by William Diller Matthew; the specific epithet served as a consolation to the almost bankrupt Sternberg whose 1923 fossils were initially not acquired by the museum that had to use its 1923/1924 budget to process the finds of the great Asian expeditions by Roy Chapman Andrews.^[6]

The holotype was the skull discovered by Sternberg in 1922, specimen AMNH 6325. It was found in a layer of the Fruitland Formation, dating from the Campanian, about seventy-five million years old. The other three AMNH specimens were AMNH 1624, a smaller skull; AMNH 1622, a pair of brow horns; and AMNH 1625, a piece of skull frill.^[5]

In 1930, Wiman named a second species of Pentaceratops: P. fenestratus. It was based on Sternberg's 1921 specimens and the specific name referred to a hole in the left

Sometimes the identification of a specimen as Pentaceratops has proven to be highly contentious. In 1998 Thomas Lehman described OMNH 10165, a very large skull and its associated skeleton found in New Mexico in 1941. The skull is presently on display at the Sam Noble Oklahoma Museum of Natural History, and is the largest Pentaceratops exemplar known, with the distinction of having produced the largest known skull of any land vertebrate.^[10][11] However, in 2011, the skeleton was renamed as a separate genus, Titanoceratops, due to its more derived morphology, similarities to Triceratops, and lack of unique characteristics shared with Pentaceratops.^[2]

In 2014

Pentaceratops was a large

The torso of Pentaceratops is tall and wide. The rear dorsal vertebrae bear long spines from which ligaments possibly ran to the front, to balance the high frill. The prepubis is long. The ischium is long and strongly curves forward. In smaller specimens the thigh bone bows outwards.^[16]

Classification

Osborn originally assigned Pentaceratops to

Longrich stated that the holotype and referred specimen of P. aquilonius fall within the diagnosis of Pentaceratops, and were recovered very close to the type species in the phylogeny. He noted that the placement of Utahceratops does not make the genus

Pentaceratops, like all ceratopsians, was an

Paleoecology

Pentaceratops lived around 76–73

• Timeline of ceratopsian research
• Ah-Shi-Sle-Pah Wilderness Study Area, the type locality
  for Pentaceratops fenestratus

Sources

• "Delayed Debut for Jumbo Dino Skull". Science. 282 (5390): 871b–871. 1998.
  S2CID 190533792
  .
• Dodson, P. (1996). The Horned Dinosaurs. Princeton University Press, Princeton, New Jersey.
  ISBN 978-0-691-05900-6
  .
• Lehman, T. M., 2001, Late Cretaceous dinosaur provinciality: In: Mesozoic Vertebrate Life, edited by Tanke, D. H., and Carpenter, K., Indiana University Press, pp. 310–328.
• ISBN 978-0-19-910207-5
  .
• Sullivan, R.M., and Lucas, S.G. 2006. "The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America^{[permanent dead link]}." New Mexico Museum of Natural History and Science, Bulletin 35:7-29.
• Nicholas R. Longrich (2011). "Titanoceratops ouranous, a giant horned dinosaur from the Late Campanian of New Mexico". Cretaceous Research. 32 (3): 264–276.
  doi:10.1016/j.cretres.2010.12.007
  .
• Lucas, S.G., Sullivan, R.M., Hunt, A.P., 2006, Re-evaluation of Pentaceratops and Chasmosaurus (Ornithischia, Ceratopsidae) in the Upper Cretaceous of the Western Interior: New Mexico Museum of Natural History and Science, Bulletin 35

External links

Wikimedia Commons has media related to Pentaceratops.

• Pentaceratops sternbergii, DinoData, archived from the original on 30 September 2011, retrieved 6 January 2014
• Pentaceratops, The Dinosaur Encyclopaedia, archived from the original on 27 May 2008, retrieved 6 January 2014
• Kids Zone: Groups of Dinosaurs, Town of Drumheller, archived from the original on 31 May 2009, retrieved 6 January 2014