Pentaceratops

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Pentaceratops
Temporal range: Late Cretaceous (Campanian), 76–73  Ma
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Pentaceratops skull.jpg
Holotype skull of P. sternbergii, AMNH  6325
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade:† Ornithischia
Suborder:† Ceratopsia
Family:† Ceratopsidae
Subfamily:† Chasmosaurinae
Genus:† Pentaceratops
Osborn, 1923
Type species
†Pentaceratops sternbergii
Osborn, 1923

Pentaceratops ("five-horned face") is a genus of herbivorous ceratopsid dinosaur from the late Cretaceous Period of what is now North America. Fossils of this animal were first discovered in 1921, but the genus was named in 1923 when its type species, Pentaceratops sternbergii, was described. Pentaceratops lived around 76–73 million years ago, its remains having been mostly found in the Kirtland Formation [1] in the San Juan Basin in New Mexico. About a dozen skulls and skeletons have been uncovered, so anatomical understanding of Pentaceratops is fairly complete. One exceptionally large specimen later became its own genus, Titanoceratops , due to its more derived morphology, similarities to Triceratops, and lack of unique characteristics shared with Pentaceratops. [2] [3]

Contents

Pentaceratops was about 8.4–11 meters (39–50 feet) 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

Map of the southeast San Juan Basin; H is the purported collection area of the P. sternbergii holotype Geological map of the southeast San Juan Basin.png
Map of the southeast San Juan Basin; H is the purported collection area of the P. sternbergii holotype

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.

P. sternbergii holotype skull with reconstructed parts, AMNH Pentaceratops sternbergii (1).jpg
P. sternbergii holotype skull with reconstructed parts, AMNH

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]

Holotype skull diagram of P. fenestratus Pentaceratops fenestratus holotype skull.png
Holotype skull diagram of P. fenestratus

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 squamosal. [7] This was later considered to be the same species as Pentaceratops sternbergii and thus a junior synonym, the hole being the likely effect of an injury. Fowler and Freedman Fowler (2020) considered Pentaceratops fenestratus to be a distinct taxon from Pentaceratops sternbergi. In their opinion, it may be identical to Navajoceratops or Terminocavus , but the state of preservation of the remains makes it impossible to precisely determine the systematics of its owner. [8]

In 1929 Sternberg's son, George Fryer Sternberg, discovered specimen USNM V12002, a right squamosal. Pentaceratops proved to be a quite common fossil in the Fruitland and Kirtland formations. It has even been used as a guide fossil: 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] Subsequent finds include specimens MNA Pl. 1668, MNA Pl. 1747, NMMNH P-27468 and USNM 2416, partial skeletons with skull; YPM 1229, a skeleton lacking the skull; UALP 13342 and UKVP 16100, skulls; UNM B-1701, USNM 12741, USNM 12743, USNM 8604, SMP VP-1596, SMP VP-1488, SMP VP-1500 and SMP VP-1712, fragmentary skulls. Apart from the San Juan Basin finds, a juvenile specimen of Pentaceratops, SDMNH 43470, was found in the Williams Fork Formation of Colorado in 2006. [9]

Specimen being airlifted with help from the New Mexico National Guard, 2015 Pentaceratops fossil airlift.jpg
Specimen being airlifted with help from the New Mexico National Guard, 2015

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 Nicholas Longrich named a new species: Pentaceratops aquilonius, "the northern one", based on fragmentary fossils discovered during the 1930s near Manyberries in Alberta, Canada. The species has been described as having a first epiparietal pointing upwards instead of forwards. [12] In 2016, Mallon et al. found P. aquilonius to be morphologically similar to Spiclypeus shipporum , with it possibly being the same species, and considered P. aquilonius a nomen dubium . [13]

Description

Restoration of P. sternbergii Pentaceratops BW.jpg
Restoration of P. sternbergii

Pentaceratops was a large ceratopsid; Dodson estimated the body length at 6 meters (20 ft). The skull length of AMNH 1624 is 2.3 meters (7.5 ft) while PMU R.200 has a length of 2.16 meters (7.1 ft). [7] In 2016 Paul estimated its length at 5.5 meters (18 ft) and its weight at 2.5 metric tons (2.75 short tons). [14] The nose horn of Pentaceratops is small and pointing upward and backward. The brow horns are very long and curving strongly forward. The somewhat upward tilted frill of Pentaceratops is considerably longer than that of Triceratops , with two large holes (parietal fenestrae) in it. It is rectangular, adorned by large triangular osteoderms: up to twelve episquamosals at the squamosal and three epiparietals at the parietal bone. These are largest at the rear corners of the frill, and are separated by a large U-shaped notch at the midline, a feature not recognized until 1981 when specimen UKVP 16100 was described. [15] Within the notch the first epiparietals point forwards. The very thick jugal and the squamosal do not touch each other, a possible autapomorphy. [2]

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 Ceratopsia. Within this group Pentaceratops belonged to the Ceratopsinae or Chasmosaurinae. It appears to be most closely related to Utahceratops . Their clade was perhaps more derived than the earlier genus Chasmosaurus but more basal than Anchiceratops , the latter representing a line of which Triceratops was a member, which lived a few million years later, right at the end of the Cretaceous period, when all ceratopsians died out.

The cladogram of the phylogeny of Pentaceratops according to a study by Scott Sampson et al. in 2010 found that the genus was most closely related to Utahceratops, from a similar age and region. [17] The below cladogram follows Longrich (2014), who named a new species of Pentaceratops, and included nearly all chasmosaurine species. [18]

Paratype of P. aquilonius (CMN 9813), interpreted as an epiparietal of P. aquilonius (left) or Spiclypeus Pentaceratops aquilonius paratype.PNG
Paratype of P. aquilonius (CMN 9813), interpreted as an epiparietal of P. aquilonius (left) or Spiclypeus
Size of P. sternbergi compared to a human Pentaceratops Size.svg
Size of P. sternbergi compared to a human
Chasmosaurinae

Mercuriceratops

Judiceratops

Chasmosaurus

Chasmosaurus sp. CMN 2280

Chasmosaurus belli

Chasmosaurus irvinensis

Mojoceratops

Agujaceratops

Pentaceratops aquilonius

Williams Fork chasmosaur

Pentaceratops sternbergii

Utahceratops

Kosmoceratops

Kosmoceratops richardsoni

Kosmoceratops sp. CMN 8301

Anchiceratops

Almond Formation chasmosaur

Bravoceratops

Coahuilaceratops

Arrhinoceratops

Triceratopsini

Titanoceratops

Torosaurus

Triceratops

T. utahensis

T. horridus

T. prorsus

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 paraphyletic, as there is no requirement that genera are monophyletic. The Williams Fork chasmosaur differs from the Pentaceratops and Utahceratops species, and might require a new specific or generic name. [18]

Paleobiology

Restoration of Bistahieversor hunting Pentaceratops Bistahieversor hunting Pentaceratops.jpg
Restoration of Bistahieversor hunting Pentaceratops

Pentaceratops, like all ceratopsians, was an herbivore. During the Cretaceous, flowering plants were "geographically limited on the landscape"[ according to whom? ][ clarification needed ] 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 branches which were then shredded - leaves, needles and all - by the tooth batteries, providing a self-sharpening continuous cutting edge in both upper and lower jaws. Ultimately the plant material was digested by the large gut.

Paleoecology

Pentaceratops lived around 76–73 million years ago, its remains having been mostly found in the Kirtland Formation [1] in the San Juan Basin in New Mexico. Other dinosaurs that shared its habitat include Parasaurolophus cyrtocristatus , the pachycephalosaur Sphaerotholus , the armored dinosaur Nodocephalosaurus and the tyrannosauroid Bistahieversor .

See also

Related Research Articles

<i>Triceratops</i> Genus of ceratopsid dinosaur from the Late Cretaceous

Triceratops is a genus of chasmosaurine ceratopsian dinosaur that lived during the late Maastrichtian age of the Late Cretaceous period, about 68 to 66 million years ago in what is now western North America. It was one of the last-known non-avian dinosaurs and lived until the Cretaceous–Paleogene extinction event 66 million years ago. The name Triceratops, which means 'three-horned face', is derived from the Greek words trí- meaning 'three', kéras meaning 'horn', and ṓps meaning 'face'.

<i>Torosaurus</i> Extinct genus of dinosaurs

Torosaurus is a genus of herbivorous chasmosaurine ceratopsian dinosaur that lived during the late Maastrichtian age of the Late Cretaceous period, between 68 and 66 million years ago, though it is possible that the species range might extend to as far back as 69 million years ago. Fossils have been discovered across the Western Interior of North America, from as far north as Saskatchewan to as far south as Texas.

<i>Chasmosaurus</i> Extinct genus of dinosaurs

Chasmosaurus is a genus of ceratopsid dinosaur from the Late Cretaceous Period in North America. Its given name means 'opening lizard', referring to the large openings (fenestrae) in its frill. With a length of 4.3–4.8 metres (14.1–15.7 ft) and a weight of 1.5–2 tonnes —or anywhere from 2,200 to nearly 5,000 lbs., give or take—Chasmosaurus was of a slightly smaller to ‘average’ size, especially when compared to larger ceratopsians. The Chasmosaurs were similar, in overall build and weight, to a white rhinoceros or an Indian rhinoceros; just like rhinos, and all other ceratopsians, they were purely herbivorous, needing to consume around 54 kilograms, or 120 lbs., of plant matter each day.

<i>Nedoceratops</i> Extinct genus of dinosaurs

Nedoceratops is a controversial genus of ceratopsid dinosaur from the Late Cretaceous period Lance Formation of North America. It is known only from a single skull discovered in Wyoming. Its status is the subject of ongoing debate among paleontologists: some authors consider Nedoceratops a valid, distinct taxon, while others consider it to be an unusual specimen of Triceratops.

<i>Anchiceratops</i> Extinct genus of dinosaurs

Anchiceratops is an extinct genus of chasmosaurine ceratopsid dinosaur that lived approximately 72 to 71 million years ago during the latter part of the Cretaceous Period in what is now Alberta, Canada. Anchiceratops was a medium-sized, heavily built, ground-dwelling, quadrupedal herbivore that could grow up to an estimated 4.3 metres (14 ft) long. Its skull featured two long brow horns and a short horn on the nose. The skull frill was elongated and rectangular, its edges adorned by coarse triangular projections. About a dozen skulls of the genus have been found.

<i>Monoclonius</i> Extinct genus of dinosaurs

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Avaceratops is a genus of small herbivorous ceratopsian dinosaurs which lived during the late Campanian during the Late Cretaceous Period in what are now the Northwest United States. Most fossils come from the Judith River Formation.

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<span class="mw-page-title-main">Chasmosaurinae</span> Extinct subfamily of dinosaurs

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<i>Ojoceratops</i> Extinct genus of dinosaurs

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<i>Utahceratops</i> Extinct genus of dinosaurs

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<i>Kosmoceratops</i> Dinosaur genus from the Late Cretaceous period

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<i>Vagaceratops</i> Extinct genus of reptiles

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<i>Titanoceratops</i> Extinct genus of dinosaurs

Titanoceratops is a controversial genus of herbivorous ceratopsian dinosaur. It was a giant chasmosaurine ceratopsian that lived in the Late Cretaceous period in what is now New Mexico. Titanoceratops was named for its large size, being one of the largest known horned dinosaurs and the type species was named T. ouranos, after Uranus (Ouranos), the father of the Greek titans. It was named in 2011 by Nicholas R. Longrich for a specimen previously referred to Pentaceratops. Longrich believed that unique features found in the skull reveal it to have been a close relative of Triceratops, classified within the subgroup Triceratopsini. However, other researchers have expressed skepticism, and believe "Titanoceratops" to simply be an unusually large, old specimen of Pentaceratops.

<span class="mw-page-title-main">Triceratopsini</span> Extinct tribe of dinosaurs

Triceratopsini is a tribe of herbivorous chasmosaurine dinosaurs that lived between the late Campanian to the late Maastrichtian stages of the Cretaceous period, between 74.73 and 66 million years ago. Fossils of these animals have been found in western North America, in particular West Canada, Western and Midwestern United States, which was once part of the ancient continent of Laramidia. The tribe was named by Nicholas R. Longrich in 2011 for the description of Titanoceratops, which he defined as "all species closer to Triceratops horridus than to Anchiceratops ornatus or Arrhinoceratops brachyops". Triceratopsins were the largest of the chasmosaurines; suggesting that gigantism had evolved in the Ceratopsidae once. In addition there is an evolutionary trend in the solidification of the frills, the most extreme being in Triceratops.

<i>Judiceratops</i> Extinct genus of dinosaurs

Judiceratops is an extinct horned dinosaur. It lived around 78 million years ago, during the Late Cretaceous Period in what is now Montana, United States. Like other horned dinosaurs, Judiceratops was a large, quadrupedal herbivore. It is the oldest known chasmosaurine.

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<span class="mw-page-title-main">Timeline of ceratopsian research</span>

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.

<i>Spiclypeus</i> Extinct genus of dinosaurs

Spiclypeus is an extinct genus of chasmosaurine ceratopsian dinosaur known from the Late Cretaceous Judith River Formation of Montana, United States.

<i>Bisticeratops</i> Extinct genus of chasmosaurine dinosaurs

Bisticeratops is a genus of chasmosaurine ceratopsian from outcrops of the Campanian age Kirtland Formation found in the Bisti/De-Na-Zin Wilderness in northwestern New Mexico, United States. The type and only species is B. froeseorum, known from a nearly complete skull.

References

  1. 1 2 3 Sullivan and Lucas (2006). [ permanent dead link ]
  2. 1 2 3 Longrich, Nicholas R. (1 June 2011). "Titanoceratops ouranos, a giant horned dinosaur from the late Campanian of New Mexico". Cretaceous Research. 32 (3): 264–276. Bibcode:2011CrRes..32..264L. doi:10.1016/j.cretres.2010.12.007. ISSN   0195-6671.
  3. ↑ Wick, S. L.; Lehman, T. M. (2013). "A new ceratopsian dinosaur from the Javelina Formation (Maastrichtian) of West Texas and implications for chasmosaurine phylogeny". Naturwissenschaften. 100 (7): 667–82. Bibcode:2013NW....100..667W. doi:10.1007/s00114-013-1063-0. PMID   23728202. S2CID   16048008.
  4. ↑ Liddell, et al. (1980). pp. 373, 542-43, 804.
  5. 1 2 H.F. Osborn, 1923, "A new genus and species of Ceratopsia from New Mexico, Pentaceratops sternbergii, American Museum Novitates93: 1-3
  6. ↑ Sullivan, R.M. and S.G. Lucas, 2011, "Charles Hazelius Sternberg and his San Juan Basin Cretaceous dinosaur collections: Correspondence and photographs (1920-1925)", New Mexico Museum of Natural History and Science Bulletin53: 429-471
  7. 1 2 C. Wiman, 1930, "Über Ceratopsia aus der Oberen Kreide in New Mexico", Nova Acta Regiae Societatis Scientiarum Upsaliensis, Series 47(2): 1-19
  8. ↑ Fowler, D.W.; Freedman Fowler, E.A. (2020). "Transitional evolutionary forms in chasmosaurine ceratopsid dinosaurs: evidence from the Campanian of New Mexico". PeerJ. 8: e9251. doi: 10.7717/peerj.9251 . PMC   7278894 . PMID   32547873.
  9. ↑ Lucas, et al. (2006).
  10. ↑ Lehman, T.M., 1998, "A gigantic skull and skeleton of the horned dinosaur Pentaceratops sternbergi from New Mexico: Journal of Paleontology, 72(5): 894-906
  11. ↑ Delayed Debut for Jumbo Dino Skull
  12. ↑ Longrich, N., 2014, "The horned dinosaurs Pentaceratops and Kosmoceratops from the upper Campanian of Alberta and implications for dinosaur biogeography", Cretaceous Research, 51: 292-308
  13. ↑ Jordan C. Mallon; Christopher J. Ott; Peter L. Larson; Edward M. Iuliano; David C. Evans (2016). "Spiclypeus shipporum gen. et sp. nov., a Boldly Audacious New Chasmosaurine Ceratopsid (Dinosauria: Ornithischia) from the Judith River Formation (Upper Cretaceous: Campanian) of Montana, USA". PLOS ONE. 11 (5): e0154218. Bibcode:2016PLoSO..1154218M. doi: 10.1371/journal.pone.0154218 . PMC   4871577 . PMID   27191389.
  14. ↑ Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs 2nd Edition. New Jersey: Princeton University Press. p. 298.
  15. ↑ Rowe, T., Colbert, E.H. and Nations, J.D., 1981, "The occurrence of Pentaceratops with a description of its frill", In: Lucas, S.G., Rigby, J.K. and Kues, B.S. (eds.) Advances in San Juan Basin Paleontology, University of New Mexico Press, Albuquerque p. 29-48
  16. ↑ Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 272
  17. ↑ Scott D. Sampson, Mark A. Loewen, Andrew A. Farke, Eric M. Roberts, Catherine A. Forster, Joshua A. Smith, and Alan L. Titus (2010). Stepanova, Anna (ed.). "New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism". PLOS ONE. 5 (9): e12292. Bibcode:2010PLoSO...512292S. doi: 10.1371/journal.pone.0012292 . PMC   2929175 . PMID   20877459.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  18. 1 2 Longrich, N. R. (2014). "The horned dinosaurs Pentaceratops and Kosmoceratops from the upper Campanian of Alberta and implications for dinosaur biogeography". Cretaceous Research. 51: 292–308. Bibcode:2014CrRes..51..292L. doi:10.1016/j.cretres.2014.06.011.

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