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Pachyrhinosaurus (meaning in Greek "thick-nosed lizard", from Παχυ (pachy), thick; ρινό (rinó), nose; and σαυρος (sauros), lizard) is an extinct genus of centrosaurine ceratopsid dinosaur from the Late Cretaceous period of North America. The first examples were discovered by Charles M. Sternberg in Alberta, Canada, in 1946, and named in 1950. Over a dozen partial skulls and a large assortment of other fossils from various species have been found in Alberta and Alaska. A great number were not available for study until the 1980s, resulting in a relatively recent increase of interest in Pachyrhinosaurus.

Three species have been identified. P. lakustai, from the Wapiti Formation, the bonebed horizon of which is roughly equivalent age to the upper Bearpaw and lower Horseshoe Canyon Formations, is known to have existed from about 73.5–72.5 million years ago. P. canadensis is younger, known from the lower Horseshoe Canyon Formation, about 71.5–71 Ma ago and the St. Mary River Formation. Fossils of the youngest species, P. perotorum, have been recovered from the Prince Creek Formation of Alaska, and date to 70–69 Ma ago. The presence of three known species makes this genus the most speciose among the centrosaurines.

Discovery and species[]

Pachyrhinosaurus species skulls

Skulls of the three species compared: P. perotorum (with inaccurate epiparietal placement), P. canadensis, and P. lakustai

Pachyrhinosaurus canadensis, was described in 1950 by Charles Mortram Sternberg based on the holotype incomplete skull NMC 8867, and the paratype incomplete skull NMC 8866, which included the anterior part of the skull but was lacking the right lower mandible, and the "beak". These skulls were collected in 1945 and 1946 from the sandy clay of the Horseshoe Canyon Formation in Alberta, Canada. In the years to come, additional material would be recovered at the Scabby Butte locality of the St. Mary River Formation near Lethbridge, Alberta, from terrestrial sediments considered to be between 74 and 66 million years old. These were among the first dinosaur sites found in the province, in the 1880s. The significance of these discoveries was not understood until shortly after World War II when preliminary excavations were conducted.

Another Pachyrhinosaurus skull was taken out of the Scabby Butte locality in 1955, and then in 1957 Wann Langston Jr. and a small crew excavated additional pachyrhinosaur remains. The University of Calgary has plans to reopen this important site some day as a field school for university-level paleontology students. Several specimens, NMC 21863, NMC 21864, NMC 10669 assigned in 1975 by W. Langston, Jr. to Pachyrhinosaurus were also recovered at the Scabby Butte locality.

Another Pachyrhinosaurus bonebed, on the Wapiti River south of Beaverlodge in northwestern Alberta, was worked briefly by staff of the Royal Tyrrell Museum in the late 1980s but is now worked annually for a couple weeks each summer (since 2006) by the University of Alberta. Material from this site appears referable to Pachyrhinosaurus canadensis. In 1974, Grande Prairie, Alberta science teacher Al Lakusta found a large bonebed along Pipestone Creek in Alberta. When the area was finally excavated between 1986 and 1989 by staff and volunteers of the Royal Tyrrell Museum of Palaeontology, paleontologists discovered an amazingly large and dense selection of bones—up to 100 per square meter, with a total of 3,500 bones and 14 skulls. This was apparently the site of a mass mortality, perhaps a failed attempt to cross a river during a flood. Found amongst the fossils were the skeletons of four distinct age groups ranging from juveniles to full-grown dinosaurs, indicating that the Pachyrhinosaurus cared for their young. The adult skulls had both convex and concave bosses as well as unicorn-style horns on the parietal bone just behind their eyes. The concave boss types might be related to erosion only and not reflect male/female differences.

In 2008, a detailed monograph describing the skull of the Pipestone Creek pachyrhinosaur, and penned by Philip J. Currie, Wann Langston Jr., and Darren Tanke, classified the specimen as a second species of Pachyrhinosaurus, named P. lakustai after its discoverer.

In 2013, Fiorillo et al. described a new specimen, an incomplete nasal bone attributable to Pachyrhinosaurus perotorum which was collected from the Kikak-Tegoseak Quarry on the Colville River in Alaska. Fiorillo et al. named this unique northern Alaskan species after the Texas oil billionaire and benefactor, Ross Perot. This bone, designated DMNH 21460 belongs to an immature individual. This discovery expands the known age profile of this dinosaur genus from this particular site. The specimen has nasal ornamentation that is dorsally enlarged, representing an intermediate stage of growth. Of note, the authors pointed out that the posterior part of the nasal shows evidence for "a degree of integument complexity not previously recognized in other species" of Pachyrhinosaurus. It was determined that the dorsal surface of the nasal boss bore a thick, cornified pad and sheath.

Description[]

Pachyrhinosaurus Scale 2

Size comparison of P. canadensis

Size estimates for the largest Pachyrhinosaurus species, P. canadensis indicate lengths of 6–8 metres (20–26 ft) and a weight of 3 tonnes (3.3 tons).[1] The other species, P. lakustai and P. perotorum, have been estimated at 5 metres (16 ft) in length and 2 tonnes (2.2 tons) in weight. They were herbivorous and possessed strong cheek teeth to help them chew tough, fibrous plants.

PachyrhinosaurusSK

Artist's rendering of Pachyrhinosaurus

Pachyrhinosaurus BW

Restoration of P. lakustai

The skull had no true horns, but a thick, flat boss on the nose and above the eyes. Two horn-like spikes stuck out from the top of the frill and extended up and the skull bore some small horns that varied between individuals and between species. In P. canadensis and P. perotorum, the bosses over the nose and eyes nearly grew together, and were separated just by a narrow groove. In P. lakustai, the two bosses were separated by a wide gap. In P. canadensis and P. lakustai, the frill bore two more small, curved, backward-pointed horns. These were not found in P. perotorum, and in fact some specimens of P. lakustai lack them too, which may mean that the presence of these horns varied by age or sex.

Various ornaments of the nasal boss have been used to tell the species of Pachyrhinosaurus apart. Both P. lakustai and P. perotorum bore a rough, comb-like extension at the tip of the boss which P. canadensis lacked. P. perotorum was unique in having a narrow dome in the middle of the back portion of the nasal boss, and P. lakustai had a pommel-like structure sticking out from the front of the boss (the boss of P. canadensis was mainly flat on top and rounded). P. perotorum bore two unique, flattened horns which pointed forward and down from the top edge of the frill, and P. lakustai bore another comb-like horn arising from the middle of the frill behind the eyes.[2]

Species[]

P. canadensis[]

P. canadensis is known from the Horsehoe Canyon Formation[3] and the laterally equivalent St. Mary River Formation.[4] It was estimated by to be 6 meters long, 2 meters tall[5], and weigh 3 metric tones.[6] P. canadensis can be distinguished from the other species of Pachyrhinosaurus by: the lack of a small rostral comb dorsal to the rostral (shared with P. "youngi"); nasal boss and supraorbital bosses that contact each other on the skull roof (shared with P. perotorum and P. "youngi"); presence of a supranarial ossification on the lateral surface of the rostrum (shared with P. perotorum, not perserved in P. "youngi"); nasal boss and other anterior facial ornamentations (including "fist-sized knobs") are more hypertrophied than P. lakustai, but less so than P. perotorum and P. "youngi"; lack of a single transverse shelf of bone on the medial side of the premaxilla (shared with P. perotorum and P. "youngi")' "long slender, finger-like premaxillary process that extends forward and then curves 90° medially"; "irregularly developed and vertical fluting", a flat parietal bar in lateral view"; "lateral parietal spike twists dorsolaterally"; and the presence of a "Supranasal Boss" (not shared with any other species).[7][8][9][8] In 1967/1968 a skull from Drumheller was discovered by the Drumheller Dinosaur and Fossil Museum, which is now the Badlands Historical Centre. A taxon number wasn't given to this skull, but Currie, Langston, and Tanke dub this specimen the "Drumheller Skull". It is a large Pachyrhinosaurus canadensis.[10][11]

P. lakustai[]

Pachyrhinosaurus Royal Tyrrell 1

Skeleton of P. lakustai '.

P. lakustai is known from the Wapiti Formation[11]. It was around 5m long, and weigh 2 metric tons[6]. P. lakustai can be distinguished from other known Pachyrhinosaurus species by: the "presence of a small rostral comb dorsal to the rostral" (shared with P. perotorum); the "presence of a supranarial ossification on the lateral surface of the rostrum" (shared with P. canadensis); nasal boss and other anterior facial ornamentations (including "fist-sized knobs") less hypertrophied than both P. canadensis, P. perotorum, and P. "youngi"; a single transverse shelf of bone on the medial side of the premaxilla (not shared by any other species); the "short robust premaxillary process projects straight forward into nares"; the parietal bar curves slightly upwards in lateral (possibly shared with P. "youngi"); "lateral parietal spike twists anteroventrally" (shared with P. "youngi" and to a lesser extent P. perotorum [more horizontal]); the lack of a "Supranasal Boss" (shared with P. perotorum and P. "youngi").[11][7][9][8]

P. perotorum[]

Pachyrhinosaurus perotorum skeleton

P. perotorum mounted at the Perot Museum; note the small forwards pointing epiparietals at the top of the frill, which were inaccurately reconstructed following the original description, while these would actually have faced up like in the other species

P. perotorum is known from the Prince Creek Formation[8]. It was around 5m long, and weigh 2 metric tons[6] P. perotorum can be distinguished from other species of Pachyrhinosaurus by: "rostrum anterior tip upturned with anteroventrally directed premaxillary oral margin, resulting in a rostral bone shifted to a level dorsal to the maxillary tooth row"; "rostral bone lacks the acute, ventrally downturned, parrot-like beak common to other ceratopsians"; "nasal boss dorsal surface with median ridge near posterior end of boss" (none of these feature is shared with another species of Centrosaur).[9] Both "epiparietal 2 (P2) posterior margin excavated by enhanced, trough-like, mediolaterally oriented sulcus" and "epiparietal 2 (P2) horn base penetrated by canal passing dorsoventrally through body of horn." are tentative autapomorphies of P. perotorum.[9] Further, these features can be used to better distinguish P. perotorum from its relatives. "small rostral comb dorsal to the rostral" (shared with P. lakustai); the "nasal boss and supraorbital bosses that contact each other on the skull roof" (shared with P. canadensis and P. "youngi"); "presence of a supranarial ossification on the lateral surface of the rostrum" (shared with P. canadensis and not perserved in P. "youngi"); nasal boss and other anterior facial ornamentations (including "fist-sized knobs") are more hypertrophied than P. canadensis, P. lakustai, and P. "youngi"; the lateral parietal spike twists anteroventrally (similar, but less pronounced than P. lakustai and P. "youngi"; the lack of a "supranasal boss (shared with P. lakustai and P. "youngi".[11][7][9][8]

P. "youngi"[]

P. "youngi" was found in the Wapiti Formation[7]. Kruk didn't provide estimates on size of P. "youngi", however it can be assumed to be around 5-6m long and weighed 2-3 tons due to its phylogenetic position. P. "youngi" can be differentiated from other Pachyrhinosaurus species by: the lack of a "small rostral comb dorsal to the rostral" (shared with P. canadensis); the "nasal boss and supraorbital bosses that contact each other on the skull roof" (shared with P. canadensis and P. perotorum); "dorsolaterally curved parietal horns"; a "distinctive tall separation between supraorbital bosses"; an "anteriorly protruding “pommel"" (all 3 unique to P. "youngi"); lack of a "single transverse shelf of bone on the medial side of the premaxilla" (shared with P. canadensis and P. perotorum); the lack of "Supranasal Boss" (shared with P. perotorum and P. lakustai.)

P. sp. nov.[]

TMP 2002.76.1 is known from the Dinosaur Park Formation[12]. This specimen is known from a mostly complete skull missing the back of the frill, both radii and ulnae of the front feet, the right humerus, both scapulae, both scapulacoracoids, 3 complete feet, 2 tibiae (one partial one complete), a fibula, around 5 cervical vertebrae, around 14 dorsal vertebrae, and around 11 caudal vertebrae, and around 12 pairs of ribs, as well as a highly incomplete sacrum.[13] If this taxon is Pachyrhinosaurus it would be the oldest species of the genus. Both Kruk (2015) and Tykoski et. al. (2019) recover this taxon as a taxon closer to Pachyrhinosaurus rather than Achelousaurus.[7][9]However, Savhannah Carpenter's unpublished phylogeny from 2021 (labeled as Achelousaurus [Iddesleigh]) as well as Ryan et. al. (2010) places TMP 2002.76.1 in a polytomy with Achelousaurus and Pachyrhinosaurus.[14] [15]The reason why it's position within Pachyrostra hasn't been consistent is due to the preservation of TMP 2002.76.1. TMP 2002.76.1 is missing the top of its frill, which is a vital character that distinguished Ceratopsids in general and Pachyrhinosaurus in particular. Until further expeditions to the Dinosaur Park Formation uncover another specimen of this species, it is unlikely to receive a name (despite several characters that distinguish it from Achelousaurus horneri and the other known Pachyrhinosaurus species[15]) due to the uncertainty of whether it is a new genus, a new species of Achelousaurus, or a new species of Pachyrhinosaurus.

Pachyrhinosaurus Royal Tyrell

Mount of TMP 2002.76.1 at the Royal Tyrrell Museum of Palaeontology.

In October 2013 a Darla Zelenitsky and her team discovered the skull of a "gargantuan pachyrhinosaur" within the limits of Drumheller, Alberta. The Pachyrhinosaur was unveiled at the University of Calgary in February of 2014. It was the largest skull of a Pachyrhinosaur discovered, over 6 meters in length. Zelenitsky estimates that the skull is 75-80% complete. She and her team planned on returning to the site in spring/summer of 2014 to determine if more of the "gargantuan pachyrhinosaur" is preserved, and to determine "if this specimen represents a new species.” So far, no more news of the Pachyrhinosaur has been publicized since the original unveiling.[16][17]

Classification[]

Pachyrhinosaurus is in the family Ceratopsidae in the subfamily Centrosaurinae. Its closest relative, Achelousaurus is likely to have been well characterized by the lack of nose horn . Together they formed the tribe Pachyrhinosaurini.

The cladogram below shows the phylogenetic position of all currently known Pachyrhinosaurus species following Chiba et al. (2017):

Centrosaurinae


Diabloceratops eatoni



Machairoceratops cronusi




Nasutoceratopsini

Avaceratops lammersi (ANSP 15800)



MOR 692



CMN 8804



Nasutoceratops titusi



Malta new taxon





Xenoceratops foremostensis





Sinoceratops zhuchengensis



Wendiceratops pinhornensis




Albertaceratops nesmoi



Medusaceratops lokii


Eucentrosaura
Centrosaurini


Rubeosaurus ovatus



Styracosaurus albertensis





Coronosaurus brinkmani




Centrosaurus apertus



Spinops sternbergorum





Pachyrhinosaurini

Einiosaurus procurvicornis


Pachyrostra

Achelousaurus horneri




Pachyrhinosaurus canadensis




Pachyrhinosaurus lakustai



Pachyrhinosaurus perotorum











Paleobiology[]

Pachyrhinosaurus perotorum ontogeny with updated epiparietals

Skull differences between different growth stages of P. perotorum

Modern life at high elevations in lower latitudes resembles life at low elevation in higher latitudes. There may be parallels to this phenomenon in Cretaceous ecosystems, for instance, Pachyrhinosaurus species are found in both Alaska and upland environments in southern Alberta.

In the Edmontonian, in North America's northern biome, there is a trend of reduced centrosaurine mix, with just Pachyrhinosaurus surviving. Inland faunas are distinguished by a Saurolophus-Anchiceratops association while more coastal areas were characterized by Pachyrhinosaurus and Edmontosaurus.[18]

It was a herding, social animal that usually traveled in large groups. It's distinguished by the large frill on the back of its head and the thick stump on its snout. It was about 26 feet (8 meters) long and weighed 4 tons.

Like most ceratopsians, it couldn't see very well, but was also muscularly built and was designed to defend itself instead of flee. Like other ceratopsians, it had a unique frill and horn structure, with several larger horns on the outside and two smaller horns on the top of the frill. It had four muscular legs that supported its heavily built body and could probably run at about 15 mph at top speed. It had a strong beak designed to snap branches and break off ferns and other plant material.Most recent restorations of the animal feature an assumed 'pelt' of proto feathering, given that a similar climate to today's Canada would require heavy insulation. This addition is not yet confirmed, but highly speculated in a likely aspect.

Paleoecology[]

St. Mary River Formation[]

Habitat[]

Albertosaurus confronting Pachyrhinosaurus

Restoration of a confrontation between P. canadensis and Albertosaurus

The St. Mary River Formation has not undergone a definitive radiometric dating, however, the available stratigraphic correlation has shown that this formation was deposited between 74 and 66 million years ago, during the Campanian and the late Maastrichtian, during the final regression of the mid-continental Bearpaw Seaway. It ranges from as far south as Glacier County, Montana to as far north as the Little Bow River in Alberta. The St. Mary River Formation is part of the Western Canadian Sedimentary Basin in southwestern Alberta, which extends from the Rocky Mountains in the west to the Canadian Shield in the east. It is laterally equivalent to the Horseshoe Canyon Formation. The region where dinosaurs lived was bounded by mountains to the west, and included ancient channels, small freshwater ponds, streams, and floodplains.

Paleofauna[]

Prince Creek Formation fauna

A herd of P. perotorum resting next to contemporaneous paleofauna from the Prince Creek Formation

Pachyrhinosaurus shared its paleoenvironment with other dinosaurs, such as the ceratopsians Anchiceratops and Montanoceratops cerorhynchus, the armored nodosaur Edmontonia longiceps, the duckbilled hadrosaur Edmontosaurus regalis, the theropods Saurornitholestes and Troodon, possibly the ornithopod Thescelosaurus, and the tyrannosaurid Albertosaurus, which was likely the apex predator in its ecosystem. Vertebrates present in the St. Mary River Formation at the time of Pachyrhinosaurus included the actinopterygian fishes Amia fragosa, Lepisosteus, Belonostomus, Paralbula casei, and Platacodon nanus, the mosasaur Plioplatecarpus, the turtle Boremys and the diapsid reptile Champsosaurus. A fair number of mammals lived in this region, which included Turgidodon russelli, Cimolestes, Didelphodon, Leptalestes, Cimolodon nitidus, and Paracimexomys propriscus. Non-vertebrates in this ecosystem included mollusks, the oyster Crassostrea wyomingensis, the small clam Anomia, and the snail Thiara. Flora of the region include the aquatic angiosperm Trapago angulata, the amphibious heterosporous fern Hydropteris pinnata, rhizomes, and taxodiaceous conifers.

Horseshoe Canyon[]

Pachyrhinosaurus canadensis is known from both the Horseshoe Canyon Formation and the laterally equivalent St. Mary River Formation. It shared its environment with the Leptoceratopsid Montanoceratops, The Chasmosaurs Regaliceratops[19], Anchiceratops, and Arrhinoceratops. It would have also coexisted with hadrosaur Edmontosaurus regalis, The Ornithomimosaurs Ornithomimus and Struthiomimus, the Tyrannosaur Albertosaurus sarcophagus, The Ankylosaurs Anodontosaurus and Edmontonia longiceps. It would have also coexisted with the Troodontid Albertavenator, the Dromeosaur Atrociraptor[20], and the Caenagnathid Ovoraptorosaurs Apatoraptor[21] and Epichirostenotes[22][4][23]. Among Non-Dinosaurians the mammal Didelphodon coyi from Drumheller.[24][25] Stangerochampsa is from Horseshoe Canyon isn't clear in the article's description, but probably belongs to the Drumheller unit, making it coocurring.[26] Basilemys[27] is known from the Horseshoe Canyon Formation, but isn't given a locality, based on other formations it probably cooccurs with P. canadensis. The Choristoderan Champsosaurus albertensis and the plesiosaur Leurospondylus[28] were found in Horseshoe Canyon, but no further locality information can be gathered.

Wapiti Formation[]

Pachyrhinosaurus lakustai and P. "youngi" are known from the Wapiti Formation. It would have shared its environment with A large Tyrannosaur, possibly Albertosaurus (represented by teeth[29] and Bellatoripes tracks[30]), the Velociraptorine Boreonykus certekorum[31], the Hadrosaur Edmontosaurus[32], and Saurornitholestes sp.[33]. "Troodon" and the morphotaxon Richardoestesia.[33] are also present.

Prince Creek Formation[]

Pachyrhinosaurus perotorum is known from the Prince Creek Formation. It would have shared its environment with an indeterminate Leptoceratopsid[34], The Hadrosaur Edmontosaurus sp. (previously within the junior synonym "Ugrunaaluk") [35], an indeterminate Lambeosaurine represented by the supraoccipital DMNH 2014-12-266. The Pachycephalosaur Alaskacephale gangloffi is also present.[36] Nanuqsaurus was also present within this formation. Dromaeosaurus cf. albertensis, Saurornitholestes cf. langstoni[37], indeterminate Thescelosaurinae and indeterminate "Hypsilophodontid" teeth have been found within the formation.[38]An indeterminate genus of saurornitholestinae, represented by the dentary fragment DMNH 21183 is present.[39] A Distal metatarsal IV from an indeterminate Ornithomimosaur[40] and the tracks of ichnogenus bird Gruipeda[41] have also been reported. Of all the remains, only one non-dinosaurian faunal taxon is known, the metatherian mammal Unnuakomys.[42]

Dinosaur Park Formation[]

TMP 2002.76.1 is known from the Dinosaur Park Formation, specifically the Lethbridge Coal.[15] Very little has been reported from the Lethbridge Coal, among the known remains from the Dinosaur Park Formation: Centrosaurus, Chasmosaurus belli and C. russeli are Ceratopsids it would have coexisted with.[43] The Hadrosaurids Corythosaurus, Gryposaurus, and Parasaurolophus walkeri.[44] The Tyrannosaur Gorgosaurus would have lived at the same time and possibly hunted this taxon.[43]

JPInstitute.com Description[]

Pachyrhinosaurus is an odd-looking member of the ceratopsian family of horned dinosaurs. It had a large lump on its nose instead of a sharp horn like most of its relatives. This large plant-eater grew to about the same size as its more famous relative, Triceratops. It would have lived in herds, moving about the Cretaceous land eating tough, low-growing plants. It had a sharp beak that would cut off leaves and lots of teeth in the back part of its mouth for chewing up tough plants.

This dinosaur has caused a great deal of debate among scientists because it is so different from other ceratopsians. While most feel that the nasal boss on Pachyrhinosaurus was used as a butting device during display, others have suggested it was the base for a huge keratin horn. It seems that these bosses were quite individualized and may have differed between genders. Also, the shape and size of the frills seems to have varied more among this genus than any other ceratopsian genus.

There weren?t many specimens available for study until the late 1980?s. It was only then that scientist began to draw conclusions and raise more questions about this peculiar dinosaur.

Appearance in other media[]

Jurassic Park[]

  • Pachyrhinosaurus was planned to appear in Jurassic World: Fallen Kingdom official trailers, but it was changed to Sinoceratops. However, while not in the trailers so far, it has been revealed that there are surviving Pachyrhinosaurus populations on Isla Nublar, although they will now face an impending danger, alongside many other creatures, in the form of an erupting volcano. It is possible that Pachyrhinosaurus was saved offscreen. Its name appears o list, implying that at least one Pachyrhinosaurus and possibly others of it's kind was captured offscreen, and may have also escaped, or had been sold off at the Lockwood Manor auction.
  • Pachyrhinosaurus is one of the dinosaurs in Jurassic World: The Game. It is a legendary tournament herbivore. Originally, along with the Kentrosaurus, it was a tournament dinosaur that did not yet have a tournament to fight in and could only only be collected by buying the Earth WWF pack. Now since March 8th, 2018, it could be won in a Pachyrhinosaurus tournament.


The Land Before Time[]

  • Pachyrhinosaurus featured in the 8th episode and some TV episodes of Land Before Time as "Mr. Thicknose".


Links[]

http://web.archive.org/web/20040420203445fw_/http://www.jpinstitute.com/dinopedia/dinocards/dc_pachyrhinosaurus.html

References[]

  1. Holtz, Thomas R. Jr. (2008) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages Supplementary Information
  2. Fiorillo, A.R. and Tykoski, R.S.T. (in press). "A new species of the centrosaurine ceratopsid Pachyrhinosaurus from the North Slope (Prince Creek Formation: Maastrichtian) of Alaska." Acta Palaeontologica Polonica, available online 26 Aug 2011. doi:10.4202/app.2011.0033
  3. Cite error: Invalid <ref> tag; no text was provided for refs named :1
  4. 4.0 4.1 1.4 Alberta, Canada; 13. St. Mary River Formation," in Weishampel, et al. (2004). Pages 577-578
  5. https://commons.wikimedia.org/wiki/File:Pachyrhinosaurus_Scale_2.svg
  6. 6.0 6.1 6.2 Paul, Gregory, S. Princeton Field Guide to Dinosaurs, Princeton, NJ, Princeton University Press, 2010, pg. 292-293
  7. 7.0 7.1 7.2 7.3 7.4 Cite error: Invalid <ref> tag; no text was provided for refs named :0
  8. 8.0 8.1 8.2 8.3 8.4 Cite error: Invalid <ref> tag; no text was provided for refs named :4
  9. 9.0 9.1 9.2 9.3 9.4 9.5 Ronald S. Tykoski, Anthony R. Fiorillo & Kentaro Chiba (2019) New data and diagnosis for the Arctic ceratopsid dinosaur Pachyrhinosaurus perotorum, Journal of Systematic Palaeontology, 17:16, 1397-1416, https://doi.org/10.1080/14772019.2018.1532464
  10. https://badlandsmuseum.wordpress.com/
  11. 11.0 11.1 11.2 11.3 Cite error: Invalid <ref> tag; no text was provided for refs named :3
  12. https://www.researchgate.net/publication/284893179_A_new_Pachyrhinosaurus-like_ceratopsid_from_the_upper_Dinosaur_Park_Formation_Late_Campanian_of_southern_Alberta_Canada
  13. https://www.flickr.com/photos/58554451@N00/4552995690/ (mount of TMP 2002.76.1 from RTMP)
  14. https://youtu.be/Qr7u0U4u5bo?t=1488
  15. 15.0 15.1 15.2 Cite error: Invalid <ref> tag; no text was provided for refs named :6
  16. THE CANADIAN PRESS (2015, January 25). 'gargantuan' pachyrhinosaur skull found in Drumheller 72 million years after horned dinosaur roamed Alberta. nationalpost. Retrieved May 8, 2022, from https://nationalpost.com/news/canada/gargantuan-pachyrhinosaur-skull-found-in-drumheller-72-million-years-after-horned-dinosaur-roamed-alberta
  17. CBC/Radio Canada. (2014, February 21). 'gargantuan' pachyrhinosaur skull found near Drumheller | CBC News. CBCnews. Retrieved May 8, 2022, from https://www.cbc.ca/news/canada/calgary/gargantuan-pachyrhinosaur-skull-found-near-drumheller-1.2544925
  18. 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.
  19. Brown, Caleb M.; Henderson, Donald M. (June 4, 2015). "A new horned dinosaur reveals convergent evolution in cranial ornamentation in ceratopsidae". Current Biology (online). doi:10.1016/j.cub.2015.04.041.
  20. Currie, P. J. and D. J. Varricchio (2004). "A new dromaeosaurid from the Horseshoe Canyon Formation (Upper Cretaceous) of Alberta, Canada". Pp. 112–132 in P. J. Currie, E. B. Koppelhus, M. A. Shugar and J. L. Wright. (eds.), Feathered Dragons. Indianapolis: Indiana University Press
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