Parksosaurus

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Parksosaurus
Temporal range: Late Cretaceous, 69.5  Ma
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ParksosaurusSkull.JPG
Skull cast of Parksosaurus
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Ornithischia
Clade: Neornithischia
Clade: Pyrodontia
Family: Thescelosauridae
Subfamily: Thescelosaurinae
Genus: Parksosaurus
C. M. Sternberg, 1937
Species:
P. warreni
Binomial name
Parksosaurus warreni
(Parks, 1926 [originally Thescelosaurus ])
Synonyms

Parksosaurus (meaning "William Parks's lizard") is a genus of neornithischian dinosaur from the early Maastrichtian-age Upper Cretaceous Horseshoe Canyon Formation of Alberta, Canada. It is based on most of a partially articulated skeleton and partial skull, showing it to have been a small, bipedal, herbivorous dinosaur. It is one of the few described non-hadrosaurid ornithopods from the end of the Cretaceous in North America, existing around 70 million years ago.

Contents

Description

Size of Parksosaurus (center) compared to its relatives Thescelosaurus (right) and Orodromeus (left), as well as a human Parksosaurids-Scale-Comparison-SVG-001.svg
Size of Parksosaurus (center) compared to its relatives Thescelosaurus (right) and Orodromeus (left), as well as a human

Explicit estimates of the entire size of the animal are rare; in 2010 Gregory S. Paul estimated the length at 2.5 meters, the weight at forty-five kilograms. [1] William Parks found the hindlimb of his T. warreni to be about the same length overall as that of Thescelosaurus neglectus (93.0 centimeters (3.05 ft) for T. warreni versus 95.5 centimeters (3.13 ft) for T. neglectus), even though the shin was shorter than the thigh in T. neglectus, the opposite of T. warreni. [2] Thus, the animal would have been comparable to the better-known Thescelosaurus in linear dimensions, despite proportional differences (around 1 meter (3.3 ft) tall at the hips, 2-2.5 meters (6.56-8.2 ft) long). [2] The proportional differences probably would have made it lighter, though, as less weight was concentrated near the thigh. Like Thescelosaurus, it had thin partly ossified cartilaginous (intercostal) plates along the ribs. [3] The shoulder girdle was robust. [1] Parksosaurus had at least eighteen teeth in the maxilla and about twenty in the lower jaw; the number of teeth in the premaxilla is unknown. [4]

Discovery and history

Fossil, Royal Ontario Museum Parksosaurus warreni, Near Drumheller, Alberta, Canada, Late Cretaceous - Royal Ontario Museum - DSC00035.JPG
Fossil, Royal Ontario Museum

Paleontologist William Parks described skeleton ROM 804 in 1926 as Thescelosaurus warreni, which had in 1922 been discovered in what was then called the Edmonton Formation near Rumsey Ferry on the Red Deer River. When found, it consisted of a partial skull missing the beak region, most of the left pectoral girdle (including a suprascapula, a bone more commonly found in lizards, but which is believed to have been present in cartilaginous form in some ornithopods due to the roughened ends of their scapulae), [5] the left arm except the hand, ribs and sternal elements, a damaged left pelvis, right ischium, the left leg except for some toe bones, articulated vertebrae from the back, hip, and tail, and a number of ossified tendons that sheathed the end of the tail. The body of the animal had fallen on its left side, and most of the right side had been destroyed before burial; in addition, the head had been separated from the body, and the neck lost. Parks differentiated the new species from T. neglectus by leg proportions; T. warreni had a longer tibia than femur, and longer toes. [2]

Charles M. Sternberg, upon the discovery of the specimen he named Thescelosaurus edmontonensis, revisited T. warreni and found that it warranted its own genus (it was named in an abstract, which is not typical, but the specimen had already been thoroughly described). [6] In 1940, he presented a more thorough comparison and found a number of differences between the two genera throughout the body. He assigned Parksosaurus to the Hypsilophodontinae with Hypsilophodon and Dysalotosaurus , and Thescelosaurus to the Thescelosaurinae. [7] The genus attracted little attention until Peter Galton began his revision of hypsilophodonts in the 1970s. Parksosaurus received a redescription in 1973, wherein it was considered to be related to a Hypsilophodon \ Laosaurus \L. minimus lineage. [4] After this, it once again returned to obscurity.

George Olshevsky emended the species name to P. warrenae in 1992, [8] because the species name honors a woman (Mrs. H. D. Warren who financially supported the research), but outside of Internet sites, the original spelling has been preferred. [9]

Classification

Parksosaurus has been considered to be a hypsilophodont since its description. [2] Recent reviews have dealt with it with little comment, [10] [9] [11] although David B. Norman and colleagues (2004), in the framework of a paraphyletic Hypsilophodontidae, found it to be the sister taxon to Thescelosaurus, [9] and Richard Butler and colleagues (2008) found that it may be close to the South American genus Gasparinisaura . [11] However, basal ornithopod phylogeny is poorly known at this point, albeit under study. Like Thescelosaurus, Parksosaurus had a relatively robust hindlimb, and an elongate skull without as much of an arched shape to the forehead compared to other hypsilophodonts. [9] A 2015 study placed it as an intermediate member of Iguanodontia more derived than Elasmaria. [12]

Cladogram based in the phylogenetic analysis of Rozadilla et al., 2015:

The cladogram below results from analysis by Herne et al., 2019, which placed Parksosaurus as the most basal member of Ornithopoda. [13]

Ornithischia

Paleoecology and paleobiology

Life restoration of Parksosaurus warreni Parksosaurus Steveoc86.jpg
Life restoration of Parksosaurus warreni

Parksosaurus is known from the base of Unit 4 of the Horseshoe Canyon Formation, [14] which dates to about 69.5 million years ago. [15] Other dinosaur species from this same unit include the theropods Albertosaurus sarcophagus and Albertavenator curriei as well as the spike-crested hadrosaurid Saurolophus osborni , hollow-crested hadrosaurid Hypacrosaurus altispinus , and ankylosaurid Anodontosaurus lambei . Teeth of an unidentified ceratopsian species are known from the same stratigraphic level. [14] The dinosaurs from this formation are sometimes known as Edmontonian, after a land mammal age, and are distinct from those in the formations above and below. [16] The Horseshoe Canyon Formation is interpreted as having a significant marine influence, due to an encroaching Western Interior Seaway, the shallow sea that covered the midsection of North America through much of the Cretaceous. [16]

In life, Parksosaurus, as a hypsilophodont, would have been a small, swift bipedal herbivore. It would have had a moderately long neck and small head with a horny beak, short but strong forelimbs, and long powerful hindlimbs. [9] Paul in 2010 suggested that the long toes were an adaptation for walking over mud or clay near rivers and that the strong arms were used for burrowing. [1]

Related Research Articles

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

Hypsilophodon is a neornithischian dinosaur genus from the Early Cretaceous period of England. It has traditionally been considered an early member of the group Ornithopoda, but recent research has put this into question.

<span class="mw-page-title-main">Ornithopoda</span> Extinct suborder of dinosaurs

Ornithopoda is a clade of ornithischian dinosaurs, called ornithopods. They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively small-sized, while advanced members of the subgroup Iguanodontia became quadrupedal and developed large body size. Their major evolutionary advantage was the progressive development of a chewing apparatus that became the most sophisticated ever developed by a non-avian dinosaur, rivaling that of modern mammals such as the domestic cow. They reached their apex of diversity and ecological dominance in the hadrosaurids, before they were wiped out by the Cretaceous–Paleogene extinction event along with all other non-avian dinosaurs. Members are known worldwide.

<i>Edmontosaurus</i> Hadrosaurid dinosaur genus from Late Cretaceous US and Canada

Edmontosaurus, with the second species often colloquially and historically known as Anatosaurus or Anatotitan, is a genus of hadrosaurid (duck-billed) dinosaur. It contains two known species: Edmontosaurus regalis and Edmontosaurus annectens. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian age of the Cretaceous period 73 million years ago, while those of E. annectens were found in the same geographic region from rocks dated to the end of the Maastrichtian age, 66 million years ago. Edmontosaurus was one of the last non-avian dinosaurs to ever exist, and lived alongside dinosaurs like Triceratops, Tyrannosaurus, Ankylosaurus, and Pachycephalosaurus shortly before the Cretaceous–Paleogene extinction event.

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

Valdosaurus is a genus of bipedal herbivorous iguanodont ornithopod dinosaur found on the Isle of Wight and elsewhere in England, Spain and possibly also Romania. It lived during the Early Cretaceous.

<i>Pachyrhinosaurus</i> Ceratopsid dinosaur genus from Late Cretaceous US and Canada

Pachyrhinosaurus 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.

<span class="mw-page-title-main">Hypsilophodontidae</span> Extinct family of dinosaurs

Hypsilophodontidae is a traditionally used family of ornithopod dinosaurs, generally considered invalid today. It historically included many small bodied bipedal neornithischian taxa from around the world, and spanning from the Middle Jurassic until the Late Cretaceous. This inclusive status was supported by some phylogenetic analyses from the 1990s and mid 2000s, although there have also been many finding that the family is an unnatural grouping which should only include the type genus, Hypsilophodon, with the other genera being within clades like Thescelosauridae and Elasmaria. A 2014 analysis by Norman recovered a grouping of Hypsilophodon, Rhabdodontidae and Tenontosaurus, which he referred to as Hypsilophodontia. That clade is formally defined in the PhyloCode as "the smallest clade within Ornithopoda containing Hypsilophodon foxii and Tenontosaurus tilletti provided it does not include Iguanodon bernissartensis". All other analyses from around the same time have instead found these latter taxa to be within Iguanodontia. The family Hypsilophodontidae is formally defined in the PhyloCode by Daniel Madzia and colleagues in 2021 as "the largest clade containing Hypsilophodon foxii, but not Iguanodon bernissartensis and Rhabdodon priscus".

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

Hypacrosaurus was a genus of duckbill dinosaur similar in appearance to Corythosaurus. Like Corythosaurus, it had a tall, hollow rounded crest, although not as large and straight. It is known from the remains of two species that spanned 75 to 67 million years ago, in the Late Cretaceous of Alberta, Canada, and Montana, United States, and is the latest hollow-crested duckbill known from good remains in North America. It was an obscure genus until the discovery in the 1990s of nests, eggs, and hatchlings belonging to H. stebingeri.

<i>Saurolophus</i> Hadrosaurid dinosaur genus from the Late Cretaceous period

Saurolophus is a genus of large hadrosaurid dinosaur from the Late Cretaceous period of Asia and North America, that lived in what is now the Horseshoe Canyon and Nemegt formations about 70 million to 66 million years ago. It is one of the few genera of dinosaurs known from multiple continents. The type species, S. osborni, was described by Barnum Brown in 1912 from Canadian fossils. A second valid species, S. angustirostris, is represented by numerous specimens from Mongolia, and was described by Anatoly Konstantinovich Rozhdestvensky.

Thescelosaurus is an extinct genus of neornithischian dinosaur that lived during the Late Cretaceous period in North America. It was among the last of the non-avian dinosaurs to appear before the entire group went extinct during the Cretaceous–Paleogene extinction event around 66 million years ago. The genus Thescelosaurus is the type genus and also the largest member of the eponymous Thescelosauridae. Adult Thescelosaurus would have measured roughly 3–4 metres (10–13 ft) long and probably weighed several hundred kilograms. It moved on two legs, and its body was counter-balanced by its long tail, which made up half of the body length and was stiffened by rod-like ossified tendons. The animal had a long, low snout that ended in a beak. It had more teeth than related genera, and the teeth were of different types. The hand bore five fingers, and the foot four toes. Thin plates attached to its ribs, the function of which is unknown. It is also unknown to what extent the body was feathered, but at least parts of the legs appear to have been covered in scales.

<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>Montanoceratops</i> Extinct genus of dinosaurs

Montanoceratops is an extinct genus of small ceratopsian dinosaur that lived approximately 70 million years ago during the latter part of the Cretaceous Period in what is now Montana and Alberta. Montanoceratops was a small sized, moderately-built, ground-dwelling, quadrupedal herbivore, that could grow up to an estimated 2.5 m (8.2 ft) in length and 170 kg (370 lb) in body mass.

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

Notohypsilophodon is a genus of ornithopod dinosaur from the Late Cretaceous of Argentina. It was described as the only "hypsilophodont" known from South America, although this assessment is not universally supported, and Gasparinisaura is now believed to have been a basal euornithopod as well.

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

Anabisetia is a genus of ornithopod dinosaur from the Late Cretaceous Period of Patagonia, South America. It was a small bipedal herbivore, around 2 metres long.

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

Talenkauen is a genus of basal iguanodont dinosaur from the Campanian or Maastrichtian age of the Late Cretaceous Cerro Fortaleza Formation, formerly known as the Pari Aike Formation of Patagonian Lake Viedma, in the Austral Basin of Santa Cruz, Argentina. It is based on MPM-10001A, a partial articulated skeleton missing the rear part of the skull, the tail, and the hands. The type and only species is Talenkauen santacrucensis.

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

Laosaurus is a genus of neornithischian dinosaur. The type species, Laosaurus celer, was first described by O.C. Marsh in 1878 from remains from the Oxfordian-Tithonian-age Upper Jurassic Morrison Formation of Wyoming. The validity of this genus is doubtful because it is based on fragmentary fossils. A second species from the Morrison Formation, L. gracilis, and a species from the late Cretaceous Allison Formation of Alberta, Canada, Laosaurus minimus, are also considered dubious.

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

Nanosaurus is an extinct genus of neornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic in North America. Its fossils are known from the Morrison Formation of the south-western United States. The type and only species, Nanosaurus agilis, was described and named by Othniel Charles Marsh in 1877. The taxon has a complicated taxonomic history, largely the work of Marsh and Peter M. Galton, involving the genera Laosaurus, Hallopus, Drinker, Othnielia, and Othnielosaurus, the latter three now being considered to be synonyms of Nanosaurus. It had historically been classified as a hypsilophodont or fabrosaur, types of generalized small bipedal herbivore, but more recent research has abandoned these groupings as paraphyletic and Nanosaurus is today considered a basal member of Neornithischia.

<span class="mw-page-title-main">Horseshoe Canyon Formation</span> Geological formation in Canada

The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.

<i>Edmontosaurus regalis</i> Extinct species of dinosaur

Edmontosaurus regalis is a species of comb-crested hadrosaurid dinosaur. Fossils of E. regalis have been found in rocks of western North America that date from the late Campanian age of the Cretaceous Period 73 million years ago, but it may have possibly lived into the early Maastrichtian.

<span class="mw-page-title-main">Thescelosauridae</span> Extinct family of dinosaurs

Thescelosauridae is a clade of neornithischians from the Cretaceous of East Asia and North America. The group was originally used as a name by Charles M. Sternberg in 1937, but was not formally defined until 2013, where it was used by Brown and colleagues as the group uniting Thescelosaurus and Orodromeus, based on their phylogenetic results. During a phylogenetic revision of neornithischians by Clint Boyd in 2015, the authorship of Thescelosauridae was given to Brown and colleagues, which meant that the similar name Parksosauridae, informally defined in 2002 by Buchholz, would have had priority over Thescelosauridae. The two clades had slightly different definitions, with Parksosauridae referring to all animals closer to Parksosaurus than Hypsilophodon, but they contained the same taxa so Boyd used Parksosauridae under the assumption it had priority. However, in formalizing the clade following the regulations of the PhyloCode, Madzia, Boyd, and colleagues identified in 2021 that Sternberg was the proper authority for Thescelosauridae, giving it priority over Parksosauridae. As well, they gave Thescelosauridae the definition of the largest clade containing Thescelosaurus neglectus but not Iguanodon bernissartensis, as long as Hypsilophodon foxii was not in the group, modifying previous definitions for Thescelosauridae in order to maintain its modern use, so that the clade was not applied if Thescelosaurus fell within Hypsilophodontidae, a family that has not been recently used but may be revived if the systematic position of Hypsilophodon was solidified at some point in the future. Madzia et al. identified the analysis of Madzia et al. in 2018 as the reference analysis for the name Thescelosauridae, an analysis based on a revised version of the 2015 Boyd analysis.

<span class="mw-page-title-main">Elasmaria</span> Extinct clade of dinosaurs

Elasmaria is a clade of ornithopods known from Cretaceous deposits in South America, Antarctica, and Australia that contains many bipedal ornithopods that were previously considered "hypsilophodonts".

References

  1. 1 2 3 Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p. 277
  2. 1 2 3 4 Parks, William A (1926). "Thescelosaurus warreni, a new species of orthopodous dinosaur from the Edmonton Formation of Alberta". University of Toronto Studies (Geological Series). 21: 1–42.
  3. Butler, Richard J.; Galton, Peter M. (2008). "The 'dermal armour' of the ornithopod dinosaur Hypsilophodon from the Wealden (Early Cretaceous: Barremian) of the Isle of Wight: a reappraisal". Cretaceous Research. 29 (4): 636–642. Bibcode:2008CrRes..29..636B. doi:10.1016/j.cretres.2008.02.002.
  4. 1 2 Galton, Peter M. (1973). "Redescription of the skull and mandible of Parksosaurus from the Late Cretaceous with comments on the family Hypsilophodontidae (Ornithischia)". Life Sciences Contribution, Royal Ontario Museum. 89: 1–21.
  5. Gilmore, Charles W. (1915). "Osteology of Thescelosaurus, an orthopodus dinosaur from the Lance Formation of Wyoming" (PDF). Proceedings of the U.S. National Museum. 49 (2127): 591–616. doi:10.5479/si.00963801.49-2127.591.
  6. Sternberg, Charles M. (1937). "Classification of Thescelosaurus, with a description of a new species". Geological Society of America Proceedings for 1936: 365.
  7. Sternberg, Charles M. (1940). "Thescelosaurus edmontonensis, n. sp., and classification of the Hypsilophodontidae". Journal of Paleontology. 14 (5): 481–494.
  8. Olshevsky, G. (1991). A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings No. 2. San Diego: Publications Requiring Research. p. 268.
  9. 1 2 3 4 5 Norman, David B.; Sues, Hans-Dieter; Witmer, Larry M.; Coria, Rodolfo A. (2004). "Basal Ornithopoda". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 393–412. ISBN   0-520-24209-2.
  10. Sues, Hans-Dieter; Norman, David B. (1990). "Hypsilophodontidae, Tenontosaurus, Dryosauridae". In Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (1st ed.). Berkeley: University of California Press. pp. 498–509. ISBN   0-520-06727-4.
  11. 1 2 Butler, Richard J.; Upchurch, Paul; Norman, David B. (2008). "The phylogeny of the ornithischian dinosaurs". Journal of Systematic Palaeontology. 6 (1): 1–40. Bibcode:2008JSPal...6....1B. doi:10.1017/S1477201907002271. S2CID   86728076.
  12. Rozadilla, Sebastián (2016). "A new ornithopod (Dinosauria, Ornithischia) from the Upper Cretaceous of Antarctica and its palaeobiogeographical implications". Cretaceous Research. 57: 311–324. Bibcode:2016CrRes..57..311R. doi:10.1016/j.cretres.2015.09.009. hdl: 11336/46572 .
  13. Herne, Matthew C.; Nair, Jay P.; Evans, Alistair R.; Tait, Alan M. (2019). "New small-bodied ornithopods (Dinosauria, Neornithischia) from the Early Cretaceous Wonthaggi Formation (Strzelecki Group) of the Australian-Antarctic rift system, with revision of Qantassaurus intrepidus Rich and Vickers-Rich, 1999". Journal of Paleontology. 93 (3): 543–584. Bibcode:2019JPal...93..543H. doi: 10.1017/jpa.2018.95 .
  14. 1 2 Larson, D. W.; Brinkman, D. B.; Bell, P. R. (2010). "Faunal assemblages from the upper Horseshoe Canyon Formation, an early Maastrichtian cool-climate assemblage from Alberta, with special reference to the Albertosaurus sarcophagus bonebed This article is one of a series of papers published in this Special Issue on the theme Albertosaurus". Canadian Journal of Earth Sciences. 47 (9): 1159–1181. doi:10.1139/e10-005.
  15. Arbour, Victoria (2010). "A Cretaceous armoury: Multiple ankylosaurid taxa in the Late Cretaceous of Alberta, Canada and Montana, USA". Journal of Vertebrate Paleontology. 30 (Supplement 2): 55A. doi:10.1080/02724634.2010.10411819. S2CID   220429286.
  16. 1 2 Dodson, Peter (1996). The Horned Dinosaurs: A Natural History . Princeton: Princeton University Press. pp.  14–15. ISBN   0-691-05900-4.