29-501: 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 ,
58-484: A hypsilophodont since its description. Recent reviews have dealt with it with little comment, although David B. Norman and colleagues (2004), in the framework of a paraphyletic Hypsilophodontidae , found it to be the sister taxon to Thescelosaurus , and Richard Butler and colleagues (2008) found that it may be close to the South American genus Gasparinisaura . However, basal ornithopod phylogeny
87-559: 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 . The genus attracted little attention until Peter Galton began his revision of hypsilophodonts in the 1970s. Parksosaurus received a redescription in 1973, wherein it
116-435: A position previously held by Stormbergia dangershoeki (a taxon considered by the authors to be an adult form of Lesothosaurus and therefore a junior subjective synonym). However, Baron et al. go on to state that this result is only poorly supported and that future studies will be needed in order to better resolve the base of the ornithischian tree. Pyrodontia was named by André O. Fonseca and colleagues in 2024 to unite
145-669: A species within the genus. It appears to be closely related to Parksosaurus , although this relationship has been called into question. The dissolution of Hypsilophodontidae was followed by the recognition of the distinct family Parksosauridae by Buchholz in 2002, defined as the most inclusive clade containing Parksosaurus warreni , but not Hypsilophodon foxii , Dryosaurus altus , or Iguanodon bernissartensis . Boyd et al. (2009) and Brown et al. (2011) found North American "hypsilophodonts" of Cretaceous age to sort into two related clusters, one ( Orodrominae ) consisting of Orodromeus , Oryctodromeus , and Zephyrosaurus , and
174-473: A thicker layer of asymmetrical enamel on the inside of their lower teeth. The teeth wore unevenly with chewing and developed sharp ridges that allowed neornithischians to break down tougher plant food than other dinosaurs. Neornithischians include a variety of basal forms historically known as " hypsilophodonts ", including the Thescelosauridae . As these taxa do not all form a monophyletic clade,
203-658: A true clade. Thescelosaurus has been regarded as both very basal and very derived among the hypsilophodonts. One issue that has potentially interfered with classifying Thescelosaurus is that not all of the remains assigned to T. neglectus necessarily belong to it. Clint Boyd and colleagues found that while the clade Thescelosaurus included the genus Bugenasaura and the species that had been assigned to that genus, there were at least two and possibly three species within Thescelosaurus , and several specimens previously assigned to T. neglectus could not yet be assigned to
232-598: 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. Explicit estimates of
261-504: Is known for Oryctodromeus which was found in burrows, based upon the packing of their bones in situations where they typically would have been scattered. [REDACTED] [REDACTED] [REDACTED] Neornithischia Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia . It is the sister group of the Thyreophora within the clade Genasauria . Neornithischians are united by having
290-781: 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. A 2015 study placed it as an intermediate member of Iguanodontia more derived than Elasmaria . Cladogram based in the phylogenetic analysis of Rozadilla et al ., 2015: Hypsilophodon Thescelosaurus Gasparinisaura Morrosaurus Trinisaura Macrogryphosaurus Notohypsilophodon Talenkauen Anabisetia Parksosaurus Kangnasaurus Rhabdodontidae Tenontosaurus Dryomorpha The cladogram below results from analysis by Herne et al. , 2019, which placed Parksosaurus as
319-412: The shin was shorter than the thigh in T. neglectus , the opposite of T. warreni . 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). The proportional differences probably would have made it lighter, though, as less weight
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#1732790653775348-503: 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
377-424: 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
406-474: 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. 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). In 1940, he presented
435-399: 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. 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
464-405: 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
493-521: The members of Thescelosauridae and Cerapoda . It's name translates to "fire teeth" in reference to the rapid diversification of this clade during the Middle Jurassic. The clade is formally defined in the PhyloCode as "the smallest clade containing Ceratops montanus , Iguanodon bernissartensis , Pachycephalosaurus wyomingensis , and Thescelosaurus neglectus . Cerapoda is
522-650: The most diverse clade within Neornithischia. The name "Cerapoda" is a portmanteaux of "Ceratopsia" and "Ornithopoda". As the name suggests, the clade is divided into two groups: Ornithopoda ("bird-foot") and Marginocephalia ("fringed heads"). The latter group includes the Pachycephalosauria ("thick-headed lizards") and Ceratopsia ("horned faces"). The following taxonomy follows Richard J. Butler , Paul Upchurch and David B. Norman , 2008 (and Butler et al. , 2011) unless otherwise noted. Cerapoda
551-540: The other ( Thescelosaurinae ) consisting of Parksosaurus and Thescelosaurus . Brown et al. (2013) recovered similar results, with the addition of the new genus Albertadromeus to the Orodromeus clade (called Orodrominae ) and several long-snouted Asian forms (previously described under Jeholosauridae ) to the Thescelosaurus clade (called Thescelosaurinae ). Orodromines may have burrowed , as
580-1233: The previous analyses of Boyd and Herne and colleagues, with thescelosaurids outside Ornithopoda and heterodontosaurids outside Neornithischia, while other aspects of relationships, like the placement of Changmiania or the grouping within Ornithopoda were novel results. Their equal-weights results are below. Asilisaurus Lutungutali Silesaurus Technosaurus Kwanasaurus Eucoelophysis Pisanosaurus Heterodontosauridae Eocursor Laquintasaura Lesothosaurus Emausaurus Scutellosaurus Scelidosaurus Yuxisaurus Jakapil Eurypoda Agilisaurus Hexinlusaurus Sanxiasaurus Minimocursor Yandusaurus Nanosaurus Zephyrosaurus Orodromeus Oryctodromeus Albertadromeus Koreanosaurus Yueosaurus Changmiania Haya griva RTMP 2008.045.0002 Changchunsaurus Jeholosaurus Parksosaurus Thescelosaurus Kulindadromeus Pachycephalosauria Ceratopsia Hypsilophodontidae Rhabdodontomorpha Parksosaurus Parksosaurus (meaning " William Parks's lizard ")
609-629: The reference analysis for the name Thescelosauridae, an analysis based on a revised version of the 2015 Boyd analysis. Lesothosaurus Agilisaurus Hexinlusaurus Yandusaurus Kulindadromeus Jeholosaurus Yueosaurus Nanosaurus Hypsilophodon Cerapoda Notohypsilophodon Parksosaurus Thescelosaurus assiniboiensis Thescelosaurus garbanii Thescelosaurus neglectus Haya Changchunsaurus Koreanosaurus Oryctodromeus Albertadromeus Kaiparowits orodromine Orodromeus Zephyrosaurus Although Hypsilophodontidae
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#1732790653775638-601: The term 'small-bodied early diverging ornithischian' (SBEDO) has been used to refer to these as a collective group. In addition, there are derived forms classified in the groups Marginocephalia and Ornithopoda . The former includes clades Pachycephalosauria and Ceratopsia , while the latter typically includes Hypsilophodon and the more derived Iguanodontia . Neornithischia was first named by Cooper in 1985 and defined as "all genasaurians more closely related to Parasaurolophus walkeri than to Ankylosaurus magniventris or Stegosaurus stenops ". In 2021, Neornithischia
667-461: Was concentrated near the thigh. Like Thescelosaurus , it had thin partly ossified cartilaginous (intercostal) plates along the ribs. The shoulder girdle was robust. 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. Paleontologist William Parks described skeleton ROM 804 in 1926 as Thescelosaurus warreni , which had in 1922 been discovered in what
696-428: Was considered to be related to a Hypsilophodon \ Laosaurus \ L. minimus lineage. After this, it once again returned to obscurity. George Olshevsky emended the species name to P. warrenae in 1992, 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. Parksosaurus has been considered to be
725-736: Was first named by Sereno in 1986 and defined by him as " Parasaurolophus walkeri Parks, 1922, Triceratops horridus Marsh, 1889, their most recent common ancestor and all descendants". A similar clade Neornithopoda was tentatively proposed by David B. Norman to unite ceratopsians with advanced ornithopods in a 1984 paper. In 2021, Cerapoda was given a formal definition under the PhyloCode : "The smallest clade containing Iguanodon bernissartensis Boulenger in Beneden, 1881, Pachycephalosaurus wyomingensis (Gilmore, 1931), and Triceratops horridus Marsh, 1889." The phylogenetic study of Fonseca and colleagues in 2024 recovered results similar to
754-485: Was given a formal definition under the PhyloCode : "The largest clade containing Iguanodon bernissartensis and Triceratops horridus but not Ankylosaurus magniventris and Stegosaurus stenops ." A 2017 study by Matthew G. Baron, David B. Norman , and Paul M. Barrett recovered the Early Jurassic taxon Lesothosaurus diagnosticus from Southern Africa as the most basal known member of Neornithischia –
783-422: Was interpreted as a natural group in the early 1990s, this hypothesis has fallen out of favor and Hypsilophodontidae has been found to be an unnatural family composed of a variety of animals more or less closely related to Iguanodontia ( paraphyletic ), with various small clades of closely related taxa. "Hypsilophodontidae" and "hypsilophodont" are better understood as informal terms for an evolutionary grade , not
812-488: 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
841-547: 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 ), the left arm except
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