Parksosauridae

Parksosauridae is a clade or family of small ornithischians which have previously been generally allied to hypsilophodontids. Parksosauridae is often considered a synonym of Thescelosauridae, but the two groups cannot be synonyms because Parksosauridae is defined as a stem, while Thescelosauridae is defined as a node.[2]

Parksosauridae
Temporal range: Early CretaceousLate Cretaceous, 130–66 Ma
Burpee - Thescelosaurus
Mounted specimen of Thescelosaurus, Burpee Museum of Natural History
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Clade: Neornithischia
Family: Parksosauridae
Bucholtz, 2002
Subfamilies[1]

Classification

Parksosauridae/Thescelosauridae
Orodrominae

TMP 2008.045.0002

Oryctodromeus

Albertadromeus

Orodromeus

Zephyrosaurus

Thescelosaurinae

Parksosaurus

Changchunsaurus

Haya

Jeholosaurus

Thescelosaurus

This cladogram is from Brown et al., (2013).[1]

Although Hypsilophodontidae was interpreted as a natural group in the early 1990s,[3][4] 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 (paraphyly), with various small clades of closely related taxa.[5][6][7][8][9] "Hypsilophodontidae" and "hypsilophodont" are better understood as informal terms for an evolutionary grade, not a true clade. Thescelosaurus has been regarded as both very basal[4] and very derived[7] 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.[10] 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 a species within the genus.[5] It appears to be closely related to Parksosaurus.[5][7][8][11][12]

Thescelosaurus skeleton
Head and arms of Thescelosaurus, Rocky Mountain Dinosaur Resource Center

The dissolution of Hypsilophodontidae has been followed by the recognition of the distinct family Parksosauridae. This area of the dinosaur family tree has historically been complicated by a lack of research, but papers by Clint Boyd and colleagues[5] and Caleb Brown and colleagues[11][12] have specifically addressed these dinosaurs. Boyd et al. (2009) and Brown et al. (2011) found North American "hypsilophodonts" of Cretaceous age to sort into two related clusters, one consisting of Orodromeus, Oryctodromeus, and Zephyrosaurus, and the other consisting of Parksosaurus and Thescelosaurus.[5][11] Brown et al. (2013) recovered similar results, with the addition of the new genus Albertadromeus to the Orodromeus clade and several long-snouted Asian forms (previously described under Jeholosauridae)[6] to the Thescelosaurus clade. They also formally defined Parksosauridae (Thescelosaurus neglectus, Orodromeus makelai, their most recent common ancestor, and all descendants) and the smaller clades Orodrominae and Thescelosaurinae.[12]

A 2015 analysis by Clint Boyd recovered Parksosaurids outside Ornithopoda, as the sister taxon to Cerapoda.[2]

References

  1. ^ a b Brown, C. M.; Evans, D. C.; Ryan, M. J.; Russell, A. P. (2013). "New data on the diversity and abundance of small-bodied ornithopods (Dinosauria, Ornithischia) from the Belly River Group (Campanian) of Alberta". Journal of Vertebrate Paleontology. 33 (3): 495–520. doi:10.1080/02724634.2013.746229.
  2. ^ a b Boyd, Clint A. (2015). "The systematic relationships and biogeographic history of ornithischian dinosaurs". PeerJ. 3 (e1523): e1523. doi:10.7717/peerj.1523. PMC 4690359. PMID 26713260. Retrieved 5 January 2016.
  3. ^ 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 978-0-520-06727-1.
  4. ^ a b Weishampel, David B.; Heinrich, Ronald E. (1992). "Systematics of Hypsilophodontidae and Basal Iguanodontia (Dinosauria: Ornithopoda)" (PDF). Historical Biology. 6 (3): 159–184. doi:10.1080/10292389209380426. Retrieved 2007-03-10.
  5. ^ a b c d e Boyd, Clint A.; Brown, Caleb M.; Scheetz, Rodney D.; Clarke, Julia A. (2009). "Taxonomic revision of the basal neornithischian taxa Thescelosaurus and Bugenasaura". Journal of Vertebrate Paleontology. 29 (3): 758–770. doi:10.1671/039.029.0328.
  6. ^ a b Han, Feng-Lu; Paul M. Barrett; Richard J. Butler; Xing Xu (2012). "Postcranial anatomy of Jeholosaurus shangyuanensis (Dinosauria, Ornithischia) from the Lower Cretaceous Yixian Formation of China". Journal of Vertebrate Paleontology. 32 (6): 1370–1395. doi:10.1080/02724634.2012.694385.
  7. ^ a b c 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 978-0-520-24209-8.
  8. ^ a b Weishampel, David B.; Jianu, Coralia-Maria; Csiki, Z.; Norman, David B. (2003). "Osteology and phylogeny of Zalmoxes (n.g.), an unusual euornithopod dinosaur from the latest Cretaceous of Romania". Journal of Systematic Palaeontology. 1 (2): 1–56. doi:10.1017/S1477201903001032.
  9. ^ Varricchio, David J.; Martin, Anthony J.; Katsura, Yoshihiro (2007). "First trace and body fossil evidence of a burrowing, denning dinosaur" (PDF). Proceedings of the Royal Society B: Biological Sciences. 274 (1616): 1361–1368. doi:10.1098/rspb.2006.0443. PMC 2176205. PMID 17374596. Retrieved 2007-03-22.
  10. ^ Butler, Richard J.; Upchurch, Paul; Norman, David B. (2008). "The phylogeny of the ornithischian dinosaurs". Journal of Systematic Palaeontology. 6 (1): 1–40. doi:10.1017/S1477201907002271.
  11. ^ a b c Brown; Caleb M.; Boyd, Clint A.; and Russell, Anthony P. (2011). "A new basal ornithopod dinosaur (Frenchman Formation, Saskatchewan, Canada), and implications for late Maastrichtian ornithischian diversity in North America". Zoological Journal of the Linnean Society. 163 (4): 1157–1198. doi:10.1111/j.1096-3642.2011.00735.x.CS1 maint: Uses authors parameter (link)
  12. ^ a b c Brown, Caleb Marshall; Evans, David C.; Ryan, Michael J.; Russell, Anthony P. (2013). "New data on the diversity and abundance of small-bodied ornithopods (Dinosauria, Ornithischia) from the Belly River Group (Campanian) of Alberta". Journal of Vertebrate Paleontology. 33 (3): 495–520. doi:10.1080/02724634.2013.746229.
Albertadromeus

Albertadromeus is an extinct genus of orodromine parksosaurid dinosaur known from the upper part of the Late Cretaceous Oldman Formation (middle Campanian stage) of Alberta, Canada. It contains a single species, Albertadromeus syntarsus.

Averostra

Averostra, or "bird snouts", is a clade that includes most theropod dinosaurs that have a promaxillary fenestra (fenestra promaxillaris), an extra opening in the front outer side of the maxilla, the bone that makes up the upper jaw. Two groups of averostrans, the Ceratosauria and the Orionides, survived into the Cretaceous period. When the Cretaceous–Paleogene extinction event occurred, ceratosaurians and two groups of orionideans within the clade Coelurosauria, the Tyrannosauroidea and Maniraptoriformes, were still extant. Only one subgroup of maniraptoriformes, Aves, survived the extinction event and persisted to the present day.

Avetheropoda

Avetheropoda, or "bird theropods", is a clade that includes carnosaurians and coelurosaurs to the exclusion of other dinosaurs.

Cerapoda

Cerapoda ("ceratopsians and ornithopods") is a clade of the dinosaur order Ornithischia.

Changchunsaurus

Changchunsaurus (meaning "Changchun lizard") is an extinct genus of small herbivorous parksosaurid dinosaur from Early Cretaceous deposits of Gongzhuling, Jilin, China. It is the first named dinosaur genus from Jilin.

Dinosauriformes

Dinosauriformes is a clade of archosaurian reptiles that include the dinosaurs and their most immediate relatives. All dinosauriformes are distinguished by several features, such as shortened forelimbs and a partially to fully perforated acetabulum, the hole in the hip socket traditionally used to define dinosaurs. The oldest known member is Asilisaurus, dating to about 245 million years ago in the Anisian age of the middle Triassic period.

Haya griva

Haya is an extinct genus of basal neornithischian dinosaur known from Mongolia.

Jeholosauridae

Jeholosaurids were herbivorous neornithischian dinosaurs from the Cretaceous Period (Aptian - Santonian, with a possible Campanian record) of Asia. The family was first proposed by Han et al. in 2012. The jeholosaurids were defined as those ornithischians more closely related to Jeholosaurus shangyuanensis than to Hypsilophodon foxii, Iguanodon bernissartensis, Protoceratops andrewsi, Pachycephalosaurus wyomingensis, or Thescelosaurus neglectus. The Jeholosauridae includes the type genus Jeholosaurus and Yueosaurus.

Jingshanosaurus

Jingshanosaurus (meaning "Jingshan lizard") is a genus of sauropodomorph dinosaurs from the early Jurassic period.

Koreanosaurus

Koreanosaurus (meaning "Korean lizard") is a genus of ornithopod dinosaur. One species has been described, Koreanosaurus boseongensis.

Neornithischia

Neornithischia ("new ornithischians") is a clade of the dinosaur order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria. Neornithischians are united by having 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 Parksosauridae; 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.

Neotheropoda

Neotheropoda (meaning "new theropods") is a clade that includes coelophysoids and more advanced theropod dinosaurs, and the only group of theropods who survived the Triassic–Jurassic extinction event. Yet all of the neotheropods became extinct during the early Jurassic period except for Averostra.

Orionides

Orionides is a clade of tetanuran theropod dinosaurs from the Middle Jurassic to the Present. The clade includes most theropod dinosaurs, including birds.

Orodromeus

Orodromeus (meaning "Mountain Runner") is a genus of herbivorous parksosaurid dinosaur from the Late Cretaceous of North America.

Orodrominae

Orodrominae is a subfamily of parksosaurid dinosaurs from the Cretaceous of North America and Asia.

Oryctodromeus

Oryctodromeus (meaning "digging runner") was a genus of small parksosaurid dinosaur. Fossils are known from the middle Cretaceous Blackleaf Formation of southwestern Montana and the Wayan Formation of southeastern Idaho, USA, both of the Cenomanian stage, roughly 95 million years ago. A member of the small, presumably fast-running herbivorous family Parksosauridae, Oryctodromeus is the first dinosaur published that shows evidence of burrowing behavior.

Thescelosaurinae

Thescelosaurinae is a subfamily of ornithischian dinosaurs from the Early Cretaceous of Asia and the Late Cretaceous of North America.

Xixiposaurus

Xixiposaurus is a genus of prosauropod dinosaur which existed in what is now Lower Lufeng Formation, China during the lower Jurassic period. It was first named by Sekiya Toru in 2010 and the type species is Xixiposaurus suni.

Zephyrosaurus

Zephyrosaurus (meaning "westward wind lizard") is a genus of orodromine ornithischian dinosaur. It is based on a partial skull and postcranial fragments discovered in the Aptian-Albian-age Lower Cretaceous Cloverly Formation of Carbon County, Montana, USA. New remains are under description, and tracks from Maryland and Virginia, also in the USA, have been attributed to animals similar to Zephyrosarus.

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