Hypsilophodont

From Wikipedia, the free encyclopedia

Hypsilophodonts

Extinct (fossil)

Scientific classification

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Ornithischia
Suborder:	Cerapoda
Infraorder:	Ornithopoda
Family:	Hypsilophodontidae Dollo, 1882

Genera

See text.

Hypsilophodonts (named after the Hypsilophus genus of iguana lizard, literally meanining "high-crested tooth") were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the order of 1-2 meters long (3.3-6.6 feet). They are known from Asia, Australia, Europe, North America, and South America, from rocks of Middle Jurassic to late Cretaceous age. The group traditionally has included almost all bipedal bird-hipped dinosaurs other than iguanodonts, and some early phylogenetic analyses analyses found it to be a natural group,^[1]^[2] but recent studies have found that the group is mostly paraphyletic and the taxa within represent a series leading up to Iguanodontia.^[3]^[4]^[5]^[6]^[7]^[8] Thus, the only certain member at this time is Hypsilophodon. This area of the dinosaur family tree is complicated by a lack of research.

[edit] Taxonomy

(after Norman et al. (2004),^[7] the most recent review, with updates from Butler (2005)^[9] and Barrett et al. (2005)^[10])

Both subfamilies are informal names that have been applied by others to specific subgroups.

HYPSILOPHODONTIDAE *
- Othnielosaurus
- Orodromeus
- Subfamily Hypsilophodontinae
  - Hypsilophodon
  - Zephyrosaurus
- Gasparinisaura
- Subfamily Thescelosaurinae
  - Bugenasaura
  - Parksosaurus
  - Thescelosaurus

The following genera were regarded as valid, but weren't classified:^[7]

Atlascopcosaurus
Drinker
"Gongbusaurus" wucaiwanensis (= "Eugongbusaurus")
Fulgurotherium
Leaellynasaura
Notohypsilophodon
Qantassaurus
Yandusaurus
"Proctor Lake hypsilophodont"

Several other genera belong here somewhere, but are very poorly known or outright dubious:^[7]

Laosaurus
Nanosaurus
Othnielia (without "Laosaurus" consors)
Phyllodon

Varricchio et al. (2007) found that their new genus, Oryctodromeus, forms a clade with two other genera from Montana, Orodromeus and Zephyrosaurus.^[8]

[edit] Paleobiology

Hypsilophodonts were small (often 1-2 m [3.28 to 6.56 ft] long), bipedal, cursorial herbivores.^[7] The typical informal comparison has been to gazelles. However, there is evidence that at least some of them made burrows as places to rear their young.^[8]

[edit] References

^ Sues, Hans-Dieter; and Norman, David B. (1990). "Hypsilophodontidae, Tenontosaurus, Dryosauridae", in Weishampel, David B.; Osmólska, Halszka; and Dodson, Peter (eds.): The Dinosauria, 1st, Berkeley: University of California Press, 498-509. ISBN 0-520-06727-4.
^ Weishamepel, David B.; and Heinrich, Ronald E. (1992). "Systematics of Hypsilophodontidae and Basal Iguanodontia (Dinosauria: Ornithopoda)". Historical Biology 6: 159-184. Retrieved on 2007-03-10.
^ Scheetz, Rodney D. (1998). "Phylogeny of basal ornithopod dinosaurs and the dissolution of the Hypsilophodontidae". Journal of Vertebrate Paleontology 18 (3, Suppl.): p. 75A.
^ Winkler, Dale A.; Murry, Phillip A.; and Jacobs, Louis L. (1998). "The new ornithopod dinosaur from Proctor Lake, Texas, and the deconstruction of the family Hypsilophodontidae". Journal of Vertebrate Paleontology 18 (3, Suppl.): p. 87A.
^ Buchholz, Peter W. (2002). "Phylogeny and biogeography of basal Ornithischia", The Mesozoic in Wyoming, Tate 2002. Casper, Wyoming: The Geological Museum, Casper College, 18-34.
^ Weishampel, David B.; Jianu, Coralia-Maria; Csiki, Z.; and 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.
^ ^a ^b ^c ^d ^e Norman, David B.; Sues, Hans-Dieter; Witmer, Larry M.; and Coria, Rodolfo A. (2004). "Basal Ornithopoda", in Weishampel, David B.; Osmólska, Halszka; and Dodson, Peter (eds.): The Dinosauria, 2nd, Berkeley: University of California Press, 393-412. ISBN 0-520-24209-2.
^ ^a ^b ^c Varricchio, David J. (2007). "First trace and body fossil evidence of a burrowing, denning dinosaur". Proceedings of the Royal Society B: Biological Sciences online preprint. DOI:10.1098/rspb.2006.0443.
^ Butler, Richard J. (2005). "The "fabrosaurid" ornithischian dinosaurs of the Upper Elliot Formation (Lower Jurassic) of South Africa and Lesotho". Zoological Journal of the Linnean Society 145 (2): 175-218.
^ Barrett, Paul M.; Butler, Richard J.; and Knoll, Fabian (2005). "Small-bodied ornithischian dinosaurs from the Middle Jurassic of Sichuan, China". Journal of Vertebrate Paleontology 25 (4): 823-834.