Rauisuchia
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2008-07-17T01:57:28Z
201.81.88.34
{{nofootnotes|date=June 2008'''Bold text'''}}
{{Taxobox
| name = Rauisuchians
| fossil_range = [[Triassic]]
| image = Prestosuchus.jpg
| image_caption = ''Prestosuchus''
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Reptile|Sauropsida]]
| subclassis = [[Diapsid]]a
| infraclassis = [[Archosauromorpha]]
| unranked_ordo = [[Crurotarsi]]
| ordo = †'''Rauisuchia'''[[Paraphyletic|*]]
| ordo_authority = [[Friedrich von Huene|von Huene]], [[1942]]
| subdivision_ranks = Families
| subdivision =
* †[[Prestosuchidae]]
* †[[Rauisuchidae]]
* †[[Poposauridae]]
* †[[Ctenosauriscidae]]
}}
'''Rauisuchia''' are a poorly known assemblage of predatory and mostly large (often 4 to 6 meters) [[Triassic]] [[archosaur]]s. Originally it was believed that they were related to [[Erythrosuchidae|erythrosuchids]] (Sill, 1974), but it is now known that they are [[Crurotarsi|crurotarsans]] (Benton 2004). Three families are generally recognised: [[Prestosuchidae]], [[Rauisuchidae]], and [[Poposauridae]], as well as a number of forms (e.g. those from the [[Olenekian]] of Russia) that are too primitive and/or poorly known to fit in any of these groups. There has been considerable suggestion that the group as currently defined is [[paraphyletic]], representing a number of related lineages independently evolving and filling the same ecological niche of medium to top terrestrial predator. For example, Parrish (1993) and Juul (1994) found poposaurid rauisuchians to be more closely related to [[Crocodilia]] than to prestosuchids. In a more recent study, Nesbitt (2003) presented a different phylogeny with a [[monophyletic]] Rauisuchia. The group may even be something of a "[[wastebasket taxon]]". Determining exact phylogenetic relationships is difficult because of the scrappy nature of a lot of the material. However, recent discoveries and studies such as those of ''[[Batrachotomus]]'' (Benton & Walker 2002; Gower, 2002) are shedding light on the evolutionary relationships of this poorly known but fascinating group.
[[José Bonaparte]], and following him [[Michael Benton]] argue (Bonaparte 1981, Benton, 1984) that rauisuchians such as ''[[Saurosuchus]]'' developed an erect stance independently of and differently to [[dinosaur]]s, by means of having the [[femur]] vertical and angling the [[acetabulum]] ventrally, rather than having an angled neck or curve in the femur. They refer to this as the pillar-erect posture.
The erect gait indicates that these animals were clearly active, agile predators, with locomotor superiority over the [[Kannemeyeridae|kannemeyerid dicynodonts]] and abundant [[rhynchosaur]]s on which they fed. They were successful animals, the largest with skulls a meter or more in length, and continued right until the end of the Triassic, when, along with many other large archosaurs, they were killed off by the [[Triassic-Jurassic extinction event|end Triassic extinction event]]. With their demise, [[theropod|theropod dinosaur]]s were able to emerge as the sole large terrestrial predators. Meat-eating dinosaur footprints suddenly increase in size at the start of the [[Jurassic]], when rauisuchians are absent (Olsen ''et al.'' 2002).
Well-known Rauisuchians include ''[[Ticinosuchus]]'' of the Middle Triassic of Europe (Switzerland and Northern Italy), ''[[Saurosuchus]]'' of the late Triassic (Late [[Carnian]]) of South America (Argentina), and ''[[Postosuchus]]'' of the late Triassic (Late [[Carnian]] to Early [[Norian]]) of North America (SW USA). One rauisuchian, ''[[Teratosaurus]]'', was for a long time even considered an early [[theropod|theropod dinosaur]].
==External links==
* [http://www.dinosauria.com/dml/names/raui.htm Translation and Pronunciation Guide]
*[http://www.palaeos.com/Vertebrates/Units/270Archosauromorpha/270.600.html#Rauisuchia Palaeos]
==References==
* {{cite journal|last=Benton|first=M. J.|authorlink=Michael J. Benton|year=1984|title=Rauisuchians and the success of dinosaurs|url=|journal=Nature|issn=|volume=310|issue=|pages=101|doi=10.1038/310101a0}}
* {{cite book|last=Benton|first=M. J.|authorlink=Michael J. Benton|title=[[Vertebrate Paleontology (Benton)|Vertebrate Paleontology]]|edition=3rd ed.|publisher=[[Blackwell's|Blackwell Science Ltd]]|location=Oxford|year=2004|isbn=0632056371|series=}}
* {{cite journal|last=Benton|first=M. J.|authorlink=Michael J. Benton|coauthors=Walker, A. D.|year=2002|title=Erpetosuchus, a crocodile-like basal archosaur from the Late Triassic of Elgin, Scotland|url=|journal=Zool. J. Linn. Soc|issn=0024-4082|volume=136|issue=1|pages=25–47|doi=10.1046/j.1096-3642.2002.00024.x}}
* {{cite journal|last=Bonaparte|first=J. F.|coauthors=|year=1984|title=Locomotion in rauisuchid thecodonts|url=|journal=Journal of Vertebrate Paleontology |issn=|volume=3|issue=4|pages=210–218|doi=}}
* {{cite book|last=Carroll|first=R. L.|coauthors=|authorlink=Robert L. Carroll|title=[[Vertebrate Paleontology and Evolution]]|edition=|publisher=WH Freeman & Co|location=New York|year=1988|isbn=0716718227|series=}}
* {{cite journal|last=Gower|first=D. J.|coauthors=|year=2002|title=Braincase evolution in suchian archosaurs (Reptilia: Diapsida): evidence from the rauisuchian Batrachotomus kupferzellensis|url=|journal=Zool. J. Linn. Soc|issn=|volume=136|issue=1|pages=49–76|doi=10.1046/j.1096-3642.2002.00025.x}}
* {{cite journal|last=Juul|first=L.|coauthors=|year=1994|title=The phylogeny of basal archosaurs|url=|journal=Palaeontologia Africana|issn=|volume=31|issue=|pages=1–38|doi=}}
* {{cite journal|last=Nesbitt|first=S. J.|coauthors=|year=2003|title=Arizonasaurus'' and its implications for archosaur divergence|url=http://www.journals.royalsoc.ac.uk/content/2vetg3w8xha9e992|journal=Proceedings of the Royal Society B|issn=0962-8452|volume=270|issue=Suppl. 2|pages=S234–S237
|doi=10.1098/rsbl.2003.0066}}
* {{cite journal|last=Olsen|first=P. E.|coauthors=Kent, D. V.; Sues, H.-D.; Koeberl, C.; Huber, H.; Montanari, E. C.; Rainforth, A.; Fowell, S. J.; Szajna, M. J.; and Hartline, B. W.|year=2002|title=Ascent of Dinosaurs Linked to an [[Iridium anomaly|Iridium Anomaly]] at the Triassic-Jurassic Boundary|url=|journal=Science|issn=|volume=296|issue=|pages=1305–1307|doi=10.1126/science.1065522|pmid=12016313}}
* {{cite journal|last=Parrish|first=J. M.|coauthors=|year=1993|title=Phylogeny of the Crocodylotarsi, with reference to archosaurian and crurotarsan monophyly|url=|journal=Journal of Vertebrate Paleontology|issn=|volume=13|issue=|pages=287–308|doi=}}
* {{cite journal|last=Sill|first=W. D.|coauthors=|year=1974|title=The anatomy of Saurosuchus galilei and the relationships of the rauisuchid thecodonts|url=|journal=Bulletin of the Museum of Comparative Zoology|issn=0027-4100|volume=146|issue=|pages=317–362|doi=}}
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{{Archosauromorpha}}
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