Rauisuchia

For an explanation of very similar terms, see Paracrocodylomorpha.

"Rauisuchians"
Temporal range: Triassic, 249–200 Ma Descendant taxon Crocodylomorpha survives to present; and possible early Jurassic presence.[1]
Mounted skeleton of Prestosuchus chiniquensis (a basal loricatan) in the American Museum of Natural History.
Mounted skeleton of Prestosuchus chiniquensis (a basal loricatan) in the American Museum of Natural History.
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Clade: Archosauria
Clade: Pseudosuchia
Clade: Suchia
Informal group: †Rauisuchia
Huene, 1942
Groups included
Cladistically included but traditionally excluded taxa

"Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs.[2] Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians than to birds and other dinosaurs. First named in the 1940s, Rauisuchia was a name exclusive to Triassic archosaurs which were generally large (often 4 to 6 metres (13 to 20 ft)), carnivorous, and quadrupedal with a pillar-erect hip posture, though exceptions exist for all of these traits. Rauisuchians, as a traditional taxonomic group, were considered distinct from other Triassic archosaur groups such as early dinosaurs, phytosaurs (crocodile-like carnivores), aetosaurs (armored herbivores), and crocodylomorphs (lightly-built crocodilian ancestors).[3]

However, more recent studies on archosaur evolution have upended this idea based on phylogenetic analyses and cladistics, a modern approach to taxonomy based on clades (nested monophyletic groups of common ancestry). Since the early 2010s, archosaur classification schemes have stabilized on a system where Rauisuchia is rendered an evolutionary grade, or even a wastebin taxon. Crocodylomorphs most likely originated from a rauisuchian ancestor based on a myriad of shared traits, and some "rauisuchians" (such as Postosuchus and Rauisuchus) appear to be more closely related to crocodylomorphs than to other "rauisuchians" (such as Prestosuchus and Saurosuchus).[2]

As a result, Rauisuchia in its traditional usage may be considered paraphyletic: a group which is defined by shared ancestry but also excludes a descendant taxon (in this case, crocodylomorphs). To designate it as an informal group in scientific literature, the name is often enclosed in quotation marks.[2] Several monophyletic groups have been erected to classify "rauisuchians" in a cladistic framework. The closest concept is the clade Paracrocodylomorpha, which includes most "rauisuchian" taxa and their crocodylomorph descendants. Paracrocodylomorpha is divided into two branches: Poposauroidea, which includes a variety of strange "rauisuchians" (some of which were bipedal and/or herbivorous) and Loricata, which includes most typical "rauisuchians" and crocodylomorphs.[2]

  1. ^ Cite error: The named reference Nesbitt-etal-2019 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference NSJ11 was invoked but never defined (see the help page).
  3. ^ Nesbitt, Sterling J.; Brusatte, Stephen L.; Desojo, Julia B.; Liparini, Alexandre; De França, Marco A. G.; Weinbaum, Jonathan C.; Gower, David J. (2013). "Rauisuchia". Geological Society, London, Special Publications. 379 (1): 241–274. doi:10.1144/SP379.1. ISSN 0305-8719. S2CID 219193351.