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Archosauria |
The Vertebrates |
Thecodontia Classification |
Archosauria: Thecodontia: Classification
Order (or Paraorder) Thecodontia
Traditional classification
In applying an Evolutionary-Systematic, rather than a cladistic, classification scheme, Linnean taxonomy is employed. Instead of Basal or Stem Group Archosaur(omorphs), reference can be made to Order Thecodontia, a name that appears in text-books on palaeontology and evolution upto the 1980s, but rarely since.
The Thecodontia were traditionally (up to the 1960s) divided into four suborders, the Proterosuchia, Phytosauria, the Aetosauridae, and the "Pseudosuchia" (more or less equivalent to the Crurotarsi, minus the more derived forms). The Proterosuchia included various primitive ancestral types, the phytosaurs were crocodile like forms, the aetosaurs specialized armoured creatures, remarkably like the armoured ornithischian dinosaurs, and the Pseudosuchia were a sort of catch-all or "waste-basket" category for everything that didn't fit in any of the other suborders. This last group was also considered ancestral to dinosaurs, birds, and crocodiles. The Pseudosuchia as an artificial group, having the same "grab-bag" status within the Thecodontia as the Thecodontia have within the Archosauria. Robert Carroll in his book Vertebrate Paleontology and Evolution replaces the Pseudosuchia with the Rauisuchia and the Ornithosuchia, and moves the suborder Sphenosuchia (for small pseudosuchians) to the Crocodilia. The following arrangement relies mainly on Carroll 1988, with a few updates here and there
Infraclass
Archosauromorpha Huene, 1946 (
cont.)
Order
Thecodontia Owen, 1859
Triassic archosaurs with teeth implanted in sockets
Suborder Proterosuchia Broom 1906
primitive forms, Late Perm to Late Trias, cosmopolitan
Family
Proterosuchidae Huene, 1914
sprawling lizard or crocodile like, ancestral thecodonts, late Perm to Mid Trias, Cosm
Family
Erythrosuchidae large to huge, semi-sprawlingh terrestrial carnivores, Early to Mid Trias, S Afr, EEur, EAs,
Family
Euparkeriidae small faculatively bipedal types - Early Trias, S Afr, EEur, EAs
Family
Proterochampsidae specialised semi-aquatic types, Mid to Late Trias of SAm
Suborder Suchia Huxley, 1875 (= Phytosauria Meyer, 1861)
crocodile-like forms, L Trias of Eur, N Am, Ind, N Afr
Family
Phytosauridae Jaeger, 1828 (= Suchidae Lydekker, 1885 )
Suborder Ornithosuchia Huene, 1908
At one time considered ancestral to dinosaurs, now monotypal (Ornithosuchidae only)
Family
Ornithosuchidae Huene, 1908
medium-sized facultively bipedal carnivores, Late Trias of Eur & S Am
Suborder
Rauisuchia Huene, 1942, or Bonaparte, 1982
medium to very large terrestrial preditors, erect mamal, bird and dinosaur like posture, The phylogeny of the group and the status of some of the included families is uncertain. Some specialsied groups became herbivores. Early to Late Trias of Eur, EEur, N Am, Afr, E As
Family Ctenosauriscidae Kuhn, 1964
Family
Doswelliidae Weems, 1980
Family Lotosauridae Zhang, 1975
Family
Poposauridae Nopsca, 1928 (Postosuchidae)
Family
Prestosuchidae Romer, 1966
Family
Rauisuchidae Huene, 1936 (= Teratosauridae Cope, 1871)
Family Shuvosauridae
Suborder
Aetosauria Lydekker, 1889
armoured herbivores, L Trias of Eur, N Am, S Am, N Afr
Family Stagonolepididae Lydekker, 1887
Suborder unspecified (
proto-crocodylomorphs)
Family
Erpetosuchidae Watson, 1917
Family
Gracilisuchidae
Suborder unspecified (
Ornithodira)
Family
Scleromochlidae Huene, 1914
Notes
In the interests of taxonomic continuity (Romer, Colbert, Carroll, etc), we have chosen not to follow Olshevsky (1991) in elavating Thecodontia to Superordinal rank.
Hybrid classification
One alternative to the conventional linnaean classification that retains ranks (unlike strict cladistic-based phylogenetic nomenclature) is provided by Olshevsky 1991, who distinguishes between paraphyletic and monophyletic taxa. Whereas Olshevsky only used one prefix, para- in front of the rank of paraphyletic taxa (e.g. parafamily, monophyletic taxa being unmodified), we have used the following:
When no prefix is used, we haven't gotten around to assessing the taxon (or the current page is still under construction)
Hence, under this system, the Thecodontia consitute a Paraorder.
The following hybrid classification is the same as the linnaean one, but with additional suffixes. This system however is probably too complex and confusing to be practical, although we have include dit for the same of interst
Parainfraclass
Archosauromorpha Huene, 1946 (
cont.)
Paraorder
Thecodontia Owen, 1859
Triassic archosaurs with teeth implanted in sockets
Parasuborder Proterosuchia Broom 1906
primitive forms, Late Perm to Late Trias, cosmopolitan
Evofamily
Proterosuchidae Huene, 1914
sprawling lizard or crocodile like, ancestral thecodonts, late Perm to Mid Trias, Cosm
Evofamily
Erythrosuchidae large to huge, semi-sprawlingh terrestrial carnivores, Early to Mid Trias, S Afr, EEur, EAs,
Evofamily
Euparkeriidae small faculatively bipedal types - Early Trias, S Afr, EEur, EAs
Holofamily
Proterochampsidae specialised semi-aquatic types, Mid to Late Trias of SAm
Holosuborder Parasuchia Huxley, 1875 (= Phytosauria Meyer, 1861)
crocodile-like forms, L Trias of Eur, N Am, Ind, N Afr
Holofamily
Phytosauridae Jaeger, 1828 (= Parasuchidae Lydekker, 1885 )
Holosuborder Ornithosuchia Huene, 1908
At one time considered ancestral to dinosaurs, now monotypal (Ornithosuchidae only)
Holofamily
Ornithosuchidae Huene, 1908
medium-sized facultively bipedal carnivores, Late Trias of Eur & S Am
Ambisuborder
Rauisuchia Huene, 1942, or Bonaparte, 1982
medium to very large terrestrial preditors, erect mamal, bird and dinosaur like posture, The phylogeny of the group and the status of some of the included families is uncertain. Some specialsied groups became herbivores. Early to Late Trias of Eur, EEur, N Am, Afr, E As
Holofamily Ctenosauriscidae Kuhn, 1964
Monofamily
Doswelliidae Weems, 1980
Monofamily Lotosauridae Zhang, 1975
Ambifamily
Poposauridae Nopsca, 1928 (Postosuchidae)
Parafamily
Prestosuchidae Romer, 1966
Ambifamily
Rauisuchidae Huene, 1936 (= Teratosauridae Cope, 1871)
Holofamily Shuvosauridae
Holosuborder
Aetosauria Lydekker, 1889
armoured herbivores, L Trias of Eur, N Am, S Am, N Afr
Holofamily Stagonolepididae Lydekker, 1887
Parasuborder unspecified (
proto-crocodylomorphs)
Monofamily
Erpetosuchidae Watson, 1917
Monofamily
Gracilisuchidae
Monosuborder unspecified (
Ornithodira)
Monofamily
Scleromochlidae Huene, 1914
page MAK120311, last modified 120506