Palaeos Vertebrates Theropoda: Classification

The current page is the first (in order of writing it, 20 Feb 2012, not in topic sequence) of a new page type for Palaeos, the taxonomic classification page. These pages have been written to fill the need for a traditional rank-based (rather than phylogeny based) taxonomic list of various organisms and groups covered in each unit. The following therefore is not a cladistic or phylogenetic classification of the sort pioneered by Gauthier (1986) or Holtz (2000), but , which was purely Linnaean, a la Carroll 1988). As we have often stated, the Linnaean and Cladistic methodologies of organising the natural world are only contradictory when it is assumed that there can only be one. Since we believe that these (and any number of other possible) methodologies are non-exclusive, there is no reason why both cannot equally be used in their respective contexts.

We have not attempted to equate Linnaean ranks with clades, because the result would be the need for a near-infinite series of ranks, and a confusing of similarity-based categories with phylogenetic branching points. As we have often stated, the Linnaean and Cladistic methodologies of organising the natural world are only contradictory when it is assumed that there can only be one. Since we believe that these (and any number of other possible) methodologies are non-exclusive, there is no reason why both cannot equally be used in their respective contexts.

The following taxonomy is based mainly on Carroll (1988), as the most recent comprehensive linnaean classification of the Vertebrates, and an update of Romer 1966 Vertebrate Paleontology. This has in turn been updated in a few places, but we have tried to limit the number of new taxa, as it is so easy to go overboard with this sort of thing. Newly coined taxa are indicated by inverted commas. Each taxon is listed by rank, name, and original author, and followed by a short description. For the phylogenetic arrangement see the dendrogram page. For a rather unweildly attempt at a linnaean-cladistic synthesis, see below. The remainder of the theropoda can be found listed in the Coelurosauria classification page MAK120220 120312 120506

Infraclass Archosauromorpha Huene, 1946 (cont.) Order Theropoda Marsh, 1881 bipedal, mostly carnivorous, dinosaurs. Suborder Herrerasauria Galton 1985 small to medium-sized ancestral theropods, limited to the late Trias. Family Staurikosauridae Colbert, 1970 Typal family for Staurikosaurus pricei, a primitive herrerasaur Family Herrerasauridae Reig, 1963 Typical herrerasaurs, medium-sized very primitive theropods Suborder unspecified Eodromaeus, Eoraptor, Daemonosaurus, and Tawa small, primitive/ancestral late Trias types Suborder Ceratosauria Marsh, 1884 diverse group of small to very large, primitive theropods with three-toed feet, four-fingered hands, and a tendency to deveop crests and horns for intraspecific display. Family Podokesauridae Huene, 1914 small to large, lightly built, ancestral theropods, frequently with paired head crests. The head is long, the front of the snout with a distinctive kink. Late Trias to early Jur, cosmopolitan Subfamily Podokesaurinae small ancestral types, LTr to EJu, previously included under "Coelurosauria". Subfamily Dilophosaurinae Charig & Milner, 1990 large ancestral types, essentially overgrown podokesaurs with a few more advanced features, EJu, Cosmopolitan, intermediate between Podokesaurinae and both Carnosauria and higher Ceratosaurs. Family Ceratosauridae Marsh, 1884 large, persistantly primitive, late Jur theropods, mostly in the shadow of their more successful and advanced Allosaurid contemporaries, monotypal (Ceratosaurus) Family "Limusauridae" Nov. medium-sized, lightly built, highy specialised late Jur theropods, include toothless ostrich mimics Family Bahariasauridae Huene, 1948 huge, lightly built, long-legged, ceratosaurs; so far known only from the MidCret of north-central Gondw (nth Afr) Family Noasauridae Bonaparte & Powell, 1980 small, lightly built ceratosaurs, intermediate between more primitive types and abelisaurids, and closely related to the latter. Mid to Late Cret of Gondw Family Abelisauridae Bonaparte & Novas, 1985 large to very large, advanced and highly specialised ceratosaurs, frequently with horns or crests. Forearms extremely diminutive. Advanced forms were the fastest large theropods. Mid to Late Cret of Gondw & Eur Suborder Carnosauria Huene, 1920 originally the term for all large to huge theropods. Here used to refer to the evolutionary range of large types intermediate between ceratosaurs and coelurians Superfamily Megalosauroidea Huxley, 1889 ancestral and persistantly primitive Carnosaurs Family Megalosauridae Huxley, 1889 unspecialised Jurassic forms Subfamily Megalosaurinae Huxley, 1889 the most common primitive carnosaurs, flourished during the mid and late Jur Subfamily: Eustreptospondylinae Paul, 1988 similar to and contemporary with the Megalosaurinae, ancedtral to the spinosaurids Family Spinosauridae Stromer, 1915 large to gigantic fish-eating megalosaurs with elongated vertebral spines and crocodile-like jaws with specialized teeth, have a long kinked snout reminscient of podokesaurs Early to Mid Cret of Eur & Gondw Subfamily Baryonychinae Charig & Milner, 1986 large to very large, little or no sail on back Subfamily Spinosaurinae medium-sized to gigantic spinosaurs Tribe Spinosaurini gigantic fin-backed theropods, Mid Cret of North Africa, monotypal (Spinosaurus) Tribe Irritatorini Martill, Cruickshank, Frey, Small & Clarke, 1996 smallish west Gondwanan spinosaurines, monotypal (originally family Irritatoridae) Superfamily Allosauroidea Marsh, 1878 advanced Carnosaurs Family "Monolophosauridae" Bakker, 1997 ancestral crested forms, perhaps intermediate between megalosaurs and allosaurs, known so far only from a single species from the Mid Jur of China Family Sinraptoridae Currie & Zhao, 1994 large to gigantic Mid to Late Jur allosaurs known from Asia & Europe, intermediate between megalosaurs and higher allosaurs. Alternatively, could be a subfamily of the Allosauridae Family Allosauridae Marsh, 1878 large to gigantic, advanced carnosaurs, late Jur to Late Cret Subfamily Allosaurinae the classic large Late Jur theropod, strong three-fingered forearm, monotypal (Allosaurus), usually ranked as a family Subfamily Carcharodontosaurinae Stromer, 1931 gigantic early to Mid Cret allosaurs, including the largest terrestrial predators. Usually given family ranking Subfamily Neovenatorinae Benson, Carrano & Brusatte, 2010 here used as a monotypic taxon for the large but slender Neovenator saleri Hutt, Martill & Barker, 1996, Neoventoridae is a monophyletic taxon that includes Neovenator and the megaraptors Family Megaraptoridae Benson, Carrano & Brusatte, 2010 medium-sized lightly built allosaurs, same as Clade Megaraptora, convergent with coelurosaurs, Mid to Late Cret of Gondwanan, We believe this group is distinct enough to deserve family ranking Suborder Coeluria Marsh, 1881 (= Coelurosauria Huene, 1914) (see next unit)

Theropoda is conventially paced as a suborder of Order Saurischia Seeley, 1887. But since the three dinosaurian groups (Theropoda, Sauropodomorpha, and Ornithischia) all diverged at the same time and remained consistently distinct and diverse lineages, we felt that Theropoda should be promoted to Ordinal status, and Saurischia become an unranked taxon. Similarily, although Superorder Dinosauria Owen, 1842 is a totally valid taxon, this has not been listed because it would require creating artificial monotypic superorders for other archosauromorph orders (e.g. Thecodonts, Pterosauria, Crocodylia). In keeping with our classification system, Theropoda is here ranked as a paraphyletic order, because under the gradist evolutionary paradigm theropods evolve into birds, but are not themselves birds. In a cladistic classification system that uses Linnaean ranks, Birds would be a suborder of Theropoda. In these classification pages however we follow Carroll 1988 and traditional linnaeanism in giving birds their own class rank. Transitional forms such as Archaeopteryx could equally correctly be clasisfied under birds or dinosaurs.

With Theropoda becoming an order, previous infraorders (such as Herrerasauria) now become suborders.

The changing cladistic definition of the Ceratosauria is discussed here. At one time considered a monophyletic clade, this latter usage has now been redefined for more advanced forms only. To avoid excessive multiplication of suborders (such as a new suborder Ceolophysoidea or similar), Ceratosauria is here used in the context of Suborder Ceratosauria sensu Paul (1988) (but with abelisaurs added), or Parasuborder Ceratosauria sensu Olshevsky 1991 (but minus Megalosaurids); i.e. as a paraphyletic group including both ancestral (podokesaurid) and specialised (= monophyletic Ceratosauria) forms.

Metriacanthosauridae Paul, 1988 was coined earlier but was not associated with a formal description, and so cannot be used as an official name.

Hybrid classification

While for the most part we have following a conventional linnaean approach in these taxonomic pages, we have also been inspired by Olshevsky 1991. In his important amateur (non-peer reviewed) paper, Olshevsky distinguished between paraphyletic and monophyletic taxa (grades and clades). But whereas he only used one prefix, para- in front of the rank of paraphyletic taxa (e.g. parafamily, monophyletic taxa being unmodified), by adopting the following key:

When no prefix is used, we haven't gotten around to assessing the taxon (or the current page is still under construction). Cont. for Continued means that the taxon begins in a previous unit.

Linnaean names may not match their cladistic equivalents. For example, that a linnaean and evolutionary/gradist taxon, in excluding certain descendent groups from a taxon, can be a Paraorder or Parainfraclass in this schema. By including those descendents the same taxon would be an unranked monophyletic clade according to a strictly cladistic scheme. Hence Theropoda can be both a para(sub)order of dinosaurs and an unranked clade.

The following hybrid taxonomy It is also so experimental and unweidly that we at first thought of deleting it, but in the end decided to subordinate it to a more conventional page. Other attempts at cladistic/linnaean synthesis include Paul (1988) (the obvious inspiration for Olshevsky (1991)), and Benton (2005). MAK120220 120312 120506

Parainfraclass Archosauromorpha Huene, 1946 (cont.) Paraorder Theropoda Marsh, 1881 bipedal, mostly carnivorous, dinosaurs. Parasuborder Herrerasauria Galton 1985 small to medium-sized ancestral theropods, limited to the late Trias. Monofamily Staurikosauridae Colbert, 1970 Monotypal family for Staurikosaurus pricei, a primitive herrerasaur Ambifamily Herrerasauridae Reig, 1963 Typical herrerasaurs, medium-sized very primitive theropods Parasuborder unspecified Eodromaeus, Eoraptor, Daemonosaurus, and Tawa small, primitive/ancestral late Trias types Parasuborder Ceratosauria Marsh, 1884 diverse group of small to very large, primitive theropods with three-toed feet, four-fingered hands, and a tendency to deveop crests and horns for intraspecific display. Parafamily Podokesauridae Huene, 1914 small to large, lightly built, ancestral theropods, frequently with paired head crests. The head is long, the front of the snout with a distinctive kink. Late Trias to early Jur, cosmopolitan Evosubfamily Podokesaurinae small ancestral types, LTr to EJu, previously included under "Coelurosauria". Ambisubfamily Dilophosaurinae Charig & Milner, 1990 large ancestral types, essentially overgrown podokesaurs with a few more advanced features, EJu, Cosmopolitan, intermediate between Podokesaurinae and both Carnosauria and higher Ceratosaurs. Monofamily Ceratosauridae Marsh, 1884 large, persistantly primitive, late Jur theropods, mostly in the shadow of their more successful and advanced Allosaurid contemporaries, monotypal (Ceratosaurus) Evofamily "Limusauridae" Nov. medium-sized, lightly built, highy specialised late Jur theropods, include toothless ostrich mimics Monofamily Bahariasauridae Huene, 1948 huge, lightly built, long-legged, ceratosaurs; so far known only from the MidCret of north-central Gondw (nth Afr) Ambifamily Noasauridae Bonaparte & Powell, 1980 small, lightly built ceratosaurs, intermediate between more primitive types and abelisaurids, and closely related to the latter. Mid to Late Cret of Gondw Holofamily Abelisauridae Bonaparte & Novas, 1985 large to very large, advanced and highly specialised ceratosaurs, frequently with horns or crests. Forearms extremely diminutive. Advanced forms were the fastest large theropods. Mid to Late Cret of Gondw & Eur Parasuborder Carnosauria Huene, 1920 originally the term for all large to huge theropods. Here used to refer to the evolutionary range of large types intermediate between ceratosaurs and coelurians Parasuperfamily Megalosauroidea Huxley, 1889 ancestral and persistantly primitive Carnosaurs Evofamily Megalosauridae Huxley, 1889 unspecialised Jurassic forms Evosubfamily Megalosaurinae Huxley, 1889 the most common primitive carnosaurs, flourished during the mid and late Jur Evosubfamily: Eustreptospondylinae Paul, 1988 similar to and contemporary with the Megalosaurinae, ancedtral to the spinosaurids Holofamily Spinosauridae Stromer, 1915 large to gigantic fish-eating megalosaurs with elongated vertebral spines and crocodile-like jaws with specialized teeth, have a long kinked snout reminscient of podokesaurs Early to Mid Cret of Eur & Gondw Holosubfamily Baryonychinae Charig & Milner, 1986 large to very large, little or no sail on back Holosubfamily Spinosaurinae medium-sized to gigantic spinosaurs Monotribe Spinosaurini gigantic fin-backed theropods, Mid Cret of North Africa, monotypal (Spinosaurus) Monotribe Irritatorini Martill, Cruickshank, Frey, Small & Clarke, 1996 smallish west Gondwanan spinosaurines, monotypal (originally family Irritatoridae) Evosuperfamily Allosauroidea Marsh, 1878 advanced Carnosaurs Monofamily "Monolophosauridae" Bakker, 1997 ancestral crested forms, perhaps intermediate between megalosaurs and allosaurs, known so far only from a single species from the Mid Jur of China Evofamily Sinraptoridae Currie & Zhao, 1994 large to gigantic Mid to Late Jur allosaurs known from Asia & Europe, intermediate between megalosaurs and higher allosaurs. Alternatively, could be a subfamily of the Allosauridae Holofamily Allosauridae Marsh, 1878 large to gigantic, advanced carnosaurs, late Jur to Late Cret Monosubfamily Allosaurinae the classic large Late Jur theropod, strong three-fingered forearm, monotypal (Allosaurus), usually ranked as a family Holosubfamily Carcharodontosaurinae Stromer, 1931 gigantic early to Mid Cret allosaurs, including the largest terrestrial predators. Usually given family ranking Monosubfamily Neovenatorinae Benson, Carrano & Brusatte, 2010 here used as a monotypic taxon for the large but slender Neovenator saleri Hutt, Martill & Barker, 1996, Neoventoridae is a monophyletic taxon that includes Neovenator and the megaraptors Holosubfamily Megaraptorinae Benson, Carrano & Brusatte, 2010 medium-sized lightly built allosaurs, same as Clade Megaraptora, convergent with coelurosaurs, Mid to Late Cret of Gondwanan, If ranked as Holofamily Megaraptoridae, then Allosauridae and Carcharodontosaurinae become a Parafamily and Parasubfamily respectively Parasuborder Coeluria Marsh, 1881 (= Coelurosauria Huene, 1914) (see next unit)

Theropod Classification

Order Theropoda

Traditional classification

Hybrid classification

Links