| Megalosauroids | |
|---|---|
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| Torvosaurus skeletal mount,Museum of Ancient Life | |
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| Spinosaurus skeletal mount,National Geographic Museum | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | Theropoda |
| Clade: | †Carnosauria (?) |
| Superfamily: | †Megalosauroidea Huxley, 1889 |
| Type species | |
| †Megalosaurus bucklandii Mantell, 1827 | |
| Subgroups | |
| Synonyms | |
Megalosauroidea (meaning 'great/big lizard forms') is asuperfamily (orclade) oftetanuran theropoddinosaurs that lived from theMiddle Jurassic to theLate Cretaceous period. The group is defined asMegalosaurus bucklandii and all taxa sharing a more recent common ancestor with it than withAllosaurus fragilis orPasser domesticus.[2] Members of the group includeSpinosaurus,Megalosaurus, andTorvosaurus. They are possibly paraphyletic in nature with respect toAllosauroidea.
The nameSpinosauroidea is sometimes used in place of Megalosauroidea. The superfamily Spinosauroidea was named in 1915 byErnst Stromer. It is a synonym of Megalosauroidea in almost all modern phylogenetic analyses, and it is therefore redundant. Spinosauroidea was defined as aclade in 1998 byPaul Sereno as the node clade containing the common ancestor ofSpinosaurus andTorvosaurus and all its descendants. Thomas Holtz in 2004 defined a branch clade with the same name containing all species closer toSpinosaurus than toPasser domesticus. TheICZN holds that even clade names (which do not yet have any governing body) should be replaced if having a traditional taxon suffix and being synonyms of ranked taxa at or below the superfamily level. The seniority of Megalosauroidea was not followed in most paleontological literature during the 1990s and early 2000s. A series of papers supporting the validity ofMegalosaurus as a genus, the relationships of megalosauroids, and the placement of "spinosauroids" among them, published between 2008 and 2010 argued that Megalosauroidea was in fact the valid name for the group.[2]
The classification of megalosauroids follows a study by Benson in 2010. Note that several "wildcard"[2] taxa that are probably megalosauroids were excluded from the final tree, includingMagnosaurus,Piveteausaurus andStreptospondylus.[2] Later,Magnosaurus andStreptospondylus were added in the final tree.[3] These are known from remains too fragmentary to be reliably classified.[2] Some of these 'wildcard' taxa, such asPoekilopleuron andMegaraptor, have been considered possible megalosauroids in the past, but the analysis found that they are more likelyallosauroids.[3]
| Megalosauroidea | |
Carrano, Benson & Sampson (2012) performed much largerphylogenetic analysis of theTetanurae that includes more taxa. They used the clade nameMegalosauria (Bonaparte, 1850) in their analysis and defined it as the node comprisingMegalosaurus,Spinosaurus, their most recent common ancestor, and all its descendants. Furthermore, a new megalosauroid familyPiatnitzkysauridae was named to include all megalosauroids more closely related toPiatnitzkysaurus than to eitherSpinosaurus orMegalosaurus. Within Megalosauridae a new subfamily was named,Afrovenatorinae, to include all megalosaurids more closely related toAfrovenator than toMegalosaurus. Unlike Bensonet al., 2010, they recoveredPoekilopleuron as an afrovenatorine, whileXuanhanosaurus was recovered as the basalmostmetriacanthosaurid. However, the position of these taxa is very unstable, and their exclusion from the analysis gave more resolved and stable cladogram.Streptospondylus was also excluded to get more resolved Megalosauridae and Afrovenatorinae. The Chinese tetanuranLeshansaurus was included for the first time in a phylogenetic analysis, and was recovered as an afrovenatorine. BothChuandongocoelurus andMonolophosaurus were found to be just outsideOrionides. Thecladogram presented here follows that study.[4]
| Tetanurae |
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In 2019, Rauhut and Pol describedAsfaltovenator vialidadi, a basal allosauroid displaying a mosaic of primitive and derived features seen withinTetanurae. Their phylogenetic analysis found traditional Megalosauroidea to represent a basalgrade of carnosaurs,paraphyletic with respect toAllosauroidea.[5]
| Carnosauria | traditional Megalosauroidea | |
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