Megalosauridae
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| Megalosaurids Fossil range: mid - Late Jurassic |
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 The megalosaurid Eustreptospondylus.
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Megalosauridae was a family of tetanuran theropod dinosaurs, order Saurischia. They were small-to-large carnivores with sharp teeth and three claws on each hand. Some members of this group were Megalosaurus, Eustreptospondylus and Torvosaurus. Megalosaurids only lived in the mid-to-late Jurassic Period and have representatives found in Europe, North America, South America and Africa to date. They are considered by most researchers (Sereno 2005, Olshevsky 1995, Holtz 2004, etc.) to be close relatives of the spinosaurs.
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[edit] Systematics
Like Megalosaurus itself, the family Megalosauridae, coined by Huxley in 1869, had traditionally been used as a 'wastebasket' group, which included a wide variety of unrelated species (such as Dryptosaurus, Ceratosaurus and Indosaurus). Because of this traditionally polyphyletic use, some scientists, such as Paul Sereno, reject the family name Megalosauridae in favor of Torvosauridae (coined by Jensen in 1985), despite the fact that Megalosauridae has priority under the ICZN rules governing family-level names in zoology.[1] Similarly, Sereno rejects the use of the superfamily name Megalosauroidea in favor of Spinosauroidea.[1] A 2008 review of Megalosaurus by Benson and colleagues also found that the relationships of Megalosaurus to other theropods could not be determined, and that the assignment of basal spinosauroids to the family Megalosauridae should be discontinued.[2]
[edit] Taxonomy
- Family Megalosauridae
- Piveteausaurus
- Subfamily Eustreptospondylinae
- Subfamily Megalosaurinae
- Subfamily Torvosaurinae
[edit] Phylogeny
The clade Megalosauridae was first given a phylogenetic definition by Allain in 2002. According to Allain's definition, a megalosaurid is any dinosaur that shares a common ancestor with Poekilopleuron valesdunensis (since reclassified as Dubreuillosaurus), Torvosaurus, and Afrovenator.[3] In 2004, Holtz and colleagues proposed a new definition: all dinosaurs more closely related to Megalosaurus than to Spinosaurus, Allosaurus, or modern birds (represented by Passer domesticus).[4] In 2005, Sereno rejected the use of Megalosauridae as a clade altogether, due to the fragmentary nature of Megalosaurus, and used the name Torvosauridae instead, using the same definition as Holtz but replacing Megalosaurus with Torvosaurus.[1]
The cladogram presented here follows the 2002 analysis by Allain.[3]
| Megalosauridae |
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[edit] References
- ^ a b c Sereno, P.C. (2005). Stem Archosauria—TaxonSearch [version 1.0, 2005 November 7]
- ^ Benson, R.B.J., Barrett, P.M., Powell, H.P., and Norman, D.B. (2008). "The taxonomic status of Megalosaurus bucklandii (Dinosauria, Theropoda) from the Middle Jurassic of OxfordshireE, UK." Palaeontology, 51(2): 419–424.
- ^ a b Allain, R. (2002). "Discovery of megalosaur (Dinosauria, Theropoda) in the middle Bathonian of Normandy (France) and its implications for the phylogeny of basal Tetanurae." Journal of Vertebrate Paleontology, 22(3): 548-563.
- ^ Holtz, T.R., Molnar, R.E., Currie, P.J. (2004). "Basal Tetanurae." In Weishampel, D.B., Dodson, P., & Osmolska, H. (Eds.). The Dinosauria (2nd Edition). Berkeley: University of California Press. Pp. 71-110.
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