Magnosaurus
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| Magnosaurus Fossil range: Middle Jurassic |
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Magnosaurus was a genus of basal tetanuran theropod dinosaur from the Middle Jurassic of England. It is based on fragmentary remains and has often been mixed up with Megalosaurus.
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[edit] History and taxonomy
In 1923, Friedrich von Huene named Megalosaurus nethercombensis from a partial skeleton (UMO J12143) from the Aalenian-Bajocian-age Middle Jurassic Inferior Oolite, near Nethercomb, north of Sherborne, in Dorset, England. The material included partial dentaries, dorsal and caudal vertebrae, a partial right pubis, internal casts of femora, and tibiae, from a possibly juvenile individual. Huene interpreted it as a more primitive species of Megalosaurus.[1]
In 1926, he named the tooth species Megalosaurus lydekkeri for a specimen from the Lower Lias (Lower Jurassic) of England that Richard Lydekker had first described in 1888.[2][3] Finally, in 1932, he created the genus Magnosaurus for M. nethercombensis, referred M. lydekkeri to it, and created a third species, M. woodwardi, for the genus. M. woodwardi was based on a tibia (BMNH R.3542) from the Lower Lias, which he simultaneously and accidentally named Sarcosaurus andrewsi.[4]
Until the 1990s, the genus had been ignored as a species of Megalosaurus.[5] However, with growing concern over what exactly is constituted by Megalosaurus, Magnosaurus has been generally separated as its own genus.[6][7][8] Also, there are morphological differences: for example, possible Megalosaurus tibiae are compressed at the far end, unlike those of Magnosaurus.[8] Rauhut (2003) considered it and Eustreptospondylus to be the same genus, because the two share a similarly-expanded front tip of the dentary and enlarged third dentary tooth, but this has not been generally followed.[7] Reviews have found it to most likely be a basal tetanuran, probably a megalosauroid, possibly a eustreptospondyline.[9][8]
[edit] Other species
- M. lydekkeri is a dubious tooth genus, usually referred back to Megalosaurus as "M." lydekkeri.[8]
- M. woodwardi is also dubious and was referred to ?Sarcosaurus andrewsi by Carrano and Sampson (2004).[10]
[edit] Paleobiology
Because the remains are sparse, fragmentary, and possibly juvenile, details about the life and behaviour of Magnosaurus are unknown. It would have been a bipedal carnivore of moderate size for a dinosaur. The most similar animals probably would be animals like Eustreptospondylus, Dubreuillosaurus, and Afrovenator.[8] Paul (1988) roughly estimated the mass of the type individual as around 175 kg (386 lb), which would correspond to a length of roughly 4 m (13.1 ft), judging by his estimates for the sizes of other theropods.[9]
[edit] References
- ^ von Huene, F. (1923). Carnivorous Saurischia in Europe since the Triassic. Bulletin of the Geological Society of America 34:449-458.
- ^ von Huene, F. (1926). The carnivorous Saurischia in the Jura and Cretaceous formations, principally in Europe. Revista del Museo de La Plata 29:35-167.
- ^ Lydekker, R. (1888). Catalogue of the Fossil Reptilia and Amphibia in the British Museum (Natural History). Part I. Containing the Orders Ornithosauria, Crocodilia, Dinosauria, Squamata, Rhynchocephalia, and Proterosauria. British Museum (Natural History):London, 309 p.
- ^ von Huene, F. (1932). Die fossile Reptil-Ordnung Saurischia, ihte Entwicklung und Geschichte. Monographien zur Geologie und Palaeontologie 1(4). 361 p. [German]
- ^ Waldman, M. (1974). Megalosaurids from the Bajocian (Middle Jurassic) of Dorset. Palaeontology 17(2):325-339.
- ^ Molnar, R.E., Kurzanov, S.M., and Dong, Z. (1990). Carnosauria. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.), The Dinosauria. University of California Press:Berkeley and Los Angeles, p. 169-209. ISBN 0-520-06727-4
- ^ a b Rauhut, O.W.M. (2003). The Interrelationships and Evolution of Basal Theropod Dinosaurs. Special Papers in Palaeontology 69. The Palaeontological Association:London, 213 p.
- ^ a b c d e Holtz Jr., T.R., Molnar, R.E., and Currie, P.J. (2004). Basal Tetanurae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.), The Dinosauria (second edition). Berkeley: University of California Press:Berkeley, p. 71-110. ISBN 0-520-24209-2
- ^ a b Paul, G.S. (1988). Predatory Dinosaurs of the World. Simon & Schuster:New York, 464 p. ISBN 0-671-61946-2
- ^ Carrano, M.T., and Sampson, S.D. (2004). A review of coelophysoids (Dinosauria: Theropoda) from the Early Jurassic of Europe, with comments on the late history of the Coelophysoidea. Neues Jahrbuch für Geologie und Paläontologie Monatshefte 2004(9):537-558.
