Magnosaurus

''Magnosaurus'' (meaning 'large lizard') was a genus of theropod dinosaur from the Middle Jurassic of England. It is based on fragmentary remains and has often been confused with or included in ''Megalosaurus''.

History and taxonomy

In 1923, Friedrich von Huene named ''Megalosaurus nethercombensis'' from a partial skeleton (OUM J12143) from the Bajocian age Middle Jurassic Inferior Oolite, found in the nineteenth century by W. Parker near Nethercomb, north of Sherborne, in Dorset, England. The material included partial dentaries, dorsal and caudal vertebrae, a partial ilium, a partial right pubis, internal casts of the femora, and tibiae, from a possible juvenile individual. Huene interpreted it as a more primitive species of ''Megalosaurus''.von Huene, F. (1923). Carnivorous Saurischia in Europe since the Triassic. ''Bulletin of the Geological Society of America'' 34:449-458.

In 1926, he named the tooth species ''Megalosaurus lydekkeri'' for a specimen, BMNH 41352, from the Lower Lias (Lower Jurassic) of England that Richard Lydekker had first described in 1888.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. 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 also named '' Sarcosaurus andrewsi'';von Huene, F. (1932). ''Die fossile Reptil-Ordnung Saurischia, ihre Entwicklung und Geschichte''. Monographien zur Geologie und Palaeontologie 1(4) erman/ref> in 1956 the latter name was given priority by von Huene. Even more confusing, in the same 1932 publication von Huene renamed ''Sarcosaurus woodi'' into ''Magnosaurus woodi''.

Until the 1990s, the genus had been ignored as a species of ''Megalosaurus''.Waldman, M. (1974). "Megalosaurids from the Bajocian (Middle Jurassic) of Dorset". ''Palaeontology'' 17(2):325-339. However, with growing concern over what exactly is constituted by ''Megalosaurus'', ''Magnosaurus'' has been generally separated as its own genus.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. Rauhut, O.W.M. (2003). "The Interrelationships and Evolution of Basal Theropod Dinosaurs." ''Special Papers in Palaeontology'' 69. The Palaeontological Association:London, 213 p.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. Also, there are morphological differences: for example, possible ''Megalosaurus'' tibiae are compressed at the far end, unlike those of ''Magnosaurus''. 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. He therefore renamed ''Eustreptospondylus oxoniensis'' a ''Magnosaurus oxoniensis'' but this has not been generally followed. Reviews have found it to most likely be a basal tetanuran, probably a megalosaurid.Paul, G.S. (1988). ''Predatory Dinosaurs of the World.'' Simon & Schuster:New York, 464 p. A detailed redescription by Roger Benson in 2010 concluded ''Magnosaurus'' was valid taxon, a megalosaurid megalosauroid, and at about 175 million years old the oldest certain known member of the Tetanurae.

Species

''Magnosaurus'' is known from many species, most of were originally named as a different genus.Weishampel, D.B.; Dodson, P.; Osmolska, H. (eds.). "The Dinosauria: Second Edition". ''Berkeley: University of California Press'', p 99. .

*''Magnosaurus nethercombensis'' (Huene, 1923) Huene, 1932 = ''Megalosaurus nethercombensis'' Huene, 1923
*''Magnosaurus lydekkeri'' (Huene, 1926) Huene, 1932 ''(nomen dubium)'' = ''Megalosaurus lydekkeri'' Huene, 1926
*''Magnosaurus woodwardi'' Huene, 1932 ''(nomen dubium)'' = ''Sarcosaurus andrewsi'' Huene, 1932 = ''Megalosaurus woodwardi'' (Huene, 1932)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.

The type species of ''Eustreptospondylus'', ''Megalosaurus'' and ''Sarcosaurus'' are also sometimes assigned to ''Magnosaurus''. In such cases the combinations are:
*''Magnosaurus woodi'' (Andrews, 1921) = ''Sarcosaurus woodi'' Andrews, 1921
*''Magnosaurus oxoniensis'' (Walker, 1964) Rahut, 2003 = ''Eustreptospondylus oxoniensis'' Walker, 1964
*''Magnosaurus bucklandi'' (Meyer, 1832) Weishampel ''et al.'', 2004 = lapsus calami, ''Megalosaurus bucklandi'' Meyer, 1832 = ''Megalosaurus bucklandii'' Mantell, 1827

Description

Because the remains are sparse and fragmentary, most details about its anatomical features are unknown. It would have been a bipedal carnivore of moderate size for a dinosaur. The most similar animals to it would probably be ''Eustreptospondylus'', '' Dubreuillosaurus'', and ''Afrovenator''. Paul (1988) roughly estimated the mass of the type individual as around 175 kg (386 lb), which would correspond to a length of roughly four metres (13.1 ft), judging by his estimates for the sizes of other theropods. Benson however, in 2010 gave a higher estimation of about half a tonne; the animal would have stood at over a metre at the hip.

Classification

The phylogenetic position of ''Magnosaurus'' according to Carrano ''et al.'' (2012) is shown by this cladogram:M.T. Carrano, R.B.J. Benson, and S.D. Sampson, 2012, "The phylogeny of Tetanurae (Dinosauria: Theropoda)", ''Journal of Systematic Palaeontology'' 10(2): 211-300

References

{{Taxonbar, from=Q736000

Megalosauridae
Dinosaur genera
Bajocian dinosaurs
Fossil taxa described in 1932
Taxa named by Friedrich von Huene
Dinosaurs of the United Kingdom