page_title: Megalosaurus
section_title: Size and general build
hierarchical_section_title: Megalosaurus / Description / Size and general build
caption_attribution_description: English: Photographer: User:Ballista
context_page_description: Megalosaurus is an extinct genus of large meat-eating theropod dinosaurs of the Middle Jurassic period of Southern England. Although fossils from other areas have been assigned to the genus, the only certain remains of Megalosaurus come from Oxfordshire and date to the late Middle Jurassic.
  Megalosaurus was, in 1824, the first genus of non-avian dinosaur to be validly named. The type species is Megalosaurus bucklandii, named in 1827. In 1842, Megalosaurus was one of three genera on which Richard Owen based his Dinosauria. On Owen's directions a model was made as one of the Crystal Palace Dinosaurs, which greatly increased the public interest for prehistoric reptiles. Subsequently, over fifty other species would be classified under the genus, originally because dinosaurs were not well known, but even during the 20th century after many dinosaurs had been discovered. Today it is understood these additional species were not directly related to M. bucklandii, which is the only true Megalosaurus species. Because a complete skeleton of it has never been found, much is still unclear about its build.
context_section_description: Traditionally, most texts, following Owen's estimate of 1841, give a body length of thirty feet or nine metres for Megalosaurus. The lack of an articulated dorsal vertebral series makes it difficult to determine an exact size. David Bruce Norman in 1984 thought Megalosaurus was seven to eight metres long. Gregory S. Paul in 1988 estimated the weight tentatively at 1.1 tonnes, given a thighbone seventy-six centimetres long. The trend in the early twenty-first century to limit the material to the lectotype inspired even lower estimates, disregarding outliers of uncertain identity. Paul in 2010 stated Megalosaurus was six metres long and seven hundred kilogrammes heavy. However, the same year Benson claimed that Megalosaurus, though medium-sized, was still among the largest of Middle Jurassic theropods. Specimen BMNH 31806, a thighbone 803 millimetres long, would indicate a body weight of 943 kilogrammes, using the extrapolation method of J.F. Anderson — which method, optimised for mammals, tends to underestimate theropod masses by at least a third. Furthermore, thighbone specimen OUM J13561 has a length of about eighty-six centimetres.
  In general, Megalosaurus had the typical build of a large theropod. It was bipedal, the horizontal torso being balanced by a long horizontal tail. The hindlimbs were long and strong with three forward-facing weight-bearing toes, the forelimbs relatively short but exceptionally robust and probably carrying three digits. Being a carnivore, its large elongated head bore long dagger-like teeth to slice the flesh of its prey. The skeleton of Megalosaurus is highly ossified, indicating a robust and muscular animal, though the lower leg was not as heavily built as that of Torvosaurus, a close relative.
caption: Hip, femur and sacrum
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