page_title: Megalosaurus
section_title: Appendicular skeleton
hierarchical_section_title: Megalosaurus / Description / Appendicular skeleton
caption_attribution_description: Left ilium (i.e. the left dorsal element of the pelvis) of Megalosaurus „from the Oolitic Slate, of Stonesfield, Oxfordshire“ (i.e. the Stonesfield Slate of the Taynton Limestone Formation, middle Bathonian), in lateral (Fig.&#160;1) and ventral (Fig.&#160;2) views.Note that in the original source (Owen, 1849–1884; see below) this bone was erroneously identified as coracoid, i.e. an element of the pectoral girdle – this is why the bone is shown turned by 90 degrees clockwise, i.e. its ‘upper’ end is actually the anterior (cranial) end and its ‘lower’ end is actually the posterior (caudal) end.Meaning of letters according to modern nomenclature: b&#160;=&#160;ischial peduncle, c&#160;=&#160;rim of preacetabular process of ilium, l&#160;=&#160;tip of postacetabular process of ilium (with pronounced brevis fossa on ventral side of postacetabular process), m&#160;=&#160;dorsal surface of acetabulum, n&#160;=&#160;preacetabular notch, o&#160;=&#160;pubic peduncle, s--s&#160;=&#160;dorsal rim of iliac blade.
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: The shoulderblade or scapula is short and wide, its length about 6.8 times the minimum width; this is a rare and basal trait within Tetanurae. Its top curves slightly to the rear in side view. On the lower outer side of the blade a broad ridge is present, running from just below the shoulder joint to about midlength where it gradually merges with the blade surface. The middle front edge over about 30% of its length is thinned forming a slightly protruding crest. The scapula constitutes about half of the shoulder joint, which is oriented obliquely sideways and to below. The coracoid is in all known specimens fused with the scapula into a scapulocoracoid, lacking a visible suture. The coracoid as such is an oval bone plate, with its longest side attached to the scapula. It is pierced by a large oval foramen but the usual boss for the attachment of the upper arm muscles is lacking.
  The humerus is very robust with strongly expanded upper and lower ends. Humerus specimen OUMNH J.13575 has a length of 388 millimetres. Its shaft circumference equals about half of the total humerus length. The humerus head continues to the front and the rear into large bosses, together forming a massive bone plate. On the front outer side of the shaft a large triangular deltopectoral crest is present, the attachment for the Musculus pectoralis major and the Musculus deltoideus. It covers about the upper half of the shaft length, its apex positioned rather low. The ulna is extremely robust, for its absolute size more heavily built than with any other known member of the Tetanurae. The only known specimen, BMNH 36585, has a length of 232 millimetres and a minimal shaft circumference of 142 millimetres. The ulna is straight in front view and has a large olecranon, the attachment process for the Musculus triceps brachii. Radius, wrist and hand are unknown.
  In the pelvis, the ilium is long and low, with a convex upper profile. Its front blade is triangular and rather short; at the front end there is a small drooping point, separated by a notch from the pubic peduncle. The rear blade is roughly rectangular. The outer side of the ilium is concave, serving as an attachment surface for the Musculus iliofemoralis, the main thigh muscle. Above the hip joint, on this surface a low vertical ridge is present with conspicuous vertical grooves. The bottom of the rear blade is excavated by a narrow but deep trough forming a bony shelf for the attachment of the Musculus caudofemoralis brevis. The outer side of the rear blade does not match the inner side, which thus can be seen as a separate "medial blade" that in side view is visible in two places: in the corner between outer side and the ischial peduncle and as a small surface behind the extreme rear tip of the outer side of the rear blade. The pubic bone is straight. The pubic bones of both pelvis halves are connected via narrow bony skirts that originated at a rather high position on the rear side and continued downwards to a point low on the front side of the shaft. The ischium is S-shaped in side view, showing at the transition point between the two curvatures a rough boss on the outer side. On the front edge of the ischial shaft an obturator process is present in the form of a low ridge, at its top separated from the shaft by a notch. To below, this ridge continues into an exceptionally thick bony skirt at the inner rear side of the shaft, covering over half of its length. Towards the end of the shaft, this skirt gradually merges with it. The shaft eventually ends in a sizeable "foot" with a convex lower profile.
  The thighbone is straight in front view. Seen from the same direction its head is perpendicular to the shaft, seen from above it is orientated 20° to the front. The greater trochanter is relatively wide and separated from the robust lesser trochanter in front of it, by a fissure. At the front base of the lesser trochanter a low accessory trochanter is present. At the lower end of the thighbone a distinct front, extensor, groove separates the condyles. At the upper inner side of this groove a rough
caption: Lithograph of the Ilium. Work from the 1800s drawn by J. Erxleben
exif: {"Image ImageWidth": "10000", "Image ImageLength": "9904", "Image BitsPerSample": "[8, 8, 8]", "Image Compression": "Uncompressed", "Image PhotometricInterpretation": "2", "Image Make": "i2s Digibook Scanner", "Image Model": "Suprascan A0 10000 RGB", "Image Orientation": "Horizontal (normal)", "Image SamplesPerPixel": "3", "Image XResolution": "800", "Image YResolution": "800", "Image PlanarConfiguration": "1", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop CS3 Windows", "Image DateTime": "2013:12:27 19:23:52", "Image ExifOffset": "320", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "458", "Thumbnail JPEGInterchangeFormatLength": "4518", "EXIF ColorSpace": "Uncalibrated", "EXIF ExifImageWidth": "1920", "EXIF ExifImageLength": "2844"}