Megalosaurus bucklandii

Megalosaurus bucklandii occupies a special place in science as the oldest validly named non-avian dinosaur. William Buckland described giant reptile bones from Oxfordshire in 1824, eighteen years before Richard Owen coined Dinosauria. Modern research has stripped away many fossils historically assigned to the famous name and retains a diagnostic right lower jaw plus compatible material from the Stonesfield area. The result is more scientifically reliable but less complete than the full skeletons often shown in popular art. Megalosaurus was a six-metre predatory tetanuran and a close relative of other megalosaurids, but much of its precise body outline must be reconstructed from those relatives.

Its fossils occur between approximately 168 and 166 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

The lectotype OUMNH J.13505 is the rear portion of a robust right dentary containing replacement and erupted teeth. A distinctive longitudinal groove and a narrow opening on its inner surface help diagnose the species. Referred Oxfordshire material includes parts of the skull, vertebral column, shoulder and pelvic girdles, and limbs, but no single articulated skeleton unites them. The teeth were recurved and serrated, the hind limbs supported bipedal locomotion, and close relatives indicate three-fingered grasping hands. Exact skull depth, arm proportions and the full sequence of back and tail vertebrae remain partly reconstructed.

• Robust right dentary bearing large recurved serrated teeth
• Diagnostic groove low on the outer surface of the dentary
• Slit-like anterior Meckelian opening on the inner jaw surface
• Large bipedal hind limbs known from referred Oxfordshire material
• Early-diverging tetanuran body plan shared with other megalosaurids
• No complete or articulated skeleton securely assigned to the species

Stonesfield quarry workers recovered large fossil bones over many decades. William Buckland began studying the material by about 1818 with help from Mary Morland, whose careful drawings illustrated his 1824 paper. Buckland formally introduced the genus Megalosaurus, meaning great lizard; Gideon Mantell supplied the species name bucklandii in 1827 to honour him. Later authors assigned fragmentary theropod fossils from around the world to Megalosaurus, turning it into a taxonomic wastebasket. Roger Benson's detailed revisions in 2008 and 2010 restricted the valid species to the Oxfordshire type and securely comparable material.

Discovery credit: Stonesfield quarry workers, William Buckland.

Naming authors: William Buckland, Gideon Mantell.

The Taynton Limestone formed in a warm, shallow coastal setting across low islands and lagoons in Jurassic Oxfordshire. River and storm processes transported terrestrial bones into marine or near-shore sediments, mixing them with shellfish and marine fossils. Megalosaurus therefore lived on nearby land rather than in the sea. Plant-eating dinosaurs and other terrestrial vertebrates occupied the region, although transported isolated bones rarely preserve direct ecological interactions.

Serrated teeth and a large, reinforced lower jaw identify Megalosaurus as a carnivore able to cut flesh from substantial prey or carcasses. Its hind limbs establish bipedal movement, but speed and hunting method cannot be calculated from the incomplete skeleton. No nest, trackway or multi-individual association is securely attributable to M. bucklandii, so claims about pack hunting, territorial display or parental care go beyond the fossil evidence.

• Megalosaurus received its scientific name before the word dinosaur existed.
• Mary Morland's fossil drawings were central to Buckland's landmark 1824 description.
• The famous lectotype is one half of a lower jaw rather than a complete skeleton.
• Victorian Crystal Palace sculptures portrayed it as a huge quadruped, reflecting the limited anatomy then known.

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1. 01
   A description of Megalosaurus bucklandii (Dinosauria: Theropoda) from the Bathonian of the UK and the relationships of Middle Jurassic theropods

   Roger B. J. Benson · Zoological Journal of the Linnean Society 158(4) · 2010

   Open source
2. 02
   The Oxford dinosaur that started it all: Megalosaurus bucklandii

   Oxford University Museum of Natural History

   Open source