Nepedia
Back to Discover
Advanced Reader
🧬

Megalosaurus

life science Maturity 5-7 Next article →

Megalosaurus is an extinct genus of large carnivorous theropod dinosaurs. The name comes from the Greek words "megas," meaning large, and "sauros," meaning lizard.

Megalosaurus dinosaur
Megalosaurus dinosaur

These animals lived during the Middle Jurassic Epoch. This period occurred during the Bathonian stage, roughly 166 million years ago. While some fossils have been assigned to this genus elsewhere, the most certain remains come from Oxfordshire, England.

Megalosaurus size chart
Megalosaurus size chart

Understanding Megalosaurus is vital because it was one of the very first dinosaurs to be scientifically recognized by humans.

Scientists reconstruct the biology of Megalosaurus by studying specific skeletal features. It was a bipedal animal, meaning it walked on two legs.

Megalosaurus fragments
Megalosaurus fragments

It used stout hindlimbs to support its weight while moving. To stay balanced, it held its horizontal torso steady with a horizontal tail.

Megalosaurus vertebra
Megalosaurus vertebra

The dinosaur had short but very robust forelimbs. Its head was relatively large and featured long, curved teeth.

Megalosaurus bucklandi tooth 2
Megalosaurus bucklandi tooth 2

Modern research uses comparisons with direct relatives in the Megalosauridae family to understand its shape. We now know it was about 20 feet long and weighed approximately 1,000 kilograms.

Because a complete skeleton has never been found, scientists must work with many different parts. The original material used to describe the genus was a syntype series. This means the description was based on several different individuals.

Megalosaurus 5
Megalosaurus 5

These parts included a right lower jaw, a dorsal vertebra, a caudal vertebra, and several ribs. They also included parts of the pelvis, such as the ilium, ischium, and pubis.

Megalosaurus fragments
Megalosaurus fragments

In 1990, researcher Ralph Molnar selected the front part of the lower jaw, known as the dentary, as the official lectotype. This single specimen now serves as the primary reference for the species.

The history of discovering Megalosaurus involves many centuries of changing ideas. In 1676, a bone fragment was found in the Taynton Limestone Formation.

Scrotum humanum (cropped)
Scrotum humanum (cropped)

Naturalist Robert Plot described this femur, but he did not know it was a dinosaur. He initially thought it belonged to a Roman war elephant or a biblical giant. Later, in 1699, Edward Lhuyd described a tooth that was eventually linked to Megalosaurus.

OU 1328 fossil tooth
OU 1328 fossil tooth

These early finds were significant, even if the researchers did not yet understand what they were looking at.

William Buckland played the most important role in naming the dinosaur. He formally announced Megalosaurus to the Geological Society of London on February 20, 1824.

Buckland, Megalosaurus jaw
Buckland, Megalosaurus jaw

This was a landmark event because it was the first dinosaur genus to be validly named. In 1827, Gideon Mantell named the type species M. bucklandii to honor Buckland.

Megalosaurus bucklandi
Megalosaurus bucklandi

Later, in 1842, Richard Owen used Megalosaurus as one of three original genera to define the group Dinosauria. This group also included Iguanodon and Hylaeosaurus.

The discovery of Megalosaurus had a massive impact on public interest in prehistory. In the mid-1800s, a model of the dinosaur was built for Crystal Palace Park.

London - Crystal Palace - Victorian Dinosaurs 1
London - Crystal Palace - Victorian Dinosaurs 1

This helped the public imagine what prehistoric reptiles might have looked like. For a long time, scientists incorrectly classified over 50 other species under the Megalosaurus name. They did this because very few types of dinosaurs were known at the time. Today, we know those other species were not actually closely related to M. bucklandii.

During the Middle Jurassic, the environment for Megalosaurus was very different from today. Europe was an island archipelago surrounded by the Atlantic and Tethys Oceans.

Bajocian Europe map
Bajocian Europe map

Megalosaurus lived on an island formed by the London–Brabant Massif. It likely acted as the apex predator of its ecosystem.

Iguanodon versus Megalosaurus
Iguanodon versus Megalosaurus

It lived alongside many other famous creatures. These included the large sauropod Cetiosaurus, various stegosaurs, and ankylosaurs. By studying these connections, scientists can reconstruct the entire food web of the Jurassic world.

598 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (27)
File:OU 1328 fossil tooth.png
OU 1328 fossil tooth.png
File:Scrotum humanum (cropped).jpg
Scrotum humanum (cropped).jpg
File:Buckland, Megalosaurus jaw.jpg
Buckland, Megalosaurus jaw.jpg
File:Megalosaurus vertebra.JPG
Megalosaurus vertebra.JPG
File:London - Crystal Palace - Victorian Dinosaurs 1.jpg
London - Crystal Palace - Victorian...
File:Iguanodon versus Megalosaurus.jpg
Iguanodon versus Megalosaurus.jpg
File:Humped Megalosaurus.jpg
Humped Megalosaurus.jpg
File:Megalosaur footprints.JPG
Megalosaur footprints.JPG
File:Megalosaurus, World Museum Liverpool (2).JPG
Megalosaurus, World Museum Liverpool (2).JPG
File:Megalosaurus size chart.png
Megalosaurus size chart.png
File:Megalosaurus 5.svg
Megalosaurus 5.svg
File:Megalosaurus fragments.JPG
Megalosaurus fragments.JPG

+ 15 more

More to explore

🔬 Go deeper

More advanced topics to explore

🪜 Step back

Simpler topics to build understanding

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.