Megalosaurus: The First Dinosaur

Megalosaurus (“Great Lizard”) holds a title that no other dinosaur can claim: it was the very first dinosaur ever described and named scientifically. In 1824, nearly 20 years before the word “dinosaur” was even invented, British geologist William Buckland described a massive lower jaw with serrated teeth found in a slate quarry in Stonesfield, Oxfordshire, England. This single discovery sparked the beginning of paleontology as we know it and launched humanity’s 200-year fascination with prehistoric life.

Physical Characteristics

The “Great Lizard”

When Megalosaurus was first discovered, scientists had absolutely no concept of what a dinosaur was. Their early interpretations were wildly wrong — and fascinatingly so:

• Original vision (1820s): Scientists imagined Megalosaurus as a gigantic, 20-meter-long, four-legged lizard — essentially a monitor lizard scaled up to monstrous proportions. It was depicted crawling on all fours with its belly close to the ground.
• Victorian revision (1850s): Richard Owen (who coined the word “dinosaur”) reimagined it as a heavy, rhinoceros-like quadruped with a massive body and thick legs.
• Modern understanding: We now know Megalosaurus was a bipedal theropod — walking upright on two powerful legs with its tail held horizontally for balance, much like its later relative Allosaurus.

Size and Build

Megalosaurus was a large, powerful predator:

• Length: Approximately 9 meters (30 feet)
• Weight: Around 1,100 kg (2,400 lbs)
• Height: About 3 meters (10 feet) at the hip
• Build: Robust and muscular, with strong hind legs and shorter but functional forelimbs
• Skull: Large head with powerful jaw muscles

While not as large as later giant theropods like T-Rex (12-13 meters) or Giganotosaurus (12-13 meters), Megalosaurus was the apex predator of its Middle Jurassic ecosystem — a time 100 million years before those later giants existed.

Distinctive Teeth

The teeth of Megalosaurus were what first caught William Buckland’s attention and remain one of its best-known features:

• Curved and serrated — like steak knives, with fine serrations along both edges for slicing through flesh
• Laterally compressed — flattened from side to side, typical of meat-eating theropods
• Constantly replacing — like sharks and all dinosaurs, Megalosaurus continuously grew new teeth to replace broken or worn ones throughout its life
• Variable sizes — larger teeth at the front of the jaw for grabbing prey, slightly smaller ones further back for processing meat

Relation to Other Theropods

Megalosaurus belongs to the family Megalosauridae, which includes several other large Jurassic predators:

Megalosaurid	Length	Location	Period
Megalosaurus	9 m	England	Middle Jurassic
Torvosaurus	10-11 m	USA, Portugal	Late Jurassic
Eustreptospondylus	6 m	England	Middle Jurassic
Afrovenator	8 m	Niger	Middle Jurassic

Habitat and Diet

Middle Jurassic Europe

166 million years ago, Europe looked nothing like it does today:

• An archipelago — instead of a continent, Europe was a series of tropical and subtropical islands scattered across a warm, shallow sea
• Warm and humid — the climate was much warmer than today, with no ice caps
• Rich marine life — the shallow seas between islands teemed with marine reptiles, fish, and invertebrates
• Lush vegetation — ferns, cycads, and conifers covered the islands

Diet and Hunting

Megalosaurus was the apex predator of its island ecosystem:

• Sauropods — it likely hunted medium-sized sauropods like Cetiosaurus that shared its habitat
• Stegosaurs — early stegosaurs were present in the Middle Jurassic and would have been potential prey
• Smaller dinosaurs — various ornithopods and small theropods
• Scavenging — its fossils are often found in marine deposits, suggesting it scavenged along coastlines and may have eaten washed-up marine animals
• Opportunistic — as the top predator on relatively small islands, Megalosaurus likely ate whatever was available

The Birth of Dinosaur Science

William Buckland’s Discovery (1824)

The story of Megalosaurus is the story of how dinosaur science began:

1. 1676: A massive bone fragment was found in Oxfordshire and described by Robert Plot as belonging to a “giant human” — it was almost certainly a Megalosaurus bone, making it the first dinosaur bone ever illustrated
2. 1815-1818: More bones, including the famous lower jaw with teeth, were collected from a quarry in Stonesfield
3. 1824: William Buckland, Oxford professor of geology, formally described and named the animal Megalosaurus — the first dinosaur ever given a scientific name
4. 1842: Richard Owen grouped Megalosaurus with Iguanodon and Hylaeosaurus to create a new group he called “Dinosauria” — literally “terrible lizards”

Without Megalosaurus, the word “dinosaur” might never have been coined, and the entire field of paleontology might have developed very differently.

The Crystal Palace Statues

In 1854, artist and sculptor Benjamin Waterhouse Hawkins created life-sized sculptures of prehistoric animals for the Crystal Palace park in London. The Megalosaurus statue depicts it as a lumbering, rhinoceros-like quadruped with a hump on its back — completely wrong by modern standards, but a remarkable achievement for the time.

These statues still stand today in Crystal Palace Park, south London. They are Grade I listed monuments and represent one of the most important landmarks in the history of science — the first time the public could see what scientists thought prehistoric animals looked like. A famous New Year’s Eve dinner was even held inside the mold of the Iguanodon statue before it was completed.

The “Wastebasket Taxon” Problem

For over a century after its discovery, Megalosaurus became a “wastebasket taxon” — a catch-all name for any unidentified meat-eating dinosaur. Whenever fragmentary theropod bones were found in Europe (or anywhere else), they were simply labeled “Megalosaurus sp.” regardless of whether they actually belonged to Megalosaurus.

At one point, over 40 “species” of Megalosaurus had been named. Modern revisions have stripped away most of these misidentifications, leaving only the original Megalosaurus bucklandii as a valid species. This cleanup has been an ongoing process since the mid-20th century.

Literary Fame

Charles Dickens’ Dinosaur

Megalosaurus holds the distinction of being the first dinosaur ever mentioned in a work of fiction. In the opening paragraph of Charles Dickens’ Bleak House (1852), Dickens describes the muddy streets of London:

“As much mud in the streets as if the waters had but newly retired from the face of the earth, and it would not be wonderful to meet a Megalosaurus, forty feet long or so, waddling like an elephantine lizard up Holborn Hill.”

This passage shows that just 28 years after Megalosaurus was named, it had already entered popular culture — the very first pop-culture dinosaur.

Frequently Asked Questions

Q: Was it bigger than T-Rex? A: No. Megalosaurus was about 9 meters long and 1.1 tons — roughly half the size of T-Rex at 12-13 meters and 8-14 tons. However, Megalosaurus lived about 100 million years earlier, during the Middle Jurassic.

Q: Why don’t we see it in movies? A: Megalosaurus is often overshadowed by later, more complete and larger dinosaurs like Allosaurus and T-Rex. Since we mostly have fragmentary bones of Megalosaurus, it’s harder to reconstruct and less visually distinctive on screen.

Q: Was it the first dinosaur that ever existed? A: No — it was the first dinosaur scientifically named, not the first to exist. Dinosaurs first appeared about 230 million years ago in the Triassic, while Megalosaurus lived about 166 million years ago. Earlier dinosaurs like Herrerasaurus and Eoraptor predate it by 65 million years.

Q: Can I see the original fossils? A: Yes! The original Megalosaurus jawbone and other specimens are on display at the Oxford University Museum of Natural History in England. The Crystal Palace statues can be visited for free in Crystal Palace Park, south London.

Q: Is it related to Allosaurus? A: They’re both large theropod predators, but they belong to different families. Megalosaurus is a megalosaurid, while Allosaurus is an allosaurid. They’re cousins rather than close relatives, and Megalosaurus lived about 15 million years before Allosaurus.