Plesiosaurus is often mistakenly referred to as a dinosaur, when in fact it is a prehistoric marine reptile that lived at the same time as the dinosaurs. It had a long neck, four paddle-like flippers and a tail.
They call it home
Plesiosaurus would have roamed the vast seas of the Jurassic.
What we heard about their hearing
Plesiosaurus is likely to have had similar hearing to that of the whales and dolphins of today.
What big teeth you have
The Plesiosaurus' mouth was the perfect fish trap: it had simple needle-like teeth curved around its U-shaped jaw.
Nose knowledge
The nostrils of Plesiosaurus were positioned closer to its eyes than the tip of its snout.
The most fantastic find
The most fantastic find was a plesiosaur uncovered in 1987. Its abdomen contained bones of an embryo, which proves the animal gave birth to live young. Plesiosaurs gave birth to just one individual, allowing us to make inferences on the degree of maternal care.
Plesiosaurus features
Height: 1m (3.28ft)
Length: 3.5m (11.48ft)
Weight: 449.96kg (992lbs)
Top speed: 16.5kph (10.25mph)
Vision: Plesiosaurus' eyes were positioned to the sides of their head, looking upwards so they could ambush their prey from below.
Skin: Plesiosaurs had smooth skin to reduce drag in the water.
Brain: Plesiosaurs had smaller brains relative to body size than most dinosaurs.
Prey: From the stomach contents of the plesiosaurs, we can tell they fed on belemnites and ammonites as well as prehistoric fish.
Bite: Plesiosaurus could use its long neck to sneak up on its prey from a distance with little chance of being detected.
Nest: Plesiosaurs are known to have given birth to a single live offspring, just like us. An unborn plesiosaur would have been 1.5m (5ft) long – that's a whopping one third of its mum.
Plesiosaurus facts and theories
- Some say Plesiosaurus looked like the legendary Loch Ness Monster.
- The largest stomach stone found in a plesiosaur was a huge 8x6x3cm (3x2x1in) and the total weight of stones in its body would have been about 2.2kg (5lb). Plesiosaurs would ingest gizzard stones to aid in the digestion of their tough prey, although it is also thought that they could have functioned as ballast in the water.
- Plesiosaurus looks something like a swimming Brachiosaurus – a big animal with a long neck, tiny skull, and barrel-shaped chest. Both of these unusual animals probably used their long necks to reach otherwise inaccessible food items. The long neck of Plesiosaurus is supported by approximately 40 individual vertebrae. For comparison, a human has only seven neck vertebrae.
- Plesiosaurus was a small plesiosaur. Mauisaurus reached a whopping 20m (66ft) long.