Analysing The Skeleton: The Plesiosaur Diet

Updated Tuesday 24th August 2004

Palaeobiology - a look at the evidence of the diet of plesiosaurs

Functional analysis of the jaws and teeth

We can also look at the jaws and teeth to learn about the diet of plesiosaurs. Pliosaurs with their massive heads and throats could eat large prey. They were not fussy eaters! Their heads and jaws were also very strong allowing them to clamp onto large prey with big deep-rooted teeth and then twist off lumps of flesh by rolling their whole body! These pieces would be of suitable size to be swallowed whole. This method of feeding is called twist feeding and is used by crocodiles. Isolated fossil bones are often found that may have been dropped by the pliosaurs during twist feeding. The teeth of some pliosaurs are unusually curved backwards, suggesting they were used to pull struggling prey into the mouth.

Functional analysis of the body

Because you must catch your meal before you can eat it, swimming speed is important for aquatic carnivores. By measuring the shape of the body, and other properties of the body that affect swimming, the speed for plesiosaurs has been estimated. Long necked plesiosaurs were estimated at 5.1 miles per hour, the speed of a slow ambush predator, and pliosaurs were slightly faster, indicating that they chased their prey rather than ambushing it.

Lookalikes - using living animals

Similarities between the teeth of marine reptiles and modern large marine carnivores provide us with clues as to the diet in extinct marine reptiles. Today killer whales (Orcinus orca) eat large mammals such as seals, sea lions and dolphins. Their teeth show many similarities with pliosaurs so they are likely to have relied on similar prey. Of course, there were no mammals then, so they must have eaten similar sized animals that were about then, such as ichthyosaurs and marine crocodiles. The teeth of plesiosaurs show similarities with the piscivorous (fish eating) gharial, also known as the gavial, a long-snouted crocodile. Both of these animal's teeth interlock, so plesiosaurs probably ate fish too.

A meat eater is not always a predator

Being a meat eater (carnivore) does not necessarily mean an animal was a predator. Stomach contents containing dinosaurs provide evidence that pliosaurs scavenged dinosaur corpses that floated out to sea. This is also evidence that large pliosaurs were opportunistic, eating whatever they came across. Cryptoclidus, a common plesiosaur in Britain during the Jurassic, had many thin needle-like teeth and may be similar to the living crabeater seal, which has sieve-like teeth for capturing krill, small shrimp-like organisms. A 'rushing upwards' style of attack is inferred for large pliosaurs like modern great white sharks, because this is an efficient way for large animals to hunt.

Combining the evidence

By combining all this evidence, we have been able to build up a picture of exactly what plesiosaurs ate.

Next: The riddle of the stomach stones


For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?

Other content you may like

The Greenland white-fronted goose Creative commons image Icon Greenland White Fronted Goose / Hilary Chambers / CC BY-ND 2.0 under Creative-Commons license audio icon

Nature & Environment 

The Greenland white-fronted goose

Waterfowl expert Tony Fox talks to Saving Species about a goose that has been on conservation concern for many years.

15 mins
A natural history glossary Copyrighted image Icon Copyright: BBC article icon

Nature & Environment 

A natural history glossary

An A to Z of key terms in natural history

Monitoring polecat populations using roadkill Creative commons image Icon 'Velvet' / Peter Trimming / CC BY 2.0 under Creative-Commons license article icon

Nature & Environment 

Monitoring polecat populations using roadkill

Are polecat populations growing? One way to check is to survey numbers of polecats live and dead on the roads

There's a mammoth in my freezer Copyright free image Icon Copyright free: Woudlooper article icon

Nature & Environment 

There's a mammoth in my freezer

Mark Hirst looks behind the headline at the possibility of creating life from frozen animal remains.

Weaver bird nests Creative commons image Icon The Open University under Creative Commons BY-NC-SA 4.0 license video icon

Nature & Environment 

Weaver bird nests

Dr Dieter Oschadleus explains how and why weaver birds build their nests the way they do.

The science of evolution Copyrighted image Icon Copyright: Used with permission free course icon Level 1 icon

Nature & Environment 

The science of evolution

This free course debates the issues surrounding the science of evolution and religion.

Free course
5 hrs
Ancestors on the beach Copyrighted image Icon Copyright: BBC article icon

Nature & Environment 

Ancestors on the beach

Patricia Ash explores the evidence of our ancestors on the coast – and how they lived their lives

What Do Human Ears Miss? Copyrighted image Icon Copyright: Production team article icon

Nature & Environment 

What Do Human Ears Miss?

Learn more about ultrasound and infrasonic communication

article icon

Nature & Environment 

Becoming A Pest: Impacts on Other Species

The impact that the invasion of exotic plants and animals has had on the British Isles - the effects on other species