Fossil Marine Reptiles

Learn what was going on in the oceans while the dinosaurs roamed the Earth. See how an ichthyosaur gave birth and discover the giant land mammal often mistaken for a dinosaur.

The Fossil Marine Reptiles gallery is located in Fossil Way between the Hintze Hall (formerly the Central Hall) and the Birds gallery.

Cases from the Marine Fossil Reptiles gallery.

This gallery has some of the best examples of marine reptile fossils ever found in Britain.

Head of an ichthyosaur fossil.

One of the  ichthyosaur fossils in the gallery is the largest and most complete of its kind. Like many others, it was discovered by determined fossil-hunter Mary Anning in Lyme Regis – a Dorset town rich in Jurassic fossils.

Pregnant ichthyosaur fossil showing three skeletons of young inside her body

Among the Museum’s many ichthyosaur fossils are examples of two pregnant creatures. One fossil has three skeletons of young inside her body. Another fossil shows a baby being born tail first, just as the mother died.

Huge plesiosaur fossil.

This huge plesiosaur fossil is 187–178 million years old and is one of the earliest known of its kind. The powerful creature preyed on other plesiosaurs, ichthyosaurs and fish.

Mary Anning

Meet our Mary Anning gallery character in Fossil Marine Reptiles and hear her stories of life as a pioneering 19th-century fossil hunter in Lyme. Mary helped discover the first ichthyosaur as a young girl.

Find out when Mary Anning is in the gallery next.

Giant sloth

At the far end of the gallery, look out for the skeleton of the giant ground sloth, Megatherium americanum. Now extinct, this creature - whose name means great beast - lived in South America up until around 10,000 years ago. At first glance it is often mistaken for a dinosaur, but the giant ground sloth was actually a mammal.