Explore our fossils to see what animals lived in our seas around 100 million years ago.
Marine and coastal life has changed dramatically over the past century. But how do we know this? And why is this useful to us now? Pieces of this puzzle can be put together through delving into our natural history collections from the past 100 years.
Ray-finned fish (Actinopterygii) evolved over 400 million years ago and are so-called because their fins have a web of skin between several spines. Today, they are the most diverse group of vertebrates with more than 30,000 species which is around half of all living vertebrates on Earth.
The specimens in this gallery are around 85 million years old. By this time, evolution had produced many sorts of fish, types like these being similar in many ways to modern fish. Many specimens of these species have been found which tell us that they probably swam in large schools.
Sea stars, sea lilies and sea urchins are all Echinoderms. The name Echinoderm comes from the Greek word meaning ‘spiny skin’. They first appeared in the fossil record in the early Cambrian period around 542-488 million years ago. The fossils in this gallery are between 100 – 85 million years old.
Sussex covered by an ancient sea
Did you know that 100 million years ago the whole of the UK was covered by a warm ocean? Only the tops of the Scottish mountains would have poked above sea-level.
How do we know this? What lived in this warm shallow sea covering Sussex? How does it compare to now? We can use the Booth Museum’s important collection of fossils from the Cretaceous period to find out more.
How do we know that Sussex was covered by a warm sea? The answer lies in the familiar white cliffs of the South Coast – Beachy Head, The Seven Sisters and Dover. These cliffs are all made of a rather special rock. Chalk.
But what is chalk?
When you hold a small piece of chalk in your hand from a walk along the South Downs, you are holding the remains of millions upon millions of microscopic marine plants called algae.
These marine plants thrived a in a warm sea that was 200 to 300 metres deep and covered the whole of the South Downs and most of the UK. The only part of the UK you would have been able to see 100 millions years ago would have been the highest peaks of the Scottish mountain range.
The cell walls of these plants were strengthened with a skeleton made of hard plates of calcium carbonate which, after the death of the algae, slowly sank and built up on the sea floor. Layers upon layers of these skeletons built up to form what is now the South Downs and the famous chalk cliffs.
Discover the animals that lived in the seas 100 million years ago in our fossil galleries.
Unique chalk habitats
The chalk has created rare habitats including chalk reefs which are home to an abundance of wildlife.T he Beachy Head West Marine Conservation Zone, which runs from Brighton Marina to Beachy Head, is a wonderful chalk reef. It is home to threatened species including blue mussel beds and short-snouted seahorses. Read our Rockpooling guide to find out more about what you can spot in Beachy Head West rockpools.