Graptolites
What were they?
Graptolites were primitive colonial animals. They are now extinct. There name is a clue to what they look like as fossils – its from the Greek – “written on rocks”. They are very useful to geologists because their simple body shape evolved many times throughout the millions of years of existence of graptolites and that allows us to tell the relative age of the rocks they are found in.
How old is it?
Graptolite fossils are found in Northumberland’s oldest rocks from the Silurian period. So they are around 420 million years old.
Where did it live?
They lived in the sea, usually feeding on microscopic food particles carried by upwelling currents.
Where are the fossils found?
They are usually found in very old mudstones but these rocks have been through a lot of stresses and strains and are often broken and shattered. Little rock cliffs of the Upper Coquet valley are good places to look.
Are these animals still alive today?
No but they are thought to have modern relatives called pterobranchs which also live in the sea.