Insects

DCM_G.06579Almost too fragile for fossils

Some of the most surprising fossils found along the Jurassic Coast are insects. This includes beetles, flies, dragonflies and even grasshoppers. They are only fossilised in a few rock layers where the sediment was fine enough to preserve their delicate bodies.

Cousins of crustaceans

Insects belong to a major group of animals called arthropods, which includes crabs and lobsters. Like their crustacean cousins, insects have an external, segmented skeleton (called an exoskeleton) and jointed legs. But the exoskeleton of insects is much thinner than that of crustaceans, so far fewer were preserved as fossils. They also lived on land and so had to be washed into the water and sink to the bottom to become fossilised.

Costa Rica dragonfly

 

Missing members

There is a very obvious group of insects that are missing from the Jurassic Coast fossil record – butterflies and moths. These insects specialise in feeding on pollen from flowering plants, but flowers only started to appear in the Cretaceous period, about 130 million years ago. By this time, the Jurassic Coast didn’t have the fine sediment that is needed for the  preservation of insects.