Did Single Celled Animals Leave Fossils?
Surprisingly, despite their very small size, many single celled animals have left a fossil record. These fossil deposits now enable scientists to identify geological time periods and climatic conditions that occurred millions of years ago. Foraminiferans, one type of single celled animal were plentiful 135 million years ago and the deposits from their chalky shells form a distinct layer that tells archeologists where the layer from the Cretaceous period is in rock layers. One well known landmark formed by such deposits are the white cliffs of Dover. By studying the fossil layers of there tiny creatures, it is possible to tell what temperature the oceans were at distinct time periods in pre history. This is because, when the water is warm, the creatures form different kinds of shells to those formed when the water is cold. By analysing the shell types found in various layers, it is possible to estimate what the climate was like at that time period.
