There is some evidence that simple life may already have invaded the land at the start of the Palaeozoic, but substantial plants and animals did not take to the land until the Silurian and did not thrive until the Devonian. Although primitive vertebrates are known near the start of the Palaeozoic, animal forms were dominated by invertebrates until the mid-Palaeozoic. Fish populations exploded in the Devonian. During the late Palaeozoic, great forests of primitive plants thrived on land forming the great coal beds of Europe and eastern North America. By the end of the era, the first large, sophisticated reptiles and the first modern plants (conifers) had developed.