The first land animals were “bugs,” these invertebrates helped tremendously in preparing the soil for vascular plants.
The first animals created for life on dry land were invertebrates such as worms and centipedes and millipedes. The earliest terrestrial arthropod fossil was of a scorpion-like arachnid found in layers that date from the Silurian and Devonian periods. The earliest insect fossils come from a few million years later. These early terrestrial arthropods dominated the land more than 100 million years before the arrival of the first dinosaurs. Vertebrates were placed onto the land in the Devonian period, about 380 million years ago. Ichthyostega, an amphibian, was among the first of the land vertebrates. A fossil of it was found in Greenland and it appears to have been derived from lobe-finned fishes called Rhipidistians. Reptiles were developed from amphibians. Reptiles were given scales to decrease water loss and a shelled egg, which permitted the young to be hatched on land. Among the earliest known reptiles was Hylonomus, fossils of which have been found in rocks in Nova Scotia.