What were the first animals to appear in water and on land?

Fossils reveal that the first soft-bodied animals appeared about 600 million years ago in the oceans, and included a form of jellyfish and segmented worms. The first land animals to conquer the land may have been the arthropods, such as scorpions and spiders. Many of these creatures have been found in the old rock layers, usually with fossils of the oldest known vascular land plants. The first land animals evolved around 440 million years ago and the dinosaurs evolved around 250 million years ago. So, it took about 190 million years for dinosaurs to appear after the first land animals. These numbers change as scientists discover new fossils.