Plants created the terrestrial biomes that animals would inhabit once vegetation had settled in. The oldest animals to adapt on land were centipedes and spindly spiderlike arachnids the size of a flea.
The early biome on solid ground supported a bevy of plants that fed arthropods, who in turn became spider snacks and centipede feed. Perhaps the most surprising thing about early arthropods was that many of them could easily be placed within groups living today. The early critters got a lot right.