Pangea prehistoric landscape. Artwork showing a landscape at the time of the Pangea supercontinent (300 to 200 million years ago) during the Paleozoic Era and Mesozoic Era. Unlike earlier supercontinents, which had been barren, at this period both plants and invertebrate animals had long since emerged from the oceans to colonise the land. Insects had evolved, as well as seed-bearing plants (gymnosperms, some examples shown here), but flowering plants (angiosperms) would not evolve for another 170 million years. The ozone layer had formed, and amphibians had emerged onto land, the first vertebrates to do so.