Answer:
In the early Paleozoic era, life was restricted to the sea.
Step-by-step explanation:
The biological content of the Paleozoic Era was quite rich; it included numerous forms of aquatic life: algae, sponges, corals, brachiopods, bivalve mollusks, gastropods and cephalopods; Among the arthropods, the trilobites and the first insects stood out; aside, also the first arachnids and echinoderms. The vascular plants and pteridophytes (or ferns) developed in that era, especially abundant during the Carboniferous period. Also in this era appeared the first vertebrates, cartilaginous fish, amphibians and even the first reptiles.
Most of the plants and animals did not colonize land until the Silurian and did not prosper until the Devonian Era.