ABSTRACT
BACKGROUND: COLONIZATION OF THE LAND The consequences of plants and animals leaving the marine realm to colonize the land were far-reaching, not least for the evolution of Man, who is part of the Earth’s terrestrial biota. Few of the metazoan phyla which emerged from the great Cambrian explosion produced terrestrial forms, but those which did have became very successful in terms of diversity. The Arthropoda includes some terrestrial crustaceans (e.g. woodlice), but of much greater importance are the terrestrial chelicerates (spiders, scorpions, mites, and their allies) and the insects, which make up 70% of all animals alive today. From fish arose the tetrapods: amphibians, reptiles, birds and mammals. Mollusks, too, in the form of slugs and snails, have been remarkably successful on land, as any gardener will testify. In order to live successfully on land, plants developed features such as stiff trunks and reproductive devices which gave rise to the familiar trees and flowers we see on land today.
