The Ordovician spans from 485 million to 444 million years ago. During this time span, tectonic forces which move the continents had collected them into a single landmass known as Pangaea (the most recent supercontinent), which then separated into the current continental landmasses. Plant life on land appeared in the early Phanerozoic eon.
The time span of the Phanerozoic starts with the sudden appearance of fossilized evidence of a number of animal phyla the evolution of those phyla into diverse forms the emergence and development of complex plants the evolution of fish the emergence of insects and tetrapods and the development of modern fauna. The time before the Phanerozoic, called the Precambrian, is now divided into the Hadean, Archaean and Proterozoic eons. It covers 541 million years to the present, and it began with the Cambrian Period when animals first developed hard shells preserved in the fossil record. The Phanerozoic Eon is the current geologic eon in the geologic time scale, and the one during which abundant animal and plant life has existed.
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