Devonian Period 405 Million Years Ago
The
Devonian Period began 405 million years ago and ended 60 million years
later. During this period there was a great expansion of fishes, land
plants and the first land animals, primitive amphibians. The fishes included
several types of jawless fishes, sharks, and the first bony fishes. From
the lobe-fish group the first amphibians arose. These amphibians had mixed
characteristics with the fish group. Brachiopods and mollusks continued
to wide spread. The first common ammonites appeared. Trilobites have been
greatly reduced in numbers. Horn corals are greatly varied and abundant.
On land the oldest spiders, millipedes and insects appeared. Early land plants appear during this period, they lacked true roots and leaves. These plants had developed functional vessels to deliver nutrients and water through the stem. This early primitive plants on land would evolve into widespread forests with great scale trees at the end of the Devonian Period.
