One of the most important milestones in the evolution of life began some 400 million years ago, when the first animals made their way from water onto land. At that time, known as the Devonian period, the world was changing dramatically: complex plant ecosystems formed on land, the first woody plants appeared, and the water's edge was becoming a new kind of environment.
The move to land was a very gradual process, and the evolution of limbs wasn't a simple adaptation resulting from animals crawling onto the shore and never looking back. In fact, the new picture of this transition shows that most of the changes needed for life on dry land happened in creatures that were still living in the water. Some fishlike vertebrates had already begun to evolve limbs by around 400 million years ago: They were called "lobe-fins," with fins that looked like fleshy paddles, and they had lungs as well as gills.
The move to land was a very gradual process, and the evolution of limbs wasn't a simple adaptation resulting from animals crawling onto the shore and never looking back. In fact, the new picture of this transition shows that most of the changes needed for life on dry land happened in creatures that were still living in the water. Some fishlike vertebrates had already begun to evolve limbs by around 400 million years ago: They were called "lobe-fins," with fins that looked like fleshy paddles, and they had lungs as well as gills.
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