Biological evolution
For more than a century and a half, scientists have been gathering evidence that expands our understanding of both the fact and the processes of biological evolution. They are investigating how evolution has occurred and is continuing to occur.
In 2004, for example, a team of researchers made a remarkable discovery. On an island in far northern Canada, they found a four-foot-long fossil with features intermediate between those of a fish and a four-legged animal. It had gills, scales, and fins, and it probably spent most of its life in the water. But it also had lungs, a flexible neck, and a sturdy fin skeleton that could support its body in very shallow water or on land.
Earlier scientific discoveries of fossilized plants and animals had already revealed a considerable amount about the environment in which this creature lived. About 375 million years ago, what is now Ellesmere Island in Nunavut Territory, Canada, was part of a broad plain crossed by many meandering streams. Trees, ferns, and other ancient plants grew on the banks of the streams, creating a rich environment for bacteria, fungi, and simple animals that fed on decaying vegetation. No large animals yet lived on the land, but Earth’s oceans contained many species of fish, and some of those species fed on the plants and animals in shallow freshwater streams and swamps.
In 2004, for example, a team of researchers made a remarkable discovery. On an island in far northern Canada, they found a four-foot-long fossil with features intermediate between those of a fish and a four-legged animal. It had gills, scales, and fins, and it probably spent most of its life in the water. But it also had lungs, a flexible neck, and a sturdy fin skeleton that could support its body in very shallow water or on land.
Earlier scientific discoveries of fossilized plants and animals had already revealed a considerable amount about the environment in which this creature lived. About 375 million years ago, what is now Ellesmere Island in Nunavut Territory, Canada, was part of a broad plain crossed by many meandering streams. Trees, ferns, and other ancient plants grew on the banks of the streams, creating a rich environment for bacteria, fungi, and simple animals that fed on decaying vegetation. No large animals yet lived on the land, but Earth’s oceans contained many species of fish, and some of those species fed on the plants and animals in shallow freshwater streams and swamps.
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