Summary:
- Fossils provide evidence of species that lived in the past and have since gone extinct.
- Consider the example of the horse, shown in the Figure below.
- Fossil evidence, depicted by the skeletal fragments, demonstrates evolutionary milestones in this process.
- Notice the transformation of the leg bones from having four distinct digits to that of today's horse.
- The oldest horse fossils show what the earliest horses were like.
- They were about the size of a fox, and they had four long toes.
- Other evidence shows they lived in wooded marshlands, where they probably ate soft leaves.