Fossils as evidence for evolution
Biology · Key Stage 2 · The School
What a fossil is
A FOSSIL is what is left of a living thing from long ago. Fossils form very slowly. It can take millions of years. They usually form inside layers of rock. Soft body parts rot away. But hard parts, like bone and shell, can leave a fossil behind. Finding a real fossil is a bit like finding a very old letter. Reading it takes patience, and a trained eye.
A record of change over time
Fossils found deep in old rock are usually simple. Fossils found higher up, in younger rock, are often more complex. This tells us something big. Living things have changed a great deal. And they have done so over a very, very long time. Each layer of rock is like a page from that story.
Some fossils show creatures alive today
Some fossils look almost the same as animals alive today. A fossil shark tooth looks a lot like a tooth from a shark alive now. Other fossils show creatures that do not exist any more, anywhere on Earth.
Bones help show a dinosaur's size and shape. Footprints show how it walked. Nests and eggs show how some dinosaurs had their young. Now follow one real fossil, step by step. In 1861 a skeleton was found in Germany. It belonged to an animal called Archaeopteryx (say ark-ee-opt-er-ix), which lived about 150 million years ago. Step 1: look at the rock. It has clear marks of feathers around the bones. Birds have feathers. Some dinosaurs had feathers too, so feathers are only one clue. Step 2: look at the bones. Fossils of this animal show sharp teeth, clawed fingers and a long bony tail. Living birds have no teeth. Some dinosaurs had these features too. Step 3: put the clues together. This animal had features of living birds, such as feathers. It also had features living birds lack. These are sharp teeth, clawed fingers and a long bony tail. Answer: it is a mix of both. The Natural History Museum says it is widely regarded as a link between dinosaurs and birds. It adds that many people now think it should be called a dinosaur.