Evolutionary Evidence & Fossils

What is a fossil?

The preserved remains or traces of an organism from the past.

Why are fossils important?

They provide evidence of organisms that lived in the past.

How can fossils form from hard body parts?

Hard parts may be buried and preserved in sedimentary rock.

How can fossils form through mineral replacement?

Minerals gradually replace original biological material, preserving its shape.

How can fossils form as casts or impressions?

An organism leaves an impression in sediment that later hardens.

How can fossils form when decay does not occur?

Organisms may be preserved in amber, ice or peat.

Why are fossils of soft-bodied organisms less common?

Soft tissues usually decay before they can be preserved.

Why is the fossil record incomplete?

Many organisms decayed without fossilising, and geological processes have destroyed fossils.

How can fossils provide evidence for evolution?

They reveal changes in organisms over geological time.

What is an extinct species?

A species with no living individuals remaining.

How can fossils reveal extinct species?

They preserve evidence of organisms no longer found alive.

What is a transitional fossil?

A fossil showing a combination of characteristics associated with different evolutionary groups.

Why are transitional fossils useful?

They provide evidence of evolutionary relationships and changes over time.

How can the age of a fossil be estimated?

By examining rock layers or using radiometric dating.

What is the principle of superposition?

In undisturbed sedimentary rocks, older layers are usually beneath younger layers.

Why is fossil evidence not always sufficient to reconstruct evolution completely?

The fossil record contains gaps and uneven preservation.

How can new fossil discoveries affect evolutionary explanations?

They can provide new evidence and refine evolutionary relationships.

What does the fossil record suggest about life on Earth?

Organisms have changed over time, and many species have become extinct.