fossils

What are fossils?

Remains of organisms from millions of years ago, found in rocks.

What do fossils tell us?

How organisms lived long ago and how they have changed over time.

How do fossils provide evidence for evolution?

They show how organisms have changed over millions of years.

Why is the fossil record incomplete?

Many early life forms were soft-bodied and left few traces, and some traces were destroyed by geological activity.

What are three ways fossils can form?

1. Gradual replacement by minerals-things like teeth shells vibes don’t decay easily so can last a long time when burned eventually they’re replaced by minerals as they decay

Casts and impressions-sometimes fossils are formed when an organism is buried in a loft material like clay. The claw layer hardens around it and the organism decays leaving cast

1. Preservation in places where decay doesn’t happen-the microbe involved in decay need the right conditions to break down material (lots of oxygen,moisture) if conditions aren’t right decay won’t take place and the dead organisms remains wil be preserved

How do fossils form in places where decay doesn’t happen?

Conditions like extreme cold, lack of oxygen, or dryness prevent decay microbes from surviving.

Why was there a lack of valid evidence for origins of life/fossils

-Scientist believed many early organisms were softbodied and soft tissue tends to decay away completely without forming fossils.

– fossils that did form millions of years ago may have been destroyed by geological activity e.g. the movement of tectonic plates.

This means that the fossil record is incomplete bracket we don’t have fossils of every organism or even every type of organism that has ever lived