7. Evidence of the events in Earth's history is found within the rocks. |
Fossils buried within the rock layers are evidence for the events in Earth’s history.
Click on each of the fossils shown to find out what they are.
We can apply the Law of Superposition to the fossils as well as to the
rocks. Which of the fossils is the earliest (oldest)?
a.) Brachiopod | |
b.) Eurypterid | |
c.) Trilobite | |
d.) Ammonite |
These are ammonites, a chambered mollusc not unlike the living Nautilus. Ammonites went extinct at the same time as the dinosaurs, about sixty-five million years ago. |
The eurypterids were one of the fiercest predators in ancient seas. Some reached more than two meters (six feet) in length, making them the largest arthropods that ever lived. The last ones went extinct about 245 million years ago. |
Brachiopods are marine animals that look a bit like clams. They are still common in cold waters today, but the height of their diversity occurred about 400 million years ago. |
Trilobites ("three lobes") are so called because their bodies are divided into three lobes: a middle lobe and one on either side. They first appeared about 540 million years ago. |
Ooops! Remember that the Law of Superposition means that the oldest rocks and fossils will be at the bottom!   Try again.