Chapter 11

Evidence About Earth’s Past

11.1 Fossils

Lesson Objectives

• Explain why it is rare for an organism to be preserved as a fossil.


• Distinguish between body fossils and trace fossils.


• Describe five types of fossilization.


• Explain the importance of index fossils, and give several examples.


• Describe what a living fossil is.

Introduction

Throughout human history, people have discovered fossils and wondered about the creatures
that lived long ago. In ancient times, fossils inspired legends of monsters and other strange
creatures. TheChinesewriterChangQureportsthediscoveryof“dragonbones,”whichwere
probably dinosaur fossils in China 2,000 years ago. The griffin, a mythical creature with a
lion’s body and an eagle’s head and wings, was probably based on skeletons ofProtoceratops
that were discovered by nomads in Central Asia (Figure11.1).

Another fossil reminded the Greeks of the coiled horns of a ram. The Greeks named them
ammonites after the ram godAmmon. Similarly, legends of the Cyclops may be based on
fossilized elephant skulls found in Crete and other Mediterranean islands. Can you see why
(Figure11.2)?

Many of the real creatures whose bones became fossilized were no less marvelous than the
mythical creatures they inspired (Figure 11.3). The giant pterosaurQuetzalcoatlus had
a wingspan of up to 12 meters (39 feet). The dinosaurArgentinosaurushad an estimated