Chapter 15, Problem 20A

Summary Introduction

To explain:

The reason that fossils are considered to provide the strongest evidence supporting the theory of evolution.

Introduction:

A fossil is any preserved evidence of an organism. Plants, animals and even bacteria can form fossils. More than 99 percent of the species that existed have become extinct. Only a small percentage of these organisms are preserved as fossils. The evidence for evolution is more convincing when it is supported by many pieces of evidence.

Answer to Problem 20A

Fossils provide information about the ancestry of organisms and patterns of evolution. Scientists have found many transitional fossils that contain features shared by different species. These provide detailed patterns of evolutionary change for the ancestors of many modern animals like humans, whales and horses.

Explanation of Solution

The evidence for evolution is more convincing when it is supported by many pieces of evidence. Fossils provide most significant evidence of evolutionary change. They provide a record of species that once existed on earth. They show how ancient species were similar to species that live on Earth today.

However not all extinct fossils have modern counterparts and some ancient species like the horseshoe crab have remained virtually unchanged for millions of years. The fossil records are an important source of information for determining the ancestry of organisms and the patterns of evolution.

Darwin predicted the existence of fossil intermediates. Today hundreds of thousands of transitional fossils have been found. Many dinosaur fossils show feathers of modern birds and the teeth and bony tails of reptiles.

Hence, fossils provide strongest evidence supporting evolution.