1. Evidence of Evolution

2. I. The Fossil Record
fossils of animals show a pattern of development from early ancestors to modern descendants
fossils offer the most direct evidence that evolution takes place

3. fossils provide an actual record of Earth’s past life-forms
however, the fossil record and thus the record of the evolution of life, is not complete because many species have lived in environments where fossils do not form

4. Horse Fossil Record

5. Fossil Layers
Most
Primitive

6. Which layer gave rise to the fossils in layer B
Which layer gave rise to the fossils in layer B? Which layer is the most primitive?

7. II. Anatomy & Development
Comparisons of the anatomy of different types of organisms often reveal basic similarities in body structures even though the structure’s functions may differ between organisms

8. vestigial structures – a structure in an organism that is reduced in size and function and that may have been complete and functional in the organism’s ancestor
ex: hind limbs of whales, tailbone of
human
homologous structures – anatomical structures that share a common ancestry;
same structure but different function
ex: forelimbs of certain animals

9. Vestigial Structures A structure that has been reduced in size and function but may once have been complete and functional.
leg bones
tailbone
Whale
Human

10. Homologous Structures The bones in a human’s arm, cat’s arm, whale’s arm, and bat’s arm are the same (homologous), but the function is different.

11. Embryological Development
Similarities seen are pharyngeal pouches (gills), tail, and buds that become limbs; this suggests a common ancestor

12. III. Biological Molecules
similarities in amino acid sequences suggest that organisms are related, and may indicate the degree of relatedness
differences in amino acid sequences suggest that mutations have introduced genetic variation into populations of organisms that eventually result in evolution

14. Questions:
1. List 3 types of evidence that show evolution has occurred.
2. Of the three types of evidences that evolution has occurred, which gives the strongest evidence that evolution has occurred?
3. What is the difference between homologous and vestigial structures?