Do Fossils Show Change?

Purpose: To examine fossils and compare them to the present day horse. To determine if changes in horses have taken place over time.

Data: Define the following Keywords.

adaptation __________________________________________________________________________________
fossil_______________________________________________________________________________________
natural selection ______________________________________________________________________________
transition fossils_______________________________________________________________________________

Part A. Examine the diagrams in Figure 1. Use the diagrams to fill in Table 1.

	Hyracotherium	Miohippus	Merychippus	Equus
Size (cm)
Type of Environment

Hyracotherium	Miohippus	Merychippus	Equus
65 million years ago	30 million years ago	13 million years ago	Today

Part B. Fossil Bone Structure. Examine the fossils of bone structure and teeth for each species. Bone structure and teeth can be used to determine how each animal was adapted for its environment and the type of food it ate.

The bones in the following diagrams show fossils of the front foot bones and teeth of each species. The foot bones at the upper right of each diagram indicate the relative sizes of each species.

Look for and color the following bones in each species:
1. Color the toe bones red. These bones are marked with an x.
2. Color the foot bones blue. These bones are marked with an y.
3. Color the ankle bones green. These bones are marked with an w.
4. Color the heel bones yellow. These bones are marked with an z.
Using the diagrams in Figure 2, make measurements to fill in Table 2.

Species	Hyracotherium	Miohippus	Merychippus	Equus
Number of toes
Number of toe bones
Number of foot bones
Number of ankle bones
Number of heel bones
Total number of foot bones
Length of foot (mm)
Height of teeth (mm)

Questions:

What changes occurred in the surroundings of the species from Hyracotherium to Equus?
What change occurred in the shape of each species from Hyracotherium to Equus?
What change occurred in the size of each species from Hyracotherium to Equus?
As the surroundings changed, what happened to the teeth of each species?
Describe the overall changes in foot length, number of toes, and size of toes in each species over time.
Could natural selection have caused changes in the size, feet, and teeth of each species?

Conclusion:

What did you learn about fossil evidence related to change in species? Does this show evidence of evolution of the horse? Could these fossils represent transition forms of the modern horse? What else could they represent?