Evolutionary Evidence Uncovered

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Fossil specimens and comparative anatomy charts showing evolutionary relationships

🦕 Part 1: Fossil Evidence Analysis

Study the fossil data below:

Fossil A: Horse ancestor from 50 million years ago - small, 4-toed feet, forest habitat
Fossil B: Horse ancestor from 25 million years ago - medium size, 3-toed feet, grassland habitat
Fossil C: Modern horse - large, single-toed (hoof), grassland habitat

1. What pattern do you observe in horse foot structure over time?

Feet became smaller and gained more toes

Feet became larger and lost toes

Feet stayed the same size but changed color

No clear pattern exists

2. Based on the fossil evidence, what environmental change likely influenced horse evolution?

3. How do these fossils provide evidence for evolutionary change over time?

🦴 Part 2: Comparative Anatomy

Examine these homologous structures:

Human arm: humerus, radius, ulna, hand bones
Whale flipper: humerus, radius, ulna, flipper bones
Bat wing: humerus, radius, ulna, elongated finger bones

4. What do these three limbs have in common?

Same bone structure pattern

Same function

Same size

Evidence of common ancestry

5. Even though a whale flipper and human arm have different functions, they have similar bone structures. What does this suggest about whales and humans?

6. Circle the term that best describes structures with similar bone patterns but different functions:

Analogous structures Homologous structures Vestigial structures

🧬 Part 3: Evidence Connections & Extension

7. Explain how both fossil evidence and comparative anatomy support the theory of common ancestry.

8. Scientists discover a new fossil with wing bones similar to bats, but also with small teeth like early mammals. The fossil is 60 million years old. What might this fossil tell us about bat evolution?

9. Why is it important for scientists to study both fossils AND comparative anatomy rather than just one type of evidence?