1. Scientific Evidence of Common Ancestry
Reporting Category 3
Biological Evolution and Classification
Station 10
Scientific Evidence of
Common Ancestry

2. Essential Question – Bell Ringer
What information can be gained by examining the fossil remains of the ancestors of modern organisms?
By studying fossil remains, scientists can determine how closely related fossil organisms are to modern species. Fossil remains also give scientists insight into what environmental conditions were like where the fossil organisms lived.

3. Pre-Review Question
Information about past life, including the structure of organisms, what they ate, what ate them, their environment, and the order in which they lived can be determined using….
A. Vestigiology
B. The fossil record
C. Stratology
D. Ecology

4. Pre-Review Question
What does this diagram represent?
Fossil Record

5. Pre-Review Question
Based on DNA sequencing, which organisms are more closely related?
A. AAC GCA TTA GCC
B. GAC GCA TTA GCA
C. AAC AAT CCA GCA
A and B

6. Pre Review Question
Why did you choose A and B as your answer to the previous question?
Because they have the fewest DNA sequence differences.
What type of homology does this represent? A. Molecular B. Anatomical C. Developmental
A. Molecular

7. Pre-Review Question
These two cladograms represent the same information. Based on the graphic, which two organisms are most closely related?

8. Lab Activities
You will now go to the lab and complete the activities for today’s topics.

9. Draw this chart in your journal and fill in the name of the organism and the DNA sequencing from the lab activity.

10. Check your work

11. Examine this diagram to answer the following questions in your journal.

12. How has the anatomy of the horse changed over time? Skull? Legs?
All parts of the horse’s anatomy have become larger.
The face is longer, and the cheek teeth have changed in number and size (longer and less sharp).
The lower legs and feet have
changed, and the number of toes has been reduced from four smaller toes to one
large toe that we now call the hoof.

13. More Specifically
The number of toes these horses have decreases in number:
The oldest fossil has four toes; oligohippus has three; mercyhippus also has three but two are not fully formed; pliohippus has one toe but remnants of two additional ones near the knee. The modern horse, equus, has only one toe, which has evolved into a hoof while the toes have decreased in number, the skulls have increased in size.

14. I need to remember…….. I need to remember . . .
DNA sequences are used to determine how closely related organisms are to one another.
Examining fossil remains enables scientists to understand how modern organisms developed over time.

15. Post Review Question Vestigial structures Analogous structures
What do these
structures
represent?
Vestigial structures
Analogous structures
Homologous structures
Radiant structures

16. Post Review Question
If two different species have homologous structures, what does this tell you about their evolutionary history?
They share a common ancestor.
They do not share a common ancestor

17. Post Review Question
The process by which unrelated organisms independently evolve similarities when adapting to similar environments.
A. Convergent Evolution
B. Divergent Evolution
C. Adaptive Radiation
D. Symbiosis 17

18. Post Review Question What does the circled structure represent?
Vestigial structure
Analogous structure
Homologous structure
Radiant structure