WHALE EVOLUTION EVIDENCE TO SUPPORT THEORIES [3 points each]

MESONYCHIDS Explain what specific characteristics the Mesonychids exhibits based on the fossils found in Pakistan. In what range of years do the scientists estimate at which these animals may have lived. What [whale-like] features supply evidence that they may have been early ancestors of the modern whale?

PAKICETUS Philip Gingerich and his team discovered fossils in Pakistan and joked that he found a “walking whale”. What are some of the fossils they found that describe what this land mammal may have looked like? What pieces of evidence support that Pakicetus may have been an early ancestors of the modern whale (think about the fossils and the location of where they were found)?

BASILOSAURUS Basilosaurus was a huge ocean dwelling creature that scientists infer would not be possible to move on land. What non-whale like features did the Basilosaurus possess that helps support the theory that whales evolved from land-dwelling creatures?

RODHOCETUS Explain how the fossil evidence is used to support the transition from a land creature to an ocean dwelling one.

SKELETAL ANALYSIS: SKULL, SPINE, FORE LIMBS AND HIND LIMBS [5 points] Note your finding/ ideas about the type of organism, its features and how it may have survived. Skull & Teeth

Spine, Neck & Ribs

Fore Limbs

Hind Limbs Which of the three modern-day organisms have similar body features similar to these “mystery” fossils?

Summarize: Hypothesize how the “mystery” organism may have moved, what it fed on and where it may have lived (habitat).

FEATURES [2 points] When a new fossil skeleton is discovered, one of the first questions a scientist asks is what animal or family of animals it is similar to. Even a partial skeleton allows a paleontologist to identify features that match with other animals. By identifying similar features, scientists can sort which animals are closer relatives and where an animal fits into the overall scheme of living things. In the case of extinct animals, scientists can attempt to sort out if they are the ancestors of living animals, and how they evolved over time. Take the next few minutes to consider the assembled Rodhocetus skeleton. Compare it to the skeleton of a modern dolphin (a type of small whale) and a modern shark. These two aquatic animals are similar in size but belong to different families. Check out the creature’s features. Then decide if Rodhocetus is more closely related to a shark than to a dolphin. Justify your reasoning.

MISSING LINKS [3 points] Dr. Gingerich’s original article about Rodhocetus did not include information about its tail. At that time, no tail for the fossil had been discovered. Try to predict what kind of tail belongs on this ancient whale. Consider the information given below. Then draw the tail on the partial Rodhocetus skeleton on the Creature Features: Comparing Anatomy sheet. Explain why you think this is the likely tail for this animal.

DRAWING CONCLUSIONS [6 points] Darwin described the perceived lack of transitional fossils as, "...the most obvious and gravest objection which can be urged against my theory," Explain why the absence of transitional (any fossilized remains of a life form that exhibits traits common to both an ancestral group and its derived descendant group) fossils is not a fair argument against evolution.

3 POINT SHORT RESPONSE RUBRIC SCORE

3

2

1 0

Response Features Student has demonstrated a thorough understanding of the scientific concepts. Valid evidence is included to support the prompt. Relevant facts, definitions and details are and the student explanations and/or interpretations are clear and complete. The response may contain minor flaws that do not detract from the demonstration of a thorough understanding of the concept. The student has provided a response that is only partially correct. The student may provide some relevant facts and concrete details but still demonstrates a misunderstanding of the underlying scientific concepts. Some spelling errors and incomplete sentences are present. Student has provided a response that does not demonstrate an understanding of the scientific concepts and/or expectations embodied in the task. The student’s explanation may lack sufficient information contain misunderstandings of the underlying scientific concepts and/or may be incorrect. Many grammatical errors are present. The student has not provided a response.