Photo AI
3.1.1 Explain why shark fossils that have been discovered are limited to denticles and teeth - NSC Marine Sciences - Question 3 - 2022 - Paper 2
Question 3
3.1.1 Explain why shark fossils that have been discovered are limited to denticles and teeth. Sharks do not preserve very well. Usually, only their dermal denticles... show full transcript
Worked Solution & Example Answer:3.1.1 Explain why shark fossils that have been discovered are limited to denticles and teeth - NSC Marine Sciences - Question 3 - 2022 - Paper 2
Step 1
Explain why shark fossils that have been discovered are limited to denticles and teeth.
Answer
Shark fossils are predominantly limited to their dermal denticles and teeth because their skeletons are primarily made of cartilage, which does not easily fossilize. The hard structure of teeth made from calcium-based substances preserves more effectively, leading to a greater likelihood of fossilization.
Step 2
Step 3
Discuss which limitations these organisms overcame as they returned to the marine environment.
Answer
- Locomotion: Limbs that were used for walking had to adapt to swimming.
- Gaseous exchange: Adaptations were needed to exchange gases efficiently underwater.
- Osmoregulation: Managing hydration became essential for survival in a saline environment.
Step 4
Differentiate between the reproductive processes in amphibians and reptiles.
Answer
Amphibians typically use external fertilization, laying their eggs in water, which exposes them to environmental stressors. In contrast, reptiles primarily utilize internal fertilization, laying eggs on land with a tougher, calcified shell that provides better protection from desiccation.