Question
TOPIC 7.6 Evidence of Evolution
(a) TOPIC 7.6 Evidence of Evolution
(b) TOPIC 7.6 Evidence of Evolution
Fossils of lobe-finned fishes, which are ancestors of amphibians, are found in rocks that are at least 380 million years old. Fossils of the oldest amphibian-like vertebrate animals with true legs and lungs are found in rocks that are approximately 363 million years old. Three samples of rocks are available that might contain fossils of a transitional species between lobe-finned fishes and amphibians: one rock sample that is 350 million years old, one that is 370 million years old, and one that is 390 million years old.
(a) Select the most appropriate sample of rocks in which to search for a transitional species between lobe-finned fishes and amphibians. Justify your selection.
(b) Describe TWO pieces of evidence provided by fossils of a transitional species that would support a hypothesis that amphibians evolved from lobe-finned fishes.
Answer/Explanation
Ans:
(a) Select the most appropriate sample of rocks in which to search for a transitional species between lobe-finned fishes and amphibians. Justify your selection. (2 points maximum)
• Selection: Rocks from 370 MYA sample.
• Justification: Transitional fossils are found between 380 MYA (when lobe-finned fishes lived) and 363 MYA (when amphibians appeared) OR between different strata/layers in the correct order.
(b) Describe TWO pieces of evidence provided by fossils of a transitional species that would support a hypothesis that amphibians evolved from lobe-finned fishes. (2 points maximum)
Descriptions include but are not limited to the following:
• Bones OR specific skeletal structures
legs /limbs/digits
vertebrae
flat skulls
(interlocking) ribs
flexible neck
• Scales
• Teeth
• Other homologous structures
• Has traits of both the lobe-finned fish and the amphibian
• Finding the transitional fossils in the same area/same environment as either the lobe-finned fish or the amphibian
• Molecular (DNA) evidence
(a) Sample 2 which is 370 million years old is most appropriate for a transitional species. This is proven by the sample being 370 million yrs old which is right between the lube-finned fishes which are 380 million years old and the amphibians which is 363 millions years old. So sample 2 was just in the middle of transitioning to an amphibian.
(b) Location of the fossils can support the hypothesis because if they are near each that shows that they evolved from the same thing. And structures of the fossils show that amphibians evolved from lobe-finned fishes because their body structure is similar and they have similar organelles.