Summary
Tiktaalik is a prehistoric fish. Tiktaalik is the earliest known animal with fingers. Tiktaalik would not have stood out as unusual since variations were great among prehistoric fish. Tiktaalik is likely an ancestor to the land animals that have fingers.
Strongly Supported Conclusions
Land animals with fingers today likely trace their ancestry back to a prehistoric fish. Comparing Tiktaalik to other fish at its time would not reveal its evolutionary importance.
A
Tiktaalik likely used its fingers to move on land.
This is unsupported because we don’t know where Tiktaalik lived, and its life may have been confined to the sea.
B
Tiktaalik’s fingers were its only feature to play a significant role in the development of modern land animals.
This is unsupported because the author never reveals if Tiktaalik also had other features that were unique or significant. The discussion is confined to its fingers.
C
Tiktaalik is not the ancestor of any currently surviving fish species.
This is unsupported because Tiktaalik may have had several descendants of fish, either with or without fingers.
D
No fish without fingers would ever be able to move on land.
This is unsupported because there may be other appendages besides fingers that could enable a fish to move on land.
E
The evolutionary significance of Tiktaalik could not be determined just through comparison to fish species of its time.
This is strongly supported because comparing Tiktaalik to other fish wouldn’t yield significant results since many different fish had unique characteristics. The evolutionary significance of Tiktaalik comes from its later land ancestors with fingers.