Ichthyosaurs were aquatic dinosaurs. Fossils show us that they had dorsal fins and tails, as do fish, even though their closest relatives were terrestrial reptiles that had neither dorsal fins nor aquatic tails. The dorsal fins and tails of ichthyosaurs and fish are
A) homologous.
B) examples of convergent evolution.
C) adaptations to a common environment.
D) Three of the responses above are correct.
E) Two of the responses above are correct.

Question

Quizplus · Accepted Answer

The dorsal fins and tails of ichthyosaurs and fish are examples of convergent evolution (B) and adaptations to a common environment (C), making them not homologous but rather analogous structures that evolved independently in response to similar environmental challenges.

Ichthyosaurs Were Aquatic Dinosaurs