Unlike on most salamanders, this part of a newt is flat?

The answer is tail because unlike most salamanders, a newt's tail is flat. Salamanders typically have round or cylindrical tails, while newts have evolved a flattened tail that helps them swim more efficiently. The flattened tail gives newts better stability and propulsion in the water, aiding in their aquatic lifestyle. This adaptation allows newts to navigate through their habitat with ease, making them unique compared to other salamander species.