Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Herbivores that evolved on grassy plains are likely to naturally select for traits different than herbivores that evolved in rain forests. Which trait is a plains herbivore most likely to develop over thousands of years?
Long legs.