Re: What is the evolution of a hare/rabbit? What did their ancestors look like?

Good questions!!

Hares and rabbits are in the order Lagomorpha, in the class Mammalia. Pikas are also lagomorphs (for a picture of a pika, see http://www. nature.ca/notebooks/english/pika.htm). Pikas are in the family Ochotonidae and hares and rabbits are in the family Leporidae.

Strangely enough, no one is certain what other order(s) is (are) most closely related to lagomorphs. They look a lot like rodents and at one point (until the early 1900s) they were considered to be just another kind of rodent. However, they are different from rodents in a number of ways (for example, they have more teeth and their tooth structure is different). Anatomically, lagomorphs are most similar to the order Artiodactyla, the even-toed ungulates like cows, pigs and deer.

The earliest fossil lagomorphs occurred in Mongolia in the Paleocene period (which started 65 million years ago). The leporids (hares and rabbits) diverged from the other lagomorphs in the Oligocene period (37 million years ago). Around that time, there was a fossil rabbit called Palaeolagus that might be very similar to the common ancestor of hares and rabbits. Palaeolagus probably looked a lot like modern hares and rabbits (for a picture, see Savage and Long, 1986).

References:

Diersing, V. E. 1984. "Lagomorphs." In: Anderson, S. and J. K. Jones, Jr. (eds.) Orders and Families of Recent Mammals of the World. New York: John Wiley and Sons.

Myers, P. and A. B. Sorin. 1999. Order Lagomorpha. University of Michigan’s Animal Diversity Web. http://animaldiversity.ummz.umich.edu/chordata/mammalia/lagomorpha.html

Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution: An Illustrated Guide. New York: Facts on File.