"Money shall he restore to its owner': This tells me only of money. Whence do I derive the same for a beast? (i.e., that he may pay with a beast.) It follows, viz.: It is written here "and the carcass shall belong to him," and elsewhere, (Exodus 21:36) "Then shall he pay an ox for an ox, and the carcass shall belong to him. Just as there (he pays) a beast, so, here (he may pay) a beast. Just as here, money; so, there, money.
The Torah Specifies Money. but the Mekhilta Asks Can the Pit-digger
Mekhilta Tractate Nezikin 11:18