Is there a vendor for animal parts?

Yes there's a merchant, but no it's not outright.

There's a merchant in Meridian that sells specialty loot crates with random items in each. One of these crates (Dark Scavenger Box) drops animal skins and bones. You will need green processed metal blocks to buy the crates.

In Meridan, there's a special Mystery Boxes Merchant who sells assorted mystery boxes in exchange for various machine parts. The one you want is the Scavenger Dark Box, which costs one Processed Metal Block, a fairly common drop from Scrappers and Glinthawks. This box usually contains a random animal bone or animal skin.

There doesn't seem to be any more precise way to buy a particular animal part, so hunting them yourself is usually more efficient unless you have a ton of Processed Metal Blocks or are looking for raccoons, which are very uncommon.