Castoroides [PvE Cross]

Castoroides is a giant beaver born for wood farming. It reduces the weight of Wood, Fiber, Thatch, and Stone by 50% while they're in its inventory, so it hauls bulk building materials far better than its size suggests.
 
It can carry less wood than Roll Rat, but its saddle turns its inventory into a Smithy, so you can craft and repair items straight from it. Take it to a build site, and farm and craft on the spot.
 
It's slow on land but swims fast, and its oxygen never drains underwater, which makes it a good river-travel mount, but it's a farmer, not a fighter or travel dino.