There's also a third concept with a second primate(either woolly monkey or spider monkey), so there's was more variants going around.Nor really a theory, but SA pack originally featured different animals.
1. There is concept art of jaguar being part of base game.
2. There is concept art of giant otters in SA pack. It also features jaguar and capuchin for that matter.
So overall it means there used to be at least 3 SA pack variants:
Third one is what we got.
- without jaguar and with giant otter
- with jaguar and giant otter
- with jaguar and without giant otter