Hmm. Interesting indeed. I'm with Thain Esh Kelch as well, it closely resembles the Irrawaddy Dolphin, or at least the genus Cephalorhynchus due to
the short snout/blunt head and the lack of vestigial hind flippers.
There are a couple of factors making the Irrawaddy very unlikely... It's a freshwater dolphin, it's from Asia (a long way from Mexico) and the mouth
is way to small (of this animal) compared to that of the Irrawaddy.
I would however rather put my money on porpoise. It's a very small animal (porpoises are smaller than dolphins), it has the broad-based, low and
triangular dorsal fin of the porpoise and is blunt-nosed.
I'll give it some more thought. Watch this space.
(I’m pretty certain it’s not some sort of “mini whale”.)
