eximago:

Meet Odobenocetops (literally “walrus-faced whale”). Yes, it’s a freak, but that’s why we love it. This genus of dolphin with its own family (Odobenocetopsidae) forms a sister group with Monodontidae, which houses both narwhals (Monodon monoceros) and beluga whales (Delphinapterus leucas), which is part of what makes them so bizarre. Both Odobenocetops and the narwhal have tusks evolved from incisors, but the beluga whale does not. This means tusks would have evolved separately and independently in both. What’s more, is that the only male Odobenocetops found has profoundly uneven tusks. This is interesting because only one incisor normally becomes a tusk in narwhals, so these are two rare instances of asymmetry evolving convergently in related species, which only makes it more spectacular. Also astonishing is how different these dolphins were from their cousins. For one, they have flattened skulls and lacked the bulbous melons (which gives dolphins their rounded foreheads) of other toothed whales which are involved in echolocation. To compensate, their eyes are set comparatively high on the head and face forward, giving them binocular vision, kinda like us. These features suggest that it was likely a bottom feeder, evolving convergently with walruses (Odobenus rosmarus), and sucking small shelled invertebrates from the sea bed and prying them out with powerful tongues. Odobenocetops may have used its tusks to help dig up food, as walruses were once believed to.