Colossus Tuskwhale

This is for @SailWorldbuilds 's Spectember art challenge.

25 million years in the future, most of Madagascar's megafauna have been wiped out. The giant lemurs, elephant birds, dwarf hippos, and many of the native chevrotains were killed off by humans within a few hundred years of their arrival on the island, and the end of the Cenozoic claimed further victims. The lemurs are virtually extinct, with only a handful of small generalist species surviving. The Malagasy chevrotains, already reduced in number from over forty species at the time of the first human settlement, were also nearly killed off. But one particular lineage of them has survived, and has left a gigantic descendant.
The Colossus Tuskwhale (Tragulacetus giganteus) is the largest mammal to have evolved since the extinction of the great baleen whales, and at first glance it might be mistaken for some bizarre whale. However, while it is an artiodactyl, it is only distantly related to whales. Its ancestor was the Mpisitrika (Ungulontra pachylabia), a semi-aquatic otter-like Malagasy chevrotain, and one of the few members of this group to survive the age of Man. While the Mpisitrika could swim and dive in water to search for food, it still spent a great deal of time on land. Over time, however, its descendants spent more and more time foraging in the water, eventually becoming committed to such a lifestyle full-time.
The Colossus Tuskwhale is the result of over 20 million years of evolution in this direction. At 75 feet long and weighing close to 80 tons, it is truly an enormous animal, with only the giant whales of the past rivaling it in size. Its name comes from the long, pointed tusks that protrude from the mouths of both males and females. These tusks are not weapons or display aids, but rather adaptations to the animal's unusual lifestyle. To feed, the Colossus Tuskwhale uses its tusks to scrape furrows in the mud and silt of the seabed, using its suction-like mouth to consume any prey-- be it worms, snails, clams, crabs, or bottom-dwelling fish-- that it "unearths". Like pigs rooting for nuts and grubs on the forest floor, these giant sea mammals churn up the seabed as they feed, and therefore must move constantly.
Colossus Tuskwhales are solitary creatures, only coming together in order to mate. The female gives birth to a single calf after what only be called an astonishing 20-month-long pregnancy. After being born, the calf remains by its mother's side until it is roughly a third her size and its tusks have fully grown in, at which point it leaves her behind. No predators will take on an adult Colossus Tuskwhale, but juveniles are occasionally attacked by large sharks and also by the mosasaur-like marine crocodiles that inhabit the seas of this world. However, their thick skin is difficult for predators to bite through, and it is not uncommon to see an adult covered in scars from past encounters with predators. The tusks, though they look intimidating, are actually fragile and will break if used as weapons against another large animal; their main function, as mentioned before, is to help the Colossus Tuskwhale feed.
Unlike modern whales, the Colossus Tuskwhale does not have a thick layer of blubber, since it mainly inhabits tropical waters in what is now the Indian Ocean. However, its bones are extremely dense, and it spends most of the time swimming near the bottom in the shallows.