Speculative Apes of April: Aquatic

This picture is part of an art challenge on the r/speculativeevolution subreddit, dedicated to creating 30 species of apes-- that is, members of the superfamily Hominoidea. Some of these will be from alternate timelines, others are future scenarios, and still others are hypothetical species that could have existed in our own past. 

The notion of an aquatic ape is most closely associated with fringe theories about human evolution. However, in the greater scheme of ape taxonomy, Baptopithecus trichechus has nothing to do with humans, because humans do not exist in its world. An inhabitant of a timeline where the drying and cooling trends of the late Cenozoic never happened, and Earth remained warm and wet, Baptopithecus evolved from ancestors that waded in mangrove swamps to feed on sea-grasses and other aquatic plants. These were not as nutritious as the fruit that most apes ate, but were much more plentiful, and before long adaptations for swimming appeared. 
As far as apes go, Baptopithecus is not terribly intelligent, as it doesn't need much brain power for its manatee-like lifestyle.