Literature
Metacetacea
On Terra Alternativa, the absence of cetaceans allowed the evolution of several groups of aquatic tetrapods to fill their niche. One of the most successfull groups was, predictably, a mammalian one, the metacetes.
These mammals evolved from the otter like pantolestids of the Eocene. Their exact relations with other mammals are not well understood, but seem to be early placentals, possibly even non-placental eutherians; the presence of a well developed placenta in metacetes may not be indicative of their relationships, since it could have evolved independently. The earliest known form is the middle Eocene north american form Eocetolutra, a fo