Hamilton et al. (2001)
suggested that the marine ancestors of Inia, subsequent to their divergence from Pontoporia, invaded freshwater ecosystems of Amazonia during eustatic
sea -
level highs of the middle Miocene, and evolved freshwater habits prior to the subsequent
drop in eustatic
sea -
level late in the Neogene.
One problem is that if the ocean has lost heat at the
suggested rate, then the thermal exapansion part of recent
sea level rise should have decreased (i.e.
sea level should have
dropped).