Earlier the large reptile tree (LRT, 1160 taxa) split Cetacea into separate clades arising from tenrecs (Odontoceti) and hippos (Mysticeti). Today the Mysticeti splits Balaenidae (right and pygmy right whales) from all other mysticetes (Fig. 1). Desmostylians are basal to both. So either the Mysticeti is diphyletic (like turtles) developing in parallel…or this clade is expanded to now include some members with legs, teeth and not much of a tail.
by phylogenetic bracketing, that some desmostylians had baleen.
This was brought about by
adding the smallest baleen whale, Miocaperea (Miocene, Bisconti 2012) and reexamining previously included taxa. DNA could not have recovered this split, as it requires fossil taxa. To those who know whales pretty well, the right whales are distinct from the others in morphology and feeding strategy.
Images and more data next time. I have to revise some web pages now.
Bisconti M 2012. Comparative osteology and phylogenetic relationships of Miocaperea pulchra, the first fossil pygmy right whale genus and species (Cetacea, Mysticeti, Neobalaenidae). Zoological Journal of the Linnean Society 166: 876-911.