Just to clarify, I didn't mean to give the impression that all (or
even most) paleontologists dismissing the hypothesis of any kind of
hippo-whale clade (Cetancodonta or Whippomorpha). Sorry about that.
What I was saying is that those phylogenies based purely on
morphological/fossil data have not always upheld the derived
position of the Whippomorpha clade as recovered by molecular-based
phylogenies. As noted by Tom, the morphological/fossil phylogenies
usually recover some configuration of Cetancodonta/Whippomorpha; but
a link between cetancodonts and ruminants (Cetruminantia), as
proposed by molecular-based phylogenies, is usually not supported by
morphological/fossil data. The importance (or not) of the
anthracotheres in hippo and/or whale evolution is also the subject
of different viewpoints. Having a hippo-whale clade as derived
artiodactyls, closest to ruminants, is the essence of the
Whippomorpha hypothesis (Gatesy et al., 1996; Waddell et al., 1999),
and it's this aspect that I'm skeptical about. But I'm happy to be
proved wrong... by more fossils, not more molecular analyses.