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Re: Morpho v molecular (was Re: Tinamous: living dinosaurs)



 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.

But what you're actually talking about isn't the position of the whales anymore. It's the position of the ruminants -- as I first said on this list a couple of years ago.

--+--camels
  `--+--pigs
     `--whippomorphs

Morphology traditionally puts the ruminants next to the camels (together Selenodontia), molecules put them next to the whippomorphs.

My impression is that recent morphological analyses that contain halfway serious numbers of fossils do not find any strongly supported position for Ruminantia. There are lots and lots of Paleogene artiodactyls that could be stem-ruminants or not, and apparently nobody has tried to sort most of them out yet.

*Indohyus* has been compared to the tragulids (the extant sister-group of all other extant ruminants) a lot. What if some of the similarities are actually symplesiomorphic...?

Someone please sit down with the Paleogene artiodactyls and make a data matrix with all of them. And order your potentially continuous characters (Wiens 2001, Syst. Biol.).