Re: Reduced Consensus (Was: Afrotheria revisited)

[Michael Mortimer <mickey_mortimer111@msn.com>]

Mike Taylor wrote-

>  >> Would it be possible to get a DIFFERENT well-resolved tree by
>  >> excluding one of the other taxa (this is something that time and
>  >> computer power could check!)?
>  >
>  > Yes it would.
>
> Just to be clear -- you're talking here about _a priori_ exclusion,
> right?

Yup.  Just like the authors excluded Arsinoitherium a priori.

> You're asking for a whole phylogeny of placentals in that case.  For 
> example, if you include carnivoramorphs, then you have to include 
> 'creodonts'... and so on.

Of course.  Tambuci et al. want their analysis to meaningfully support 
Afrotheria, but how can they expect that when they have a whopping 2 
boreoeutherians (3 assuming mesonychids are...)?  And they're not even basal 
members of the clade.  Indeed, they're members of boreoeutherian clades that 
are most convergent with paenungulates.

> Is this partly the consequence of low taxon sampling?  Would adding more 
> taxa for certain clades help 'firm up' the bootstrap support for some of 
> the clades?  In the analysis above, some very speciose clades (like 
> Proboscidea, Perissodactyla, or Artiodactyla) are each represented by only 
> one (fairly basal) taxon.

Very much so.  Imagine a theropod analysis of tyrannosauroids that threw in 
an abelisaurid and a carcharodontosaurid without bothering with basal 
ceratosaurs or carnosaurs.  Then add in Megalosaurus as the outgroup because 
it's a fairly plesiomorphic "Carnosauria" incertae sedis.  And analyze the 
mix with 10 characters, but only from the maxilla and femur.  That 
approaches the futility of Tambuci et al.'s matrix.  It's great somebody's 
finally trying to figure out where everything goes, but it needs a TON of 
work.

I have a hard time imagining how mammalogists don't go insane with so many 
major groups of mammals that have utterly unknown relationships.  That never 
happens with dinosaurs.  At worst we have grades of taxa with uncertain 
branching order ('hypsilophodonts', 'compsognathids/coelurids', 
'prosauropods'), unresolved trichtomies (Troodontidae vs. Dromaeosauridae 
vs. birds) or multiple well-supported conflicting topologies 
(Alvarezsauridae).  But mammalogists have asioryctitheres, leptictids, 
anagaloids, zhelestids, dinoceratans, xenungulates, astrapotheres, 
litopterns, notungulates, arctostylopids, etc. etc..  Madness.

Mickey Mortimer