Re: _Eomaia_ and dung-eating vultures...

["Jaime A. Headden" <qilongia@yahoo.com>]

David Marjanovic (david.marjanovic@gmx.at) wrote:

<Is one of them *Ukhaatherium*, or is that yet another paper? In the
*Eomaia* paper *Ukhaatherium* comes out closer to us than (to) *Eomaia*,
with all other included Mongolian eutherians as its sister groups
(polytomy). It has long been considered probable that one of those,
*Zalambdalestes*, retained epipubes, too; has one been found meanwhile?
(Would IMHO provide strong evidence against the recent idea that
Zalambdalestidae and Glires are closely related.)>

  Both *Ukhaatherium* and *Zalambdalestes* have epipubic bones. These are
the only known eutherians that have them besides *Eomaia*. The possible
primitive nature of these taxa, presence of a unique apomoprhy not found
in Placentalia, and presence of this apomoprhy in the sister groups
Multituberculata, Marsupialia (and Metatheria in general), and the
Protheria and Monotremata, would be one reason why they are grouping
together.

  Eutheria and Placentalia are not synonymous. One is a stem-clade, the
other a crown-clade. Only descendants of the most recont common ancestor
of all living placentals can be Placentalia, but any stem sister taxon to
Placentalia is a eutherian if it does not enjoin a closer relationship
with marsupials (it's a metatherian, then), or monotremes (then it's a
protherian). It is useful to have both the effective node-clade of the
crown, plus a stem, to include more primitive fossil taxa ... this is the
best example of one. Neornithes versus Aves is another; also note
Crurotarsi versus Crocodylia[Crocodilia], Synapsida versus Mammalia, etc..

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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