Re: Gondwana Split May Complicate Mammalian Evolution

["David Marjanovic" <david.marjanovic@gmx.at>]

> I think it not necessarily complicate mammalian evolution, but make it
> clearer. It seems a logical pattern.

Hmm... no. In the Mesozoic we have all known metatherians in the Northern
Hemisphere, likewise all known eutherians (except the ausktribosphenids do
at last turn out to belong here... but if so, they would be extremely basal
eutherians, not in or near the crown group Placentalia) and all known
closely mammals (*Kielantherium*...), starting in the EK. The newest
molecular scenario totally screws up this beautiful picture. I already
mentioned what mammals are known from K South America.
        BTW, molecular phylogenies (sometimes in the same paper) have so far
supported all three possible arrangements:

+--Afrotheria
`--+--Xenarthra
     `--Boreoeutheria

+--Xenarthra
`--Epitheria
     |--Afrotheria
     `--Boreoeutheria

+--Boreoeutheria
`--Atlantogenata
     |--Xenarthra
     `--Afrotheria

The uppermost of these is supported by the most recent study, which may or
may not be evidence it's closer to the truth. IMHO the (apparent?)
uncertainty about these arrangements might reflect very fast divergence
right after the K-T... but it's not like I had fossil evidence for this. (At
the moment, I couldn't in principle, because there are 0 known morphological
synapomorphies of Afrotheria...)

> The problem is that science has allways
> been very influenced by cultural concepts. Since most of paleontologists
> came from Northern countries, mainly USA and Western Europe, these regions
> was allways be considered as the center of evolution. Northern faunae are
> ever been named as "advanced" and "superior", and Souther faunae as
> "inferior" or "archaic". Modern discoveries are revealing a pattern that
> will turn current points of view.

|-O <yawn> The 1960s are over. The cultural influences on science have IMHO
strongly decreased since then.

> Can we assume a similar pattern for avian orders? A basal  "African"
stock;
> then a Neogondwanan stock; then a Northern stock?

It looks pretty certain that Neornithes is a Neogondwanan, if not Antarctic,
phenomenon... but I don't know of _any_ Mesozoic African bird fossil. Africa
is terribly undersampled.