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Re: Sheesh



----- Original Message -----
From: "evelyn sobielski" <koreke77@yahoo.de>
Sent: Friday, October 27, 2006 12:31 AM

I'm not talking about the number of differences, I'm
talking about the number of shared innovations.
Confuciusornithidae and Neornithes share
plenty of derived features that Archie and
everything else lacks: short tail,

large snip

and so on.

I'd rather wait and see how much of these are not considered independently derived in say 5 years from now. [...] This is not to say that any of these charaters *are* pseudo-autapomorphies. But most if not all *may* be; I do not think it has been considered in enough detail that they might not be.

The fact that each character in the list I wrote _could have_ evolved convergently is not evidence that any of them _did_. In the absence of such evidence, science must employ Ockham's Razor: the hypothesis that needs the fewest additional assumptions wins. Each assumption of convergence in the list above is such an additional, ad hoc, assumption; therefore -- for the time being -- science must prefer the hypothesis that Neornithes and *Confuciusornis* are more closely related to each other than to Archie.


Most biologists have been understanding this since the late 80s/early 90s. Almost all linguists still haven't got it (...but I digress).

You do not mention beaks, or feathers, or flight;
had C. been found in 1950 and this conversation would
take place 50 years ago, you would have.

I wouldn't have mentioned the beak, or at least the absence of teeth, because *Hesperornis* and *Ichthyornis* were already known. I'd certainly not have mentioned feathers or flight, because *Archaeopteryx* was thought to have both.


And what about the skulls?

What exactly do you mean? (It's still not clear if Archie had a complete postorbital bar...)


Uncinate processes in Neornithes and C. are
autapomorphic IIRC?

No, their absence in Archie (at least as bones) is probably autapomorphic, because dromaeosaurs and oviraptorosaurs often have them.


Confuciusornis was the Archie of our time: hey, it's
so advanced (in some aspects) - it must be on the line
between modern birds and their Archie-like ancestor!

It may have been that in 1995. So many birds and maybe-birds that are contemporary with it have since been discovered that it's no longer anything special (apart from the fact that it's known from thousands of specimens and has received a serious description).


No, it is part of the same *evolutionary trend* of
maniraptorans (theropods?) Archie and Neornithes are.

This sounds a lot like the 1960s idea that (like almost everything else) the mammals were polyphyletic: it is imaginable that the "defining characters" of mammals evolved more than once, so we cannot use them as evidence for mammal monophyly, which means that there is no evidence for mammal monophyly, which means mammals are not monophyletic. (One logical flaw after another.) If this differs from your stance, please do explain it!


The similarity of flight adaptations between
Confuciusornis and Ornithothoraces is something that
goes not very deep. Confuciusornis must have been
evolving fairly long and/or rapidly along the lineage
it did, which is as different from ornithothoracine
flight as foot-propelled from wing-propelled diving
both aerodynamically and physiologically. It is not
close to Archie's either, but Archie's was in all
respects primitive.

This is still a phenetic argument: you are only saying that Confuciusornithidae and Ornithothoraces are different, which is correct, but doesn't say anything about whether they are sister-groups* or not. I'm not talking about branch lengths, I'm only talking about the topology of the tree.


* Kindly ignoring *Jibeinia* and who knows what else for the moment.

There was a marine ecosystem collapse at the end of
the Pleistocene???

Err... Pliocene.

Oh. I may have heard about that. <scratching head>

Interestingly, the seabird:pinniped(/cetacean?)
biodiversity ratio seems to have switched around that
time fairly abruptly.

Interesting indeed!