Re: Sobral and Langer 2008 (was pteros have lift-off)

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

> Sobral, G. and Langer, M. 2008 JVP 28: supplement to (3): 145A
> A supertree approach to prolacertiform phylogeny

Well, that's a supertree. It's an average of published trees. It does not 
contain new information; it is not necessarily the most parsimonious hypothesis 
that fits the data, because it doesn't even use the data, it uses just the 
published trees and averages them together.

> I quibble with the second tree, but the key here is the connection  
> with some fenestrasaurs (sensu Peters 2000b) and pterosaurs has been  
> confirmed by this study.

For the reasons explained above, supertrees are incapable of confirming 
anything outside the field of history of science.

I'm not saying (here) that your topology is wrong, mind you. I'm saying it has 
not been tested by Sobral & Langer.

> No taxon appears suddenly in the fossil record! There are always
> clues to ancestry.

While I won't quibble with the second sentence, the former is flat-out wrong. 
Throw your blithe assumptions about the fossil record into the trash already!

> You just have to include the candidates, do the work and PAUP will 
> reveal what you seek.

If you've taken the "do the work" part very, very seriously and actually 
understand what you're doing, then yes... which nullifies the "just" part. I'm 
speaking from experience here.

> That's a very bad sign when the 'preferred' cladogram can't nail down 
> a sister taxon.

A supertree isn't a cladogram. It's not the outcome of a cladistic analysis.

> The word 'should' you'll recognize as a "weasel word." By that I
> mean, it's a prediction leaving some room for retraction, not a
> statement of fact supported by evidence. The word 'probably' falls
> into the same category. If these guys were playing poker, I'd say
> they were bluffing by including such weasel words.

The game isn't called poker, it's called science. All knowledge is provisional, 
there is no absolute certainty. So, words like "probably" are to be expected.

> I can state without fear of retraction and with lots of evidence (see 
> prior "pteros have lift-off for a preview) that Cosesaurus,
> Sharovipteryx and Longisquama were sister taxa to the Pterosauria.

I'll test that anyway...

> But let's forget about those taxa for a second: we can go back to
> Langobardisaurus, Tanytrachelos and Tanystropheus, all of which share
> that attenuated tail, hyper-elongated fifth toe and lots of other
> characters. But let's forget about those taxa for a second: we can go
> back to Macrocnemus, Jesairosaurus and drepanosaurs, which Senter and
> others seem to like. I would take you back further, but then you'd
> have to see the MacClade file.

Why don't you publish already, instead of teasing us for years?

> Yes, you're right, but let's take it up a notch. Forelimb length is  
> about 100% of the hindlimb length in Archaeopteryx.

Such lengths are approached by the Early Cretaceous *Sinornithosaurus* and 
*Microraptor*, and even more so by the possibly Early Cretaceous *Anchiornis*. 
But that, so far, is it. No dinosaur that lived between *Guanlong* and 
*Archaeopteryx* is at present known to have had forelimbs more than around 60 % 
hindlimb length.

> i'm still wondering, what is the explanation for such an extension
> on this taxon -- or any pre-Archaeopteryx taxon -- with such elongated
> forelimbs, non-supinating/pronating antebrachia and trenchant manual
> unguals if not for arboreality?

Reaching out to grab prey?

Because then, the trenchant ( = cutting) claws would even make sense. Cutting 
off the tree branch you want to put your weight on is a less good idea. Also, 
the forelimb mobility of all dinosaurs to this day is pathetic, and the 
hindlimb mobility even more so, all the opposite of what would be expected of a 
climber. There's an SVP meeting abstract I need to retype about this topic.
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