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RE: Nemicolopterus phylogeny




David Peters wrote:


> [This is really cool. You imagine my response then you
> argue against it. Why am I even responding to this? I sense a rant.]


Not from me.


> [Tim, just for the record, the arboreality of SMNK PAL 3830
> is in the "super claws" which curve an unbelievable semi-circle,
> tripling the length of each ungual. Plus, the penultimate phalanges
> are the longest in each digit series. These are the clues that
> suggest arboreality. Then again, I wasn't there.]


Fair enough.  The circular claws and elongate penultimate phalanges certainly 
indicate suspensory behavior.   However, the term "arboreal" tends to be 
bandied around a lot, and I think it's helpful to define what you actually mean 
here.  Did the pterosaur in question actually feed and/or locomote in trees; or 
was its arboreal behavior mostly limited to hanging upside down from the boughs 
of trees?  I know you "weren't there"; but what is the most parsimonious 
interpretation of this animal's ecology, based on the entire anatomy?


> [Ancestors much bigger than descendants in this case. Did I
> misread Cope's rule? Is there an asterisk I missed?]


Cope's rule proposes that lineages become bigger over time.  Becoming smaller 
("ancestors much bigger than descendents") would therefore be contrary to 
Cope's rule.


> [You don't like Sharovipteryx? Which genus is your closest
> candidate? Unwin (2006), the latest word on the subject, said it was
> an unspecified diapsid. Can you get _any_ closer?]


I'm actually very fond of _Sharovipteryx_.  He's an adorable little critter.  
But the evidence that _Sharovipteryx_ is the sister taxon to Pterosauria is not 
compelling (not yet, anyway).  For example, Senter's thesis recovers 
_Sharovipteryx_ in the Prolacertiformes, whereas pterosaurs ended up in the 
Ornithodira/Avemetatarsalia, along with dinosaurs, _Marasuchus_ (sister taxon 
to dinosaurs) and _Scleromochlus_ (sister taxon to pterosaurs).  Although 
Senter's analysis was based on a large dataset (both taxa and characters), I'm 
not saying that this is the last word on the issue.  However, your own basis 
for a _Sharovipteryx_-Pterosauria clade has been soundly criticized, most 
recently by Hone and Benton (2007), on methodological grounds, including (but 
not limited to) the reliability of certain of your character codings, which are 
often drawn from parts of the specimen that are invisible to everyone else.  
I'm not necessarily dismissing your _Sharovipteryx_-Pterosauria clade; all I'm
 saying is that Senter (and others) have presented far better evidence in favor 
of alternative candidates as the sister taxon to Pterosauria.


Cheers

Tim


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