re: Pterosaur origins again, Hone and Benton 2007

[Tim Williams <twilliams_alpha@hotmail.com>]

Scott Selberg wrote:

>  This may seem to split hairs, but if I understand correctly this doesn't 
> say that dromaeosaurs were NOT secondarily flightless, just hat they were 
> not secondarily flightless BIRDS. Do I have it?

Yes, that seems to be the gist of it.  Senter (2007) was refuting a previous 
phylogeny that placed _Confucusornis_ inside the Dromaeosauridae.  
Nevertheless, dromaeosaurids like _Velociraptor_ and _Deinonychus_ might 
indeed have been secondarily flightless, given that _Rahonavis_ was 
recovered by Senter inside the Dromaeosauridae, as a unenlagiine.

Something else that occurred to me after reading Senter's paper... Aside 
from _Coelurus_ and _Tanycolagreus_, how many other small to medium-sized 
coelurosaurs may also turn up inside the Tyrannosauroidea once they are run 
through this kind of analysis.  For example, _Nqwebasaurus_, or even 
little_Scipionyx_.  I think tyrannosauroid affinities have already been 
suggested for _Proceratosaurus_, but I can't place the source.  I don't want 
to go too far with this, given that (so far) this position for coelurids has 
only been found by one analysis.  Not surprisingly, Senter does give credit 
to "intermediate tyrannosauroids" such as _Dilong_ and _Eotyrannus_ for 
pulling _Coelurus_ inside the Tyrannosauroidea.  _Tanycolagreus_ also played 
its part.

David Peters wrote:

> And if its not the Macrocnemus > Longisquama clade, then can we assume that 
> the various apparent synapomorphies found in various members of that clade 
> -- including the elongated naris, antorbital fenestra, multi-cusped teeth, 
> elongated cervical ribs, deep dorsal ribs, high sacral count, attenuated 
> caudal series, elongated scapula, tall coracoid, sternal complex (sternum + 
> keeled interclavicle + clavicles), magnified deltopectoral crest, migrated 
> centrale, elongated fourth finger, reduced fifth finger, elongated ilium, 
> fused ischium+pubis, prepubis, sprawling femora, attenuated fibula, 
> mesotarsal ankle, elongated lateral toe, and uropatagia -- are ALL 
> convergent with pterosaurs?

Out of interest, just how many of the above features are evident in 
_Longisquama_?  It was my impression that it was not too many.

> Also nice to know those tiny lateral fingers and toes will somehow become 
> hypertrophied.

Stranger things have happened.  After all, the elongated hallux that allows 
birds to perch in trees evolved from one tiny lateral toe in terrestrial 
theropods.   It's amazing what natural selection can achieve, irrespective 
of our own personal credulity.

Anthony Docimo wrote:

> that'd be...irony, right?
>
> people used to think birds evolved from crocs....and now we may be on the 
> verge of confirming that the croc family gave rise to pterosaurs?

We're along way from that point, I would say.  BTW, the idea that birds 
evolved from crocs (by which was meant "basal crocodylomorphs" like 
_Sphenouchus_) never really had much support.  Even then, the idea was more 
about birds and "crocs" sharing an especially close relationship to the 
exclusion of all other archosaurs (including dinosaurs), rather than a 
straight ancestor-descendent relationship.  The origianl idea was Alick 
Walker's, and even he changed his mind a few times on the matter of 
bird-croc relationships.

Cheers

Tim

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