[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

re: Pterosaur origins again, Hone and Benton 2007




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

_________________________________________________________________
PC Magazine?s 2007 editors? choice for best Web mail?award-winning Windows Live Hotmail. http://imagine-windowslive.com/hotmail/?locale=en-us&ocid=TXT_TAGHM_migration_HM_mini_pcmag_0507