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justification for excluding lagerpetids and/or pterosaurs from a phylogenetic analysis of the Archosauria



Tim W. wrote:

In this instance, I think the problem(s) might be yours alone.  I cannot see 
any justification for excluding lagerpetids and/or pterosaurs from a 
phylogenetic analysis of the Archosauria.


Perhaps not quite alone:

>From the JVP abstracts of 2008:  A SUPERTREE APPROACH TO PROLACERTIFORM 
>PHYLOGENY by SOBRAL, Gabriela, USP, Ribeirao Preto, Brazil; LANGER, Max, USP, 
>Ribeirao Preto, Brazil  "the majority consensus tree shows a paraphyletic 
>Prolacertiformes with two major clades: the ?Avicephala? clade includes, among 
>others, drepanosaurids, Longisquama, Sharovipteryx, and Pterosauria."

Sadly, Hone and Benton 2008 claimed to do something similar, but strangely 
chucked Longisquama and Sharovipteryx and hobbled Cosesaurus and 
Langobardisaurus. 

Then way back when, there's Benton 1985, who nested pteros closer to 
lepidosaurs than to archosaurs.

When Bennett 1996 found that the removal of hind limb characters shifted 
pterosaurs down from Scleromochlus to erythrosuchids and proterosuchids, that 
shift in and of itself is a signal that things were not rightly nested. Anyone 
should be able to delete a number of characters and not shift taxa so much, as 
all the skull only and skull-less taxa demonstrate. For that matter, one should 
also be able to delete several sister taxa and not otherwise change tree 
topology if the tree is indeed robust. I did this in 2000 when I deleted 
Longisquama, Sharovipteryx and Cosesaurus and still nested pterosaurs closer to 
Langobardisaurus than to Marasuchus.


Tim W. wrote (again):

In this instance, I think the problem(s) might be yours alone.  I cannot see 
any justification for excluding lagerpetids and/or pterosaurs from a 
phylogenetic analysis of the Archosauria.

Lucky for us, Nesbitt et al. 2010 provided all the justification anyone would 
need as they listed several (in their study) sister taxa for pterosaurs: 
Erythrosuchus + (Euparkeria + (Revueltosaurus + Aetosaurus) + ((Arizonasaurus + 
Effigia) + (Batrachotomus + (Postosuchus + Dromicosuchus)))). 

I , uh, fail to see the gradual accumulation of pterosaurian characters in this 
list. Perhaps you can help? Which of these taxa, in your mind, is closest to 
pterosaurs?

Taxon inclusion/exclusion is still the big kahuna. Pterosaurs don't belong in 
this neighborhood.

David Peters
St. Louis