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Re: AW: FW: Paravian claw studies



----- Original Message -----
From: "GSP1954@aol.com" <GSP1954@aol.com>
In a message dated 5/30/12 4:36:57 PM, koreke77@yahoo.de writes:

<< First, it must be demonstrated that the curvature of the sheath follows 
the curvature of the ungual closely enough to make measurements of the 
latter in absence of the former actually worthwhile. >>

>This is correct. It is not possible to accurately determine the curvature 
of the actual keratin claw from the bone core despite what some past 
studies have claimed. 

This needs a citation. Burnham et al say the same thing, but they only study 
fossils, from China... who knows how much of the claw impressions are real.  I 
think this point is baseless. Why not measure extant birds, or anything and 
everything with an ungual?

We (Fowler et al., 2009) measured a set of unguals with removable sheaths from 
a golden eagle (only one specimen admittedly). The sheaths are proportional to 
the unguals (ie. contra how Burnham et al. [mis]cite us). Manning et al (2009 I 
think, could be 2006) suggest the sheaths add about 15% (I think it was 15) to 
the ungual. Maybe he is wrong, but the figure looks about right to me (looking 
at extant specimens, including a few more in our osteology collection).

Looking only at fossils, especially chinese dinobird fossils, isn't enough to 
say anything. Is the suggestion that somehow basal paravians had ungual-sheath 
proportions that differ from modern birds?


I imagine Chris Glen's data may answer some of these issues, or I might just do 
it myself.