INTERCLAVICLES

["Matthew Troutman" <m_troutman@hotmail.com>]

<<< For another, despite the fact that this structure was preserved as a 
mold in the specimen I saw, one can clearly see a separation between them.  
I don't read Russian, so I don't know what Sharov actually said, but the 
translator stated that the bones were "conjoined," which is not the same as 
fused.  Fusion, in a histological sense,  implies complete obliteration of 
the cartilaginous lamina between two ossifications.  (Of course, one could 
argue that this represents an earlier stage of evolution in the furcula. One 
could also argue that the specimen represents an immature individual.)>>>

<<In this context, it's of incidental interest that the structure
regarded by Chatterjee as a furcula in _Protoavis_ also has a
suture-type line running along its midline (in line with the
hypocleidium). I forget where I learnt this, but it is not mentioned
or figured in Chatterjee's  book. Jacques Gauthier once said that
this 'furcula' was more likely an inverted neural arch from something
like a rhynchosaur.>>

Regarding the supposed furcula of _Longisquama_, Sharov (1970) described it 
as a true furcula of course, indicating conjoined clavicles, but Ostrom 
(1985; Hecht et al.) thought it possible that the "furcula" might be part of 
the interclavicle.  It might be stretching it a bit, but since Sharov (1970) 
described an(other) interclavicle element and illustrated it as well, it 
might be argued that the "furcula" is part of this element resulting in an 
interclavicle so very similar to the distinctive T-shaped lepidosauromorph 
interclavicle.  More specimens are needed but this does suggest that 
_Longisquama_ is not far removed from the lepidosauromorphs.

Matt Troutman
m_troutman@hotmail.com


_______________________________________________________________
Get Free Email and Do More On The Web. Visit http://www.msn.com