QUESTIONABLE FURCULAE

[darren.naish@port.ac.uk]

On the putative furcula/furcula-like structure seen in _Longisquama_, 
Chris Brochu wrote...

> 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.

If I remember, I'll check Chatterjee's latest paper ('The avian 
status of _Protoavis_') to see what he says there.

DARREN NAISH 
PALAEOBIOLOGY RESEARCH GROUP
School of Earth, Environmental & Physical Sciences
UNIVERSITY OF PORTSMOUTH
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