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RE: Campbell's even crazier than a MANIAC? (archeopteryx



Sim Koning wrote:



> I think that's more or less an assumption drawn from a (poor) comparison with 
> the aye aye. If you look at an aye-aye's 
> "probing" finger, you'll notice that it's not the longest finger on the hand, 
> just the thinnest. 


Every picture I've seen of an aye-aye agrees with you: the middle (third) 
finger is not necessarily the longest, just the thinnest.  However, there are 
texts that say that the middle finger of the aye-aye can be up to "three times" 
longer than the other fingers.


The striped possum (_Dactylopsila trivirgata_) of northern Australia and New 
Guinea has a similar adaptation to the aye-aye, with the fourth finger 
elongated in this case.  As with the aye-aye, this "probing" finger is used as 
a tool to extract insect larvae from under bark.


> The hand of Epidendrosaurus more closely resemble the configuration of an 
> Iguana's hind foot. The greatly elongated 
> toe of an iguana's foot is used as a simple hook to catch hard to read 
> branches, it's purely an arboreal 
> adaptation.


The elongated finger of _Epidendrosaurus_ (the third finger) is rather stiff, 
like the other fingers.  Zhang et al. (2002) actually note that the "extremely 
elongated manual digit III does not appear to be well adapted for grasping".  
This finger is also tipped by a short claw, which is shorter than the claws of 
digits I and II, and only weakly curved.  So there's nothing about this 
extra-long finger of _Epidendrosaurus_ to suggest that it would be of any use 
for hooking branches.  A probing tool is the best interpretation.


Cheers

Tim
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