RE: New Mesozoic bird papers (advance publication)

[Mickey Mortimer <mickey_mortimer111@msn.com>]

Brad McFeeters wrote-

> If the claws were used for something other than climbing, why were they lost 
> at the same time birds developed the ability to ascend without climbing?  
> It's obviously not an airtight deduction, but still an interesting 
> observation to think about, especially if the correlated claw reduction + 
> improved backstroke evolved more than once in different bird clades (did it?  
> I haven't read the paper yet either).

Simply put, claws weren't lost at that point.  Compare Sapeornis' claws to 
Eoenantiornis' and you'll see no great difference.  Both are strongly curved 
with large flexor tubercles, yet I think the consensus is that enantiornithines 
could take off from the ground while omnivoropterygids were worse off than 
confuciusornithids (unossified sternum, often short coracoid, etc.).  Even 
basal euornithines like Jianchangornis and Yixianornis had well developed 
(albeit less curved and smaller) claws, despite having a pectoral apparatus 
extremely similar to Aves.  In general, the claws do reduce going from 
Archaeopteryx to Aves but there was a lot happening on that lineage besides 
improving the takeoff.  For instance, the second digit was becoming more robust 
and stiffer to support the primaries and the first digit was becoming reduced 
in size and developing an alula.

Mickey Mortimer