Re: Microraptor also ate fish

[Mike Habib <biologyinmotion@gmail.com>]

Greg makes a good point regarding power output and climbout performance.  
Precise performance estimates are indeed impossible, but highly anaerobic burst 
flight capacity does have measurable osteological correlates, so it is not a 
complete black box.  And of course, there is always the sensitivity test: if 
microraptorans could not climb out steeply enough to get into trees etc. even 
with all anaerobic muscle, then the idea is effectively falsified, without 
knowing the actual life physiology.

--Mike H.


Sent from my Cybernetic Symbiote

On May 1, 2013, at 8:31 AM, GSP1954@aol.com wrote:

> The problem is that there is no way to ever sufficiently understand the 
> flight performance of microraptors. That it was a powered flier is the 
> greatly 
> superior hypothesis because it had so many adaptations for supporting fairly 
> large arms muscles and anchoring the primaries, well beyond those found in 
> Archaeopteryx which itself was beyond just gliding (I've discussed this in 
> the literature and won't repeat it here because that is not the specific 
> issue). 
> 
> But what we can never know is what was the specific flight performance of 
> microraptors. Because we can never know the actual size and cellular 
> configuration of the flight muscles. Big turkeys can take off vertically 
> because 
> they have huge, anaeroboic burst power flight muscles, which run out of power 
> quickly so they can't fly far. Ducks also have large flight muscles, but they 
> have to take off subhorizontally because they are configured to produce 
> limited anaerobic burst power, and are optimized for sustained aerobic power, 
> so they can cruise long distances. 
> 
> It is very unlikely that microraptors had the extreme burst climb 
> performance seen in turkeys, or the long range ability of ducks. My guess 
> would be 
> that microraptors had limited powered flight abilities, including being able 
> to take off from the ground. But could it climb well enough to get into tree 
> canopies from the ground on a regular basis? Very possibly no, be we can 
> never know. 
> 
> What I do know is that having examined a number of big format photos of 
> Microraptor central toe claws that were kindly supplied to me, that they are 
> (using the recent published data sets and my own on a large set of predaceous 
> birds) more strongly arced than the claws of any livng bird that reguarly 
> traverses ground by walking hither and on. Only birds with weakly curved 
> central toe claws walk and run a lot (I've sampled them, including the 
> raptors). 
> So Microraptor either used flight as it's main means of moving about from 
> one place on the ground to another (doubtful in view of probably limited 
> powered flight abilities, and probable lack of many open spaces in the Johel 
> forests) or was primarily an arboreal climber (very probably, considering it 
> lived in apparently dense woodlands). 
> 
> GSPaul
> 
> 
> In a message dated 5/1/13 5:24:45 AM, david.marjanovic@gmx.at writes:
> 
> << Maybe what should be researched first is whether *M.* was capable of 
> 
> powered flight and whether it was capable of gliding. (And the same, 
> 
> actually, holds all the way to *Confuciusornis*.)
> 
> 
> If it was capable of powered flight, it didn't need trees to take off. 
> 
> It used to be thought that the ability to take off from the ground is 
> 
> special and must have been the last step in the evolution of flight -- 
> 
> but,  >>
> 
> </HTML>