Re: [dinosaur] 2016 in paleontology + Dippy's last days in London + burrows around Omeisaurus + more

[Ronald Orenstein <ron.orenstein@rogers.com>]

This is a point that bothers me as well. The only examples I can think of 
(based on personal observation) of a powered flyer that needs to gain 
considerable altitude in order to launch into the air (presumably by gliding) 
are molossid bats. I can't think of a bird in that category,although some poor 
flyers (eg Kokako) do what seem to be wing-assisted leaps from upper branches 
to get airborne, and some water birds such as shearwaters need a running start 
on water. Is it possible that gliding in a non-flyer is not a good precursor 
for flapping flight, and that true gliders (eg colugos) are not "evolving 
towards" flight but are on a different, perhaps incompatible evolutionary path 
(so that powered flyers start out as leaders/flappers from an early stage)?

Ronald Orenstein 
1825 Shady Creek Court
Mississauga, ON
Canada L5L 3W2
ronorenstein.blogspot.com

> On Jan 6, 2017, at 8:04 AM, Mike Habib <biologyinmotion@gmail.com> wrote:
> 
> 
>> David Černý <david.cerny1@gmail.com> wrote:
>> 
>>> (Mayr 2016) accepts and reiterates
>>> Senter's (2006) conclusion that flapping flight was biomechanically
>>> impossible for early birds, mentions "[t]he physical and biological
>>> implausibility of a strict 'ground-up' origin of flight" (p. 39), and
>>> presents a stationary leaping take-off as a highly derived locomotory mode
>>> associated with a complex of pectoral girdle and wing adaptations that is
>>> unique to a couple of deeply nested neornithine lineages.
> 
> The Mayr (2016) argument here perplexes me a bit; I may be missing something. 
> In living birds, running takeoff is a mostly a derived feature of water 
> birds, and I cannot find a parsimonious way to map it onto any recent 
> phylogeny that avoids multiple derivations. In other words, running takeoff 
> seems to be derived, at least within the crown group. 
> 
> I'm also not clear (I'll have to go read the work in detail) why Mayr has 
> such a focus on wing characters for stationary leaping launch, since launch 
> mode is mostly dependent on hind limb morphology and substrate. Wing 
> characters influence climb out, but not running vs leaping launch mode 
> preference.
> 
> 
>> Mayr (2016) is highly skeptical of any scenario for the origin of
>> flight that that doesn't involve a "gravity-assisted" gliding stage.
> 
> The weird thing here, for me, is that living arboreal flyers still use 
> leaping launch modes to initiate flight - even the unpowered ones. There are 
> no living gravity launchers (that we have found so far, anyway). So even if 
> Mayr had good evidence for arboreal behavior near the origin of avian flight, 
> I'm not sure how that would yield a "gravity assisted" model. I suppose he's 
> referring to the gliding phase itself? 
> 
> Cheers,
> 
> --Mike