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Re: Micropredatory Microraptorids (was Microraptor Wings (and sauropods()



David Marjanovic <david.marjanovic@gmx.at> wrote:

>>  - They have the potential to glide from higher trees onto passing
>>  animals
>
> I think you mean parachuting here (close to vertical, drag maximized, no
> lift), not gliding (almost horizontal, drag minimized, lift generated).


There are competing definitions, and Jonas' use of the term 'gliding'
(as opposed to 'parachuting') is in keeping with how it is often used
in the neontological literature.  For example, this is from Byrnes &
Spence (2011; doi:10.1093/icb/icr069):


"First of all, an historical distinction between gliding and
parachuting, in which gliding is defined by descent angles <45 degrees
to the horizontal (Oliver 1951), has set up an operational definition
that gliding occurs in the steady-state and that maximizing the
ability to cover long distances ‘‘improves’’ performance. However,
numerous examples show that gliding rarely, if ever, occurs in a
steady-state in a variety of organisms, including insects (Yanoviak et
al. 2005), reptiles (McGuire and Dudley 2005; Socha et al. 2010), and
mammals (Bishop 2006; Byrnes et al. 2008). Furthermore, in
natural settings gliding animals rarely maximize the distance covered
(Table 1).  As a result, our working definition follows Dudley et al.
(2007) in that gliding is any aerial behavior that involves active
regulation of aerodynamic forces and therefore does not include any
parachuting behaviors that are strictly passive, with no active
modulation of aerodynamic forces."


Since the micraptorines aerial behavior would involve active
modulation of aerodynamic forces, it would qualify as 'gliding' under
this definition.




Cheers

Tim