Re: Spinosaurs ate pterosaurs

[Dino Guy Ralph <ralph.miller@alumni.usc.edu>]

I must confess that I've completely forgotten how we got from spinosaurs to
leaping maniraptorans.  Forgive me if the following is irrelevant to the
discussion at hand.  Be that as it may...

Certainly many raptorial birds dive bomb terrestrial prey from above, and a
variety of cats pounce onto animals from the concealment of trees.  I would
think that gliding from trees would enable a predator to pounce more safely
and with a better measure of control from a greater height (and hence from a
vantage point that is harder for the prey item to spot).

There is no reason to presume that this hunting strategy must be applied to
flying prey or prey in the trees -- it is clearly effective against prey
that is on the ground (or, conveniently, at a water hole).  The only
requirement would be that the prey item should be large enough to justify
the energy expended.  A large insect could satisfy a small predator, but
larger predators would pursue larger prey.  That's about all there is to it.

Needless to say, climbing and gliding are also both useful means of escape
from other predators.  Whether escape or prey pursuit requirements would
have fostered the initial impetus for developing gliding adaptations in a
given lineage is something I wouldn't know.

--------
"Dino Guy" Ralph W. Miller III
Docent at the California Academy of Sciences
proud member of the Society of Vertebrate Paleontology