ANSWERS TO UNANSWERED QUESTIONS AT MINI MUSEUM ON OCT 15, 2014
BY HANS LARSSON
1.
Microraptors had feathers on their hindlegs, which seem to be very incapacitating if you want to
run fast enough to get a ground-up power flight. Then, how did Microraptors manage to take off? Did
they have very strong front leg muscles just like Quetzelcoatlus?
Models of having trailing feathers on the legs actually allows the legs to shed air better and would have
aided faster running. Their hindlimbs are long and well build for fast running. An excellent model of
Archaeopteryx ground running to flight was published by Burgers and Chiappe (1999).
Burgers P, Chiappe LM (1999) The wing of Archaeopteryx as a primary thrust generator. Nature 399: 60–
62.
2.
Could evolution of hollow bones be associated with lower O2 levels on Earth? Ie low o2,
selection pressure for more efficient use of 02 = hollow bones
Possibly, I don't think any one has published on this before. The hollow bones are often not directly
associated with a one-way flow lung and the hollow bones of early theropods were more likely for
lightening their skeleton. However, these are not entirely decoupled, physiologically speaking, so I think
this is a good idea worth exploring.
3.
I have seen hawks teach their young to fly from the top of a tree. Why is it not pertinent to
antecedents of birds being arboreal as they become birds?
This argument was one of the early arguments for an arboreal origin of flight. It's so easy, for a bird, to
learn how to parachute, flap, glide, and fly from a tree. The issue as hand, though, is how the parents
got there to lay the eggs so high. Nowadays, birds just fly into the trees, but their anticedents would
have had to climb to perform this scenario. There are no musculoskeletal adaptations in the hindlimbs
of bird ancestors, and Archaeopteryx, to suggest they were capable climbers. All their hindlimb anatomy
allies with typical terrestrial running vertebrates, like horses and dogs (Dececchi and Larsson 2011).
What's a bit complicating is that the forelimbs of these ancient animals were adapted for grasping prey
and have highly mobile shoulders and elongate, clawed fingers. Some of these traits are also found
climbing animals. But, the switchblade wrist hinge joint and elongate arms are poor adaptations for
climbing.
Dececchi TA, Larsson HCE (2011) Assessing Arboreal Adaptations of Bird Antecedents: Testing the
Ecological Setting of the Origin of the Avian Flight Stroke. PLoS ONE 6: e22292.
doi:10.1371/journal.pone.0022292.