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New in Nature: Birds Galore!



Aside from the already cited paper by Xu et al., the longest list yet of
authors for any Liaoning fossil, there are several other bird-related
papers, including one which is coauthored by biomechanist Andy Biewener
and ornithologist Ken Dial. *Microraptor gui* is the second dinosaur named
in 2003, whereas the mis-dated *Heyuannia* is the first.

  First, Prum summarizes the paper by Xu et al., and points out that one
of Xu et al.s claims, that of lack of any real terrestrial ability because
of the leg feathers, must be tested with mechanical models oof the legs
and feathers during walking phases to assess whether it really was
possible or not.

  Prum, R.O. 2003. Dinosaurs take to the air. _Nature_ 421 (6921):
323-324.

  Then Weimerkirch et al. take a look at the flight of frigatebirds, and
indicate that the apparently languid lifestyle of these birds is suitable
to the low-yield, weather-dependant environment that appears to restrict
them to the low tropics. This includes thermal formation as a convention
effect between warm water and cool cumulus clouds overhead, permitting
these birds to be advent opportunists, taking advantage of their
night-and-day foraging during brooding or nesting seasons to get the most
out of the waters.

  Wimerkirch, H.; Chastel, O.; Barbraud, C.; and Tostain, O. 2003.
  Frigatebirds ride high on thermals. _Nature_ 421 (6921): 333-334.

  And finally, Tobalske et al. describe the flight power curve in three
birds, using already published data to back up an hypothesis that the
flight power curve for a bird (mechanical power versus velocity) really is
U-shaped. Earlier, magpies (*Pica pica*) were shown to have a power curve
that flattened out, mechanical output remained steady as velocity
increased. Two more birds were analyzed by in vivo study of the electrical
discharge from the pectoralis musculature, the cockatiel (*Nymphicus
hollandicus*) and the ringed turtledove (*Streptopelia risoria*); in the
first, the power curve was distinctly U-shaped, whereas that of the
turtledove was intermediate in form, and showed even higher speeds than
the two other birds with minimal increase in effort.

  Tobalske, B.W.; Hendrick, T.L.; Dial, K.P.; and Biewener, A.A. 2003.
Comparative power curves in bird flight. _Nature_ 421 (6921): 363-366.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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