Grebes Have Wings For Toes: Implications for *Hesperornis*?

["Jaime A. Headden" <qilongia@yahoo.com>]

Aside from _Science_ featuring Fortey's new book on
trilobites,

  Johansson, L.C. and Norberg, U.M.L. 2000.
Biomechanics: Asymmetric toes aid underwater swimming.
Nature 407 [6804]: 582-583.

  The unique morphology of the toes of the great
crested grebe (Podiceps cristatus), which are
asymmetrically lobed with a narrower skin flap on the
lateral side of the toe, enables these birds to swim
very efficiently. Here we study video recordings of a
diving grebe and stroboscopic pictures of its moving
feet and conclude that the bird uses a
hydrodynamically lift-based foot (power) stroke to
propel itself underwater, with the separated toes
functioning as multiple slots to increase the
lift-to-drag ratio. The asymmetric lobes are an
adaptation for self-stabilization of the toes during
the power stroke, and the toes themselves act as
separate hydrofoils, each producing lift and each
being twistable individually under hydrodynamic load.

  "I saw your dance, it was stunning ... so are you."

  Jaime A. Headden

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