Page 34 - The Origin of Birds and Flight

32 The Origin of Birds and Flight

Professor Alan Feduccia, of the North Carolina University Biology
Department, recognized as one of the world's most eminent authorities
on ornithology, describes the theory as “aerodynamic absurdity.” 11
Some 50 years later, Yale University Professor of Geology John
Ostrom proposed a new version of the cursorial theory, suggesting that
forearms turned into wings as they attempted to capture insects.
According to Ostrom, feathers first emerged for insulation of body heat
12
and later extended in length. This “insect theory” came in for criticism
on four major grounds, and in 1983 Ostrom was forced to reject his own
theory. In one statement, he cites the absence of the intermediate forms
13
his theory required:
No fossil evidence exists of any pro-avis. It is a purely hypothetical pre-
bird, but one that must have existed. 14
Those eager to continue with the theory after Ostrom suggested that
feathered wings developed in order to control the body’s direction dur-
ing running and leaping. Like their predecessors, however, these men
too came in for criticism. 15 For instance, Professor Jeremy Rayner of
University of Leeds calculated that when a living thing in this hypothe-
sis jumped up into the air, there would be a 30 to 40% drop in its speed
which would cause serious problems in flight. Rayner came to the con-
clusion that under such conditions, a considerable amount of energy
16
would be required which would mean a very low flying speed. Rayner
therefore suggested that the model was lacking in the morphological,
physiological and behavioral features required for flight, and that it
would therefore fail. 17
Despite changes brought in, the Museum of Texas Technical
University paleontologist Sankar Chatterjee was forced to accept that
the cursorial theory was bio-mechanically untenable. 18
David E. Fastovsky, a professor of earth sciences and a paleontolo-
gist, and the cellular biologist and anatomist David B. Weishampel of
the John Hopkins University Medical School, stated that functional
morphologists have been unable to satisfactorily model the running-to-
flight transition in early birds. 19