TV Program Description
Original PBS Broadcast Date: February 26, 2008
In 2002, the discovery of a beautiful and bizarre fossil
astonished scientists and reignited the debate over the origin
of flight. With four wings and superbly preserved feathers,
the 130 million-year-old creature was like nothing
paleontologists had ever seen before.
In this program, NOVA travels to the Chinese stone quarry
where the fossil was discovered—a famed
fossil treasure-trove—and teams up with the world's leading figures in
paleontology, biomechanics, aerodynamics, animation, and
scientific reconstruction to perform an unorthodox experiment:
a wind tunnel flight test of a scientific replica of the
ancient oddity.
Dubbed Microraptor, the crow-sized fossil is one of the
smallest dinosaurs ever found and one of the most
controversial, challenging conventional theories and
assumptions about the evolution of flight. (Compare
Microraptor's skeleton
with those of the earliest known bird and a nonflying dino
relative.)
But how did Microraptor use its wings? Did it array its
arm- and leg-mounted wings in the style of an early
20th-century biplane to produce high lift at low speed? Did it
use them to create a single lifting surface for efficient,
swift gliding? Did it employ some combination of these two
methods? Or were the extra wings useless for flight and likely
to have been for some other purpose, such as attracting a
mate?
To answer these questions, NOVA interviews Chinese
paleontologist Xu Xing, who first recognized the importance of
Microraptor and gave it its name; paleontologist Mark
Norell and artist Mick Ellison of the American Museum of
Natural History; paleontologist Larry Martin of the University
of Kansas; anatomist Farish Jenkins of the Museum of
Comparative Zoology at Harvard University; and aerodynamicist
Kenny Breuer of Brown University.
In addition, NOVA commissions a "flight-ready" wind tunnel
model of Microraptor complete with feathers and
articulating joints. (Test-fly Microraptor yourself in
a
virtual wind tunnel.)
Artists have historically played an important role in
paleontology by helping to reconstruct the appearance and
behavior of ancient animals. In the case of
Microraptor, two completely different reconstructions
were made, one at the American Museum of Natural History, and
the other at the University of Kansas, based on different
specimens and different techniques.
The two markedly different reconstructions play into a
long-running scientific controversy over the origin of flight
in birds. For years the debate has been a standoff between two
camps—those who believe dinosaurs were the ancestors of
birds, and those who do not. (Hear from the film's producer,
Mark Davis,
on why this debate has fascinated him for two decades.)
Believers in the dinosaur-bird connection have generally
assumed that flight must have begun from the ground up, with
fast-running dinosaurs that eventually got airborne as
feathered arms evolved into wings, and running leaps evolved
into powered flight.
Skeptics of the bird-dinosaur link say it would have been
physically impossible for running dinosaurs to overcome
gravity and get off the ground. It made more sense for flight
to evolve from the trees down, with small, arboreal reptiles
that glided from the treetops on their way to becoming
full-fledged fliers. And that seemed to rule out dinosaurs,
which presumably couldn't climb trees.
As seen in this program, the American Museum's Mark Norell is
one of the proponents of the "birds-are-dinosaurs" hypothesis,
which is the predominant view among most paleontologists,
while Larry Martin of the University of Kansas speaks out for
the minority view that birds descended from non-dinosaur tree
dwellers.
Tantalizingly, Microraptor is the unexpected missing
link that has reignited the debate and, with the help of
NOVA's model and wind tunnel tests, just might settle the
issue—or at the very least deepen our understanding of
the long-ago era when the ancestors of birds first took to the
air.
Program Transcript
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