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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