TV Program Description
Original PBS Broadcast Date: June 19, 2007
NOVA takes viewers to the stark Australian outback in search
of the elusive bones of one of the world's most bizarre
prehistoric creatures—a giant predatory marsupial called
Thylacoleo. Australia's leading paleontologists endure
extreme weather, treacherous drops into a deep cavern, and the
threat of fossil poachers as they launch a daring expedition
to find the rare megabeast.
During the Ice Age a million or more years ago, Australia was
home to a zoo of extraordinary giant animals, including
eight-foot-tall kangaroos, wombats the size of hippos, snakes
three feet in diameter, and a horned tortoise as big as a
Volkswagen. (For a diorama-like gallery of some of these
creatures, see
Australia's Vanished Beasts.) But none was quite as bizarre or fearsome as
Thylacoleo, the meat-eating marsupial lion. Pound for
pound, this creature had the most powerful bite of any mammal,
living or extinct—in fact, its bite was equal to that of
a much bigger African lion today. But even though it was the
king of ancient Australian predators, Thylacoleo was
eventually toppled from its throne, dying out along with all
the rest of the outsized beasts. What happened to drive so
many extraordinary megabeasts into oblivion?
In "Bone Diggers," NOVA joins the Australian expedition to
retrieve a rare intact skeleton of the meat-eating marsupial.
The analysis of its bones throws new light on
Thylacoleo's many peculiarities, notably the question
of how it attacked its prey (see
Anatomy of Thylacoleo). And, finally, the show digs into the mystery of what
finally overwhelmed the giant Ice Age creatures and whether
early human hunters were responsible.
The adventure begins when paleontologist John Long receives an
e-mail from an amateur explorer with a tantalizing photo
attached. The photo shows an apparently intact skeleton of
Thylacoleo in the depths of a remote cave in the
outback. Since no one has found a complete skeleton before,
the discovery would be a paleontological milestone. So Long
and his colleagues at the Western Australian Museum set out on
an arduous expedition, crossing the desolate Nullarbor Plain
to pinpoint the remote cave shown in the e-mail. Over the next
three weeks, exploring the dangerous recesses of the ancient
cavern, the team finds a remarkable trove of fossil
remains—including several astonishingly well-preserved
Thylacoleo skeletons together with previously unknown
species of giant kangaroo.
Back in Perth, the team begins studying the bones and building
up a picture of the marsupial lion's unique anatomy and
behavior. Although most marsupials such as kangaroos and
koalas are herbivores, Thylacoleo was something
completely different—a fearsome predator with
pincer-like front teeth and a slashing front claw on its
thumb. Yet it wasn't built like a lion; with its low-slung
body and short legs, it could never have chased its prey at
high speed. Instead, it probably waited in ambush for its next
meal, perhaps dropping from trees.
In the final scenes of "Bone Diggers," NOVA investigates the
mystery of Thylacoleo's disappearance and that of all
the other Australian giants. A fierce controversy turns on
when exactly this continent-wide extinction occurred. The
debate is split between advocates for a late date at the cold
climax of the Ice Age some 30,000 years ago, when climate
stresses would have been particularly severe. The competing
camp claims the extinction was much earlier, around 50,000
years ago, when the climate was milder and the first humans
arrived in Australia. While it's unlikely that humans could
have directly over-hunted all the huge animals, Aboriginal
hunters may well have set fires that gradually changed the
profile of vegetation in the outback, making it harder for
Thylacoleo's prey to get by. Although it was the king
of beasts, Thylacoleo was probably vulnerable to shifts
in the food chain. (For more on this mystery, see
The Extinction Enigma.)
Whichever theory is correct, the riddle has implications that
stretch beyond Australia. Creatures like woolly mammoths,
mastodons, cave bears, giant sloths, and many other species
all died out on other continents as the Ice Age ended and
human populations expanded. The jury is out on just how big a
role human predation played both in Australia and on the
worldwide stage.
From the gripping discovery in the desert cavern to the
detective work in the lab, "Bone Diggers" takes NOVA viewers
on a paleontological "CSI," unraveling a prehistoric puzzle
that has eluded paleontologists for a century.
Program Transcript
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