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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