<p>Thylacoleo carnifex<br> Unrivaled predator, leopard-size T. carnifex stalked open forest and shrubland in search of prey, which probably included newly arrived humans. The continent's largest mammalian carnivore, weighing up to 350 pounds and up to 30 inches tall at the shoulder, this hunter likely thrived as an ambush artist. Bursting from undergrowth, it could throttle much larger game, grasping its prey with dagger-sharp thumb claws and finishing it off with its large front teeth.</p>

Marsupial Lion

Thylacoleo carnifex
Unrivaled predator, leopard-size T. carnifex stalked open forest and shrubland in search of prey, which probably included newly arrived humans. The continent's largest mammalian carnivore, weighing up to 350 pounds and up to 30 inches tall at the shoulder, this hunter likely thrived as an ambush artist. Bursting from undergrowth, it could throttle much larger game, grasping its prey with dagger-sharp thumb claws and finishing it off with its large front teeth.

Australia's Lost Giants

Seven-foot-tall kangaroos, rhino-size browsers, enormous flightless birds, and a predator that could kill them all: Such were the megafauna that once dominated Australia. Then humans arrived, and most of the giant animals vanished. Did the Ice Age finally catch up with them? Or did humans hunt megafauna to extinction?

This story appears in the October 2010 issue of National Geographic magazine.
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