animais que existiram

O antecessor do cão!
Extinct ancestor of today's hogs, this Archaeotherium—"ancient beast"—lived some 23 to 34 million years ago in what is now South Dakota. Strong neck muscles suggest that the roughly 4-foot-long (120-centimeter-long) animal was well suited to digging up roots and tubers with its snout.



A coil of teeth caps the lower jaw of a sculpture of a 13-foot (4-meter) whorl-tooth shark, or Helicoprion, a fish genus that lived about 250 million years ago.
Artist Gary Staab depicts the animal's jaw as something of a spiral conveyor belt, in which new teeth would advance to replace old ones (concealed here by skin). But the true arrangement and purpose of the teeth remains a mystery. Some scientists suggest that it may have operated like a spiked whip, possibly curled underneath the lower jaw like a weaponized elephant trunk.
The shark adds bite to "Bizarre Beasts, Past and Present," a new exhibition of Staab's sculptures at the National Geographic Museum in Washington, D.C. (through February 2, 2007). The animals depicted are, or were, all real—testaments to the twists, turns, and blind alleys of evolution.
in National Geo