Animals of the Pleistocene

Mastadons, Mammoths, Giant Sloths, Saber Tooth Cats

Mastadons

• Became extinct about 11,000 years ago• The American mastodon (scientific name

Mammut americanum) roamed North America from at least 3.75 million to 11,000 years ago.

• Mastodons, along with mammoths and modern elephants, are members of the order Proboscidea.

• As adults they stood between 2.5 and 3 meters (8-10 feet) at the shoulder and weighed betweeen 3500 and 5400 kilograms (4-6 tons).

Mammoths• Mammoths (genus Mammuthus) are extinct

elephant-like animals that were adapted to cold weather. These herbivores (plant-eaters) had long, dense hair and underfur, large ears (but much smaller than modern-day elephants), a long proboscis (nose), and long tusks. Both the males and the females had tusks; the tusks were really incisor teeth.

• Mammoths lived from about 2 million years ago to 9,000 years ago, during the last ice age (the Pleistocene Epoch). This was millions of years after the dinosaurs went extinct. These huge mammals lived throughout the world.

• The various mammoths ranged in size from about 9 ft (2.7 m) tall to over 15 ft (4.5 m) tall. Some species had tusks that were straight, some had tusks that were curved. The longest tusks were over 17 feet (5.2 m) long. The tusks were used in mating rituals, for protection, and for digging in the snow for food.

The Difference

• Mammoths and Mastodons:Mammoths had longer tusks than mastodons, a wider head, a sloping back, flat, chewing teeth, a trunk with two finger-like projections, and were mostly taller. Mastodons evolved earlier and lasted longer in geologic time.

Sabertooth Cat • With their enormous, deadly-sharp canines, saber-toothed

carnivores are well known to many people as frightening and ferocious predators of the Cenozoic. Surprisingly, there is more than one "saber-toothed cat." The sabertooth morphology has appeared several times during the history of the mammals.

• Why the enormous teeth? Certainly they were used in hunting, but opinions vary as to exactly how they were used. Some paleontologists have suggested that they were used to grab and hold onto prey. However, attacking a large herbivore this way could easily break the saber teeth and saber teeth that were demonstrably broken during an animal's lifetime are rare in fossil deposits. A more plausible hypothesis suggests that saber teeth were used to deliver a fatal ripping wound to the belly or throat of a prey animal. Sabertooth carnivores may not have tried to grapple with prey. More likely, they delivered one crippling stab wound and then waited for the prey to die.

Giant Sloth• A few thousand years ago the Americas were the

land of giant ground sloths. They were a bit more impressive than their tree-dwelling cousins, but would probably have been equally odd-looking. Megatherium was a huge sloth, almost 6m long, and because it became extinct so recently, mummified skin and dung has been discovered in dry caves in North America helping to reconstruct exactly what it looked like and how it behaved.

• The biggest surprise has come from the fossilised trackways of Megatherium. These have revealed the amazing fact that these giants regularly walked upright on their hind legs. The giant sloths must have weighed almost four tonnes (nearly as much as an African elephant), and so walking on only two legs would have put a tremendous strain on their skeletons.