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Science World for grades 6–10 brings science to life with fascinating feature articles and hands-on activities that reinforce science concepts and help students build test-taking and critical-thinking skills.
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Extreme Mammals

Meet some amazing animals — from the past and present

Some hunt with fangs, some glide through the air, and still others sport impressive body armor. Are these mythical monsters? No — just a few examples of some extraordinary mammals.

Mammals have backbones and hair, and make milk for their young. Most give birth to their young, but a few mammals lay eggs. They are also warm-blooded, meaning that they maintain a constant body temperature. But despite these common characteristics, mammals are a diverse group of animals that includes some unusual species.

To spotlight some of these amazing creatures, Science World spoke with John Flynn, a paleontologist who studies the history of life on Earth. Flynn is curator of the new exhibition Extreme Mammals at the American Museum of Natural History in New York City. The exhibition features both prehistoric and modern mammals. Ancient animals can tell us about the past as well as help us unlock secrets about present-day creatures, says Flynn. Knowing the vast history of mammals helps us judge what is truly unusual. Read on to learn about some extreme mammals.


Extreme Predator
A saber-toothed cat, concealed behind some bushes, watches a deer browsing nearby. As the deer inches closer, the cat pounces. Knocking the deer to the ground, the cat holds the prey steady and then slashes the deer's throat with knife-like teeth. Death comes quickly.

Saber-toothed cats hunted throughout much of the world until the last surviving species became extinct approximately 10,000 years ago. They had impressive canine teeth, and their jaw muscles were most specialized for fast-killing bites. That means they may have had to restrain struggling prey with their muscular front limbs and sharp claws. Only then could they safely bite into it. To prevent their long teeth from snapping, they probably speared soft body areas away from hard bones, says Flynn.

Lions are similarly impressive predators. A lion's canine teeth are less than half as long as a saber-toothed cat's, but its jaws are stronger. Sometimes a lion will use its jaws to break its prey's neck, or it will grab the animal's throat or muzzle in its mouth and suffocate it. Either way, says Flynn, it's typically a swift death.

Extreme Horns
Out of a hole in the ground pokes a small pair of horns. A furry face follows. Peeking from its burrow, the mammal twitches its ears and sniffs the wind. Nearby, a snake slithers. The small horned mammal scurries into its burrow. The snake follows. Raising its head, the horned mammal lunges at the invader. The surprised snake retreats, slinking away.

For about 10 million years, four species of "horned beavers" tunneled through the American Plains. Their horns served mainly to defend themselves from predators or to help them identify their kin, says Flynn. These horned beavers became extinct about 5 million years ago. They are the smallest-known horned mammals to ever exist.

Many modern plant-eating mammals — like sheep, antelope, and bison — still display horns. "Horns evolved to serve a number of purposes," says Flynn. They provide protection from predators and make it easier for animals to recognize members of their own species. Males may use their large horns to attract females or to tussle with other males for mates.

Extreme Armor
With its tail twined around a tree branch, a long-tailed pangolin sniffs for its dinner. It climbs down to the ground to follow the scent, and uses its huge powerful claws to rip apart a busy termite nest. The pangolin whips out its tongue, lapping up the wriggling termites in an instant. Pangolins are toothless, so they can't chomp up the insects, but the acids in its churning stomach will finish them off.

Pangolins, which today live in Africa and southern Asia, could almost pass for tiny armored dinosaurs. Unlike other mammals, their heads, backs, legs, and tails are covered with scales. Their scales are composed of keratin, the sturdy material that hair, hooves, and fingernails are also made of. Scientists believe that a pangolin's scales evolved from hair and fingernail-like thickenings of the skin, says Flynn. The overlapping scales, which are sharp-edged and hard, provide a continuous covering to protect the soft body beneath it. When threatened, a long-tailed pangolin can coil into a tight ball, tucking its head under its tail. The tough plates keep its face and soft belly safe.

The pangolin's scaly shield must be effective: Based on fossil finds, insect-slurping pangolins have been around for at least 50 million years.

Extreme Motion
At sunset in the days of the dinosaurs, a furry hunter prowls in a tree. An insect skitters by and . . . SNAP! The creature grabs the small bug and crushes it with its pointy teeth. Finished with its meal, the mammal leaps into the air. A flap of skin between its limbs stretches like a kite and the little mammal coasts silently to a neighboring tree.

About 125 million years ago, this bug-eating mammal glided through the skies of China. Air travel opened up new ways of feeding, says Flynn. Sailing from tree to tree allowed for the capture of flying insects and was faster than clambering up and down tree trunks.

This ancient glider is now long extinct. But similar-looking mammals live today, like the sugar glider — an Australian possum. Sugar gliders sip flower nectar and tree sap, and scarf down insects. Their life in the treetops helps them avoid foxes, wild cats, and lizards — but not owls and other predatory birds, which like to feast on the tiny gliders.


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