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Mammals evolved from reptiles about 220 million years ago. After the extinction of dinosaurs around 65 million years ago, mammals diversified to fill the many vacated niches in a wide range of habitats. Mammals such as bats now patrol the skies, whales and dolphins inhabit the seas, and animals as diverse as otters and elephants fill habitats across the land.
Wolves, foxes and other canines are hardy and adaptable, altering their habits and behavior to make the most of the habitat. Learn more
The cetacean family includes the world's largest animal... and some of the most intelligent. Learn more
The wild relatives of the domesticated house cat include some of the planet's most graceful predators. Learn more
Found in rivers around the world, the otter family also includes some sea-faring species. Learn more
As the largest land animal, the African bush elephant reaches up to 24 feet in length and 13 feet in height. Learn more
The largest land mammal in North America, adult males may stand as tall as six feet at the shoulders and weigh 1000-2000 pounds. Learn more
Learn why no species, other than humans, can change the landscape as much as the beaver. Learn more
Are brown bears really dangerous? Learn why the threat of them attacking you is greatly exaggerated. Learn more
Reindeer versus caribou: What's the difference? Not much, actually…until you get to conserving them. Learn more
Dugongs occupy a large range arcing along the coast of east Africa, across south Asia, and down to Australia. Learn more
The greater kudu is found throughout eastern and southern Africa, in mixed woodlands, bushlands, hills and mountains. Learn more
The hippopotamus is a large, mostly plant-eating mammal found in rivers and lakes throughout Africa. Learn more
Despite the name, the kangaroo rat is simply a rodent, not a marsupial. Its name derives from the kangaroo-like leaps. Learn more
The pine marten ranges in forests and woodlands across Alaska, Canada, and the northern United States. Learn more
The manatee occupies the same niche in American waters that its cousin, the dugong, holds in Asia. Learn more
Whether scary or exciting, nature has a way of sneaking up on you. See stories
Hear some of nature's success stories and see how nature matters to us all. Watch videos
Coast live oak trees punctuate the prairie grasslands at Chimineas Ranch, a protected wildlife corridor linking the Carrizo Plain National Monument with Los Padres National Forest, located within San Luis Obispo County, California. © Mark Dolyak