Two big rams bolted from the steel trailer, took a few hesitant steps and glanced around nervously at their new home: dramatic mountains in west Texas more than 200 miles from where they grew up.

For example, the world's smartest dog breed is more intelligent than a four-year-old child. Plus, there's another animal that ...

The mountain pygmy possum, a tiny nocturnal marsupial, was once known only from Ice Age fossils. Today, we know where its ...