Extreme Bodies
The babirusa’s upper canines don’t grow downward as normal ones would. Instead, they grow directly up, through the top of the skull bones and out through the skin on the snout. Babirusas use them for display and in fights against mating-season rivals.
Wildlife/Peter Arnold, Inc.
Let's be honest, some mammals look bizarre - giant teeth, deadly feet, skin covered in everything from piercing quills to impenetrable plates of bony armor, and six-foot long hands.
Despite our differences, all mammals inherited the same basic body features - some type of hair or fur; backbones; and mammary glands, among others. But, clearly, an amazing variety of creatures have evolved over the 200-million year history of mammals.
How could mammals evolve such a wide variety of seemingly strange features? Well, evolution proceeds by acting on the tiniest differences among individuals.
For example, a mammal with a distinguishing feature like large front teeth might have an advantage in one particular environment. Over time, as individuals with that trait produce more offspring, all or most members of that species might have large front teeth. Eventually, some might end up with extreme adaptations--like giant tusks.
Headgear
""Check out the ossicones on that giraffe." OK, that may sound a little weird, but it's better than, "Look at the tooth on that narwhal."
Noses
After a look at some of the more extreme noses among mammals, you might rethink the saying, "It's as plain as the nose on your face." In fact, you might never say that again.
Teeth
Mammals' mouths contain up to four main types of teeth: incisors, canines, premolars, and molars. This basic but incredibly flexible tool kit evolved early in the evolutionary history of mammals.
Brains
Mammals have large brains for their body size--larger than most members of other vertebrate groups.
Skin, Hair, Armor
What's 11 feet tall, 10,000 years old, and wears a skirt? The woolly mammoth...obviously!
Tails
But our ancestors lost their tails about 18 million years ago. Today, humans retain only the shortest remnants--just a few hidden bones at the base of the pelvis.
Reproduction
When you take a look at the reproductive habits of some mammals, you'll find it is sometimes a little more interesting than the standard "birds and the bees."