In the animal kingdom, no group is more impressive than the mammals. Mammals range in size from the blue whale to the tiny shrew, but all mammals share four characteristics: (1) Females produce milk and nurse their young, (2) Hair, (3) Three middle-ear bones, and (4) Warm-bloodedness. Most mammals also give live birth as opposed to laying eggs. Many people are more familiar with mammals than with members of any other class of animals, because mammals are found all over the world. Some mammals, like dogs and cats, are kept as pets.
There are about 5,000 species of mammals, and these include animals that have remarkable characteristics and do amazing things. Consider just a few: The cheetah is the fastest land animal, reaching speeds of 71 miles per hour. The hero shrew has the strongest backbone of any animal, size-for-size. This shrew’s backbone accounts for four percent of its total weight, compared to about one percent in other small mammals. Carolus Linnaeus was the first to categorize whales as mammals, but scientists have been observing mammalian characteristics of whales and dolphins since at least the ancient Greeks (Aristotle wrote about mammals, although he did not categorize them exactly as we do today).
Marsupials are mammals with pouches for carrying their newborn offspring, and many of them are found in Australia. Kangaroos, wallabies, koalas, and wombats are marsupials (the red kangaroo is the biggest marsupial). The Tasmanian “devil,” the largest meat-eating marsupial in Australia, got its name because of the creepy growls it makes as it fights other “devils” for food. The only marsupial that lives naturally in the United States is the opossum.
Taxonomists call human beings mammals,
because we have all four main characteristics that mammalian animals have. This does not mean, however, that we are related to the animals by evolutionary ancestry. Evolutionists teach that the first mammals evolved around 200 million years ago, and that humans eventually
evolved from the more “advanced” mammals. But, the fact is, God created animals and humans separately on days five and six of Creation (Genesis 1:20-28).