What Are Mammals?
Characteristics Mammals have three different characteristics that other creatures don’t have. One is hair. At some point in their life mammals have hair. Did you know that whales and dolphins have sensitive bristles on their snouts, considered as hair? Hair can be an insulation to keep a warm body temperature. This enables them to go in just about any climate. It also gives a color pattern and a sense of touch. If you have ever touched a cat or dog you would know how soft their hair is. Another characteristic is that all females have mammary glands. Mammary glands produce milk. This is so that mothers can feed their young with milk since the young can’t have actual food until they’re older. The third characteristic is that all mammals have 3 middle ear bones. Mammals also have teeth, a lower jaw, and a well developed brain.
Mammals are warm-blooded vertebrates that evolved in the Jurassic Period, about 175 million years ago. They evolved from reptiles. For over a hundred million years, mammals were small and not very diverse, but with the extinction of dinosaurs in the Cretaceous-Tertiary extinction 65 million years ago, mammals grew in size and diversified. Common mammals include rodents, bats, dogs, bears, cats, deer, sheep, goats, and humans. In all, there are about 5,400 species of mammals, distributed in about 1,200 genera, 153 families, and 29 orders. Most mammals are terrestrial, whales and dolphins being important exceptions. Mammals are characterized by sweat glands, including variants that produce milk (mammary glands), hair all over their body, and a neocortex, a layer of brain that gives mammals superior intelligence to reptiles and birds. The success of mammals over reptiles and other animal groups in the last 65 million years has been a classic example of brain triumphing over brawn. Mammals
Mammals are the animals most familiar to people. More than 400 mammal species are native to North America and 88 are found in Kansas. Mammals are the only animals that have hair and feed young with mother’s milk. Other characteristics include being warm-blooded, having a backbone, jaws with teeth and a four-chambered heart. Although large mammals may be the most well known, the small and secretive species are the most abundant. How are Mammals classified? All mammals belong to the Class Mammalia. Within Kansas are found representatives of eight Orders: Didelphimorphia (opossums), Insectivora (shrews and moles), Chiroptera (bats), Xenartha (armadillos), Lagomorpha (rabbits, hares and pikas), Rodentia (rodents), Carnivora (carnivores) and Artiodactyla (even-toed ungulates). A complete checklist of Kansas’s mammals is found below. You may also download a pdf version by clicking on this icon (97K). This checklist is revised and updated from “A Checklist of the Vertebrate Animals of Kansas”
