There’s nothing like a little David Attenborough to remind you of just how awesome this planet – and your Linnaean class – really is. (I’m watching Life of Mammals and made it through only the first episode before turning it off to write this.)
Mammals made a quiet entrance into the world of dinosaurs as tiny, mouse-sized creatures more than 200 million years ago. Since then, mammals have branched off into hoofed animals, primates like us, felines, canines, and more.
All mammals share a few common traits:
1. Skin glands. These can include sweat, sebaceous, scent, musk, and most well-known, the mammary glands that produce milk.
2. Pelage (pronounced, “PEL-edge”), also known as hair or fur. Even mammals like whales, dolphins, and the pangolin can have some sparse hair.
3. Our red blood cells don’t have nuclei, and we are warm-blooded (meaning we produce our own energy from our food, rather than soaking up the sun for energy.)
4. Three middle ear bones, which help us to hear better.
6. A four-chambered heart.
7. A lower jaw comprised of only one bone, rather than several.
Other traits, however, like live birth or placentas, depend on the sub-class. Cross the jump to get a quick introduction to the three sub-classes of mammals and their awesome unique traits!