What are the main groups of mammals?

There are three main live groups of mammals: placental mammals, monotrems and marsupials. The fourth group, multituberculators, is now extinct. Of the three living groups, placental mammals are by far the largest and probably best known; After all, you are a placental mammal, and if you own mammalian pets, the chances are very high, that they are also placental mammals. These groups of mammals are what are known as infraClasses taxonomically, which means they are included under class and subclass, but above the order. All mammals have Neokortex, an area of ​​the brain that is unique for mammals, and also have three middle ears and one jaws. Mammals also have sweat glands and are able to produce milk using specialized glands. Mammals also have hair and specially designed skulls that connect with their neck vertebrae in their protection. Placentary mammals are more correctly classified as belonging to Eutheria infraclass, but many people use "placental" to describe the mammal in this infraction with o o o oby a duty on his defining feature. All placental mammals use the placenta during pregnancy. Some examples of placental mammals for people and pets include bats, goats, sloths and dolphins.

Marsupials, on the other hand, do not use the placenta. Instead, they develop a small yolk bag that nourishes a young marsh for a short time before they are born in a highly undeveloped state. At this stage, the young animal crawls into the nutrition mother and further development. Marsupials are sometimes known as mammal bags, in reference to their intermetic development. Well -known messages include Opssums, Kangaroos and Koalas.

Monotrems are quite unique and today only six species live. They are reproduced by eggs rather than giving birth to live young, and have many other interesting physiological features that distinguish them from other members of the mammal class. Platypus is one of the known examples of monotrem; First newsThey were so unbelievable about the platypus that they believed that the animal was a scam!