Mammals are a class of tetrapods that include camels, chimpanzees, cats and rats and elephants, goats and sheep, horses and cows. [1] The class of mammals can be divided into two main infraclasses: eutheria and the marsupials.

Orders of Mammals
Infraclass Superorder Order Common Representatives
Eutheria Afrotheria Afrosoricida golden moles
Eutheria Afrotheria Hyracoidea hyraxes
Eutheria Afrotheria Macroscelidea elephant shrews
Eutheria Afrotheria Sirenia manatees
Eutheria Afrotheria Proboscidea elephants
Eutheria Afrotheria Tubulidentata aardvarks
Eutheria Euarchontoglires Dermoptera flying lemurs
Eutheria Euarchontoglires Lagomorpha rabbits
Eutheria Euarchontoglires Primates chimps
Eutheria Euarchontoglires Rodentia mice
Eutheria Euarchontoglires Scandentia tree shrews
Eutheria Laurasiatheria Artiodactyla pigs, goats, sheep, cows
Eutheria Laurasiatheria Carnivora cats and dogs
Eutheria Laurasiatheria Cetacea whales and dolphins
Eutheria Laurasiatheria Chiroptera bats
Eutheria Laurasiatheria Erinaceomorpha hedgehogs
Eutheria Laurasiatheria Perissodactyla horses
Eutheria Laurasiatheria Pholidota scaly anteaters
Eutheria Laurasiatheria Soricomorpha white-toothed shrews
Eutheria Xenarthra Cingulata armadillos
Eutheria Xenarthra Pilosa giant anteaters
Marsupial Ameridelphia Didelphimorphia Virginia opossums
Marsupial Ameridelphia Paucituberculata shrew opossums
Marsupial Australidelphia Dasyuromorphia Tasmanian devils
Marsupial Australidelphia Diprotodontia kangaroos
Marsupial Australidelphia Microbiotheria monito del monte
Marsupial Australidelphia Notoryctemorphia marsupial moles
Marsupial Australidelphia Peramelemorphia marsupial omnivores




EUTHERIA = the crown placental mammals


Eutheria (Greek: "true beasts") is a group of mammals consisting of the first placental mammal and all of her decendants. The earliest known fossil eutherian, Eomaia, was found in Asia, and is dated to the Early Cretaceous period, about 125 million years ago. [2] Most placental mammals belong to one of four main superorders: Afrotheria, Euarchontoglires, Laurasiatheria, and Xenarthra.

Eutheria 
 
Boreoeutheria 
 

Euarchontoglires

Laurasiatheria

Atlantogenata 
 

Xenarthra

Afrotheria


Euarchontoglires + Laurasiatheria = Boreoeutheria

and

Xenarthra + Afrotheria = Atlantogenata.


Xenarthra diverged from Afrotheria relatively rapidly after Atlantogenata diverged from Boreoeutheria. There was considerable gene flow among the nascent clades prior to their divergence. This made it difficult to resolve the above phylogenic tree until relatively recently. [3]



MARSUPIALS

The seven living orders of marsupials are divided into two clades: Ameridelphia and Australidelphia. [4]



MONOTREMATA

mammals 
 
Theria 
 

Eutheria

Marsupials

Monotremata


Order monotremata = Subclass prototheria


Eutheria + Marsupials = Subclass theria





References

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  1. http://species.wikimedia.org/wiki/Mammalia
  2. http://en.wikipedia.org/wiki/Eutheria
  3. http://mbe.oxfordjournals.org/content/24/9/2059.short
  4. http://www.ncbi.nlm.nih.gov/pubmed/12878458