Mammals eutherians

Marsupials (6/19) These present no known instances of loss or reduction. The Metatheria (Australian and South American marsupials) differ little in the layout of their VN complex from those of the higher placental mammals (Eutherians) (Broom, 1896 Kratzing, 1984 Poran, 1998). Attention to Australasian forms has until recently predominated [Kratzing, 1978, 1982 and 1984(a)-(c) Salamon, 1996]. A few genera... 

A clear demarcation of the external nose in marsupials and many eutherian mammals presents as a hairless area of skin surrounding the nostrils and the inter-narial space and can include the median part of the upper lip. This typically pigmented zone — the rhinarium — is... 

The variety of breeding patterns displayed by the American and Australian metatheria and the lack of comparative experimentation hampers general conclusions on any fundamental division from eutherian mammals. 

Eutherians. About 95% of all mammals belong to this subclass. The developing embryo in utero receives nourishment via the placental blood supply (they are referred to as placental mammals) and is born at a high, but variable, species-related state of maturity. All eutherians secrete milk, which, depending on the species, is more or less essential for the development of the young the young of some species are born sufficiently mature to survive and develop without milk. 

Heteromorphic sex chromosomes were hypothesized to have evolved from a homologous pair of chromosomes by the suppression of crossing-over between the ancestral pair of sex chromosomes and subsequent loss of gene function on the ancestral Y (or W) chromosome.2 One prediction of this hypothesis is that recombination between the X and Y chromosomes (or between the Z and W chromosomes) will be reduced or nonexistent. This prediction is well supported for eutherian mammals with rare exception, recombination between the X and Y chromosomes is reduced to a small region referred to as the pseudoautosomal region. As a consequence, most of the mammalian Y chromosome is isolated in the genome and is thus clonally inherited from father to son. 

McNab, B. (1986). The influence of food habits on the energetics of eutherian mammals. Ecological Monographs, 56, 1-19. 

Bedford, J.M. (1983). Significance of the need for sperm capacitation before fertilization in eutherian mammals. Biol. Reprod. 25 108-120. 

Harrison, R.A.P, (1996). Capacitation mechanisms, and the role of capacitation as seen in eutherian mammals. Reprod. Fertil. Dev. 8 581-594. 

---