∞ generated and posted on 2016.11.09 ∞
Subset of eutherians that bear live young and lack pouches.
|Placental Mammals are mammals that employ well developed placentas during the gestation of their young. The vast majority of mammals in the world today are placental mammals. We are placental mammals.|
Among extant mammals neither the monotremes nor the marsupials are placental mammals. The non-monotreme and non-marsupial mammals nonetheless are described as eutherians, which is a mammalian clade that includes the clade Placentalia, i.e., the placental mammals.
The following video, though OK, is not the most exciting in the world, but in two minutes and six seconds it does provide an overview of what placental mammals are all about, at the level of order (that is, one major taxonomic category below that of class Mammalia):
By far and away the majority of mammals on Earth today are placental mammals.
Note the following evolutionary progression is seen among tetrapods going basically from amphibians to mammals: