Eutheria

Eutheria is the mammalian clade containing placental mammals and their extinct relatives. Its members are more closely related to placental mammals than to marsupials.

Mammal: A vertebrate in the class Mammalia, typically characterized by hair and milk-producing glands. Eutheria is one major branch within the mammalian evolutionary tree.
Juramaia: An extinct mammal from the Jurassic of China, known from a fossil dated to about 160 million years ago. Its proposed eutherian status makes it a candidate for an early fossil member of the clade.
Epipubic bone: A bone projecting forward from the pelvis in many mammals, including monotremes and marsupials, but absent in placentals. Its distribution helps compare reproductive anatomy across major mammalian lineages.
Cenozoic: The geological era beginning about 66 million years ago and continuing to the present. Much of the familiar diversification of placental mammals unfolded during this era.
Theria: The mammalian group comprising marsupials and eutherians, excluding monotremes. This broader clade places Eutheria alongside its closest living relatives.
Eomaia: An extinct mammal from the Early Cretaceous of China, known from an exceptionally preserved fossil. Its skeletal features provide evidence about early eutherian anatomy and life history.
Ankle bone: A tarsal bone that connects the leg to the foot and preserves useful features in mammal fossils. Ankle anatomy has supplied characters for classifying early eutherian fossils.
Adaptive radiation: The rapid diversification of a lineage into species adapted to different ecological roles. Placental lineages expanded into many ecological roles after major ecological openings.
Placental mammal: A living mammal whose young develop in the uterus with substantial maternal support through a placenta. Living members of Eutheria belong to this group, though the clade also includes extinct relatives.
Zalambdalestes: An extinct Cretaceous mammal known from fossils in Mongolia, often classified among early eutherians. Its fossils help document eutherian diversity before the end-Cretaceous extinction.

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