Temporal range: Late Jurassic–Holocene,
|Fossil of Leptictis, a non-placental eutherian from the Paleogene of North America|
Eutheria (/juːˈθɪəriə/; from Greek εὐ-, eú- 'good, right' and θηρίον, thēríon 'beast'; lit. 'true beasts') is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials.
Eutherians are distinguished from noneutherians by various phenotypic traits of the feet, ankles, jaws and teeth. All extant eutherians lack epipubic bones, which are present in all other living mammals (marsupials and monotremes). This allows for expansion of the abdomen during pregnancy.
The oldest-known eutherian species is Juramaia sinensis, dated at 161 million years ago from the early Late Jurassic (Oxfordian) of China.
Eutheria was named in 1872 by Theodore Gill; in 1880 Thomas Henry Huxley defined it to encompass a more broadly defined group than Placentalia.
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