Eutheria Temporal range:
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Skeleton of Microtherulum, a basal eutherian from the Early Cretaceous of China | |
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Northern treeshrew (Tupaia belangeri), a placental eutherian from Southeast Asia | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Subclass: | Theria |
Clade: | Eutheria Gill, 1872 |
Subgroups | |
see text. |
Eutheria (from Greek εὐ-, eú- 'good, right' and θηρίον, thēríon 'beast'; lit. 'true beasts'), also called Pan-Placentalia, is the clade consisting of placental mammals and 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,[1] though epipubic bones are present in many primitive eutherians.[2] Eutheria was named in 1872 by Theodore Gill; in 1880, Thomas Henry Huxley defined it to encompass a more broadly defined group than Placentalia.[3]
The earliest unambiguous eutherians are known from the Early Cretaceous Yixian Formation of China, dating around 120 million years ago.[4] Two tribosphenic mammals, Durlstodon and Durlstotherium from the Berriasian age (~145-140 million years ago) of the Early Cretaceous in southern England have also been suggested to represent early eutherians.[5][6] Another possible eutherian species Juramaia sinensis has been dated at 161 million years ago from the early Late Jurassic (Oxfordian) of China.[7] However some authors have considered Juramaia as a stem therian instead,[5][6] and some sources have doubted the dating of the specimen.[8]
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