Eutheria
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.
| Eutheria Temporal range: Late Jurassic–Holocene, | |
|---|---|
| Skeleton of Microtherulum, a basal eutherian from the Early Cretaceous of China | |
| 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. | |
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. However epipubic bones are present in some primitive eutherians.
The oldest-known eutherian species is Juramaia sinensis, dated at 161 million years ago from the early Late Jurassic (Oxfordian) of China. However, this early dating has been questioned, and Juramaia may originate from Early Cretaceous instead, which would make it contemporaneous to several other known eutherians.
Eutheria was named in 1872 by Theodore Gill; in 1880, Thomas Henry Huxley defined it to encompass a more broadly defined group than Placentalia.