Katana VentraIP

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

Further information: Evolution of mammals

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] However epipubic bones are present in some 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 oldest-known eutherian species is Juramaia sinensis, dated at 161 million years ago from the early Late Jurassic (Oxfordian) of China.[4] 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.[5]

an enlarged ("little hammer") at the bottom of the tibia, the larger of the two shin bones[6]

malleolus

the between the first metatarsal bone and the entocuneiform bone (the innermost of the three cuneiform bones) in the foot is offset farther back than the joint between the second metatarsal and middle cuneiform bones—in metatherians these joints are level with each other[6]

joint

various features of jaws and teeth including: having three molars in the halves of each jaw, each upper canine having two roots, the paraconid on the last lower premolar is pronounced, the talonid region of the lower molars is narrower than the trigonid.[7]

[6]

Distinguishing features are:

Holoclemensiidae

Genus †

Acristatherium

Clade

Tamirtheria

?Genus †

Purgatorius

?Genus †

Protungulatum

?Genus †

Oxyprimus

Infraclass sensu stricto

Placentalia

Eutheria (i.e. Placentalia sensu lato, Pan-Placentalia):[8][9][10][11][12][7][13][14][15][16][17][18][19][20][21]


Notes:

Ecology[edit]

Many non-placental eutherians are thought to have been insectivores, as is the case with many primitive mammals.[37] However, the zhelestids are thought to have been herbivorous.[36]