Eomaia

Live reconstruction of Eomaia scan soria

• People's Republic of China ( Jehol Group)

Eomaia scan soria is an extinct mammal, which is considered one of the oldest ancestors of the higher mammals.

The fossil was found in the Jehol Group of Liaoning Province of the People's Republic of China. Eomaia lived in the Barremian of the Cretaceous, approximately 125 million years ago.

Description

The fossil is received 10 inches long and almost completely. Body weight of the living animal is estimated to be 20-25 gram. For 125 million years old petrified she is exceptionally well preserved. Although the skull is flattened, teeth, small foot bones, cartilage and even the skin can be seen.

The narrowness of the basin suggests that Eomaia gave birth to live young, but they were not well developed. This is an indication of a poorly developed placenta.

An article published in Nature article considers the animal had a bag of bones. It is highly unusual for higher mammals, however, known from early representatives. Otherwise, it is a feature of marsupials, monotremes and the therapsids, from which developed the mammals.

Eomaia possessed the characteristic original tooth formula of the higher mammals: 5.1.5.3/4.1.5.3. That is, the animal had five upper and four lower incisors and premolars five. These figures are not typical of the modern higher mammals; Here there are three incisors top and bottom and four premolars.

Before the discovery of Eomaia the oldest evidence of hair was 60 million years old; Eomaia is approximately 65 million years older. This does not mean that older mammals would have been hairless. Skeletal features suggest that already had the ancestors of mammals in the Triassic or the Permian hair. However, fur petrified very rare, and the good maintenance of the Liaoning fossils is exceptional.

System

Paleontologist Anne Weil According to the Eomaia was no placenta animal. It was rather an early and primitive representatives of the tribe of all placental mammals.

On the basis of 268 characters which have been compiled from all the major mammalian strains of the Mesozoic and the main Eutheriafamilien the Cretaceous period, the authors Eomaia scan soria place along with Murtoilestes and Prokennalestes at the root of Eutherienstammbaums. The three taxa are present placentals obviously closer than today's marsupials. Eomaia is expected due to various apomorphies of the dentition, wrist and ankle to the higher mammals.

Taxonomy

The species name Eomaia scan soria means " climbing dawn mother ".

Sinodelphys szalayi

Cenozoic marsupial

Juramaia sinensis

Montanalestes keeblerorum

Murtoilestes Abramovi

Eomaia scan soria

Prokennalestes trofimovi

Cenozoic placental mammals