The earliest known eutherian mammal

@article{Ji2002TheEK,
  title={The earliest known eutherian mammal},
  author={Qiang Ji and Zhe‐Xi Luo and Chong-xi Yuan and John R. Wible and Jian-Ping Zhang and Justin A. Georgi},
  journal={Nature},
  year={2002},
  volume={416},
  pages={816-822}
}
The skeleton of a eutherian (placental) mammal has been discovered from the Lower Cretaceous Yixian Formation of northeastern China. We estimate its age to be about 125 million years (Myr), extending the date of the oldest eutherian records with skull and skeleton by about 40–50 Myr. Our analyses place the new fossil at the root of the eutherian tree and among the four other known Early Cretaceous eutherians, and suggest an earlier and greater diversification of stem eutherians that occurred… 

A Jurassic eutherian mammal and divergence of marsupials and placentals

This mammal has scansorial forelimb features, and provides the ancestral condition for dental and other anatomical features of eutherians, reducing and resolving a discrepancy between the previous fossil record and the molecular estimate for the placental–marsupial divergence.

An Early Cretaceous Tribosphenic Mammal and Metatherian Evolution

New data from this fossil support the view that Asia was likely the center for the diversification of the earliest metatherians and eutherians during the Early Cretaceous.

An Early Cretaceous eutherian and the placental–marsupial dichotomy

A new Jehol eutherian, Ambolestes zhoui, with a nearly complete skeleton that preserves anatomical details that are unknown from contemporaneous mammals, including the ectotympanic and hyoid apparatus is reported, demonstrating that Sinodelphys is a eutherians and that postcranial differences between Sinodelsphys and the Jehol Eutherian Eomaia are variations among the early members of the placental lineage.

Eutheria (Placental Mammals)

Eutheria includes one of three major clades of mammals, the extant members of which are referred to as placentals, the most ecologically diverse group of living vertebrates as they vary greatly in size, locomotory types, and diet.

New basal eutherian mammal from the Early Cretaceous Jehol biota, Liaoning, China

The morphological differences between Acristatherium and Eomaia indicate that eutherians already had a significant degree of generic diversification ca 125 Ma, and place A. yanensis as the most basal eutherian in the selected group.

Mammalian Faunal Succession in the Cretaceous of the Kyzylkum Desert

The next younger localities in North America have both a zhelestid and Paranyctoides, suggesting dispersal of eutherians from Asia, and it is believed three are referable to the deltatheroid Sulestes karakshi and the fourth, Sailestes quadrans, may belong to ParanyCToides.

A radiation of arboreal basal eutherian mammals beginning in the Late Cretaceous of India

This comprehensive phylogeny indicates that faunal exchange occurred between India, Africa, and Europe in the Late Cretaceous-Early Paleocene, and suggests a previously unrecognized ∼30 to 45 Myr “ghost lineage” for these Gondwanan eutherians.

The origin and early evolution of metatherian mammals: the Cretaceous record

Metatherian diversification patterns suggest that they were not strongly affected by a Cretaceous Terrestrial Revolution, but they clearly underwent a severe extinction across the K-Pg boundary.

A new Early Cretaceous eutherian mammal from the Sasayama Group, Hyogo, Japan

S. kawaii is the earliest known eutherian mammal possessing only four premolars, which demonstrates that the reduction in the premolar count in eutherians started in the late Early Cretaceous.
...

References

SHOWING 1-10 OF 53 REFERENCES

Tribosphenic mammal from the North American Early Cretaceous

  • R. Cifelli
  • Environmental Science, Geography
    Nature
  • 1999
A new tribosphenic mammal from the Early Cretaceous of North America is described, based on an unusually complete specimen, and its molar structure is primitive, emphasizing the need for caution in interpretation of isolated teeth.

Late Cretaceous relatives of rabbits, rodents, and other extant eutherian mammals

It is argued that some Late Cretaceous eutherian eutherians belong within the crown group Placentalia, and the ages of these taxa are in line with molecularly based estimates for the superordinal diversification of some placentals, but provide no support for the Late CRETaceous diversifying of extant placental orders.

A new genus of eutherian mammal from the Early Cretaceous of Transbaikalia, Russia

Eutherian (placental) mammals are the dominant group of modern mammals, with very good Cenozoic and reasonable complete Late Cretaceous fossil record. However, the earliest, Early Cretaceous history

A new symmetrodont mammal from China and its implications for mammalian evolution

This analysis suggests that this new taxon represents a part of the early therian radiation before the divergence of living marsupials and placentals; that therians and multituberculates are more closely related to each other than either group is to other mammalian lineages.

Dual origin of tribosphenic mammals

Phylogenetic and morphometric analyses including these newly discovered taxa suggest a different interpretation: that mammals with tribosphenic molars are not monophyletic.

A Chinese triconodont mammal and mosaic evolution of the mammalian skeleton

The derived pectoral girdle of this new triconodont indicates that homoplasies are as common in the postcranial skeleton as they are in the skull and dentition in the evolution of Mesozoic mammals.

Epipubic bones in eutherian mammals from the Late Cretaceous of Mongolia

The occurrence of epipubic bones in two Cretaceous eutherians suggests that the dramatic modifications connected with typical placental reproduction, may have been later events in the evolution of the Eutheria.

Implications of Deltatheridium specimens for early marsupial history

The presence of specialized marsupial patterns of tooth replacement and cranial vascularization in Deltatheridium and the basal phylogenetic position of this taxon indicate that these features are characteristic of Metatheria as a whole.

A eutherian mammal from the Early Cretaceous of Russia and biostratigraphy of the Asian Early Cretaceous vertebrate assemblages

Prokennalestes abramovi n.sp. is described based on M2 from the upper Barremian-middle Aptian (Early Cretaceous) Mogoito locality in Transbaikalia, Russia. It differs from the Mongolian species of

Eutherian mammals from the Early Cretaceous of Mongolia

A collection of eutherian mammals consisting of 39 specimens (teeth and jaw fragments) from the ?Aptian or Albian Khoboor Beds in the Gobi Desert, Mongolia, is described. It contains 3 taxa:
...