''Sinodelphys'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

from the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

, estimated to be 125 million years old. It was discovered and described in 2003 in rocks of the Yixian Formation in

Liaoning ) , image_skyline = , image_alt = , image_caption = Clockwise: Mukden Palace in Shenyang, Xinghai Square in Dalian, Dalian coast, Yalu River at Dandong , image_map = Liaoning in China (+all claims hatched).svg , ...

Province,

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

, by a team of scientists including Zhe-Xi Luo and John Wible. While initially suggested to be the oldest known metatherian, later studies interpreted it as a eutherian.

Description

Only one fossil specimen is known, a slab and counterslab given catalog number CAGS00-IG03. It is in the collection of the Chinese Academy of Geological Sciences. ''Sinodelphys szalayi'' grew only 15 cm (5.9 in) long and possibly weighed about 30 g (1.05 oz). Its fossilized skeleton is surrounded by impressions of fur and soft tissue, thanks to the exceptional

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

that preserves such details. Luo et al. (2003) inferred from the foot structure of ''Sinodelphys'' that it was a scansorial tree-dweller, like the contemporary '' Eomaia'' and modern opossums such as '' Didelphis''. ''Sinodelphys'' probably hunted worms and insects.

Taxonomy

''Sinodelphys szalayi'', living in China around 125 million years ago, was initially interpreted as the earliest known

metatheria Metatheria is a mammalian clade that includes all mammals more closely related to marsupials than to placentals. First proposed by Thomas Henry Huxley in 1880, it is a more inclusive group than the marsupials; it contains all marsupials as wel ...

n. This makes it almost contemporary to the eutherian '' Acristatherium'', which has been found in the same area. However, Bi ''et al.'' (2018) reinterpreted ''Sinodelphys'' as an early member of

Eutheria Eutheria (from Greek , 'good, right' and , 'beast'; ), also called Pan-Placentalia, is the clade consisting of Placentalia, placental mammals and all therian mammals that are more closely related to placentals than to marsupials. Eutherians ...

References

Cretaceous mammals Prehistoric eutherians Early Cretaceous mammals of Asia Transitional fossils Fossil taxa described in 2003 Prehistoric mammal genera {{cretaceous-mammal-stub

Description

Taxonomy

See also

References