Sinodelphys

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Sinodelphys
Temporal range: Early Cretaceous
Sinodelphys szalayi fossil displayed in Hong Kong Science Museum.
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Subclass: Theria
Infraclass: Metatheria
Genus: Sinodelphys
Species: S. szalayi

Sinodelphys is an extinct mammal from the Early Cretaceous. To date, it is the oldest metatherian fossil known, estimated to be 125 million years old. It was discovered and described in 2003 in rocks of the Yixian Formation in Liaoning Province, China, by a team of scientists including Zhe-Xi Luo and John Wible.

Contents

[edit] Fossil record

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 that preserves such details. Luo et al. (2003) inferred from the foot structure of Sinodelphys that it was a scansorial tree-dweller, like its non-marsupial contemporary Eomaia and modern opossums such as Didelphis. Sinodelphys probably hunted worms and insects. Most Mesozoic metatherians have been found in North America and Asia. Most lived during the Late Cretaceous between 90-65 million years ago.[1]

[edit] Etiology of marsupials

Sinodelphys szalayi, living in China around 125 million years ago, is the earliest known metatherian.[1][2][3][4] This makes it almost contemporary to the earliest placental fossils, which have been found in the same area.[5]


 Metatheria

 Sinodelphys szalayi



 Cainozoic metatherian



 Eutheria

 Juramaia sinensis



 Montanalestes keeblerorum




 Murtoilestes abramovi



 Eomaia scansoria



 Prokennalestes trofimovi




 Cainozoic placentalia




[edit] See also

[edit] References

  1. ^ a b Luo, Zhe-Xi; Ji, Qiang; Wible, John R.; Yuan, Chong-Xi (2003-12-12). "An early Cretaceous tribosphenic mammal and metatherian evolution". Science 302 (5652): 1934–1940. doi:10.1126/science.1090718. PMID 14671295. http://www.sciencemag.org/content/302/5652/1934.abstract. Retrieved 2010-12-27. 
  2. ^ Rincon, P. Oldest Marsupial Ancestor Found, BBC, December 2003.
  3. ^ Pickrell, J. Oldest Marsupial Fossil Found in China, National Geographic, December 2003.
  4. ^ Klinger, M. A. Sinodelphys szalayi, Carnegie Mellon Natural History, 2003.
  5. ^ Ji, Q., et al. "The Earliest Known Eutherian Mammal", Nature, 416, pp. 816-822, April 2002.


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