Hadrocodium
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Hadrocodium
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Hadrocodium wui (hadro from Greek ἁδρός/hadros, "large, heavy, fullness";[1] Latin: codium, from Greek κώδεια/kodeia, "head [of a plant]" [2] (alluding to its enlarged cranial cavity);[3] and wui, the Latinized version of discoverer Xiao-Chun Wu's name[4]) is an extinct mammaliaform that lived during the Sinemurian stage of the Early Jurassic approximately 195 million years ago[5] in the Lufeng basin in what is now the Yunnan province in south-western China[4] (Lua error in package.lua at line 80: module 'strict' not found., paleocoordinates Lua error in package.lua at line 80: module 'strict' not found.).[6]
The fossil of this mouse-like, paper-clip sized animal was discovered in 1985 but was then interpreted as a juvenile morganucodontid.[1] Hadrocodium remained undescribed until 2001; since then its large brain and advanced ear structure[7] have greatly influenced the interpretation of the earliest stages of mammalian evolution, as these mammalian characters could previously be traced only to some 150 million years ago.[8] Hadrocodium is known only from a skull, but the body is estimated to have been a mere 3.2 cm (1.3 in) in length and about 2 g (0.071 oz) in mass, making it one of the smallest mammals ever.
Features
Hadrocodium might have been the first animal to have a nearly fully mammalian middle ear. It is the earliest known example of several features possessed only by mammals,[9] including the middle-ear structure characteristic of modern mammals and a relatively large brain cavity.[7] These features had been considered limited to the crown group mammals, who emerged in the Middle Jurassic; the discovery of Hadrocodium suggests that these attributes appeared earlier (45 million years earlier) than previously thought.
Whether Hadrocodium was warm-blooded or cold-blooded has not been settled, although its apparent nocturnal features would seem to place it in the endotherm group.
Family Tree
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See also
References
- ↑ 1.0 1.1 Luo, Crompton & Sun 2001, Note 1
- ↑ Liddell & Scott 1940
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ 4.0 4.1 Parsell 2001
- ↑ Luo, Crompton & Sun 2001, Abstract
- ↑ Hei Koa Peng, Lufeng (CUP, IVPP) (Jurassic of China) in the Paleobiology Database. Retrieved April 2013.
- ↑ 7.0 7.1 CNN 2001
- ↑ CMNH 2001
- ↑ Symmetrodonta - Palaeos
Bibliography
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- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found. (Supporting online material)
External links
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Wikispecies has information related to: Hadrocodium |
- Lua error in package.lua at line 80: module 'strict' not found. — 3D models from CT scans of the original fossil
- Palaeocritti - a guide to prehistoric animals
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