Hadrocodium
| Hadrocodium | |
|---|---|
| |
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Clade: | Synapsida |
| Clade: | Therapsida |
| Clade: | Cynodontia |
| Clade: | Mammaliaformes |
| Genus: | †Hadrocodium Luo, Crompton, & Sun, 2001 |
| Species | |
Hadrocodium wui is an extinct mammaliaform that lived during the Sinemurian stage of the Early Jurassic approximately 195 million years ago[1] in the Lufeng Formation in what is now the Yunnan province in south-western China[2]
(25°12′N 102°06′E / 25.2°N 102.1°E, paleocoordinates 34°18′N 104°54′E / 34.3°N 104.9°E).
The fossil of this mouse-like, paper-clip sized animal was discovered in 1985 but was then interpreted as a juvenile morganucodontid.[4] Hadrocodium remained undescribed until 2001; since then its large brain and advanced ear structure[5] 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.[6] Hadrocodium is known only from a skull 1.2 cm (0.47 in) long, and its body would have measured 3.2 cm (1.3 in) long in total and weighed up to 2 g (0.071 oz), making it one of the smallest Mesozoic mammaliaforms.[1][7][8] The specimen is thought to have been that of a mature adult.[9]
The name Hadrocodium alludes to its large cranial cavity,[10] deriving from the Greek word hadrós (ἁδρός 'large, heavy, fullness')[4] and the Latin word codium, from Greek kṓdeia (κώδεια 'head [of a plant]').[11] The species name, wui, is the Latinized version of discoverer Xiao-Chun Wu's name.[2]
While initially suggested to have possessed a fully mammalian ear akin to those of modern mammals, a 2022 restudy suggested that it actually had a primitive mandibular middle ear similar to those of other primitive mammaliaforms.[9]
Phylogeny
Cynodontia
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- Phylogeny [12]
| Mammaliaformes |
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See also
References
- ^ a b Luo, Crompton & Sun 2001, Abstract
- ^ a b Parsell 2001
- ^ Hei Koa Peng, Lufeng (CUP, IVPP) (Jurassic of China) in the Paleobiology Database. Retrieved April 2013.
- ^ a b Luo, Crompton & Sun 2001, Note 1
- ^ CNN 2001
- ^ CMNH 2001
- ISBN 9780198507611. Retrieved 22 September 2022.
- ISBN 9780691156828.
- ^ ISSN 0567-7920.
- S2CID 8738213.
- ^ Liddell & Scott 1940
- PMID 26190074.
Bibliography
- "Hadrocodium wui". Carnegie Museum of Natural History. 2001. Archived from the original on 2012-06-17. Retrieved 1 April 2013.
- "Tiny creature may be ancestor of all mammals". CNN. May 24, 2001. Retrieved 1 April 2013.
- Liddell, Henry George; Scott, Robert (1940). "A Greek–English Lexicon: κώδεια". Perseus Digital Library. Retrieved 1 April 2013.
- Luo, Zhe-Xi; Crompton, Alfred W.; Sun, Ai-Lin (2001). "A New Mammaliaform from the Early Jurassic and Evolution of Mammalian Characteristics" (PDF). Science. 292 (5521): 1535–1540. S2CID 8738213. Archived from the original(PDF) on 2013-08-20.
- Parsell, D.L. (May 24, 2001). "Tiny Fossil From Early Jurassic Fills New Niche in Mammal Evolution". National Geographic News. Archived from the original on August 13, 2001. Retrieved 1 April 2013.
- Rowe, Timothy; Macrini, Thomas E; Luo, Zhe-Xi (May 2011). "Fossil Evidence on Origin of the Mammalian Brain". Science. 332 (955): 955–7.
External links
- Rowe, Timothy; Macrini, Thomas E; Luo, Zhe-Xi (2006). "Hadrocodium wui (On-line)". Digital Morphology at the University of Texas. Retrieved 1 April 2013. — 3D models from CT scans of the original fossil
- Palaeocritti - a guide to prehistoric animals