Maotherium

Maotherium
Temporal range: Early Cretaceous, 124.6 Ma
↓
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Clade: Synapsida
Class: Mammalia
Order: †Symmetrodonta
Family: †Zhangheotheriidae
Genus: †Maotherium
Type species
Maotherium sinensis
Rougier et al., 2003
Species
  • M. sinensis
  • M. asiaticus

Maotherium is a genus extinct symmetrodont mammal that was discovered in Early Cretaceous rocks in Liaoning Province, China, in 2003.[1] Its scientific name means "Mao's beast" after the Chinese politician Mao Zedong. Maotherium belongs to an extinct group of Mesozoic mammals called symmetrodonts. Though little is known about this group, the symmetrodonts have several similarities - specifically their teeth. They have tall pointed, but simple molars in a triangular arrangement. Originally symmetrodonts were known since the 1920s. Now a vast majority have been restored, such as Zhangheotherium and Akidolestes, during the early 21st century. One of the fossils of Maotherium preserved the imprints of fur, like the mammals Eomaia and Sinodelphys.

A species described in 2009, Maotherium asiaticus, sheds light on the evolution of the mammalian middle ear. In modern mammals, the Meckel's cartilage appears during development but disappears before adulthood. In Maotherium asiaticus, that cartilage not only remained, but turned into bone.[2] This event in evolution may be an example of heterochrony, a change in the timing of development.[3]

References

  1. ↑ Rougier, Guillermo W.; Qiang, JI; Novacek, Michael J. (2003). "A New Symmetrodont Mammal with Fur Impressions from the Mesozoic of China". Acta Geologica Sinica 77 (1): 7–14. doi:10.1111/j.1755-6724.2003.tb00104.x.
  2. ↑ Ji Qiang, Luo Zhe-Xi, Zhang Xingliao, Yuan Chong-Xi, Xu Li (2009). "Evolutionary development of the middle ear in Mesozoic therian mammals". Science 326 (5950): 278–281. doi:10.1126/science.1178501. PMID 19815774.
  3. ↑ Martin, Thomas, & Ruf, Irina (2009). "On the mammalian ear". Science 326 (5950): 243–244. doi:10.1126/science.1181131. PMID 19815765.
This article is issued from Wikipedia - version of the Friday, February 26, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.