Asfaltomylos
Asfaltomylos | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Temporal occurrence | ||||||||||||
Middle Jurassic | ||||||||||||
165 million years | ||||||||||||
Locations | ||||||||||||
|
||||||||||||
Systematics | ||||||||||||
|
||||||||||||
Scientific name | ||||||||||||
Asfaltomylos | ||||||||||||
Rauhut , Martin , Ortiz-Jaureguizar & Puerta , 2002 |
Asfaltomylos is a genus of fossil mammals from the late Central Jurassic of South America . It is known to have an almost complete lower jaw ( mandible ) with teeth and was the first mammal from the Jura of South America to be described on the basis of fossil remains . The tiny pine was the end of 2000 in Patagonia of Argentina's taxidermist Pablo Puerta in the Cañadón Asfalto Formation in the Argentine province of Chubut found and 2002 by a German-Argentine research team led by Oliver Rauhut as a new genus and species, asfaltomylos patagonicus , described .
The rear molars (molar) of asfaltomylos have a more modern, tribosphenische structure with highly complex cutting edges and surfaces rubbing on a talonid (tooth pool), the three bumps is formed. Such a structure is reminiscent of modern mammals ( Theria , or more generally Tribosphenida ). Mammals with such complex molars, which are considered the ancestors of modern mammals, were known at the earliest from the upper Lower Cretaceous of the northern hemisphere ( Laurasia ) until the discoveries of Ambondro and Asfaltomylos . The discovery of Ambondro in Madagascar's Middle Jura in 1999 was therefore a surprise, which led to the theory that modern mammals emerged much earlier than previously thought and originated in Gondwana (i.e. in the southern hemisphere). Asfaltomylos , however, showed that the complex molars are combined with a primitive lower jaw, an indication of a convergent development of these teeth. The view that tribosphenic teeth thus emerged twice in the tribal history of mammals was also confirmed by the detailed examination of the find, which indicates that the chewing mechanism differs significantly from that of modern mammals.
Thus supports asfaltomylos the theory that today's monotremes (monotremes, egg-laying mammals) and the Theria very early in the evolution of mammals separated from each other and have independently developed molars as they evolve, the one just before the discovery of American-Polish research team around Zhexi Luo had been set up (see Australosphenida ).
literature
- Zhe-Xi Luo , Richard L. Cifelli , Zofia Kielan-Jaworowska : Dual origin of tribosphenic mammals. In: Nature . 409, 2001, pp. 53-57, (PDF; 246 kB) .
- Zhe-Xi Luo, Zofia Kielan-Jaworowska, Richard L. Cifelli: In quest for a phylogeny of Mesozoic mammals . In: Acta Palaeontologica Polonica. 47, 1, 2002, ISSN 0567-7920 , pp. 1–78, (PDF; 3.5 MB) ( Memento from December 14, 2010 in the Internet Archive ).
- Oliver WM Rauhut , Thomas Martin , Edgardo Ortiz-Jaureguizar , Pablo Puerta: A Jurassic mammal from South America. In: Nature. 416, 2002, pp. 165-168.
- Thomas Martin, Oliver WM Rauhut: Mandible and dentition of "Asfaltomylos patagonicus" (Australosphenida, Mammalia) and the evolution of tribosphenic teeth. In: Journal of Vertebrate Paleontology. 25, 2, 2005, ISSN 0272-4634 , pp. 414-425.
Web links
- "Jurassic vertebrates from Patagonia" ( memento from October 19, 2014 in the Internet Archive ) by Oliver Rauhut. (PDF; 733 kB)
- Figures and table in Nature 416