Hadrocodium

• China, Lufeng Formation

Hadrocodium wui is regarded as the oldest known representatives of mammals ( Mammalia). The skull of the animal was a mere twelve millimeters long. It lived in the era of the Jura, which was previously known only as the first golden age of the great dinosaurs. The fossil itself was found in 1985 in the Lower Lufeng Formation in the People's Republic of China. In many years of fine work of the skull of the animal was dissected free before he could be examined. For this reason, the special position of the animal was presented to the public in the system of mammals only in 2001.

Consisting connected while the lower jaw in reptilian ancestors of mammals via a primary jaw joint from the bones quadrate and articular with the skull, takes its place among the mammals, a new joint. This is formed from the lower jaw ( dentary ) and the squamosal ( squamosal ). The former TMJ bone will get a completely new feature: they are the malleus ( Malleus ) and anvil ( incus ), which are still articulated. This condition, that is a secondary TMJ and three ossicles could be detected even at Hadrocodium wui, about 40 million years earlier than previously thought.

It assumes a gradual separation of the middle ear bones of the jaw. This is supported by other fossils as also found in China and the skull of Sinoconodon Morganuconodon. Although this had been a secondary TMJ, hammer and anvil are still connected to it. The last step of the separation between the jaw and middle ear depends loud Zhe - Xi Luo of the Carnegie Museum of Natural History with the enlargement of the brain together. The expansion of the skull to the middle ear was probably pushed away from the jaw.

Also from the Fund China region originate various skeletons and other fossils of feathered dinosaurs that have attracted extensive media coverage and relevant scientific interest.