High resolution fossil scans have shown four steps of the joint evolution of the jaw jaw

During the evolution, the Craveni Mandebler of the Crinian Mandebler Secondary Joint-Joint, which represented a modern structure in the evolutionary evolution, replacing the reproductive article-quadrate joint.

Through the CT scanning, two classic fossils, Chinese researchers first found the unidentified jaw pair and suggested a clear, four -step setting, showing how chewing and hearing functions were gradually divided between the jaw and the ear.

The research was published in the study, led by Professor Mao Fengian, from the Chinese Academy of Sciences Institute of Verritibrot Pilotology and Palevanitropology. Nature.

As the syndronts were manufactured in the stars, different elementary secondary joints came out, such as servingular – Skomsal and Dentry – Ascalia contact. These structures helped help the ancient joint weakened while chewing. Advanced steam mammalia, like Dynodon, also developed a dual jaw, in which the background dentist coils-the foamyal foamy has become the main structure of the burden. However, the lack of mischief is a limited understanding of this process.

To remove the difference of this knowledge, researchers re -evaluated two old -fashioned patterns using high resolution CT scans.

A sample, Polystodon Chinnasis, a middle -aged Jurassic Trolodont Ide, from Zigong, was first described in 1984 by Sichuan – Sichuan. New research suggests that it contained a unique dental coil in tetrapedes – Jogel Fosa Secondary when the joint, which was identified as its first nature.

The second sample, from the Lofing, from the bottom of the Greek, was a sample of a Morganokodonton, identified as a new generation and species: Camorocandelus Lofiners. Its simple dental coil, which is formed by bending above the afternoon of the dental background, provides evidence that the speculation supported that the teeth coils of the stomachs were developed by this regulation.

These discoveries allowed researchers to propose the first four -step setting for the evolution of ancient and secondary couples.

• A Step One Article – Quadrait Joint (Ringer Animal)
• The second step is the ancient joint dominant, with secondary contact points (Advanced Senodons)
• Step three burden is a secondary joint dominant, which has ancient joint aid sound transmission (STEM mammaliaforms)
• Step Four is a fully dentist – the Square joint, which is transformed into an Oscal joint of the ancient middle ear (sarcastic, docodones, haramidins).

These results suggest a number of independent origin for the common types of jaw. Although dentistry-Sacmal Joint is not unique to the stars, the load-lifting version is characterized by the stars.

Dentry – Zigomettic (Jungle) Joint Polystoden’s Joint herbs represents a unique adaptation for herbs, fusurel lifestyle, while camorocide shows, which gradually is in accordance with evolution, which causes diversity of stars.

In addition, researchers searched various evolutionary driving mechanisms. Currently the existing “Manitorization Drive Hypotis” applies to small insects such as Camorocandelis, but looks less proud for large body polystoden. The latter was the herbs and it adapted to a specific environmental environment, which also aligns the potential triatoid broom system in the polytodon sample area.

Based on these observations, researchers suggested that phenotypic plasticity – environmentally stimulated variations – could play an important role in the diversity of secondary couples in late Snowmets.

This study expands our understanding of the evolution of the stars and provides a window in the complex bilateral interference of developmental, functional and environmental factors that form a developmental form.