High -precision fossil survey operations reveal a four -step process for the development of the breast jaw joint

During the development, the secondary breast mammary secondary joint-which is carried by urgent steering bodies and a ganglid hole, which replaced the detailed joint-the reptile joint-enhances an innovative structure in the development of vertebrates.

By CT-Scanning two classic fossils, Chinese researchers found unknown joints before and suggested a clear sequence of four steps that explains how chewing and hearing functions were gradually divided between jaw and ear.

The research, led by Professor Mao Vanwan from the Institute of Poor Excavations and the Science of the Chinese Academy of Sciences, was Published in nature.

With the development of Cynodonts to mammals, various primitive secondary joints appeared, such as square connections and screws. These structures helped support the weak primitive joint while chewing. Advanced stem, such as Dianoconodon, developed a dual joint, with the luxurious lateral hole joint of side variations that have become a main body of pregnancy. However, the scarcity of fossils is limited to this process.

To treat this knowledge gap, the researchers re -examined two old fossil samples using high -resolution CT scannings.

One of the samples, the polystyodon chauaninsis – Tretilodind medium jorti from Zigong, Sichuan – was described in 1984. The new study revealed that it had a unique secondary jaw joint, the first of its kind specified in challenging previous ideas about secondary joints.

The second sample, from the lower Jurassic in Loveng, Yunnan, was the Moraganocoditan sample that was identified as sex and new types: CamuroCondylus Luffengensis. The simple bite that is formed through the budget bending of the back end of the ivory side hills provides evidence that supports the hypothesis that the urgent mammals bite developed from this hills structure.

These discoveries allowed researchers to propose the sequence of the first four stages of the development of primitive and secondary joints:

• The first stage is the mocked joint (reptiles)
• The second stage is dominant on the primitive joint, with secondary Cynodonts (Cynodonts)
• The third stage is the dominant on the secondary joint, with the sound of the primitive joint (mammaliaforms) transmission
• The fourth stage is the fully advanced volatile joint, with the primitive joint turning into the middle ear joint (mammals, Docodonts, haramiyidans)

The results indicate multiple independent assets of the jaw joint. Although the mammal’s intoxicating joint is not unique for mammals, the pregnancy version is distinctive for mammals.

The polystyodone joint, a unique adaptation of the lifestyle of herb, represents the lifestyle, while Camurocondylus shows features consistent with the gradual development that leads to diversification of mammals.

Moreover, researchers explore the various evolutionary leadership mechanisms. The prevailing “mobility of the miniaturizing engine” applies to small groups of insects such as CamuroCondylus, but it looks less logical to the larger polystyodone. The latter was the herb and showed adaptations to a specific environmental environment, which are also in line with the discovery of potential trancelodontid systems in the Polisodon sample area.

Based on these notes, the researchers suggest that the appearance plasticity – the contrast caused by the environment – played an important role in diversifying the secondary joints in the late Cynodonts.

This study expanded our understanding of the development of mammals and provides a window in the complex interaction of developmental, functional and environmental factors that make up the paraffolism of the vertebrates.