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This article comes from Weixin Official Accounts: SF Chinese (ID: kexuejiaodian), author: SF

(Image source: ABelov2014) When it comes to the largest animals, many friends think of blue whales and African elephants. But blue whales and African elephants were dwarfed by a larger group of animals that roamed the earth billions of years ago. They are dinosaurs. Among dinosaurs, the largest ones were sauropods (long-necked plant-eaters), such as Brachiosaurus and Diplodocus.

Wen| Merlin

visual design| Xia Meng

The restoration of the dragon. Long necks, large legs, and large bodies are hallmarks of sauropods. Just last week, a "member" of sauropods made it to the hot search. What was going on?

An international team, including scientists from the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences, Zigong Dinosaur Museum in Sichuan Province and Yunnan University, recently studied a fossil of Mamenchisaurus sinocanadorum, including a partial skull and cervical vertebra, discovered in 1993 in the Junggar Basin of Xinjiang, China, using computed tomography (CT). Based on CT data, scientists estimate that the Mamenxosaurus fossil specimen has a neck length of 15 meters, a body length of 35 meters and a weight of 60 to 80 tons.

In 2009, an exhibition in Japan, a Chinese horse door river keel. The skeleton, also unearthed in Xinjiang, China, may be the most complete dinosaur skeleton ever discovered by archaeologists, but no archaeologist has studied it. (Photo by Kabachi)

The giraffe, which we are all familiar with, has the longest neck of any living animal-this Mamenchisaurus had a neck six times longer than the giraffe. If you take buses as a reference, the neck length of the dragon is close to the length of two buses. Scientists say the Mamenchisaurus may have the longest neck of any dinosaur known to date-the previously discovered Mamenchisaurus was only about 10 to 20 meters long. The study has been published recently in the Journal Of Systematic Palaeontology.

Why is it so long? We probably already know that giraffes have long necks because they live in African savannas, where plants near the ground are scarce and giraffes can only feed on plants high up, so they evolved long necks. So why did the dragon have such a long neck?

In 2013, a team of researchers from Zigong Dinosaur Museum in China and the University of Frankfurt in Germany published a study on this question. The study indicated that Mamenchisaurus could not maintain an upright posture for a long time, but could maintain an angle of more than 60° with the ground and trunk, so it could feed on plants in the middle and high places, which also proved that plants in the middle and low places of Mamenchisaurus 'living area were sparse. Just as giraffes evolved long necks because of sparse vegetation in the lower reaches, so Mamen Creek Dragon's habitat had similar conditions, and Mamen Creek Dragon also evolved extremely long necks.

Most of the fossils of Mamenxisaurus were found in the Shaximiao Formation of Yibin, Sichuan Province. The figure shows a hypothetical view of the Shaximiao Formation habitat. It can be seen that the plants near the ground are sparse. (Image credit: ABelov2014) In addition, scientists also found that when walking, Mamenchisaurus usually flattened its neck, which increased the stability of movement and saved energy. Andreas Christian, a paleontologist at the University of Flanders and a member of the team, believes that if Mamendrosaurus stopped to rest or eat, the lookout Mamendrosaurus would stand upright and watch for predators from above.

It is also suggested that all Mamenchisaurus, including Mamenchisaurus chinamensis, had long necks and that the oxygen content in the air was high at that time, with the proportion of oxygen in the air being 1.5 times that of today, which means that such abundant oxygen was sufficient to maintain Mamenchisaurus, especially Mamenchisaurus chinamensis, to maintain a particularly large body, such as an extra long neck.

Of course, for breathing, the extra long neck is also unfavorable, especially the Chinese and Canadian Mamen Creek Dragon has a 15-meter long neck, ensuring respiratory efficiency and oxygen intake is somewhat difficult. However, this study found that the cervical vertebrae of the Chinese horse river dragon had an air cavity. It is speculated that these chambers may have stored some air to assist in the breathing of the long-necked Chinammendrosaurus. In addition, a longer neck means more weight, which is also a heavier burden for China-Canada Mamen River Dragon, and the presence of a large number of air cavities in the cervical spine also helps to reduce the weight of China-Canada Mamen River Dragon's neck.

Scientists used CT technology to scan the cervical spine of the Chinese and Canadian Mamen Creek Dragons. We can see that there are a large number of air cavities (F) in the cervical spine of the Chinese horse stream dragon.（Andrew J. Moore et al.，2023) References:

Andrew J. Moore et al.（2023）.Re-assessment of the Late Jurassic eusauropod Mamenchisaurus sinocanadorum Russell and Zheng, 1993, and the evolution of exceptionally long necks in mamenchisaurids.Journal Of Systematic Palaeontology，21

Andreas Christian et al.（2013）.Biomechanical Reconstructions and Selective Advantages of Neck Poses and Feeding Strategies of Sauropods with the Example of Mamenchisaurus youngi.PLOS ONE,8

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