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The study found a long-necked archosaur type-like new genus and species of cryptic thin-necked dragon

According to the characteristics of the specimen, the researchers believe that it is a new genus and species. The specimen, with its elongated neck, was named Gracilicollum latens. The research results were recently published in the international journal “The Anatomical Record”.
  The results of phylogenetic analysis also support that this specimen represents a new genus, which belongs to the early branch of archosaurs. Members of the family Dinosaurs such as Dinosaurs are more distantly related. However, due to the limited preservation information of this specimen, its specific affiliation in the long-necked dragon family or dinocephalic family needs to be further verified with more complete specimens.
  A long neck can bring many survival advantages, including a wider field of vision, easier access to food, and increased range of motion. Therefore, under the action of natural selection, many “long-necked” types have been produced in vertebrates, such as plesiosaurs, sauropod dinosaurs and giraffes, as well as a variety of egrets. However, the most exaggerated “neck-to-body ratio” in the history of the earth appeared in some Triassic Archosauromorpha. This early divergent archosauroid lineage is a group of “long-necked families”, and the neck length of some species exceeds half of its overall length! Giraffes and dinosaurs are the representatives.
  The long-necked dragon (Tanystropheus) was first discovered in Triassic Europe, concentrated in today’s Switzerland and Italy, on the west coast of the ancient Tethys Ocean. In recent years, in Southwest China, that is, in the Triassic system on the east coast of Tethys, researchers have also discovered long-necked dinosaur fossils, including some beautifully preserved complete skeletons. The large species of the Giraffe has a body length of nearly 6 meters and a neck of about 3 meters. Judging from the ratio of the neck to the trunk, it has the “longest neck” among vertebrates. Such a long neck contains only 13 cervical vertebrae. It can be seen that the long-necked dragon developed a long neck through the growth of a single cervical vertebrae, which is extremely rare in reptiles.
  Dinocephalosaurus is only distributed in my country’s Guizhou and Yunnan regions, and is the only other “long-necked sea monster” that can be compared with long-necked dragons. Similar to the long-necked dragon, the body of the dinocephalic dragon is 5 meters long and the neck is nearly 3 meters long. However, the neck of the dinocephalic dinosaur has more than 30 cervical vertebrae. By increasing the number of cervical vertebrae, it forms a super long neck. Very different from giraffes.
  Previous studies have found that both Giraffes and Dinosaurs are members of archosaurs that diverged early, but their genetic relationship with other archosaurs is still unclear. On both sides of the Tethys Ocean, especially in Southwest China in recent years, researchers have also discovered several species of reptiles that are closely related to long-necked dinosaurs and dinocephalic dinosaurs, including giant tibialosaurus, Fuyuansaurus, and comb tooth dragon. etc., but they are less than half a meter long and do not have significantly elongated necks. So how did the exaggerated long necks of these early archosaurs evolve?
  Around the cervical vertebrae of this group of early archosaurs, the researchers compared the number of cervical vertebrae in various genera and the degree of elongation of each cervical vertebrae in each genera, and introduced an “elongation index” based on the ratio of vertebral body length to height to reflect the degree of elongation , avoiding the interference of fossil preservation and vertebral arch morphology. Compared with previous studies, this study found that among these archosaurs, on the one hand, the distribution of elongation index was different among different genera and species even if the number of cervical vertebrae was similar; The distribution trends of the number of cervical vertebrae and elongation index are relatively consistent, so the number of cervical vertebrae and elongation index can be used as a new basis for distinguishing the type, genus and species of this archosaur.
  The phylogenetic position of Gracilicollum may be between the short-necked Macrocnemus and the long-necked Long-necked Dragon, and the relative length of the neck and torso of Gracilicollum is likely It is also between the two, showing a certain intermediate state. However, the elongation of the cervical spine of the thin-necked dragon was significantly lower than that of the long-necked dragon, which was only comparable to the elongation of the cervical spine of the giant tibia, which was at the general level of reptiles. Interestingly, the thin neck dragon did not lengthen the neck by extending each cervical vertebrae, but instead increased the number of cervical vertebrae. The number of cervical vertebrae exceeded 18, which was significantly more than other members of the long-necked dragon family. This increase in the number of cervical vertebrae Strategies converge with Dinosaurs. The researchers speculate that in these long-necked archosaurs, increasing the neck length by increasing the number of cervical vertebrae appeared earlier or was more common. Across all vertebrate groups with long necks, from plesiosaurs to sauropods to birds, it seems more common to lengthen necks by increasing the number of cervical vertebrae than by lengthening each vertebrae. Perhaps altering segmental regulation during embryonic development to increase the number of segments is easier or less harmful than shaping elongated vertebral bodies.
  In various vertebrates with long necks, neck growth is usually an adaptation for feeding. For example, the long neck of herons can flexibly catch fish, and the long neck of sauropod dinosaurs can expand its feeding range. The discovery of thin-necked dragons also confirms that in these Triassic archosaurs, the elongated neck is likely to be related to their fish-eating habits. The dentition of the short-necked Megatiosaurus and Combodontosaur is relatively simple, and the teeth are short-vertebrae-shaped and smooth; in the super-long-necked Styranosaurus, Long-necked Dragon and Dinosaur, the teeth are long-vertebrae. Shaped, even with prominent fangs, and with longitudinal stripes on the surface, these features are closely related to fish-eating, and undigested fish were preserved in the abdomen of individual dinocephalic specimens.
  The discovery of Styrosaurus provides yet another example of neck lengthening with multiple cervical vertebrae, indicating that the long necks of these Archosauroids may have been an adaptation for fishing. But it is a pity that the discovery of thin-necked dragons still failed to fully explain the evolution process of these early archosaurs with super-long necks, and even added more “interference factors” to their phylogenetic relationship and neck lengthening methods. Demonstrating the interweaving and repetition of skull and cervical features during the evolution of this peculiar long-necked marine reptile. The “mystery of the long neck” of the early archosaurs remains to be solved.