Kiwi fish anti-bird (Piscivorenantiornis inusitatu)

Wang Min and Zhou Zhong of the Institute of Paleontology and Paleoanthropology of the Chinese Academy of Sciences published their findings on early birds in the April 13 issue of the international journal Journal of Paleontology.
their morphological and systematic development of the first fish-eating anti-birds provided a wealth of new information on the diversity of early evolution of anti-birds, particularly the joint patterns, skulls and belt parts of the vertebral vertebrae.
In 2016, Zhou Zhonghe and his team reported on a fossil of an anti-bird found in the early Cretaceous Nine Buddhas group in Liaoxi, revealing the world's first bird food group, indicating the digestive system unique to living birds (gastric differentiation The adenostomy and muscular stomach; the muscle stomach can contract and expand strongly and continuously, compressing the remnants of hard-to-digest food into food doughs; and the esophageal tract can perform effective counter-creeping, moving the food groups from the muscular stomach to the mouth and eventually spitting out) which evolved in anti-birds 120 million years ago.
this time, the researchers conducted a detailed comparative anatomical and systematic development of the anti-bird, which is preserved as a new genus, named Piscivorenantiornis inusitatu.
the bones of exotic fish-eating anti-birds are mostly scattered and preserved, which facilitates the observation of features.
the researchers observed that the cervical vertebral joints of exotic fish-eating fish were very different from those of all living and fossilized birds.
the cervical vertebrae joints of living birds are unique "heterogeneity" (also known as "saddle type").
Take the frontal joint surface of the vertebrae as an example, when viewed from the back (abdominal) surface, the cross-section of the joint surface is recessed, while when viewed from the side, the cross-section of the joint surface is raised, the opposite of the back joint surface of the frontal vertebrae of the joint.
It is precisely because of this joint that the necks of birds are more flexible than those of other vertebrates, and some birds' heads can even rotate 180 degrees, providing an advantage for birds to observe their surroundings and eat.
Hetero-concave cervical vertebrae have appeared in Mesothrenic anti-birds, such as the early Cretaceous Hou's Pengbird and most of the late Cretaceous anti-birds, while some anti-birds still preserve the vertebral joints of the double or front concave forms common to reptiles.
In exotic fish-eating birds, the frontal joint surface of the cervical vertebrae, although also "heterogeneic", is "abnormal" - the joint surface in the back (abdominal) surface is "sink" and the outer side is "raised".
So, the frontal joint surface of the cervical vertebrae of the exotic fish-eating fish is the same as the back joint surface of the cervical vertebrae of the living bird, giving the impression that the front and rear joints of the vertebrae have been reversed in the strange anti-bird", precisely on the basis of such an abnormal phenomenon, the researchers designated its species as "strange".
"inverting" the front and rear joints appears to have little effect on neck flexibility, as the front and rear vertebrae can still rotate widely in the back and horizontal directions.
findings suggest that the way the vertebral joints were formed in the early stages of evolution was more complex than previously known.
The exotic fish-eating anti-bird also preserved many characteristics different from other anti-bird, such as the front jaw joint has a gap, the front edge of the chest bone left and right utopian bone groove significantly separated, the inner side of the tiry developed hip protrusion and so on.
the development of the anti-bird system shows that fish-eating anti-birds are in a more progressive position within the anti-bird sub-gang.
the study was supported by projects such as the National Natural Science Foundation of China and the Chinese Academy of Sciences Youth Innovation Promotion Association.
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