The oldest ancestor, now extinct, is found among all vertebrates, of which humans are also a part: it is an aquatic creature that lived 518 million years ago, called Yunnanozoo from the name of the Yunnan province in China where most part of the fossils are located. The confirmation, which finally sheds light on the missing link in evolution between invertebrates and vertebrates, comes from a study published in Science Journal and moderated by Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, and Nanjing University.
The process that led to the transformation of invertebrates into vertebrates, and what characteristics these primitive ancestors showed, remained a mystery for centuries. In particular, researchers have been studying Yunnanozoans for about 30 years, which has sparked a heated debate about how to explain the anatomical features of this animal and whether or not they can be considered vertebrates. Now, researchers led by Tian Chengyi have found new evidence supporting Yunnanzoi as the first vertebrate ancestors.
Thanks to the new types of high-resolution analyzes, the study authors note that pharyngeal arches are present in 127 fossils, structures that appear in humans at the fourth week of fetal development and that form to form various elements of the body. The results confirmed in several ways that Yunnanozoans have seven arches of cartilage in the pharynx, a feature considered typical of vertebrates. Similar to each other, these arches formed a basket-like structure, which can still be found today in some jawless fish, such as the lamprey.
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