Biologists have unearthed a very fine spider-like fossil called Ikaria wariootia. It is by far the oldest bilaterally symmetrical animal, that is, there are positive and negative sides, which are symmetrical up and down, and connect the two sides of the human body according to the stomach. Scientific research results are published in the Proceedings of the National Academy of Sciences (PNAS) in the form of graduation thesis.
At present, the earliest multicellular organism discovered by people is the Ediacara biota. Animal fossils show that they have various shapes, most of which are similar to tubes or branches, and some of them are algae. However, most of these creatures are not directly related to the animals we all know now, because they lack the essential characteristics of most animals, such as the lack of mouth or stomach.
In the whole process of animal evolution, an important process is the development trend of left and right symmetry. It is precisely because of this feature that organisms are allowed to arrive at the work station for fitness exercise and divide the human body, for example, the human body is symmetrical up and down. From the humble spiders and insects, to the outstanding Tyrannosaurus Rex, and then to the development trend and evolution of human beings, it is closely related to this unique symmetry.
Biologists in contemporary cell biology believe that according to the scientific research on the genetics of contemporary animals, it can be inferred that the oldest ancestors of symmetrical creatures probably had simple and exquisite bodies and basic visual organs. However, even if animal fossils are left, it is difficult to preserve and identify them. Because of time, they are too small to attract attention.
15 years ago, biologists found tiny traces of tunnel construction on some mineralization in South Australia 555 million light years ago, which seemed to be left by some creatures crawling. They suspect that this is probably the "work" of a symmetrical creature with a long history, but they can't find similar animal fossils and lack important direct evidence to confirm this guess.
Recently, researchers at several campuses of the University of California have made new progress in finding direct evidence. Mary Drosser, a professor of geomorphology, noticed that there were very fine oval marks near some tunnel buildings. With the support of NASA, they carried out a three-dimensional laser scanner on the imprints and found that they all looked very similar-similar to small grains of rice, showing very obvious heads and tails, as well as signs of muscle weakness all over the body, much like a creature.
The scanning results also show that if it is a creature, its length is between 2-7 mm and its total width is between 1-2.5 mm, which is just in line with the size of climbing marks in tunnel construction. Scott Evans, a scientific researcher, said, "Everyone has always believed in the existence of this creature, but they also know that it is difficult to distinguish them, but after applying the 3d scanner, everyone knows that they have made a key discovery."
The scientific researchers then named this creature Ikaria wariootia to better remember the land resources and the original indigenous people. They believe that the climbing trace of tunnel construction occurred at the bottom of mineralization, so Icaria is probably the oldest symmetrical creature discovered so far.
Although its appearance is simple, compared with other animal fossils at this stage, Icaria is very complicated. It can drill into the co2-rich thin sand layer in the deep sea to find organic compounds, which means it has basic sensory work ability. In addition, its human body curve shows obvious development in the front (overhead) and rear (tail), which is suitable for its directional movement in tunnel construction.
The edge of the crawling trace left by Icaria presents a remarkable folding pattern, similar to the undulating mountain peak, which proves that its human body can gather all muscles to peristalsis in the foregut like a spider, from aimless and purposeful wandering to targeted theme activities. Scientific researchers still observe signs of sediment deviation and organisms feeding on organic compounds in crawling traces, indicating that Icaria probably has a mouth, stomach and anus.
If the scientific research results are generally recognized by the academic circles, Ikaria wariootia will become the oldest bilaterally symmetrical animal known at this stage, including most existing animals in human beings that can be traced back to it and have a spider-like ancestor. "This is in line with the prediction and analysis of evolutionary biologists." "Everyone feels that the results are so properly combined with their prediction analysis, which is simply exciting."