The organism with the Latin name Ikaria wariootia, which was recently discovered in Australia, may be one of the oldest dbusterone-symmetric, it is reported in the Proceedings of the National Academy of Sciences. This group includes animals in which there are front and rear ends of the body: the vast majority of modern species concerns to her.
The most ancient multicellular organisms belong to the ediacaran period of the Proterozoic era (571-539 million years ago). Animals of that time had no hard skeletal elements, therefore, preserved only in the form of prints. Their combination is called the ediacaran biota.
It is assumed that among them were supposed to be bilaterally symmetrical (bilateria) — organisms that have clearly marked front and rear ends, and the body can be divided by an imaginary plane into two halves so that they are mirror images of each other. As a rule, these organisms actively move that allows them to forage for food (and not just rely on filtering or symbionts) and live in a variety of conditions. After the ediacaran period, the Cambrian, the diversity of such organisms have increased significantly and since the animals in the vast majority represented bilaterally.
Often one of the most ancient bilaterally symmetrical called kimberella — ediacaran body length up to 15 inches. However, a number of paleontologists suggests that the first bilateria was no larger than a few millimeters. To find them remains difficult: such small soft-bodied organisms was unlikely to harden. But they probably left moves the substrate, and such evidence of ancient life bilaterally symmetrical, are already known.