The Proceedings of the National Academy of Sciences of the United States recently reported that US scientists have discovered a worm-like organism through the fossils of a three-dimensional laser scanner to be the earliest ancestor of humans and most animals.

A team led by Dr. Scott Evans from the University of California, Riverside and Mary Droll, professor of geology, recently used a three-dimensional laser scanner to detect a worm fossil found in the Ediacaran deposit in southern Australia A scan was carried out, and the result was a major discovery.

Three-dimensional laser scanning revealed that this was the earliest bilaterally symmetrical creature 555 million years ago, with a front body and a back, two symmetrical sides, with openings at both ends, connected by the stomach and intestines, in a barrel shape, with a head and a tail. Clear, grooved muscle tissue. Worms have no hard tissues such as bones, and are small in size, with a length of 2-7 mm and a width of 1-2.5 mm, the size of the largest rice grain. Worms move by contracting muscles.

Dr. Evans revealed that the worm burrows into the oxygen-containing sand layer of the ocean floor to find organic matter, which shows that it has basic perception capabilities.

Professor Dror said that the earliest multicellular organisms, such as sponges and algae mats, are collectively referred to as the Ediacaran biota, which lacked most basic animal features, such as mouths or internal organs. But when a bilaterally symmetrical body shape evolved, animal evolution took a crucial step. Symmetrical development on both sides is the key to the evolution of animal life.