Scientists for the first time were able to determine which biological kingdom should be included representatives of the Ediacar biota – the first in the history of the Earth multicellular living organisms that existed in the Precambrian era. The authors of the article published in the journal Palaeontology studied the Ediacar organism of Stromatoveris psygmoglena and came to the conclusion that it should be attributed to the animal kingdom. It is possible that this organism can be a relative of sponges and eumetazoi – a “real” multicellular animal.
In the Ediacaran period (635-542 million years ago), the planet was inhabited by strange soft-bodied organisms with a symmetrical structure. Some of them looked like branches of trees, feathers, quilts. Presumably, all of them lived in the sea and appeared after the melting of glaciers that covered the Earth in the previous geological period, cryogeny . A few million years after the Cambrian period, the Ediacaran biota disappeared, it was replaced by animals that became the founders of modern arthropods, chordates, and mollusks. Attempts by paleontologists to find among the Ediacaran organisms of the Cambrian ancestors have not yet succeeded. Researchers can not even attribute representatives of the Ediacaran biota to any kingdom. According to some researchers, they were animals, which completely died out; others refer them to algae, protozoa, fungi or are considered colonies of microorganisms.
Paleontologists Jennifer Kathill ( Jennifer Cuthill ) from Cambridge University and Chiang Han ( Jian Han ) from Northeastern University province Xian studied the morphology of the organism Stromatoveris psygmoglena , who lived in the Cambrian, about 518 million years ago, but it still belonged to the Ediacaran biota, to the group of petalonamov, reminiscent of ferns or sea feathers. In the Chinese province of Yunnan found more than 200 fossils psihmoglena, which allowed a thorough study of the anatomy of the body. The researchers conducted a phylogenetic analysis of the fossils and compared them with the fossils of other representatives of the Ediacaran biota and fossil Cambrian animals: sponges, ctenophores, chordates, algae, and modern polychaete worms, crabs, corals, lichens.
Phylogenetic analysis allowed petalonam to be assigned to the animal kingdom and to separate them into a separate group, related on the one hand to sponges, and on the other to eumetases, more complex multicellular animals that have a digestive tract: worms and mollusks. “This evolutionary branch, petalonama, can form its own type, which obviously has no living descendants,” says Jennifer Cuthill.
Earlier paleontologists found algae of the Ediacaran period, inhabited more than 555 million years ago. According to scientists, they belonged to the oldest multicellular organisms.