Draftable – The traces left by small animals crawling in the mud of the sea shore about 550 million years ago are the oldest traces of the Earth, scientists say.
The mystery surrounds the one millimeter-long creatures who made the impressions, since no trace of their bodies has been found. Scientists believe that they may have been a type of arthropod, the family of animals with articulated limbs that includes insects and crustaceans or something like a worm with legs.
The traces show that the movement of the appendages (paws) of its author was not very coordinated. What is known is that the creatures were buried and walked and were bilateral, which means that they had pairs of symmetrical legs – albeit somewhat clumsy...
Traces of fossilized burrows were discovered in the Yangtze Gorge area of southern China, in a rock formation dating back to 541 and 551 million years.
Previously, no evidence was found of animals with limbs prior to the "Cambrian explosion", the most intense burst of life ever known, which occurred on Earth about 510 to 541 million years ago.
An unusual aspect of the footprints is that they seem somewhat irregular and disorganized, suggesting an element of clumsiness.
The Chinese and American team led by Dr. Shuhai Xiaoof Virginia Tech in the United States, wrote in the journal Science advances: "the irregular disposition of the footprints in the (...) Paths can be taken as evidence that the movement of the appendices of its authors was very poorly coordinated and is different from the highly coordinated Metachronic (wavy) rhythm typical of modern arthropods.