It is the oldest animal footprint on Earth . This is stated in the study published in the journal Science Advances and developed by the Institute of Geology and Paleontology of Nanking (China) and the Polytechnic Institute and Virginia State University (United States) that studied some marks found in a formation of the Ediacaran Period, located in southern China, in the Three Gorges region of the Yangtze River.
According to the examination, the traces, which were left by the appendages of an unknown animal, are between 541 and 551 million years old , making them the oldest animal footprint in the fossil record.
These traces, preserved near burrows, were discovered in the Dengying Formation, a rich fossil reserve in southern China, and constitute the first evidence confirming that the presence of an ancient group of animals called bilateral predates the explosion of the Cambrian.
This “explosion” – which began about 541 million years ago – led to the rapid appearance of a diversified variety of animals over a period of about 25 million years.
Prior to this, animal life on Earth consisted of simpler, single-celled or multicellular organisms, but the Cambrian period gave rise to more complex creatures of the kind we know today, including bilateral animals, which exhibited the first bilateral symmetry.
Bilateral animals, such as arthropods and annelids, have paired appendages and are among the most diverse animals today and in the geological past . They are supposed to have appeared and spread suddenly during the Cambrian Explosion some 541 to 510 million years ago, although their evolutionary ancestry has long been suspected to be rooted in the Eddaric Period. Until the current discovery, however, no fossil record of animal appendages from this period had been found.
This ingenious piece of evolution gave these animals heads, tails, bellies and backs, and something incredibly useful: legs.
The truth is that it is important to know when the first appendices appeared and in which animals, since this data will tell us when and how animals began to change the Earth in such a particular way.
That is why these footprints are so relevant to our understanding of evolutionary history, a small step for a bilateral animal, but a giant leap for the animal species.
The 550-million-year-old footprints are just a few millimeters wide, and consist of two rows of prints arranged in parallel and made up of small repeating marks, which could be due to variations in gait, rhythm, or interactions. with the surface of what was once the bed of an ancient river.
In other words, this prehistoric creature was not bipedal , but something akin to a centipede or a spider, with multiple paired legs. The point is that “we do not know exactly which animals made these tracks, other than that these animals were bilaterally symmetrical because they had paired appendages. Unless the animal died and [was] preserved alongside its tracks, it is difficult to say for sure who he made the footprints, “explains geobiologist Shuhai Xiao, leader of the work.
Still, due to the proximity of the pit tracks to burrows discovered nearby, the researchers hypothesize that the creature exhibited “complex behavior ,” such as periodically burrowing into sediment to extract oxygen and food from the habitat of its bed.
But beyond this, it is difficult to say if this small soft-bodied animal has left us any traces that we can find to trace animal evolution and revolution.
Reference: “Late Ediacaran trackways produced by bilaterian animals with paired appendages” Science Advances (2018). DOI: 10.1126 / sciadv.aao6691, advances.sciencemag.org/content/4/6/eaao6691
These are the footprints that have been found in southern China.
