A study performed collaboratively by a group of researchers from the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences and from the Virginia Tech in the United States, claims to have discovered the oldest known fossilized animal footprints. The parallel trackways dating back up to five hundred fifty-one million years ago were found in the Dengying Formation, which is a fossil-rich region close to the Yangtze River. As revealed by the researchers involved in the study, the strange ancient footprints showed 2 rows of tracks that appeared similar to that of a group of repeated footmarks.
Dr. Shuhai Xiao at the Virginia Tech, said in a statement, “If an animal makes footprints, the footprints are depressions on the sediment surface, and the depressions are filled with sediments from the overlying layer.” He said, “This style of preservation is distinct from other types of trace fossils, for example, tunnels or burrows, or body fossils.” The researcher explained, “The footprints are organized in two parallel rows, as expected if they were made by animals with paired appendages. Also, they are organized in repeated groups, as expected if the animal had multiple paired appendages.”
Till date, it was known that the bilaterian animals like that of the annelid worms and arthropods initially evolved at the time of the Cambrian explosion that dated back to between five hundred forty-one million and five hundred ten million years ago. However, as said by the researchers, these track findings point out that the animals having appendages lived at the time of the Ediacaran period.
The observation of this new study was published in the Science Advances journal on 6th June. Dr. Xiao told about the published paper, “We explicitly stated in the paper that we do not know exactly what animals made these footprints, other than that the animals must have been bilaterally symmetric because they had paired appendages.” He explained, “Arthropods and annelids, or their ancestors, are possibilities; and modern arthropods and annelids provide appropriate analogue to guide our interpretation of these fossils.” The researcher added, “But unless the animal died and preserved next to its footprints, it is hard to say with confidence who made the footprints.”