Researchers find earliest animal footprints

WASHINGTON: Chinese and American palaeontologists reported the discovery of earliest animal fossil footprint ever found in the journal Science Advances.

The fossilised animal footprints were made in the Ediacaran Period, about 635 to 541 million years ago in China, according to the study reported on Wednesday.

Bilaterian animals such as arthropods and annelids have paired appendages or “legs” and are among the most diverse animals today and in the geological past.

They were often assumed to have appeared and spread suddenly during the so-called “Cambrian Explosion” about 541 to 510 million years ago, but scientists now tend to consider that their evolutionary ancestry was rooted in the Ediacaran Period.

However, until the current discovery, no fossil record of animal appendages had been found from that period.

Researchers from the Nanjing Institute of Geology and Palaeontology under the Chinese Academy of Sciences and Virginia Tech in the United States studied trackways and burrows found in the Ediacaran Shibantan Member of the Dengying Formation (551 to 541 million years ago) found in the Yangtze Gorges area of southern China.

The trackways are irregular, consisting of two rows of imprints that are arranged in repeated groups, according to the study.

The features of the tracks indicated that they were produced by bilaterian animals with paired appendages that raised their bodies above where water and sediment met.

Also, the trackways appear to be connected to burrows, suggesting that the animals may have periodically dug into sediments and microbial mats, perhaps to mine oxygen and food. — Xinhua