Earth's oldest animal footprints found in central China

"The rock that contains the fossil has been very well dated between 551 and 541 million years old", study author Zhe Chen, a researcher at the Chinese Academy of Sciences, told Agence France-Presse in an email.

The scientists in China have discovered the fossilized animal footprints of the ancient times.

"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", study co-author Shuhai Xiao, a geobiologist from Virginia Tech, told the Independent.

For comparison, non-bilateral animals include sponges, corals, jellyfish, and anemones.

The tracks and burrows, dating back half a billion years to the Ediacaran Period, were made by some of the earliest bilaterian animals, and reveal that more complex lifeforms arose earlier than previously thought.

Life during the Ediacaran was characterized by algae, lichens, giant protozoans, worms, and various bacteria, but there's still a lot that paleontologists don't know about it. Researchers say that these prints were made by creatures with appendages and this discovery is proof that there were indeed animals with limbs in the Ediacaran period.

Until the current discovery, however, no fossil record of animal appendages had been found in that period.

However, until now, no records of such fossils were ever found. Researchers from the Chinese Academy of Sciences' Nanjing Institute of Geology and Palaeontology, together with colleagues from Virginia Tech in the USA, studied the trackways and burrows that were discovered in a fossil-rich area close to the Yangtze River.

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.

The fossil reportedly consists of two rows of imprints that represent the earliest known record of an animal that has legs.

'Arthropods and annelids, or their ancestors, are possibilities. Among other things, it is also worth noting the trackways appear connected to the burrows, something that indicated the animals probably dug into the sediments in order to consume food or oxygen.

"Although the exact identity of the trace maker of the Shibantan trackways is hard to determine in the absence of body remains at the end of the trackways, we suggest that the trace maker was probably a bilaterian animal with paired appendages", the authors reported.