World's oldest footprints found in China

James Marshall
June 8, 2018

The earliest animal footprints ever left on our planet were discovered in China, in an old fossil site predating the 'Cambrian Explosion'.

This remarkable discovery is hailed in a study, published yesterday in the journal Science Advances by a research team from Virginia Tech University in the US and the Nanjing Institute of Geology and Palaeontology (NIGP) of the Chinese Academy of Sciences.

This places them perhaps even 10 million years before the "Cambrian Explosion" (roughly 541 million years ago), the moment in time which sparked the incredible evolution of life that led to the awesome diversity of species that we see today.

"If an animal makes footprints, the footprints are depressions on the sediment surface, and the depressions are filled with sediments from the overlying layer". Until the current discovery, however, no fossil record of animal appendages had been found in the Ediacaran Period.

The fossil tracks offer "some of the earliest known evidence for animal appendages and extend the earliest trace fossil record of animals with appendages from the early Cambrian (485 million to 541 million years ago) to the late Ediacaran Period".

Researchers found the tiny marks by tilting rocks at different angles so they caught light from the sun.

The trackways' characteristics indicate that a bilaterian animal - that is, a creature with bilateral symmetry that has a head at one end, a back end at the other, and a symmetrical right and left side - made the tracks. "The new fossils are probably up to 10 million years older", the study's co-author Zhe Chen, from the Chinese Academy of Sciences, told AFP.

The trackways are irregular, the scientists found, with two rows of imprints that suggest they were created by a bilaterian animal whose appendages raised it above the ground. The rocks they come from are dated to between 551 million and 541 million years old.

While the researchers are unable to identify the animal behind the footprints, there are three types of living animals with paired appendages: arthropods such as bumble bees, annelids such as bristle worms, and tetrapods which include humans. "Arthropods and annelids, or their ancestors, are possibilities".

The tracks could be from 10 million years before the Cambrian Explosion, a sudden explosion in biodiversity almost half a billion years ago.

Before about 580 million years ago, most organisms were simple, composed of individual cells occasionally organised into colonies.

A recent study linked the historic rise in oxygen responsible for the formation of animal life on Earth to fossil fuels.

Other reports by Click Lancashire

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