550 million-year-old tracks in China could be the oldest ever found

Animals left the first footprints on Earth up to 551 million years ago, according to ancient tracks found in China.  

Scientists believe the tiny parallel footprints — which are only a few millimetres across — were left by an early ancestor of modern-day insects or worms.

Previously, it was believed animals with pairs of legs capable of leaving such footprints first appeared during the ‘Cambrian Explosion’ about 541 to 510 million years ago.

However, this creature — which provides the earliest evidence of an animal with legs — would have existed around 10 million years before then.

Scientists believe the tiny parallel footprints (pictured) – which are only a few millimetres across – were left by an early ancestor of modern-day insects or worms

Researchers from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and Virginia Tech studied ancient trackways and burrows found in the Yangtze Gorges area of South China. 

The fossils date back to the Ediacaran Period, which was between 635 to 541 million years ago.

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

The rock layers where the fossils were found date between 551 million and 541 million years ago, suggesting the footprints were made some time between those dates.

The shape of the tracks suggest they were made by bilaterian animals with pairs of legs and a raised body.

Prior to this discovery, it was suspected that animals with legs first appeared during this period, but no evidence had ever been found.

‘Previously identified footprints are between 540 and 530 million years old’, Dr Zhe Chen from the Nanjing Institute of Geology and Palaeontology told MailOnline.

‘The new fossils are probably up to 10 million years older than previously known footprints’, he said. 

The trackways are somewhat irregular, consisting of two rows of imprints that are arranged in series or repeated groups. 

The fossils date to the Ediacaran Period, which was between 635 to 541 million years ago. Researchers found the tiny marks (pictured) by tilting rocks at different angles so they caught light from the sun

The fossils date to the Ediacaran Period, which was between 635 to 541 million years ago. Researchers found the tiny marks (pictured) by tilting rocks at different angles so they caught light from the sun

Researchers  studied ancient trackways and burrows found in the Yangtze Gorges area of South China

Researchers studied ancient trackways and burrows found in the Yangtze Gorges area of South China

Researchers do not know what animals made the footprints but have interpreted the two parallel rows of dots as rows of tracks.

The trackways appear to be connected to burrows, suggesting that the animals may have periodically dug into sediments, perhaps to mine oxygen and food. 

‘At least three living groups of animals have paired appendages (represented by arthropods such as bumble bees, annelids such as bristle worms, and tetrapods such as humans)’, said Dr Chen.

‘Arthropods and annelids, or their ancestors, are possibilities.

‘But unless the animal died (and preserved) next to its footprints, it is hard to say who made the footprints’, he said.

WHAT WAS THE ‘CAMBRIAN EXPLOSION’?

Scientists have long speculated that a large oxygen spike during the ‘Cambrian Explosion’ was key to the development of many animal species. 

The Cambrian Explosion, around 541 million years ago, was a period when a wide variety of animals burst onto the evolutionary scene.

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

Over the following 70 or 80 million years, the rate of evolution accelerated and the diversity of life began to resemble that of today.

It ended with the Cambrian-Ordovician extinction event, approximately 488 million years ago. 

A new study has linked the historic rise in oxygen responsible for the formation of animal life on Earth to fossil fuels. Image: This black shale, formed 450 million years ago, contains fossils of trilobites and other organic material that helped support these increases in oxygen

A recent study linked the historic rise in oxygen responsible for the formation of animal life on Earth to fossil fuels. Pictured: This black shale, formed 450 million years ago, contains fossils of trilobites and organic material that helped support these in oxygen

 

 



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