Thursday, 23 May, 2019

Oldest animal fossil footprint on record discovered in China

540m-year-old bug tracks are oldest footprints ever discovered World's Oldest Footprints Discovered on Ancient Seafloor
Sandy Nunez | 09 June, 2018, 11:29

Previously no evidence of limbed animals has been found that pre-dates the "Cambrian Explosion", the sudden surge in diversity that occurred on Earth about 510 to 541 million years ago.

Scientists discovered the oldest footprint known so far in an ancient seafloor in China.

Without a complete fossil record though, any presumptions about the animal's habits or needs are pure speculation. But what they can say, with reasonable certainty, is that the tracks probably belong to a bilaterian.

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.

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.

As Xiao explains, knowing when the first legged animal appeared on Earth is a crucial detail, considering that the movement of sediments triggered by that first walking creature as it trotted over our planet's surface could have had a major impact on the Earth's geochemical cycles and climate.

Still, this discovery means that paleontologists will have to revise their vision of how life developed in Earth's primordial oceans.

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

The Shibantan fossil, as it's called, was found in the Dengying Formation of China's Yangtze Gorges area.

The research was published Wednesday in the journal Science Advances by scientists from the Chinese Academy of Sciences and Virginia Tech. Also, the trackways appear to be connected to burrows, suggesting the presence of complex behaviours.

The scientists weren't able to locate the body fossils of the animals that made these traces. The trackways are somewhat irregular, consisting of two rows of imprints that are arranged in series or repeated groups.

However, the scientists say in a press release, these new Edicaran-dated footprints show "bilaterian animals with paired appendages that raised the animal body above the water-sediment interface".

He also said that arthropods and annelids or their ancestors are possible.

In other words, this prehistoric critter wasn't a biped like you or me, but perhaps something with multiple paired legs - such as a spider, or a centipede - although given we have so little to go upon, the researchers emphasise it's impossible to know for sure what specific form this early walker embodied.