While we don't know exactly when animals first left tracks on our planet, the oldest footprints ever found were left between 551 million and 541 million years ago during the Ediacaran period, a new study finds. The fossils date back to almost 3.5 billion years ago and are strong evidence of the earliest life that existed on Earth. They published their findings Wednesday in the journal Science Advances.
An worldwide team of scientists has recently uncovered what they believe are the earliest animal fossil footprints on record, Phys.org reports.
The fossil reportedly consists of two rows of imprints that represent the earliest known record of an animal that has legs.
The fossils are just a few millimetres in width and Xiao's team spotted them after painstakingly tilting rock slabs at different angles so the sunlight would illuminate any subtle traces left by ancient bugs.
The remarkable discovery reveals how creatures with paired legs were scuttling around over 100million years earlier than previously thought. 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.
The team from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences and Virginia Tech in the USA discovered two rows of imprints that are arranged in a series or repeated groups in irregular trackways and burrows.
These legs raised the animal's body above the sediment it was moving across.
This is considered the earliest animal fossil footprint record.
Bilaterian animals such as arthropods and annelids have paired appendages and are among the most diverse animals today and in the geological past. The study says that these footprints were about five hundred and fifty-one million years ago. Other research has suggested that the evolutionary roots of bilaterians should go back further than that, but fossils had never turned up until now.
Now, the discovery of the trackways and burrows shows that animals with appendages lived during the Ediacaran period, the researchers said. They observed the trackways, which were not regular, and after analyzing their characteristics, they reached the conclusion that these were formed by bilaterian animals with paired appendages.