Fat molecules have helped identify an oval saucer-shaped, spongy entity with multiple rib-like segments - outwardly resembling a segmented jellyfish, that existed 558 million years ago as the first animals on Earth.

We humans have been walking the Earth for about 6 to 7 million years now. That is quite a while - though the Earth itself is 4.5 billion years old - we are hardly the first animals, to walk the Earth. And to find the first animal species was not that easy - after all, it took 75 years of rigorous research.

How Were They Found?

Interestingly, it was cholesterol, the fat molecules, the biomarkers of animal life, that helped the researchers to classify them as animals. One can understand the importance of this find when we tell you that it is being considered as the Holy Grail of palaeontology.

But, What Is It?

Ah, termed as Dickinsonia - an oval saucer-shaped, spongy entity with multiple rib-like segments - outwardly resembling a segmented jellyfish, it could grow to over four feet in length. It is named after Director of Mines for South Australia, Ben Dickinson, who had employed Australian geologist, Reg Sprigg, the original discover of Edicara biota - a taxonomic nomenclature encompassing all life forms during the Ediacaran Period.

The first complex multi-cellular organisms to appear on Earth, Dickinsonia, belongs to the Ediacaran biota, when the Earth was dominated by bacteria.

How Old Are They? Are They Still Living?

Dickinsonia is considered to have emerged 558-million-year ago inhabiting warmish shallow seas much before the Cambrian explosion, which happened 540 million years ago, when most of the major animal groups like mollusks, worms, and sponges, appear in the fossil records.

The Ediacaran biota, which itself dates back to around 600 million years largely disappeared with the advent of the Cambrian explosion and so did the Dickinsonia.

So That Was The Difficulty...

Precisely, incriminating pieces of evidence were eluding the researchers as they were flummoxed whether to classify Dickinsonia as a fungi (eukaryotic organisms ), protists (primarily microscopic and unicellular organisms) or animals.

While scientists from The Australian National University (ANU) led by PhD scholar Ilya Bobrovskiy had screened most of the rock fossils near their Uni, years of natural heat, pressure, and weathering had taken its toll on them. They then had to helicopter to a remote area in northwest Russia where Bobrovskiy hung from 100 metres cliffs near the bear and mosquito-infested White Sea region to dig out a specimen with organic matters still intact. Lab tests revealed its cholesterol molecule to about 93 % compared to roughly 11% that of its surroundings. Russian institutes were also involved in investigations.

What's The Significance?

Dickinsonia, comprising other tissue types as well, must be a Eumetazoa, a true animal and is essential to understand the deep origins of our lineage.