Dickinsonia fossil

Earth’s oldest animal? Maybe, say scientists studying half-billion year old fossil

Contributed by
Sep 21, 2018

Godzilla this prehistoric discovery most certainly is not. But, for a world estimated to be more than 4 billion years old, finding evidence of animal life approximately 560 million years in the primordial past would go extraordinarily far toward placing surprisingly advanced forms of life early in the soupy mix. 

Now, a team of researchers contends that they’ve discovered evidence of exactly that: animal life that, if the evidence holds, marks the earliest such discovery ever found. Unlike its monstrous sci-fi cousins, though, this specimen is about four feet long — and probably incapable of summoning atomic breath

Via Gizmodo, an international team of scientists led by Ilya Bobrovskiy of the Australian National University contends that the discovery of cholesterol traces on a specimen of Dickinsonia — a fossil long known to science, but enigmatic in terms how it should be classified — identifies the segmented, platter-shaped creature as an animal.

If the evidence holds, it would mark an appearance of animal life in the pre-Cambrian period known as the Ediacaran, a 100 million-year span immediately succeeded by the Cambrian’s notable, scientifically recognized proliferation of diverse animal life. 

The key to the cholesterol’s significance is identifying whether the Dickinsonia organism self-produced it during its own lifetime, or whether the material was picked up farther down the timeline as the specimen’s body fossilized. 

The research team contends that the creature produced the cholesterol — a defining trait of animals, but not of protozoa, fungi, or plants — while it lived, and that the lipid biomarkers that they detected in their preserved specimen are therefore evidence that Dickinsonia was, in fact, an animal. 

In a statement, study co-author Jochen Brocks explained the basis for the team’s conclusion:

“Scientists have been fighting for more than 75 years over what Dickinsonia and other bizarre fossils of the Edicaran Biota…were: giant single-celled amoeba, lichen, failed experiments of evolution or the earliest animals on Earth. The fossil fat now confirms Dickinsonia as the oldest known animal fossil, solving a decades-old mystery that has been the Holy Grail of palaeontology.

The report notes that the academic community isn’t exactly ready to close ranks in support of that finding, presenting counter-arguments from at least one Swiss academic who believes the team dismissed other plausible interpretations of its findings. 

“There is a long history of very strong claims being made because of evidence from biomarkers that in the end do not really amount to very much,” Lausanne University’s Jonathan B. Antcliffe told Gizmodo, explaining that the specimen may have been “contaminated” with the tell-tale cholesterol marker, and that there’s still not enough evidence to dismiss other Kingdoms within the early Eukaryotic phylum (like plants and fungi) as lingering possibilities. 

“No one thinks that Dickinsonia is bacterial,” he said. “No one. So we already know it is a eukaryote of some type. There are very many different eukaryotes and the authors cherry pick a few examples and quickly reject them before moving immediately to an animal conclusion.”

At least Dickinsonia itself is no longer around to be offended by whichever conclusion we humans jump to. And judging from how offended Godzilla can get at our transgressions against nature, that’s probably a good thing.

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