Ediacaran-period microfossils in Brazil reveals that suspected traces of ancient tiny animals were actually fossilized bacteria and algae. (Image generated using AI: OpenAI)Fossils that were previously seen as traces of the earliest forms of tiny animals were actually communities of algae and bacteria, a new study has claimed.Researchers who studied the microfossils in Brazil found they had cellular structures like those found in microorganisms. Earlier studies had suggested that these structures may have been ancient wormlike creatures or marine animals from the Ediacaran period.What is the study?“We observed that the microfossils have cellular structures – sometimes with preserved organic material – consistent with bacteria or algae that existed during that period. These aren’t traces of animals that may have passed through the area,” Bruno Becker-Kerber, the first author of the study, was quoted as saying by the scientific research portal Science Direct.Also Read | Scientists build 3D computing device using living brain cellsHe also explained that the idea of the marks in such old rocks being left by animals could have pushed back the fossil records of the meiofauna – tiny invertebrates that are less than one millimetre long – during the Ediacaran period.The initial findings of the research team were published in the Gondwana Research journal.What is the Ediacaran period and the Cambrian explosion?The Ediacaran period – about 639 to 539 million years ago – was a huge turning point for the evolution of life on Earth. This period is the point when oxygen levels in the ancient oceans rose, leading to the evolution and diversification of organisms in the oceans.Then came the Cambrian explosion – about 538 million years ago – where organisms went through a rapid transformation, and diversified into the very major animal groups that we know today.Story continues below this adHow did the researchers investigate the fossils?The fossils were well-preserved enough to show individual cells, internal wall divisions, and traces of organic matter – details that rule out the possibility of these being simple scratch marks left behind by moving animals.The team examined the fossils at Sirius, CNPEM’s particle accelerator in Campinas, using the MOGNO beamline – an instrument capable of imaging structures just a few micrometers across. Their analysis combined microtomography and nanotomography, two techniques that can resolve detail at the scale of micrometers (a thousandth of a millimeter) and nanometers (a billionth of a meter).The team further tested the fossils using Raman spectroscopy, which probes their chemical composition. That analysis turned up organic material within the fossil cell walls – evidence that the structures were preserved microbial bodies, not traces left by animals moving through the sediment.What was studied?Scientists took a closer look at ancient fossils dug up in two locations in Mato Grosso do Sul, Brazil – Corumbá and Bonito, both part of a geological formation called Tamengo.Story continues below this adThese rocks were once the floor of a shallow sea that existed hundreds of millions of years ago, back when the supercontinent Gondwana was still coming together before eventually breaking apart into South America and Africa.Also Read | Neanderthals may have performed the world’s 1st dental procedure around 60,000 years ago: StudyThe researchers were trying to reassess whether the marks on the fossils were possible meiofaunal burrows. What they found instead were fossilised bodies of bacteria and algae.These microbial forms came in three different sizes – the bigger ones likely belonged to green or red algae, while the smaller ones could be algae, cyanobacteria, or sulfur-oxidizing bacteria.The finding weakens a piece of evidence proposed for very early meiofauna. It indirectly challenges previous ideas about when small animals first appeared on Earth.Story continues below this ad(This article has been curated by Nityanjali Bulsu, who is an intern with The Indian Express)