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In the spring of 1957, three schoolboys were climbing in an abandoned quarry in Charnwood Forest, an area of rugged hills and bluebell-wooded valleys not far from the geographic centre of England. One of the boys spotted something unusual. “Look at this!” Richard ‘Blach’ Blachford called out.

Fifteen-year-old Roger Mason scrambled down to the base of the cliff to join his friend. The rock faces in the old quarry were framed by foliage: oak roots and branches arched overhead, and grasses and ferns sprouted from crevices wherever sufficient light, soil, and water permitted growth.

Blach pointed at something clearly imprinted on the surface of the rock at head height⁠⁠—a frond-like shape several inches in length. It looked like a plant leaf, and was bisected by a curious, zigzagging stalk. Mason was puzzled.

Then, as now, Charnwood Forest was an anomaly: an area with its own distinctive history, folklore and geography, and which was folded and faulted with some of the most ancient rocks on the planet. A geologist in the making, Mason knew the frond pattern couldn’t possibly be what it looked like⁠⁠—a fossil, and more specifically, the preserved imprint of a large, complex multicellular organism⁠⁠—because the rock dated back to a distant tranche of prehistory known as the Precambrian. Everyone knew Precambrian rocks did not contain fossils; Charles Darwin himself had noted this basic fact. Rock had been hewn from the quarry through most of the 19th century, and it had become a popular spot for recreational visitors in the decades since its closure. If the strange shape represented anything significant, someone would surely have recognised it previously.

On this last point, at least, he was entirely correct.

Later, Mason took a pencil rubbing of the peculiar pattern and brought it home to show his father. Mason’s father taught part-time in the nearby city of Leicester, at a provincial outpost of the University of London. As befitted an institution on the brink of securing independent university status, the up-and-coming Leicestershire and Rutland University College boasted its own modest geology department. The elder Mason could therefore pass the problematic impression along to a young geologist colleague named Dr Trevor Ford.

The Masons urged Ford to visit the quarry and see the original rock for himself⁠—but the scientist was sceptical. If the rubbing really came from a rock originating in that particular quarry, it was definitely Precambrian, as any local geologist worth their halite could attest. Unlike similarly ancient outcrops in Australia and elsewhere, the age of Charnwood’s underlying strata⁠—up to 600 million years old⁠—was beyond dispute. With its large population and long history of mining and quarrying, the English Midlands had been crawling with geologists since almost before the modern science of geology began, and the stratigraphy of the area was thoroughly understood. If the pattern really came from Precambrian rock, there was no way it could be a fossil.

Scientists had long been befuddled by the apparent absence of fossils from the Earth’s oldest strata. In his seminal book, On the Origin of Species, Darwin wrote: “To the question why we do not find rich fossiliferous deposits belonging to these assumed earliest periods, I can give no satisfactory answer…”

Sometimes termed ‘Darwin’s Dilemma,’ the conundrum was⁠—and still is⁠—frequently fêted by Darwin’s critics as a fundamental flaw in evolutionary theory. At first, these critics appeared to have a point. The evolution of complex, multicellular life could be easily traced through fossils from the present day back to a point 541 million years ago: the Precambrian-Cambrian boundary. The rock layers above the boundary revealed a profusion of hard-bodied marine creatures. Many of these fossils displayed a segmented bilaterian body plan⁠—meaning that one half of the organism was a symmetrical mirror image of the other⁠—and included familiar forms such as trilobites and ammonites. Yet the billions of years of rocks below the boundary were different. Apart from a few traces of single-celled algae and bacteria, they seemed devoid of life signs. The appearance of so many diverse, teeming creatures at this point was so abrupt it was later termed the ‘Cambrian explosion’ and evolution’s ‘Big Bang’.

If Roger Mason really had found a fossil of a large, complex organism in rocks some 40 million years older than the beginning of the Cambrian Period, it would be one of the most significant geological discoveries of the 20th century. Ford gazed at the fern-like outline and mulled over this unlikely possibility. Mason’s rough graphite-and-paper rendering did raise intriguing questions. Could it really represent an ancient being from the deep Precambrian? If so, what kind of organism was it, and how did it relate to the bustling biota of the later Cambrian? And why had nobody spotted it before?

But someone had spotted it before. Like other tales of 1950s schoolchildren stumbling into fantastical worlds, Roger Mason’s discovery has a prequel.

In the summer of 1956, less than a year before Mason’s climbing trio arrived at the quarry, a 15-year-old girl named Tina Batty was bilberry-picking with her parents and younger sister in the same corner of Charnwood Forest. At head height, at the base of an exposed rock face overhung by roots and ferns, she espied a curious frond-like outline. The girl examined the shape closely. She was already interested in geology and was puzzled to see such a provocatively fossil-like pattern in supposedly lifeless Precambrian rock. The bilberries went unpicked; indeed, they were not yet ripe, the fruit foraging having been merely a pretext for Tina to lure her family into an impromptu geology field trip.

Like Mason, Tina realised the frond’s potential significance, and decided she should ask someone in authority. Her parents were supportive, but lacked geological expertise or convenient contacts at local proto-universities. So she mentioned the strange “fern” to her geography teacher at school the next day.

“There are no fossils in Precambrian rocks!” was the teacher’s reply. Tina said she was aware of this; indeed, that was why the find was so perplexing. “Then they are not Precambrian rocks,” her teacher shot back, closing down the discussion.

Tina begged her parents to let her go back to the quarry. Later that year, they relented. The next time, like Mason, she made a pencil rubbing of the shape, although she wasn’t sure what to do with it after her teacher’s bruising rejection. She thought someone must have seen the fossil before, or something like it⁠—but the lack of a convincing explanation nagged at her. She visited a local museum to look for similar specimens, and continued to read any geological material she could lay her hands on.

Then she visited the quarry a third time, in the latter part of 1957, only to be faced with the new mystery of where the fossil was. The frond had gone, with only fresh drill holes to mark its passing.

A new and enthusiastic young geography teacher came to work at Tina’s school. Tentatively, Tina asked if she could study geology as an extra subject. The new teacher was keen to help, and asked her superiors for permission⁠—only for the idea to be “utterly vetoed” by the headteacher. This put paid to her plans to study geology at university. At this point, a dispirited Tina paused her pursuit of the fossil’s provenance. She put the rubbing in a drawer with the rest of her fossil collection, out of sight but not out of mind.

For Tina, answers would have to wait.

Mason fared considerably better in his investigation of the same ossified frond. He was lucky to have found a more receptive grown-up in Trevor Ford, and in May 1957, a few months after Tina’s second trip to the quarry, the Masons successfully persuaded the young geologist to visit the specimen in person. Ford inspected the imprint and its surroundings with a growing sense of surprise and wonder. There were various other unusual outlines on nearby surfaces, including several striking ring shapes. The quarry rocks were definitely Precambrian, but no non-biological process could possibly account for these patterns. They had to be fossils.

It wasn’t at all obvious what kind of an organism Mason’s fossil represented: it certainly didn’t look much like the complex bilaterian animals of later periods. For a start, it lacked any obvious sensory, digestive or reproductive structures. Indeed it lacked almost any familiar features from known terrestrial biology, past or present.

Based on its vaguely leaf-like appearance, Ford hypothesised it was a plant, and named it Charnia masoni. He employed professional quarrymen to remove the slab containing the fossil, which was later installed in Leicester’s New Walk museum. He also showed photographs of the find to one of his former tutors, now working at the University of Sheffield. The older geologist shared his protégé’s excitement and, perhaps sensing a scoop, encouraged Ford to submit a paper to the small regional journal he edited. In this way, news of one of the 20th century’s greatest scientific discoveries was brought to the world through the august Proceedings of the Yorkshire Geological Society.

In 1958, only a few months after the pivotal Yorkshire publication of Ford’s paper, similar research appeared in a periodical for less fortunate folk living elsewhere in the world, in the scientific journal Nature. This research confirmed the existence of Precambrian fossils at a location halfway around the planet: a part of the remote Flinders Ranges in South Australia named the Ediacara Hills. These antipodean finds included round, rippled imprints and segmented oblong-shaped forms, and proved that Charnia wasn’t a fluke⁠—although some type of primitive non-parasitic flatworm was just about possible.

At the time of their initial discovery ten years earlier, these fossils made little impression in geological circles outside of South Australia, as the age of the Ediacara Hills remained uncertain at that time. Ultimately, however, the Ediacara Hills were determined to be composed of Precambrian rock, and the 89-million-year chunk of time immediately preceding the Cambrian would come to be known as the Ediacaran Period.

But if anyone expected these two 1958 papers to immediately open the Precambrian fossil floodgates, they were wrong. Only a trickle of further finds emerged. Outcrops of very ancient rocks remained rare, and the fossil shapes were often unclear and open to alternative interpretation. Nevertheless, researchers identified a number of additional Ediacaran fossils of different types at various sites across the world. Many questions remained about these organisms: what they were, how they lived, and how they related to each other and to their environments. Often, researchers resorted to general statements along the lines of “this one looks like a pizza disc” or “this one is vaguely worm-shaped”. The fossils lacked recognisable internal structures to distinguish them as plant or animal, and did not fit into any known existing evolutionary lineage. Charnia might have been a plant, but it could just as easily have been an animal, a fungus, or something else entirely.

Still, even as scientists scratched their heads at the modest but growing array of complex Ediacaran fossils, they made steady progress in describing the ancient world in which those organisms lived. This context would prove crucial in understanding what kind of organism Charnia actually was, and in working out how it related both to its fellow Ediacarans⁠—and to the later Cambrians.

On its surface, the Earth wasn’t a promising place for complex life some 600 million years ago: it was another planet, where things were done differently. The Charnwood quarry rocks originated within a volcanic arc island chain near a much larger landmass far to the south. The continents were clustered together around the South Pole at this time; indeed, some scientists posit a firmer scrunch in the form of a short-lived supercontinent named “Pannotia”, centred over the Pole itself.

The sun burned less fiercely, so the weather might have been cooler than expected for the latitude. The moon loomed larger and closer in the sky than it does today and, relatedly, the day was three hours shorter. Tectonic activity was more vigorous, the Earth being half a billion years closer to the intense heat of its primordial accretion. Hot rocks and ash⁠—or tephra⁠—from a nearby stratovolcano would have splattered and hissed onto surrounding sea and land surfaces. Atmospheric oxygen levels were a scant 12 percent to 15 percent, so without high altitude training⁠—or the benefit of a respiratory bypass system⁠—any anachronistic visitors would soon suffocate, if they hadn’t already choked on ash. Away from the immediate vicinity of the eruption, drier areas of land presented a bleak landscape of bare rock and sediment, while a thin layer of living green-brown scum covered any sufficiently moist surfaces. These ‘microbial mats’ extended into shallow seas and contained a mélange of simple algae, bacteria, and cyanobacteria studded, tentative evidence indicates, with primitive fungi.

But the sea was altogether more welcoming for newly evolved multicellular organisms. The chemistry of life is based on water, which acts as a buffer for physical and biochemical extremes. By the Ediacaran Period, the action of primitive algae and cyanobacteria⁠—and possibly changes in deep water circulation⁠—had finally resulted in full-depth marine oxygenation. The Earth was emerging from a disastrous, drawn-out, and probably global snowball-inducing biogeochemical transition known as the Oxygen Catastrophe, setting the scene for elaborate oxygen-utilising organisms to evolve and emerge from the depths.

Still, the marine environment around this particular island was not without danger. Material ejected from the eruption settled into the sea and drifted down the steep underwater flanks of the volcano. Eventually, tephra settled on and around a community of things living on the seafloor: among them, the frondose form that was Tina and Mason’s fossil-to-be. The surrounding sediments reveal no signs of stirring from surface wave action, meaning that the deposition of the Charnwood strata took place in the deep dark below the photic layer. Ford’s initial surmise⁠—that Mason’s frond was some kind of photosynthesising plant⁠—was therefore unlikely to be correct.

Volcanic debris continued to accumulate through successive eruptions until the underwater Precambrian Pompeii reached its petrifying conclusion. The frond organisms were completely buried, but the gentle submarine ash-fall allowed their soft body parts to be preserved in astonishing detail. Not far from the Charnwood volcano, similar eruptions and ash falls occurred on different islands in the arc chain. The volcanic sediments from all these eruptions compacted into rock that became accreted into a microcontinent named Avalonia, which plate tectonics eventually sent shuffling northward.

Millennia flickered by: the sun warmed; complex life on Earth spread from sea to land to air; the moon receded and the days lengthened; the solar system completed one full orbit around the galactic core, and then another; and the continents danced away, jostled together, and drifted apart again. A rift opened between the former arc islands, and as the crust unzipped and pulled away, a new ocean⁠—the Atlantic⁠—filled the widening space between. All this time, the imprints of once-adjacent groups of submarine organisms survived until at last, uplift and erosion exposed them in two locations: at Charnwood Forest in Leicestershire, England, and along a jagged stretch of shoreline more than 2000 miles westward across the ocean, in Canada.

It was close examination of the second of these two locations that enabled the beginnings of a breakthrough in scientists’ understanding of Mason’s frond, and of the Ediacaran biota as a whole.

In the late 1960s, fossils were found on a Precambrian promontory named Mistaken Point on Newfoundland’s Avalon Peninsula. Although the Leicestershire fossils remain the first confirmed examples of early complex life, it was their Canadian ex-neighbours a few islands down the arc chain that opened a much clearer and wider portal into the realm of Charnia. The soil, obscuring foliage and limited extent of Charnwood Forest’s ancient “wood between worlds” makes it hard to spot fossils and ascertain relationships between them. But at Mistaken Point, many of the imprints are etched on large open exposures of coastal cliffs. At sunrise or sunset, when low light casts long shadows to accentuate the markings, entire ecosystems can be read from the rocks. Multiple different-sized and shaped specimens rest together in the same positions they occupied in life more than half a billion years ago. When these context-rich fossil assemblages were identified elsewhere, scientists could start to make comparisons across different sites around the world, and the pace of Precambrian paleobiological progress at last picked up. It finally became possible to sketch out some tentative ideas about what Mason’s frond was, and how it lived.

While the deep water habitat meant Charnia probably wasn’t a plant, a later theory⁠—that it was a distant ancestor of sea pens, contemporary creatures related to corals⁠—was discarded following close examination of growth patterns. However, researchers proposed that Charnia was attached to the seafloor with a circular holdfast structure, much like corals and sea pens today. The round patterns seen by Ford in the Charnwood Forest quarry, and by other geologists at Mistaken Point and other Ediacaran fossil sites, are now believed to represent these attachment points, meaning that Ford’s rings and fronds were actually different fossilised body parts from the same, or similar, lifeforms.

Most now believe Charnia and similar frondose species, known collectively as rangeomorphs, were early animals. Either way, when compared to present-day organisms, the rangeomorphs exhibit several unusual features⁠—and omit numerous commonplace ones. Despite their tentative animal classification, researchers have still been unable to identify any obvious sensory, digestive, respiratory, circulatory, or reproductive organs. Their regular alternating footprints-in-the-sand body plan represents a type of offset symmetry known as glide reflection. Rarely seen in contemporary biological organisms, this pattern is relatively common among the Ediacaran biota⁠—and in artificial simulations of evolving dynamical systems of cellular automata such as ‘Conway’s Game of Life’. Their body structure also exhibits fractal symmetry, with self-similar units repeating at multiple scales with up to four orders of branching. The fractal pattern maximises surface area and suggests feeding and respiration took place directly across their external membranes⁠—indeed, the frondiest of the frondose rangeomorph specimens boast estimated surface areas similar to the half-tennis court-sized internal expanse of a typical human lung. Meanwhile, reproduction is hypothesised to have occurred by asexual sprouting of snapped-off frond tips. And as bedroom coders of Mandelbrot sets know, intricate fractal patterns can be generated by very simple rules; it is possible that rangeomorph body plans could have been coded by as few as 6 to 8 genes, compared to the thousands of genes needed to describe the shape of humans and other complex bilaterians today.

Charnia has a significant place in the history of geology⁠—one distinguished Oxford paleobiologist described it as “one of the most important fossils ever found”⁠—but this significance largely derives from the accidents of past and present geography that allowed it to be recognised as the first of its kind. Other, younger Ediacaran fossil types subsequently found in Australia, China, and elsewhere have filled in some of the missing links, suggesting that purposeful movement, bilateral symmetry and sexual reproduction had arrived in multicellular organisms well before the Cambrian explosion. While many questions remain, such research has thoroughly blunted the horns of Darwin’s dilemma. The reason there are comparatively few fossils from the Earth’s ‘earliest periods’ may have more to do with the fact that most Ediacaran life was soft-bodied, and therefore resistant to fossilisation, than from a lack of original material.

Still, some Ediacaran life signs did survive half a giga-annum of erosion and plate tectonics to be exposed in at least one well-visited location, where they remained clearly visible for decades before their significance was realised. This leads back to the human-scale question of why it took so long for Precambrian life to be recognised for what it was.

On 10 March 2007, geologists and palaeontology enthusiasts gathered for a special 50th anniversary symposium in Leicester, England⁠—not far from where Mason’s rock-climbing trio happened upon their famous fossil. It was an exciting time for Ediacaran research, when many of the aforementioned origin theories were starting to coalesce. Experts from around the world came to present their findings, celebrate Mason’s discovery, and consume a Charnia-emblazoned cake baked especially for the occasion. Mason⁠—now a Professor of Metamorphic Geology at Wuhan University in China⁠—was there, and so was the now-retired Trevor Ford, whose long career covered 35 years of geology teaching at the University of Leicester, 22 PhD examinations, 500 publications, caving, meteorite chasing, and a stint as a tour guide leader in the Grand Canyon. But standing next to these luminaries at the cake-cutting ceremony was somebody else; someone many of the assembled experts did not recognise. Her name was Tina.

Despite being brushed off by her geography teacher after her discovery in the quarry, Tina Batty never gave up on her fern: she remained committed to finding out what it was. In 1961, a twenty year-old Tina was studying zoology, botany, and geography at Reading University. It was here that she finally got some answers. On her return from a trip to the Natural History Museum in London⁠—where once again, she failed to find Precambrian fossils among the exhibits⁠—she approached a lecturer in the university’s geology department, brandishing the rubbing she had made in the wooded quarry five years before. She told the story of her discovery, only to be given a “funny look.” The lecturer showed her a copy of Trevor Ford’s paper, and gave her the news that a Precambrian fossil had been “recently discovered” by a schoolboy in a quarry and removed for safekeeping.

It had to be the same fossil. She later wrote: “I had mixed feelings about this news: a sense of grievance that he had been believed while I had not, but also one of relief that I was correct, and that the fossil was in proper hands.”

Life took over. Tina graduated and conducted two years of research into the ecology of freshwater mussels. She became Tina Negus, started a family, left her scientific career behind, and added to her family. Years ticked by. In Charnwood Forest, frost and snow pulsed white across the Precambrian crags with each winter, while the bluebell woods in the valleys below strobed through brown, violet, green, and yellow with the passing of the seasons. Tina became a ceramics teacher, a painter and photographer, and later, a poet. In the 1970s, she spotted her fossil on a children’s television programme, and again in a documentary in 2004⁠—this time alongside a distinguished geologist identified by the presenter as Roger Mason.

Technology at last provided Tina with the means to achieve knowledge and recognition. She found Mason’s email address on a website and sent him a poem she had penned about Charnia, and an account of how she had identified the exact same fossil in the same quarry less than a year before his discovery.

Mason responded almost immediately, and notified his old friend and mentor Trevor Ford. Although formally retired from his University position, Ford remained geologically active in the Charnwood Forest area and was involved in planning the upcoming Charnia anniversary symposium. The aggregated geologists resolved to set the record straight. Tina was invited to the 2007 anniversary celebration, and widespread acknowledgement of her part in the Charnia story was finally assured.

Professor Mason recognised how bittersweet this belated recognition must have felt. He contrasted the dismissive attitude of some of Tina’s teachers to that of his former school, writing that “I was able to report the discovery because of my father’s encouragement and the enquiring approach fostered by my science teachers.” Incidentally, his school was the same institution from where a young naturalist, broadcaster-to-be, and frequent visitor to Charnwood Forest named David Attenborough had graduated, just a few years before Mason. Mason was also quick to point out that even within his own group of teenaged climbers, he was not the true “discoverer” of the fossil: that honour should have gone to Richard Blachford, who was the first to spot the frondose form on the rock face. Sadly, fate denied Blach a piece of the Charnia discovery cake. Mason’s childhood friend suffered from depression and took his own life in the 1960s.

But neither Mason, nor Blach, nor Tina were the first to notice strange shapes in the Charnwood Forest rocks. Quarrymen had worked the fossil site for most of the 19th century and had certainly observed the outlines, as evidenced by the local name for the quarry⁠—the ‘Ring Pit’⁠—but it remains unclear whether they attributed them to human, natural or supernatural agency. In 1848, two naturalists familiar with the newly codified science of geology, James Harley and John Plant, inspected the then-working quarry and “observed many circular and spheroid forms” in rocks contended by “certain geologists” to “contain no organic remains.” Yet somehow these finds never received widespread recognition and ultimately, scholars dismissed the quarry shapes as artifacts formed by some unspecified non-biological process. They certainly never came to Darwin’s attention, even after he outlined his dilemma in 1859.

A similar story repeated itself on the other side of the Atlantic when, in 1872, a Canadian ex-lawyer and geologist named Elkanah Billings described apparently fossiliferous shapes in ‘primordial’ Precambrian rocks in Newfoundland. But by then, the scientific consensus had fossilised around the belief that the Precambrian was ‘azoic’, or lifeless. Other scholars failed to acknowledge the significance of Billings’ finds, and he too fell victim to the same blinkered mindset Tina’s geography teacher demonstrated decades later.

Yet this was only an accurate representation of the prevailing attitude of the scientific community up to that time. The belief in a lifeless Precambrian was so firmly entrenched that clear evidence to the contrary was downplayed, ignored, or even flatly contradicted. If establishment figures such as Billings were treated this way, there was little hope for a fifteen-year-old schoolgirl. A powerful force was clearly at work⁠⁠—an intrinsic, unconscious human tendency to interpret all new evidence in support of pre-existing beliefs. In the 1960s, psychologists gave this phenomenon a name: confirmation bias.

Despite the strenuous efforts of researchers⁠—and the paltry efforts of politicians and many others in public life⁠—confirmation bias persists as a stubborn and pervasive form of systematic error in human society. But even had earlier scholars been more alert to its pernicious influence, it is not immediately obvious how any of the pre-Mason Precambrian pioneers could have done more to achieve recognition, either for themselves or their fossils. Ultimately, Mason’s success depended on a fortuitous chain of receptive contacts: a parent, a colleague, and a former tutor with editorial responsibilities and a need for good copy.

To this day, Charnia maintains its decades-long tradition of compelling scientists to question their basic assumptions. A study of Mistaken Point fossils published in 2020 revealed the existence of fine filaments joining individual rangeomorph fronds across wide areas of seafloor; multiple ferns appear to be linked in a communal ‘network’, with connections varying in length from centimetres to metres. The purpose of the linking structures possibly involved stabilisation, reproduction, or transfer of nutrients, or a combination of all these functions⁠—or perhaps something else entirely. The most obvious analogues among extant terrestrial lifeforms might be the ‘stolons’ or suckers seen on strawberry plants and other flowering plants. But there is nothing that seems to be directly comparable to these structures known anywhere in the present day biology of Planet Earth.

Faced with this new strangeness, a degree of dismay among researchers would be understandable. But what is more surprising is how much scientists actually do now know about Precambrian complex life⁠—from the starting position of a complete denial of the possibility of its existence a few short decades ago.

Such progress has not gone unnoticed: NASA’s Astrobiology research program regularly supports studies into the Ediacaran biota, presumably on the basis that if scientists can learn how to recognise bizarre forms of complex life at locations distant in deep time, they may be able to do the same for evidence of life distant in deep space. Just as a group of schoolchildren in Charnwood Forest opened a portal into an ancient and fantastical faraway realm, perhaps a silver-suited space explorer will one day gaze at some fleshy, frondose and filamentous phenomenon on a distant planet and call out to her partner: “It’s life, Jim.” And, thanks to Charnia, something like we know it.

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