On Trails

Earth's earliest known forms of animal life were trailblazers.

Late Ediacaran horizontal surface trails within the Mistaken Point formation, Avalon Peninsula, Newfoundland

Alexander G. Liu, University of Bristol

Copyright © 2016 by Robert Moor. Adapted from ON TRAILS: An Exploration by Robert Moor published by Simon & Schuster, Inc. Printed by permission.

The world’s oldest trails were discovered in 2008 by then Oxford researcher Alex Liu. He and his research assistant, Jack Matthews, were scouting for new fossil sites out on a rocky promontory called Mistaken Point, Newfoundland, where a series of well-known fossil beds overlook the North Atlantic. Bordering one surface, Liu noticed, was a small shelf of mudstone that bore a red patina. The red was rust—an oxidized form of iron pyrite, which commonly appears in local Precambrian fossil beds. They scrambled down the bluff to inspect it. There, Liu spotted what many other paleontologists before him had somehow missed: a series of sinuous traces thought to have been left behind by organisms of the Ediacaran biota, the planet’s earliest known forms of animal life.

The ancient Ediacarans, which likely went extinct around 541 million years ago, were exceedingly odd creatures. Soft-bodied and largely immobile, without mouth or anus, some were shaped like discs, others like quilted mattresses, others like fronds. One unfortunate type is often described as looking like a bag of mud. We can envision them only dimly. Paleontologists don’t know what color the Ediacarans were, how long they lived, what they ate, or how they reproduced. We do not know why they began to crawl—perhaps they were hunting for food, fleeing a mysterious predator, or doing something else entirely. Despite all these uncertainties, what Liu’s discovery undoubtedly suggests is that 565 million years ago, a living thing did something virtually unprecedented on this planet—it shivered, swelled, reached forth, scrunched up, and in doing so, at an imperceptibly slow pace, began to move across the sea floor, leaving a trail behind it.

The exact location of these fossil beds is a matter of great secrecy due to the rise of so-called “paleo-pirates,” who have been known to carve out the more notable fossils and sell them to collectors. The nearest town to the beds is Trepassey, a small fishing community on the southeastern corner of the Avalon Peninsula of Newfoundland. At an unprepossessing restaurant in the Trepassey Motel, I met with Liu.

I had imagined him as I did all paleontologists: gray at the temples, a pair of spectacles perched on his nose, and behind them, the deep-creased eyes of a man who spends his days peering at small things lit by a harsh sun. I was surprised to discover a fresh-faced, raven-haired young man, not yet thirty, with a shy smile. Beside him were his two research assistants: Joe Stewart and Jack Matthews.

We shook hands, sat down, and ordered a round of beer and plates of fried fish. They ate heartily. Because money was tight, the team spent two out of every three nights in tents set up in an abandoned trailer park, and the third night here at the motel to shower and wash their clothes. Journalism, they assured me, was not the only field with dwindling resources. Each year, said Liu, university and government budgets for the dusty science of paleontology grow stingier. He smiled with resignation. “What I do is immensely important for understanding where we came from, but it has little wider social impact,” he said. “It’s not going to solve climate change. It’s not going to boost the economy.”

As a boy, Liu had loved dinosaurs, particularly those in Jurassic Park. The romance of those craning beasts, which he never fully outgrew, coupled with his love of fieldwork and knack for geology, drew him to fossil hunting. When he was pursuing his master’s degree at Oxford, he had planned to study ancient mammals, but he found the field crowded. He turned to the much older and largely unstudied Ediacarans. “If I had taken on a mammal project, then I’d have been trying to answer questions that people have looked at for hundreds of years,” he said. “Whereas I knew that Ediacaran stuff was new, uncertain. And that was more enticing, really, because the questions are bigger.”

Of all the manifold questions surrounding these elusive, soft-bodied animals, the biggest might concern the origins of animal movement: how the first Ediacaran trail-maker may have set off a series of morphological changes leading, in fits and starts, from a serene garden of swaying anemone-like creatures to today’s violent, skeletonized kingdom of sprinters, jumpers, flyers, swimmers, diggers, and walkers. It is rare in science to newly encounter such a big open question—and harder still to answer it.     --RM

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