Mistaken Point: Newfoundland's Ediacaran Fossil Coast

Mistaken Point, on the south-eastern tip of Newfoundland’s Avalon Peninsula, is one of the world’s most important fossil sites for the earliest large, complex life. Its sloping rock surfaces preserve whole communities of soft-bodied Ediacaran organisms that lived on the deep seafloor about 580 to 560 million years ago and were buried by falls of volcanic ash. Discovered in 1967, the site was inscribed on the UNESCO World Heritage List in 2016.

Background: a deep seafloor in the Ediacaran

During the Ediacaran Period, what is now eastern Newfoundland lay far from North America, on a volcanic island arc called Avalonia near the margins of the ancient ocean. The Mistaken Point organisms lived in deep water, well below the depth to which sunlight penetrates.

Because there was no light, they could not have relied on photosynthesis. Most researchers think they absorbed dissolved nutrients or captured organic particles directly from seawater. They belong to the oldest of the three broad groupings of the Ediacaran biota, often called the Avalon assemblage after this region.

Nearby volcanoes periodically showered the sea with ash. When an ash fall settled onto the seafloor, it smothered and buried the living community beneath it, preserving the organisms where they stood. Geologists sometimes compare these surfaces to a deep-sea Pompeii.

Discovery

The fossils were found in 1967 by Shiva Balak Misra, a graduate student from India studying geology at Memorial University of Newfoundland. While mapping the coastal rocks, he noticed numerous strange impressions on the bedding surfaces. He published a description in 1969 in the Bulletin of the Geological Society of America.

The headland’s name long predates the fossils. It is said to come from sailors who, in fog, mistook it for nearby Cape Race and turned north too soon, with fatal results on the rocky coast.

The fossils

Dozens of fossil-bearing surfaces have been identified along this stretch of coast, some containing hundreds or thousands of specimens. Among the best known is a large bedding plane known as the “E Surface”.

Most fossils are rangeomorphs, frond-like organisms built from repeated branching units that resemble fractals. Fractofusus lay flat on the seabed in spindle shapes, while upright forms such as Charnia and Beothukis were anchored by disc-shaped holdfasts and rose into the water. Bradgatia formed bushy clusters. The frond Charnia is also known from Charnwood Forest in England, which lay in the same broad region of the ancient world.

Because entire communities were captured at once, scientists can study ecology as well as anatomy. Spatial analyses of the surfaces have revealed patterns of reproduction, such as clusters of Fractofusus that suggest offspring settling close to their parents, and evidence of tiering, with taller organisms reaching higher into the water.

Life after Snowball Earth

The fossils at Mistaken Point sit in a thick pile of deep-water sediments that also records the end of the Ediacaran ice ages. In 2003 Guy Narbonne and James Gehling described fronds from the Drook Formation, the oldest fossil-bearing unit in the sequence, at roughly 575 million years old. They argued that these were among the oldest complex Ediacaran fossils known anywhere.

The timing is significant. The Drook fossils appear only a few million years after the Gaskiers glaciation, a regional ice age of about 580 million years ago whose deposits are also exposed on the Avalon Peninsula. Narbonne and Gehling suggested that large, complex organisms spread soon after this cold episode, possibly helped by rising oxygen in the deep ocean.

Research at the site has continued for decades, led by teams from Memorial University, Queen’s University in Ontario and British universities including Oxford and Cambridge. Detailed mapping, laser scanning and casts of entire surfaces allow fossils to be studied without removing them from the rock.

Evidence of movement

In 2010 Alexander Liu, Duncan McIlroy and Martin Brasier described trace fossils, horizontal trails on a surface about 565 million years old in the Mistaken Point Formation. They interpreted these as evidence that some organism, perhaps a simple animal, was able to move across the seabed. These are among the oldest known traces of locomotion by a large organism.

Dating and protection

The volcanic ash layers are crucial for dating. They contain zircon crystals that can be dated very precisely using uranium-lead methods, making Mistaken Point one of the best-dated Ediacaran sites in the world.

The area was protected as the Mistaken Point Ecological Reserve in 1987. In 2016 UNESCO inscribed Mistaken Point as a World Heritage Site, recognising it as preserving the oldest known assemblages of large fossils anywhere. Visitors can see the fossils only on guided tours, which begin at the Edge of Avalon Interpretive Centre in Portugal Cove South.

Timeline

• c. 580 million years ago: The oldest large fossils in the Mistaken Point area are buried by volcanic ash.
• c. 565 million years ago: Communities on the Mistaken Point Formation surfaces, including early trace fossils, are preserved.
• c. 560 million years ago: The youngest fossil surfaces in the sequence are laid down.
• 1967: Shiva Balak Misra discovers the fossils.
• 1969: Misra publishes the first scientific description.
• 1987: The Mistaken Point Ecological Reserve is established.
• 2010: Trace fossils showing movement are reported from 565-million-year-old rocks.
• 2016: Mistaken Point is inscribed on the UNESCO World Heritage List.

Why it matters

Mistaken Point preserves the earliest known snapshots of whole communities of large organisms, still lying where they lived. It helps scientists understand how complex life first organised itself on the seafloor, long before the Cambrian Explosion filled the oceans with familiar animals.