Scientists have discovered a bizarre fossil in Norway that predates dinosaurs by hundreds of millions of years. The remains belong to Charnia, an unusual frond-shaped organism that lived in the oceans during the Ediacaran Period, long before dinosaurs or most familiar forms of animal life appeared.
The fossils are the first known examples of Charnia found in Scandinavia. Researchers discovered them in rocks of the Indreelva Member of the Stáhpogieddi Formation in Finnmark, Arctic Norway.
Lead author Yorick P. Veenma and colleagues identified two partial Charnia fossils along with other remains from an ancient marine ecosystem. The discoveries provide new evidence that these organisms were widely distributed across the world’s oceans during the late Ediacaran.
Bizarre fossil preserves unusual branches
Researchers found the two “Charnia” specimens at Blåberget and Kommagnes on Norway’s Varanger Peninsula. Both came from rocks deposited in a deep marine environment affected by underwater sediment flows. The Blåberget specimen measures about 4.7 inches (12 centimeters) long and nearly 2 inches (5 centimeters) wide. It survives as a shallow impression on a rock surface.
The Kommagnes fossil is smaller, at about 2.8 inches (7 centimeters) long and 0.8 inches (2 centimeters) wide. However, it is preserved in much greater three-dimensional detail. Both specimens display the distinctive branching structure associated with Charnia. The organism had a frond-like body divided into rows of smaller branches. Neither fossil preserves a visible stem or holdfast that would have anchored the organism to the seafloor.
The Kommagnes specimen is particularly unusual. Seven of its 10 visible main branches have pronounced central ridges. These give the branches an angular, or “keeled,” appearance instead of the more rounded form normally seen in Charnia fossils. Researchers said the feature may have been more common in the organism than the fossil record suggests. Its absence from other specimens could simply reflect how rarely such delicate details survive fossilization.
Underwater flow helped preserve ancient organism
The unusual preservation also allowed researchers to reconstruct what may have happened to the Kommagnes organism after it died. Rather than remaining where it lived, the fossil appears to have been swept into an underwater sediment gravity flow. The current carried the organism along with clay, silt, and other sediment.
Researchers believe it traveled only a relatively short distance. The clay-rich flow may also have reduced turbulence around the fragile remains. Rapid burial then helped preserve the fossil in unusually high three-dimensional relief. The discovery of Aspidella-type holdfasts in the same geological unit supports the possibility that organisms such as Charnia lived nearby.
Discovery expands Charnia’s known range
Researchers also identified two species of Palaeopascichnus, another distinctive Ediacaran organism. Some specimens overlap one another, suggesting the same surfaces were occupied at different times. The team found a possible scratch circle with a radius of at least 5.9 inches (15 centimeters), as well as additional holdfasts and two unidentified body fossils.
Despite these discoveries, large body fossils remain relatively rare in the Indreelva Member. Holdfasts are far more common. Researchers believe underwater currents, erosion, burial conditions, and later geological changes all helped determine which remains survived.
The newly identified Charnia specimens are significant because they fill another gap in the organism’s known geographic distribution. They represent the first confirmed examples from Scandinavia and only the second confirmed occurrence on the ancient continent of Baltica after discoveries in Russia’s White Sea region.
Charnia fossils have now been documented across several ancient environments and widely separated regions. The Norwegian finds strengthen evidence that the strange organisms had spread extensively through late Ediacaran seas. Other recent discoveries of Ediacaran fossils in Canada have also provided new evidence about the spread and diversity of complex life during this distant period.
The discovery also adds to the importance of Norway’s Vestertana Group as a fossil record of a crucial period in Earth’s history. Fossil discoveries previously have suggested that the rise of complex animal life began before the Cambrian Period, challenging the idea that major changes in animal diversity appeared suddenly with the Cambrian explosion.
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