The dawn of movement
On the wave-battered coast of Newfoundland's Avalon Peninsula, surfaces of rock preserve a deep moment in Earth's history: the first faint scratchings of animal life on the move. These are not fossilized bones or shells, but trace fossils—impressions left on ancient deep-sea mud 565 million years ago. The site, part of the Mistaken Point Ecological Reserve, a UNESCO World Heritage Site, shows the seafloor from the Ediacaran Period. At that time, this part of Newfoundland was a deep marine environment, located between 40° and 65° South latitude.
The organisms that roamed this primordial seabed were soft-bodied, leaving no physical remains. Their only legacy is the trails they etched into the mud. Among the more than 70 fossilized trails identified, the most significant are named Helminthoidichnites tenuis. These simple, horizontal traces, typically 1 to 3 millimeters wide, represent the oldest definitive evidence of locomotion by macroscopic animals. The creatures that made them were likely small, worm-like animals. Analysis suggests they moved by using a muscular, foot-like organ, similar to how a modern sea anemone shuffles across the sand. This indicates the presence of muscular tissue, an important evolutionary development.
A volcanic Pompeii
The preservation of these delicate tracks is extraordinary. The creatures lived on muddy slopes deep below the reach of sunlight and waves. Periodically, volcanic eruptions from a nearby island arc would rain fine ash onto the seafloor. This ash gently buried the seafloor communities, entombing both the stationary, frond-like Ediacaran lifeforms and the trails of the mobile ones. This process created a perfect mold, as the ash from Vesuvius preserved Pompeii. These layers of volcanic ash contain zircon crystals, which allow geologists to date the fossil surfaces with remarkable precision.
The fossil beds at Mistaken Point were known to locals for years as "flowers in the rocks." Their scientific importance was identified in 1967 by geologist Shiva Balak Misra. The discovery of motile animal tracks from 565 million years ago was significant because it pushed back the timeline for complex animal behavior by nearly 30 million years, well before the "Cambrian Explosion" when a huge diversity of life appears in the fossil record. These ancient trails show that purposeful movement—likely grazing on microbial mats on the seafloor—had begun long before animals developed skeletons.