New Secrets from Ancient Feathers

Fossilized feathers, discovered 136 years ago, continue to yield new secrets. Researchers have made a groundbreaking discovery, finding that the volcanic rock that preserved the feather contains microscopic details that have been preserved within the fossil.

The team’s research, published in Geology, reveals that the feathers are preserved in zeolite, a mode of preservation that has not been reported for soft tissues until now. According to Valentina Rossi, a researcher at University College Cork and lead author of the study, "Fossil feathers are usually preserved in ancient mudrocks laid down in lakes or lagoons. The fossil vulture is preserved in ash deposits, which is extremely unusual. When analyzing the fossil vulture plumage, we found ourselves in uncharted territory. These feathers are nothing like what we usually see in other fossils."

Rossi further explained that this finding "expands on what it’s possible in the fossil record," and that low-temperature flows from volcanoes are "very good media to preserve soft tissues." The discovery of the fossilized feathers in zeolite opens up new possibilities for the preservation of soft tissues in the fossil record.

Image: The Doom of the Alban Hills—a digital painting depicting a possible scene just before the vulture’s carcass was buried by the pyroclastic current.
The Doom of the Alban Hills—a digital painting depicting a possible scene just before the vulture’s carcass was buried by the pyroclastic current.

The soft sediments at the bottoms of water bodies, such as mudslides, can cover dead organisms, keeping them from being scavenged and preserving their remains in deep time. However, preservation in zeolites, aluminum- and silicon-rich minerals common in volcanic settings, is a new finding that could mean more volcanically preserved fossils in the future.

The feather belonged to a vulture that lived in Italy approximately 30,000 years ago. The animal’s entire body was preserved in three dimensions, from the bird’s eyelids to the tips of its wings, resulting in a feather fossil that is preserved down to the microscopic pigment structures in the fossil’s wing.

Dawid Iurino, the study’s coordinator and a researcher at the University of Milan, noted that "We are used to thinking that volcanic deposits are associated with hot, fast-moving pyroclastic currents that will destroy soft tissues. However, these geological settings are complex and can include low-temperature deposits that can preserve soft tissues at the cellular level."

The extreme conditions of volcanic eruptions can surprisingly preserve delicate tissues, as seen in the case of the eruption of Italy’s Mount Vesuvius in 79 AD, which turned one victim’s brain into glass, preserving the organ’s microscopic axons and neurons in a solid state.

Volcanoes spew hot gas, ash, and lava when they erupt, often with fatal effects for life in their immediate vicinity. The nature of the vulture’s preservation is an encouraging sign that more extremely well-preserved fossils may lie in wait for paleobiologists to discover, offering new insights into the ancient world.