UCC in new discovery

New research published on Tuesday has revealed a new mode of preservation of soft tissues that can occur when animals are buried in ash-rich volcanic sediments.

An analysis of a 30,000 year old fossil vulture from central Italy has revealed for the first time that volcanic rock can preserve microscopic details in feathers, the first record of such a preservation.

An international team, led by Dr Valentina Rossi (University College Cork), made the discovery which has been published in the scientific journal Geology. It reveals that the feathers are preserved in a mineral phase called zeolite, a mode of preservation of soft tissues never reported before.

The fossil vulture was found in 1889 near Rome by a local landowner who recognised its remarkable preservation. The entire body was preserved as a three-dimensional impression, with fine details such as the eye lids and wing feathers. The new research shows that preservation of feathers extends to tiny microscopic feather pigment structures.

Dr Rossi said: “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 analysing the fossil vulture plumage, we found ourselves in uncharted territory. These feathers are nothing like what we usually see in other fossils.”

By analysing tiny samples of the fossil feathers using electron microscopes and chemical tests, the team revealed that the feathers are preserved in the mineral zeolite, a mode of fossil preservation never reported before.

Dr Rossi added: “Zeolites are minerals rich in silicon and aluminium and are common in volcanic and hydrothermal geological settings. Zeolites can form as primary minerals, with pretty crystals, or can form secondarily, during the natural alteration of volcanic glass and ash, giving the rock a ‘mudrock-like’ aspect. The alteration of the ash due to passage of water induced the precipitation of zeolites nanocrystals that in turn replicated the feathers to the tiniest cellular detail.

“The fine preservation of the feather structures indicates that the vulture carcass was entombed in a low temperature pyroclastic deposit.”

Prof. Maria McNamara of UCC added: “The fossil record is continually surprising us, be it new fossil species, strange new body shapes, or in this case, new styles of fossil preservation. We never expected to find delicate tissues such as feathers preserved in a volcanic rock. Discoveries such as these broaden the range of potential rock types where we can find fossils, even those preserving fragile soft tissues.”