Artifact of the Month: Tracheal Rings

The TRCA Archaeology team recently held a professional development day, also known as the “Seed Barker Blitz,” to highlight one of our legacy sites. The Seed Barker site, dating from ca. 1530-1570, is a Late Ontario Iroquoian village.

TRCA Archaeology team members take part in the Seed Barker Blitz event

While the team was reorganizing faunal remains from the site, a number of vials containing avian tracheal rings were discovered.

The trachea, often referred to as the windpipe, is a tube made of cartilage that connects the pharynx and larynx to the lungs. Within the windpipe are tracheal rings, which help to support the trachea and allow the windpipe to move and flex during inhalations and exhalations.

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In most mammals, the tracheal rings are made up of both cartilaginous and membranous components. The rings often have a semi-circular “C” shape. The differences in shape and placement allow for different sounds to be emitted.

In birds, however, the larynx, has no vocal cords and is not involved in voice production; the tracheal rings themselves are fully closed.

Because they are made entirely of cartilage, the tracheal rings of birds are more likely to survive in the archaeological record in comparison to other species.

avian tracheal rings discovered by the TRCA Archaeology team

During an archaeological excavation, bird tracheal rings are typically recovered when using screens with mesh of 1-2 mm, or else during the flotation process. However, the Seed Barker Site was excavated using 6 mm mesh screens! Due to the small and fragile nature of tracheal rings, it is remarkable that so many were found during the site’s excavation.

We are hopeful that, as the reanalysis of archaeological material from the site begins, we may be able to identify which species of birds were present at the Seed Barker Site.

By Cassandra Hamilton

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Baker, P. and F. Worley
2014 Animal Bones and Archaeology: Guidelines for Best Practices. Portsmouth, English Heritage

Pesek, L.
2000 “The Avian Respiratory System