Ancient Trilobite Reveals Long-Lasting Organic Carbon Storage in Rocks

Researchers detect chitin, a key biological polymer, in 500-million-year-old fossil, challenging previous assumptions about carbon persistence in the geologic record.

Published on Feb. 10, 2026

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A team of researchers led by Dr. Elizabeth Bailey of the University of Texas at San Antonio have detected the presence of chitin, a key biological polymer, in a 500-million-year-old trilobite fossil from the Cambrian Carrara Formation in California. This discovery challenges previous assumptions about the persistence of organic carbon in the fossil record and suggests that common sedimentary rocks may play a larger role in long-term carbon storage than previously thought.

Why it matters

The detection of chitin in this ancient fossil adds to growing evidence that certain organic compounds can survive in the geologic record for much longer than previously believed. This has significant implications for understanding Earth's long-term carbon cycle and the potential role of common rock formations, like limestones, in naturally sequestering carbon dioxide over geological timescales.

The details

Using advanced analytical techniques like fluorescent staining and spectroscopy, the researchers were able to identify spectral peaks indicative of d-glucosamine, the monomer of chitin, within the cuticle of an Olenellus trilobite fossil. This contrasts with many previous studies that failed to detect chitin in ancient fossils, but aligns with more recent research employing similar advanced methods that have reported positive chitin detections.

  • The trilobite fossil was recovered from the Cambrian Carrara Formation in California.
  • The study was published in the journal PALAIOS in December 2025.

The players

Dr. Elizabeth Bailey

A researcher at the University of Texas at San Antonio who led the team that analyzed the trilobite fossil and detected the presence of chitin.

Olenellus

An extinct genus of trilobite that lived during the Cambrian period, approximately 500 million years ago.

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What they’re saying

“This study adds to growing evidence that chitin survives far longer in the geologic record than originally realized.”

— Dr. Elizabeth Bailey, Researcher, University of Texas at San Antonio

“When people think about carbon sequestration, they tend to think about trees. But after cellulose, chitin is considered Earth's second most abundant naturally occurring polymer.”

— Dr. Elizabeth Bailey, Researcher, University of Texas at San Antonio

What’s next

The researchers noted that further research into the preservation of organic materials in ancient fossils could reveal even more about Earth's past and inform our understanding of long-term carbon storage.

The takeaway

This discovery challenges previous assumptions about the persistence of organic carbon in the fossil record and suggests that common sedimentary rocks, like limestones, may play a larger role in long-term carbon sequestration than previously thought, with potential implications for our understanding of Earth's carbon cycle and climate.