The first confirmed detection of chitin in a 500-million-year-old trilobite fossil suggests this key biological polymer may persist in the fossil record far longer than previously believed, and that common sedimentary rocks could play a larger-than-expected role in long-term carbon storage.
A trilobite fossil. Image credit: Elizabeth Bailey / University of Texas at San Antonio.
New Findings Challenge Previous Assumptions
Researchers led by Dr. Elizabeth Bailey of the University of Texas at San Antonio analyzed the cuticle of an Olenellus trilobite recovered from the Cambrian Carrara Formation in California. Using fluorescent staining and spectroscopy techniques, they identified spectral peaks indicative of d-glucosamine, the monomer of chitin.
This discovery contrasts with many previous analyses that failed to detect chitin in fossils. However, it aligns with more recent studies employing advanced analytical techniques that have reported positive chitin detections.
Implications for Carbon Storage
“This study adds to growing evidence that chitin survives far longer in the geologic record than originally realized,” Dr. Bailey said. “Beyond paleontology, this has significant implications for understanding how organic carbon is stored in Earth’s crust over geologic time.”
The scientists noted that understanding how organic carbon persists in geological settings could help reconstruct Earth’s carbon cycle and inform how carbon is naturally stored within the planet’s crust.
Relevance to Modern Climate Discussions
The research team also pointed to the potential relevance of these findings for modern climate discussions. Limestones, frequently used as building materials, often contain chitin-bearing organisms. Dr. Bailey explained, “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.”
The study, published in December 2025 in the journal PALAIOS, suggests that limestones may play a role in long-term carbon sequestration and influence Earth’s carbon dioxide levels.
Frequently Asked Questions
What is chitin?
Chitin is one of the most abundant organic polymers produced by life on Earth, second only to cellulose. This proves the primary organic component of modern crab shells and insect exoskeletons.
Where was this chitin discovered?
Chitin was detected in an Olenellus trilobite from the Cambrian Carrara Formation in California, United States.
What are the broader implications of this discovery?
The findings suggest that organic carbon may be stored in sedimentary rocks for longer periods than previously thought, with potential implications for understanding Earth’s carbon cycle and climate.
Could further research into the preservation of organic materials in ancient fossils reveal even more about Earth’s past and inform our understanding of long-term carbon storage?
