Paleontologists Find Traces of Chitin in Cambrian Trilobite Fossil
The detection of chitin in a Olénellus The trilobite from the Carrara Formation (514.5 to 506.5 million years ago) in California, USA, not only demonstrates that this structural polymer may be able to survive in arthropod fossils for longer than previously confirmed, but also suggests that sedimentary rocks may play an unrecognized role in storing organic carbon over geologic time.
A trilobite fossil. Image credit: Elizabeth Bailey / University of Texas at San Antonio.
Chitin is one of the most abundant organic polymers produced by life on Earth, second only to cellulose.
“This study adds to growing evidence that chitin survives much longer in the geological record than initially thought,” said Dr. Elizabeth Bailey, a researcher at the University of Texas at San Antonio.
“Beyond paleontology, this has significant implications for understanding how organic carbon is stored in the Earth’s crust over geological time.”
Using fluorescent staining and various spectroscopy techniques, Dr. Bailey and his colleagues analyzed the cuticle of a Olénellus trilobite from the Cambrian Carrara Formation.
The researchers found telltale spectral peaks of d-glucosamine, the monomer of chitin.
Their result contrasts with many previous analyzes that produced negative detection of chitin in various fossils.
This is also consistent with literature published in recent decades reporting positive detections of chitin in fossils using modern analytical techniques.
“Although this study focused on a small number of fossils, the implications extend far beyond trilobites,” the scientists said.
“Understanding how organic carbon can persist in common geological settings will help us reconstruct the carbon cycle on Earth and could shed light on how carbon is stored naturally in the Earth’s crust. :
“The research also has potential relevance to modern climate discussions,” they noted.
“For example, limestones, formed from accumulated biological remains and widely used as building materials throughout human history, often contain chitin-bearing organisms.”
“When people think of carbon sequestration, they tend to think of trees,” Dr. Bailey said.
“But after cellulose, chitin is considered the second most abundant natural polymer on Earth.”
“Evidence that chitin can survive for hundreds of millions of years shows that limestones are part of long-term carbon sequestration and are relevant to understanding carbon dioxide levels on Earth.”
The study was published in December 2025 in the journal PALACE.
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Elizabeth Bailey and others. 2025. Evidence for chitin survival in Cambrian trilobites from the Carrara Formation, western North America. PALACE 40 (12): 379-387; doi: 10.2110/palo.2024.025
