The identification of chitin within an Olenellus trilobite specimen, originating from California’s Carrara Formation and dating back approximately 514.5 to 506.5 million years, not only suggests that this vital structural biopolymer possesses a greater longevity in arthropod fossil preservation than previously hypothesized but also posits that sedimentary rocks might contribute significantly, albeit perhaps overlooked, to the long-term sequestration of organic carbon throughout geological epochs.
A trilobite fossil. Image credit: Elizabeth Bailey / University of Texas at San Antonio.
Chitin stands as one of Earth’s most prolific organic polymers generated by living organisms, surpassed in abundance only by cellulose.
“This investigation contributes to an escalating body of evidence indicating that chitin persists within the geological record for considerably extended periods, exceeding prior expectations,” stated Dr. Elizabeth Bailey, a researcher affiliated with the University of Texas at San Antonio.
“Beyond the realm of paleontology, these findings carry profound implications for our comprehension of how organic carbon is retained within Earth’s crust over vast stretches of geological time.”
Employing fluorescent staining methodologies coupled with diverse spectroscopy techniques, Dr. Bailey and her fellow researchers undertook an analysis of the cuticle belonging to an Olenellus trilobite discovered in the Cambrian Carrara Formation.
The investigative team discerned spectral signatures consistent with d-glucosamine, the foundational monomer of chitin.
This outcome stands in stark contrast to numerous prior analyses that yielded negative results for chitin detection across a variety of fossil specimens.
Furthermore, it aligns with scholarly works published in recent decades that have reported positive chitin identifications in fossilized materials through the application of contemporary analytical approaches.
“Although this particular study concentrated on a limited sample size of fossils, the ramifications extend far beyond the scope of trilobites,” commented the scientists involved.
“Diligent understanding of the mechanisms by which organic carbon can endure within commonplace geological environments will prove instrumental in our efforts to reconstruct Earth’s carbon cycle and may indeed offer insights into the natural processes governing carbon storage within the planet’s lithosphere.”
“This research additionally harbors potential relevance for ongoing discourse surrounding contemporary climate dynamics,” they elaborated.
“For instance, limestones, which are biogenic sedimentary rocks formed from accumulated organic remnants and have been extensively utilized as construction materials throughout human civilization, frequently contain organisms that possess chitin.”
“When contemplating carbon sequestration strategies, prevalent thought often gravitates towards terrestrial flora,” Dr. Bailey remarked.
“However, following cellulose, chitin is recognized as Earth’s second most abundant naturally occurring polymer.”
“The substantiation that chitin can remain preserved for hundreds of millions of years underscores the role of limestones in protracted carbon sequestration and is therefore pertinent to deciphering Earth’s atmospheric carbon dioxide concentrations.”
The research undertaking was published in the December 2025 edition of the esteemed journal PALAIOS.
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Elizabeth Bailey et al. 2025. Evidence for surviving chitin in Cambrian trilobites from the Carrara Formation, Western North America. PALAIOS 40 (12): 379-387; doi: 10.2110/palo.2024.025
