An international research team at the University of Texas at San Antonio (UTSA) recently made a major discovery. They detected well-preserved chemical evidence of chitin in trilobite fossils that are more than 500 million years old. This discovery not only challenges the scientific community's traditional understanding of the preservation time limit of biological carbon, but also provides a new perspective for understanding the earth's long-term carbon cycle. The research results have been published in the journal "PALAIOS" which focuses on paleontological and sedimentological records.
Trilobites, among the most recognizable fossils on Earth, have long been viewed as mineral snapshots of ancient marine life. However, this study shatters this stereotype. Chitin is a tough organic polymer that is widely found in modern crab shells, insect exoskeletons, and fungal cell walls. Its content is second only to cellulose and is the second most abundant organic polymer in nature. For a long time, the scientific community has generally believed that chitin disappears rapidly due to microbial decomposition and chemical degradation after the death of an organism. However, this study, led by Elizabeth Bailey, assistant professor of Earth and planetary sciences at UTSA, is the first to demonstrate that this organic material can remain in the geological record for hundreds of millions of years under specific burial conditions.
Professor Bailey pointed out that this study proves that chitin has persisted in the geological record for much longer than expected. The significance of this discovery is not limited to the field of paleontology, but also has important implications for understanding how organic carbon is stored in the earth's crust over long geological periods. Research shows that because limestone is formed from the accumulation of biological materials and often contains chitin-producing organisms, this means that limestone plays an important role in the long-term carbon sequestration process and is closely related to the regulation of Earth's carbon dioxide levels.
Research on this project began during Professor Bailey's postdoctoral research at UC Santa Cruz and was funded by the Heising-Simons Foundation. Professor Bailey brings a planetary science perspective to this work, combining her professional background in stratigraphy, field geology, and the interaction of biological materials with Earth's carbon cycle. She said that revisiting these ancient and iconic fossil groups through modern analytical techniques not only reveals the durability of biomolecules in deep time, but also opens up new directions for future student-led research, especially using UTSA's Early Earth Laboratory to explore the long-term survival mechanisms of organic molecules in geological materials.