If you’re the kind of person who loves history and mysteries waiting to be solved, then you’ve found yourself in the right place. From the walls of the Harvard Museum of Comparative Zoology have emerged some unique trilobite fossils that tell a story 145 years in the making. They were just waiting to be discovered. In walked Sarah Losso, Ph.D. candidate in the Department of Organismic and Evolutionary Biology at Harvard, to embark on the journey to uncover their hidden secrets.
“I started my Ph.D. going through all of these thin sections of trilobites, imaging them, and trying to figure what we can actually see,” Losso said. “And then I came across something we never see in trilobite fossils.”
In a new study, published in Proceedings of the Royal Society B, lead author Losso describes the unusual three-dimensional trilobite fossils prepared as thin sections showing the 3D soft tissues during enrollment. The study reveals the soft undersides of enrolled trilobites and the evolutionary mechanism that allows arthropods to enroll their bodies for protection from predators and adverse environmental conditions.
The challenges associated with fossilizing soft tissues make the trilobites Losso studied even more special. The fossils are from the Mohawkian Stage of the Ordovician Period (462-451 million years ago). They were discovered in the Walcott-Rust Quarry located in upstate New York near Trenton Falls; a region originally inhabited by the Iroquois tribe. The quarry is named in part after the scientist Charles D. Walcott, who discovered the enrolled trilobites there in his youth, before going on to famously discover the Burgess Shale while Director of the Smithsonian Institution.
The real question then became how these little trilobites defied the odds and stayed preserved all these years. The answer is quite thrilling as the fossils, which Walcott sold to the MCZ and the Smithsonian in the 1870s, were trapped in a sediment slurry that quickly moved downslope and entombed the trilobites, leading to the preservation of delicate tissues before decay destroyed them. In a way, it’s as if time itself has stood still to preserve this little piece of history.