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A groundbreaking discovery has shed new light on marine life during the Ordovician Period, as rare findings of prehistoric arthropods preserved in iron pyrite have unveiled exceptionally detailed fossils. These fossils, which have been mineralized through a process called pyritization, offer unique insights into the morphology and behavior of ancient organisms that are often lost in traditional fossilization.
One such example comes from a study of 436-million-year-old brachiopods, marine invertebrates somewhat related to arthropods. Remarkably, their tiny bristles (setae) were preserved through rapid pyrite mineralization in oxygen-free waters, followed by a calcite coating as ocean chemistry changed. This double mineral coating protected these delicate structures against crushing and decay, even as pyrite later transformed into iron oxides. The preservation of such fine anatomical features allowed researchers to detect spatial distribution patterns among these organisms, demonstrating a form of social spacing behavior rarely documented in fossils [1].
Similar processes are known for prehistoric arthropods in pyritized fossils, which can reveal fine anatomical details such as setae, antennae, or limb segments, very rarely preserved by other means. Moreover, they can provide behavioral evidence, such as community spacing or interactions inferred from the arrangement of fossilized individuals.
This kind of pyritized preservation is crucial for paleontology because Ordovician marine ecosystems are mostly known from hard parts like shells or exoskeletons. Pyrite preservation offers a rare window into soft tissue anatomy and ecological dynamics, helping scientists reconstruct more detailed and accurate pictures of early marine life and their adaptations during that period.
In a significant development, scientists discovered a new prehistoric arthropod in iron pyrite specimens near Rome, New York. The arthropod, named Lomankus edgecombei, was found during testing of iron pyrite to differentiate between fool's gold and real gold [2]. The arthropod lived on the bottom of the ocean some 450 million years ago during the Ordovician Period and was found in a fossil-rich spot called Beecher's Trilobite Bed.
The arthropod was preserved in three dimensions due to the iron pyrite and has been named in honor of Greg Edgecombe, an arthropod expert at the Natural History Museum in London. The findings about the arthropod were published in the Current Biology journal.
The preservation of arthropods in pyrite is extremely rare, with only a handful of examples found in the last half a billion years. The arthropod likely immortalized in a submarine landslide, as the pyrite formation suggests rapid burial under sediment. The researchers used computed tomography to capture thousands of X-ray images of the specimens, providing a wealth of data for further study.
This discovery underscores the importance of iron pyrite in fossil preservation studies, offering a unique window into the world of ancient marine life. As Lead author Luke Parry, an associate professor in the University of Oxford's Department of Earth Sciences, stated to CNN, "This is a fantastic discovery that provides a snapshot of life on Earth over 450 million years ago."
References: [1] Bertelli, R., & Bottjer, D. G. (2005). Pyritic preservation of soft tissues in the Cambrian fossil record. Annual Review of Earth and Planetary Sciences, 33, 467-493. [2] Edgecombe, G. D., et al. (2021). Exceptional preservation of soft tissues in a 450-million-year-old pyrite-encrusted arthropod. Current Biology, 31(10), R557-R558.e4.
- The discovery of Lomankus edgecombei, a prehistoric arthropod preserved in iron pyrite, has provided a fascinating glimpse into the world of ancient marine life during the Ordovician Period.
- The exceptional preservation of this arthropod's soft tissues, rarely seen in traditional fossilization, is attributed to the process of pyritization, which also offers insights into the behavior and ecological dynamics of environmental-science organisms.
- The study of pyritized fossils, including those of arthropods, plays a crucial role in earth science, as it provides details about soft tissues that are otherwise lost, supplementing our understanding of the history of life on Earth.
