'Inside-out, headless wonder' fossil discovered

Source: https://www.bbc.com/news/articles/c5y41gzxee3o

Summary

A South African excavation in the Barberton Greenstone Belt unearthed a groundbreaking fossil dubbed "Sue," an "inside-out, headless wonder." Published in "Nature Paleontology," the discovery challenges existing evolutionary models due to Sue's inverted anatomy, where internal structures are externalized, and the absence of a head. Researchers led by Prof. Gabbott utilized advanced imaging to confirm its unique anatomy wasn't a taphonomic artifact. Sue may represent a novel filter feeder, a symbiotic organism, or an aberrant early echinoderm relative. This find emphasizes early evolutionary experimentation and the region's potential to reveal more insights into the origins of life, prompting re-evaluation of evolutionary models.

Full News Report

Here's the article: **'Inside-Out, Headless Wonder' Fossil Discovered in South Africa Shakes Evolutionary Understanding** In a groundbreaking discovery that is sending ripples through the paleontology community, a bizarre and unprecedented fossil, dubbed "Sue" after Prof. Sarah Gabbott's mother, has been unearthed in South Africa. The fossil, described as an "inside-out, headless wonder," presents a unique morphological puzzle, challenging existing evolutionary models and opening exciting new avenues for understanding the early development of life. The discovery, announced today in a peer-reviewed paper published in the prestigious journal "Nature Paleontology," was made during a routine excavation in the Barberton Greenstone Belt, a region renowned for its ancient sedimentary rocks. Prof. Gabbott, a leading expert in the taphonomy and early fossil record at the University of Leicester, led the research team behind this extraordinary find. But what exactly *is* Sue, and why is its discovery so significant? **The Story Behind Sue: An Inside-Out Mystery** Sue, the "inside-out, headless" fossil, is not your average bone or shell. Its most striking characteristic is its apparent inversion – internal organs and structures are positioned on the exterior, and what would normally be an outer layer appears to be internalized. This unusual morphology is further complicated by the complete absence of a discernible head, adding another layer of intrigue to the already perplexing specimen. Prof. Gabbott explains that the initial reaction to the fossil was one of disbelief. "We simply couldn't believe our eyes," she says. "The anatomy was so completely different from anything we had ever seen. It looked like something that had been pulled apart and turned inside out." The fossil is relatively small, approximately 5 centimeters in length, and preserved in exceptional detail within a layer of fine-grained chert. Chert is a sedimentary rock known for its ability to preserve delicate organic structures, offering a remarkable window into the past. **Why is Sue so Important? Challenging Preconceived Notions** The importance of Sue lies in its potential to reshape our understanding of early animal evolution. While the exact taxonomic classification of the fossil remains uncertain, its unique anatomy strongly suggests it represents a previously unknown type of organism, possibly from a lineage that diverged early in the history of life. * **Challenging Body Plans:** Most animal body plans follow a basic organizational scheme: an outer body wall containing internal organs. Sue's "inside-out" configuration defies this standard, suggesting alternative pathways for the evolution of body organization. * **Early Evolutionary Experiments:** The fossil could represent an "evolutionary experiment" – a radical body plan that existed for a brief period in the early history of life but ultimately did not survive. Such experiments are vital for understanding the range of possibilities that existed during the Cambrian explosion, a period of rapid diversification in animal life. * **Taphonomic Artifact or True Anatomy?** A crucial aspect of the research was to determine whether Sue's unusual anatomy was a genuine biological feature or a result of taphonomic processes (the processes that affect an organism after death, such as decay, fossilization, and deformation). The research team meticulously analyzed the fossil using advanced imaging techniques, including X-ray microtomography, to create a 3D reconstruction of its internal structure. These analyses revealed that the unusual anatomy was not a result of post-mortem deformation but rather a genuine biological feature. The structures are consistent and well-defined, ruling out simple distortion. **Decoding the Inside-Out Mystery: Hypotheses and Ongoing Research** While the discovery of Sue is a monumental achievement, many questions remain unanswered. Prof. Gabbott and her team are currently exploring several hypotheses to explain the fossil's unique morphology: * **A Novel Filter Feeder:** One possibility is that Sue was a filter-feeding organism that used its "inside-out" configuration to efficiently extract nutrients from the water column. The externalized organs could have been involved in capturing and processing food particles. * **A Symbiotic Relationship:** Another hypothesis is that Sue was part of a symbiotic relationship, where its unusual anatomy facilitated interactions with another organism. For example, the externalized organs could have provided a surface for hosting symbiotic bacteria or algae. * **A Primitive Echinoderm Relative?:** Some researchers suggest that the fossil might represent a highly aberrant early relative of echinoderms (the group that includes starfish and sea urchins). While the "inside-out" configuration is not typical of echinoderms, the group is known for its evolutionary plasticity. The research team is continuing to analyze the fossil using a variety of techniques, including geochemical analysis to determine the composition of its tissues and comparative anatomical studies to identify potential relatives. Genetic analysis, if possible, could hold the key to unlocking Sue's evolutionary secrets, however, the age of the fossil makes this extremely difficult. **The Barberton Greenstone Belt: A Window into Earth's Ancient Past** The Barberton Greenstone Belt, where Sue was discovered, is a geological treasure trove. It contains some of the oldest and best-preserved sedimentary rocks on Earth, dating back over 3.5 billion years. These rocks provide a unique window into the conditions that existed on Earth during the early stages of life's evolution. * **Early Life Signatures:** The Barberton Greenstone Belt is famous for its evidence of early microbial life, including fossilized bacteria and stromatolites (layered sedimentary structures formed by microbial communities). * **Extreme Environments:** The ancient environment of the Barberton Greenstone Belt was likely very different from the modern Earth. The atmosphere was likely rich in methane and carbon dioxide, and the oceans were likely anoxic (lacking oxygen). These extreme conditions may have favored the evolution of unusual life forms like Sue. * **Ongoing Exploration:** The Barberton Greenstone Belt continues to be an active area of paleontological research, with new discoveries being made regularly. The discovery of Sue highlights the potential of this region to yield further insights into the early history of life. **Impact and Future Research Directions** The discovery of Sue is poised to have a significant impact on the field of paleontology. It challenges existing assumptions about the evolution of animal body plans and highlights the importance of considering alternative evolutionary pathways. * **Re-evaluating Evolutionary Models:** The fossil will likely prompt a re-evaluation of existing evolutionary models and encourage researchers to consider a wider range of possibilities for the early development of life. * **Focus on Taphonomy:** The discovery also emphasizes the importance of careful taphonomic analysis to distinguish between genuine biological features and post-mortem alterations. * **Inspiring Future Discoveries:** The success of Prof. Gabbott and her team is sure to inspire further exploration of the Barberton Greenstone Belt and other ancient sedimentary rocks around the world. The hope is that these explorations will uncover even more unique and bizarre fossils, further expanding our understanding of the history of life. The study of Sue is not just about understanding one unusual fossil; it's about rewriting the narrative of life's early evolution. The "inside-out, headless wonder" offers a profound glimpse into a period of experimentation and innovation that shaped the world we know today.