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    • The world’s best-preserved dinosaur had a strange ending, study finds
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    The world’s best-preserved dinosaur had a strange ending, study finds

    Umito Posted on

    A new study published in the Proceedings of the National Academy of Sciences has disproved the long-held hypothesis that volcanic eruptions were responsible for the exceptional preservation of fossils in northeast China’s Yixian Formation. The main hypothesis for this exceptional preservation had been a sudden burial by volcanism; however, the study suggests that the fossils were preserved over a relatively short period of time under stable conditions.

    For decades, scientists believed that the preservation of these fossils was due to volcanic eruptions, with some previous studies suggesting that the creatures were encased in lahars. Experts had speculated that the key to this exceptional preservation could be linked to the region’s volcanism, with some believing the eruptions occurred in waves that buried the dinosaurs in ash or mud. This explanation compared the preservation of Yixian fossils to the way thousands of Romans were buried under ashes at Pompeii.

    However, the new study calls this volcanic disaster theory into question. According to the study results, “these fossils are just a snapshot of daily deaths under normal conditions over a relatively brief period of time,” suggesting that they were preserved over a short period of time under stable conditions. Researchers say the remarkable preservation of Yixian fossils was likely due to more common processes, such as the periodic accumulation of sediment from seasonal rains and the collapse of animal burrows, rather than volcanic eruptions .

    Dr. Paul Olsen, a paleontologist at Columbia University’s Lamont-Doherty Earth Observatory and co-author of the study, explains that we tend to “attribute extraordinary causes, that is, miracles, ordinary events when we do not understand their origins. He and his colleagues carefully analyzed the evidence and compared it to hypotheses related to volcanism. To assess the likelihood of volcanic activity, they used uranium-lead isotopes to date the Yixian fossils and surrounding materials more precisely than was previously possible.

    Using this method, the researchers determined that all of the specimens were deposited in three bursts within 100,000 years, approximately 125.8 million years ago. This period contradicts previous studies which suggested that several Pompeii-type events occurred in pulses over about a million years. This also rules out the theory that there were multiple eruptions millions of years apart.

    Additionally, the Yixian fossils do not show signs of extreme conditions typical of pyroclastic flows. Contrary to the volcanic catastrophe theory, the exceptional preservation of feathers, one of the most remarkable features of the Yixian Formation, is incompatible with extreme heat. The feathers, fur and everything else would almost certainly have been burned in a pyroclastic flow. Pyroclastic flows are known to burn, mutilate and twist bodies into a characteristic “pugilistic pose” due to the intense heat, similar to the poses of the Pompeii victims. The Yixian fossils do not exhibit these twisted positions.

    Researchers suggest that these creatures were preserved because of more mundane events like burrow collapses and periods of rain that accumulated sediment, burying the dead in oxygen-free pockets. Wet weather may have contributed to instability in the region, potentially causing sudden collapses that buried smaller animals alive. Such processes created oxygen-free environments ripe for fossilization, in which many deceased creatures were quickly buried and the oxygen that would normally fuel decomposition was sealed away.

    In these environments, the lack of oxygen slowed decomposition even further. The sediments washed away during rainy periods then completed the process of sealing the specimens. This process preserved not only skeletons but also, in some cases, soft tissues, with the sealing effect being most rapid in lakes. The researchers estimate that there was enough oxygen for a time for bacteria or insects to at least break down the animals’ skin and organs, but that the oxygen supply was cut off by finer sediment before they can do the same to the bones.

    The Yixian Formation has become famous for its unprecedented fossil discoveries, representing the largest collection of superbly preserved dinosaurs in the world, as well as remains of birds, mammals, insects, frogs and turtles. Among these treasures are the first known feathered non-avian dinosaurs, discovered in the Yixian Formation. Fossils include evidence of the last meals eaten by dinosaurs and other animals, and they have preserved delicate details such as feathers, fur, scales, internal organs and even stomach contents.

    Scientists have been excited by the scientific richness of the Yixian fossils, but are divided on the question of why their preservation is so exceptional. Paul Olsen believes that similar fossil reserves may exist elsewhere, including in the eastern United States, where several places once had environments similar to those of Yixian. Sites in North Carolina, Virginia, Connecticut and New Jersey have yielded well-preserved fossils in the past, but none have reached the scale of Yixian.

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    Paul Olsen said: “It’s just that there’s no other place where such intense collecting has been done in this kind of environment.” He pointed out: “You have to dig up, say, 100,000 fish to find a feathered dinosaur, and no one digs on the scale of Yixian. » The cost and effort required for systematic excavations are important factors limiting such discoveries, particularly in densely populated areas where land is very valuable.

    The study was co-authored by Sean Kinney and Clara Chang of the Lamont-Doherty Earth Observatory, as well as researchers from the Nanjing Institute of Geology and Paleontology, the Institute of Paleontology and Paleoanthropology from the Chinese Academy of Sciences and Princeton University.

    Sources: Interesting Engineering, Phys.org, IFLScience, La Razon

    This article was written in collaboration with generative AI company Alchemiq



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