科学者チームは、かつて5億4000万年前のブラジルの岩石に見られた微小動物の痕跡とされていた構造が、実際には細菌や藻類の化石化した群集であることを突き止めた。この再調査では、高度なイメージング技術を用いて、保存された細胞や有機物質が明らかになった。
研究者らは、マットグロッソ・ド・スル州のタメンゴ層から採取された微化石に焦点を当てた。以前の研究では、これらの痕跡はカンブリア爆発と呼ばれる複雑な生命の急増直前であるエディアカラ紀に、海底の堆積物の中を移動するミミズのような生物の証拠だと解釈されていた。しかし、シリウス粒子加速器を用いたマイクロトモグラフィーおよびラマン分光法による新たな分析の結果、それらは動物の痕跡ではなく、細胞構造であることが判明した。
Researchers at MIT have discovered chemical evidence in rocks over 541 million years old suggesting that ancient sea sponges were among Earth's first animals. The findings, published in the Proceedings of the National Academy of Sciences, identify molecular fingerprints matching compounds from modern demosponges. This builds on earlier work and confirms the signals originate from biological sources rather than geological processes.
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More than 700 fossils from the Jiangchuan Biota in Yunnan Province, southwest China, dating 554-539 million years ago in the late Ediacaran, include early relatives of starfish, acorn worms, deuterostomes, and other bilaterians. Led by Dr. Gaorong Li of Yunnan University, the discovery—after nearly a decade of fieldwork—challenges the suddenness of the Cambrian explosion by showing diverse animal communities predated it. The results, published in Science (DOI: 10.1126/science.adu2291), feature exceptionally preserved carbonaceous films revealing fine details like digestive systems.
A 250-million-year-old fossil egg containing a Lystrosaurus embryo has provided the first direct evidence that mammal ancestors laid eggs. Discovered in South Africa, the find resolves a decades-old question about early mammalian reproduction following the End-Permian extinction. Researchers used advanced imaging to reveal the embryo's pre-hatching stage inside a soft-shelled egg.
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Researchers have developed a laser technique to examine the contents of Charles Darwin's original specimens from the Galápagos Islands without disturbing the nearly 200-year-old jars. The method, known as Spatially Offset Raman Spectroscopy, reveals the chemical makeup of preservation fluids inside sealed containers. This breakthrough aids museums in preserving delicate collections worldwide.
Researchers have discovered symbiotic bacteria inside planthopper insects with the smallest genomes recorded for any organism, measuring as little as 50,000 base pairs. These microbes, which have co-evolved with their hosts for about 263 million years, blur the line between independent bacteria and cellular organelles like mitochondria. The findings highlight extreme genome reduction in nutrient-providing symbionts.
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Scientists in Japan have discovered a giant virus called ushikuvirus that infects amoebae and provides evidence for the theory that viruses contributed to the evolution of complex cells. Isolated from Lake Ushiku, the virus exhibits unique structural and replication traits linking it to other giant DNA viruses. This finding, published in the Journal of Virology, deepens understanding of viral roles in eukaryotic evolution.