Analisis ulang fosil di Brasil tantang teori asal-usul hewan purba

Para ilmuwan telah menetapkan bahwa struktur yang dulunya dianggap sebagai jejak hewan kecil dalam batuan Brasil berusia 540 juta tahun, sebenarnya adalah komunitas bakteri dan alga yang memfosil. Pemeriksaan ulang ini menggunakan pencitraan canggih untuk mengungkap sel dan bahan organik yang terawetkan.

Para peneliti berfokus pada mikrofosil dari formasi Tamengo di Mato Grosso do Sul. Penelitian sebelumnya menafsirkan tanda-tanda tersebut sebagai bukti keberadaan makhluk mirip cacing yang bergerak melalui sedimen dasar laut selama periode Ediakara, tepat sebelum ledakan kehidupan kompleks Kambrium. Analisis baru dengan mikrotomografi dan spektroskopi Raman di akselerator partikel Sirius menunjukkan struktur seluler, bukan jejak hewan.

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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.

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