On the Interpretation of Fossil Nuclei

Abstract

Although organelle preservation in plant fossils is not novel and well-preserved plant mesofossils have contributed greatly to the understanding of plant evolution, subcellular structures are still a rarity in plant mesofossils. Although it is not easy to explore subcellular structures in plant fossils, related attempts are frequently seen. Among them, some false interpretation requires further inspection. To shed more light on this issue, here I studied Cretaceous charcoalified mesofossils from USA, using LM (light microscopy), SEM (scanning electron microscopy) and TEM (transmission electron microscopy) technologies. My conclusion shows that not all publications reflect the truthful existence of nuclei in plant fossils, and this study may provide a reference for the future research.

Nucleus preservation in early Ediacaran Weng'an embryo-like fossils, experimental taphonomy of nuclei and implications for reading the eukaryote fossil record

“…This may be complicated royalsocietypublishing.org/journal/rsfs Interface Focus 10: 20200015 by the nucleus-like decay artefacts in bacterial-grade microbes [2][3][4], but the history of debate over the identification of nuclei in the Weng'an fossils demonstrates that eukaryote organelles can be discriminated based on consistency of shape, size and, for instance, how these change through cell division [19,20]. There are a number of credible examples of nuclei preserved in Phanerozoic fossil eukaryotes [5][6][7][8][9][10][11][12][13][14]. Our taphonomy experiments demonstrate the decay resistance of nuclei and the feasibility of their fossilization, both of which are corroborated by our characterization of nuclei in the Proterozoic Weng'an embryo-like fossils.…”

“…In large part, this stems from experiments which show that cytoplasmic shrinkage in decaying bacteria can produce nucleus-like remains [2][3][4]. However, it does not follow from these experiments that nuclei cannot be preserved and, indeed, there are a number of credible claims of fossilized nuclei [5][6][7][8][9][10][11][12][13][14]. Claims of nuclei and even nucleoli preserved in association with embryo-like fossils from the approximately 609 Mya Ediacaran Weng'an Biota [15][16][17][18][19][20] have proven especially contentious [1,[21][22][23].…”

Experimental taphonomy of organelles and the fossil record of early eukaryote evolution

“…Fossilized organelles would provide a more definitive criterion for identifying eukaryotegrade fossils, as well as informing on the evolutionary assembly of eukaryotes and the timing of emergence of the fundamental clades of photosynthetic eukaryotes. While there are many claims of fossilized nuclei and other organelles through the Proterozoic and Phanerozoic [e.g., (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)], their identification is often contentious and many are instead interpreted as collapsed cytoplasmic remains. This null interpretation stems largely from classical experiments in which the cytoplasm of decaying bacteria collapsed into small dense structures that resemble nuclei (15,16), and it is now commonly held that organelles cannot fossilize because they decay too quickly (13).…”