The Neoproterozoic Era was characterized by rapidly changing paleogeography, global climate changes and especially by the rise and fall of the Ediacaran macro-biota. The correlation between disparate Ediacaran fossil-bearing localities and the tentative reconstruction of their paleoenvironmental and paleogeographic contexts are usually complicated by the lack of precise and accurate age data. For this reason, Neoproterozoic sedimentary sections associating Ediacaran biota fossils and fresh volcanic material are especially valuable for radioisotopic dating. Our research in the Podolya Basin, southwestern Ukraine, revealed the presence of four Neoproterozoic volcanic ash deposits (potassium-bentonite layers) within Ediacaran fossil-bearing siliciclastic rocks of the Mohyliv-Podilskyi Group. We used zircon U-Pb LA-ICPMS and CA-ID-TIMS methods to date two of those layers. The results indicate that a diverse assemblage of body and trace Ediacaran fossils occurred as early as 556.78 ± 0.18 million years (Ma) ago. By combining morphological evidence and new age determinations, we suggest a closer paleobiogeographical relationship between the Ukrainian Ediacaran assemblage and the Avalon paleocontinent than previously estimated.
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http://dx.doi.org/10.1038/s41598-018-38448-9 | DOI Listing |
Proc Biol Sci
December 2024
School of Biological Sciences, Manter Hall 402, University of Nebraska, Lincoln, NE 68588, USA.
Understanding the roles of habitat filtering, dispersal limitations and biotic interactions in shaping the organization of animal communities is a central research goal in ecology. Attempts to extend these approaches into deep time have the potential to illuminate the role of these processes over key intervals in evolutionary history. The Ediacaran marks one such interval, recording the first macroscopic benthic communities and a stepwise intensification in animal ecosystem engineering.
View Article and Find Full Text PDFSci Adv
November 2024
Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
Evol Dev
November 2024
Earth and Planetary Sciences, University of California Riverside, Riverside, California, USA.
Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One approach to recognize such early animals is to instead focus on characteristics widespread in animals today, for example multicellularity, motility, and axial polarity.
View Article and Find Full Text PDFGeobiology
August 2024
Department of Earth & Planetary Sciences, Yale University, New Haven, Connecticut, USA.
The earliest evidence of complex macroscopic life on Earth is preserved in Ediacaran-aged siliciclastic deposits as three-dimensional casts and molds, known as Ediacara-style preservation. The mechanisms that led to this extraordinary preservation of soft-bodied organisms in fine- to medium-grained sandstones have been extensively debated. Ediacara-style fossilization is recorded in a variety of sedimentary facies characterized by clean quartzose sandstones (as in the eponymous Ediacara Member) as well as less compositionally mature, clay-rich sandstones and heterolithic siliciclastic deposits.
View Article and Find Full Text PDFProc Biol Sci
May 2024
Bristol Palaeobiology Group, School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK.
The early Ediacaran Weng'an biota (Doushantuo Formation, South China) provides a rare window onto the period of Earth history in which molecular timescales have inferred the initial phase of crown-metazoan diversification. Interpretation of the embryo-like fossils that dominate the biota remains contentious because they are morphologically simple and so difficult to constrain phylogenetically. from the Weng'an biota is distinguished by spiral internal bodies, allied through development to or and interpreted variously as metazoan embryos, encysting protists, or chlorophycean green algae.
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