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Adv."],"published-print":{"date-parts":[[2026,10,2]]},"abstract":"<jats:p>Divergent models persist for the emergence of animals. Lipid biomarkers suggest animals originated before 635 million years ago (Ma), but their body fossil record extends to only 574 Ma. Molecular clocks might differentiate between these records, but we demonstrate how their accuracy and precision hinge on maximum age calibrations. We evaluate the Ediacaran Weng\u2019an Biota (China) as a maximum calibration utilizing microfossils from the Kheseen Biota (Mongolia). These two biotas have similar preservation and microfossil assemblages, containing no definitive animals. The Kheseen Biota, deposited at a time (\u223c550\u2013526 Ma) when animals were undoubtedly present, questions the validity of the Weng\u2019an calibration. 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