The Emergence of Earliest Angiosperms may be Earlier than Fossil Evidence Indicates

Area of Science:

• Paleobotany
• Molecular Evolution
• Phylogenetics

Background:

• Discrepancies between molecular clock estimates and fossil records challenge the accuracy of time-calibrated phylogenies.
• The evolutionary origin of angiosperms (flowering plants) is a key area of uncertainty, with significant time gaps observed.

Purpose of the Study:

• To accurately determine the molecular age of angiosperm origins using robust fossil calibrations.
• To assess the impact of different calibration points and prior probability distributions on molecular age estimates.

Main Methods:

• Utilized 22 fossil calibrations, encompassing 101 genera and 40 families, to calculate molecular ages.
• Employed multiple datasets, priors, and calibration points to ensure the robustness of age estimations.
• Analyzed the effect of altered calibration points and root age constraints on overall age estimates.

Main Results:

• Estimated the origin of angiosperms to be in the late Permian, approximately 275 million years ago.
• Found that variations in prior probability curves and root age constraints had minimal impact on age estimates compared to calibration point alterations.
• Concluded that the age estimates are robust across different analytical choices.

Conclusions:

• The estimated age of angiosperm origin is robust and likely falls within the calculated extremes.
• Integrating these findings with ecophysiological data is crucial for understanding pre-Cretaceous flowering plant evolution.
• The study highlights the importance of accurate fossil calibrations in molecular phylogenetics.