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Using the Fossil Record to Evaluate Timetree Timescales
1Department of Integrative Biology, University of California, Berkeley, Berkeley, CA, United States.
Frontiers in Genetics
|December 6, 2019
Summary
Establishing timetrees relies on fossil data to estimate divergence times. Minimum age brackets are reliable, but maximum age brackets are challenging due to fossil record incompleteness and methodological complexities.
Area of Science:
- Paleontology
- Evolutionary Biology
- Geochronology
Background:
- The fossil and geologic records are crucial for constructing absolute timescales in timetrees.
- Fossils are used to bracket divergence times, essential for paleontological evaluation and node-based timetree construction methods.
Purpose of the Study:
- To review methods for establishing maximum age brackets for divergence times.
- To discuss challenges and complexities in using the fossil record for timetree calibration.
Main Methods:
- Evaluation of five primary methods for estimating maximum age brackets.
- Analysis of factors complicating maximum bracket estimation, including fossilization potential and phylogenetic uncertainty.
Main Results:
- Minimum age brackets are robustly established using well-dated fossils with positive morphological evidence.
- Maximum age brackets are difficult to ascertain due to the inherent incompleteness of the fossil and rock records.
- Challenges include bracketing the origin of morphologies (apomorphies) rather than divergence times, phylogenetic uncertainty, and gaps in records.
Conclusions:
- Estimating maximum divergence times from the fossil record presents significant challenges.
- Understanding these challenges is vital for accurate timetree construction and evolutionary studies.
- Quantitative methods and their limitations in assessing bracket magnitudes are reviewed.
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