Limits...
The evolution of methods for establishing evolutionary timescales.

Donoghue PC, Yang Z - Philos. Trans. R. Soc. Lond., B, Biol. Sci. (2016)

Bottom Line: While the molecular clock can be used to extend the time estimates from fossil species to lineages not represented in the fossil record, fossils are the only source of information concerning absolute (geological) times in molecular dating analysis.While node-calibrations are often constructed by a crude assessment of the fossil evidence and thus involves arbitrariness, tip-calibrations may be too sensitive to the prior on divergence times or the branching process and influenced unduly affected by well-known problems of morphological character evolution, such as environmental influence on morphological phenotypes, correlation among traits, and convergent evolution in disparate species.We discuss the utility of time information from fossils in phylogeny estimation and the search for ancestors in the fossil record.This article is part of the themed issue 'Dating species divergences using rocks and clocks'.

View Article: PubMed Central - PubMed

Affiliation: School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK phil.donoghue@bristol.ac.uk.

No MeSH data available.


The predictable nature of fossil occurrences. Fossil stratigraphic occurrences are distinctly non-random, determined by the environmental controls on the distribution of the living organism and secular variation in the preservation of the environment in which the organism lived and died. Thus, fossil occurrences can be predicted based on knowledge of environmental limits of their distribution and characterization of environments and how they vary through stratigraphic sections and their global composites. (a) Inferred variance in water depth through a stratigraphic section; (b) probability of recovering a fossil based on its water depth tolerance and (c) fossil recovery potential given (a,b). Reproduced from Marshall [40] with the permission of the author and publisher.
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RSTB20160020F2: The predictable nature of fossil occurrences. Fossil stratigraphic occurrences are distinctly non-random, determined by the environmental controls on the distribution of the living organism and secular variation in the preservation of the environment in which the organism lived and died. Thus, fossil occurrences can be predicted based on knowledge of environmental limits of their distribution and characterization of environments and how they vary through stratigraphic sections and their global composites. (a) Inferred variance in water depth through a stratigraphic section; (b) probability of recovering a fossil based on its water depth tolerance and (c) fossil recovery potential given (a,b). Reproduced from Marshall [40] with the permission of the author and publisher.

Mentions: In combination, these factors result in significant differences between the timing of divergence and the age of the oldest fossil, but they cannot account for the scale of the mismatch implied by many early molecular clock studies. This is because gaps in the fossil record are largely predictable, based on the quality of the fossil record, how it varies between groups, and how fossil species' stratigraphic ranges may be influenced by secular variation in the preservation of facies in the rock record. For instance, palaeobiologists conduct gruesome decay experiments to discern the relative preservation of anatomical characters, and of taxa [37]. Further, knowledge of the sedimentary facies associations of fossil species can be exploited to predict probabilistically their occurrence through stratigraphic sequences [38,39] (figureĀ 2). With suitable taphonomic controls [41], unfulfilled predictions of fossil stratigraphic occurrences can be interpreted as evidence for the absence of those fossil species in space and time.Figure 2.


The evolution of methods for establishing evolutionary timescales.

Donoghue PC, Yang Z - Philos. Trans. R. Soc. Lond., B, Biol. Sci. (2016)

The predictable nature of fossil occurrences. Fossil stratigraphic occurrences are distinctly non-random, determined by the environmental controls on the distribution of the living organism and secular variation in the preservation of the environment in which the organism lived and died. Thus, fossil occurrences can be predicted based on knowledge of environmental limits of their distribution and characterization of environments and how they vary through stratigraphic sections and their global composites. (a) Inferred variance in water depth through a stratigraphic section; (b) probability of recovering a fossil based on its water depth tolerance and (c) fossil recovery potential given (a,b). Reproduced from Marshall [40] with the permission of the author and publisher.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4920342&req=5

RSTB20160020F2: The predictable nature of fossil occurrences. Fossil stratigraphic occurrences are distinctly non-random, determined by the environmental controls on the distribution of the living organism and secular variation in the preservation of the environment in which the organism lived and died. Thus, fossil occurrences can be predicted based on knowledge of environmental limits of their distribution and characterization of environments and how they vary through stratigraphic sections and their global composites. (a) Inferred variance in water depth through a stratigraphic section; (b) probability of recovering a fossil based on its water depth tolerance and (c) fossil recovery potential given (a,b). Reproduced from Marshall [40] with the permission of the author and publisher.
Mentions: In combination, these factors result in significant differences between the timing of divergence and the age of the oldest fossil, but they cannot account for the scale of the mismatch implied by many early molecular clock studies. This is because gaps in the fossil record are largely predictable, based on the quality of the fossil record, how it varies between groups, and how fossil species' stratigraphic ranges may be influenced by secular variation in the preservation of facies in the rock record. For instance, palaeobiologists conduct gruesome decay experiments to discern the relative preservation of anatomical characters, and of taxa [37]. Further, knowledge of the sedimentary facies associations of fossil species can be exploited to predict probabilistically their occurrence through stratigraphic sequences [38,39] (figureĀ 2). With suitable taphonomic controls [41], unfulfilled predictions of fossil stratigraphic occurrences can be interpreted as evidence for the absence of those fossil species in space and time.Figure 2.

Bottom Line: While the molecular clock can be used to extend the time estimates from fossil species to lineages not represented in the fossil record, fossils are the only source of information concerning absolute (geological) times in molecular dating analysis.While node-calibrations are often constructed by a crude assessment of the fossil evidence and thus involves arbitrariness, tip-calibrations may be too sensitive to the prior on divergence times or the branching process and influenced unduly affected by well-known problems of morphological character evolution, such as environmental influence on morphological phenotypes, correlation among traits, and convergent evolution in disparate species.We discuss the utility of time information from fossils in phylogeny estimation and the search for ancestors in the fossil record.This article is part of the themed issue 'Dating species divergences using rocks and clocks'.

View Article: PubMed Central - PubMed

Affiliation: School of Earth Sciences, University of Bristol, Life Sciences Building, Tyndall Avenue, Bristol BS8 1TQ, UK phil.donoghue@bristol.ac.uk.

No MeSH data available.