A simplified correlation between vertebrate evolution and Paleozoic geomagnetism
- Published
- Accepted
- Subject Areas
- Evolutionary Studies, Paleontology
- Keywords
- Paleozoic, geomagnetism, vertebrates, evolution, paleontology, compendium
- Copyright
- © 2019 Staub
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2019. A simplified correlation between vertebrate evolution and Paleozoic geomagnetism. PeerJ Preprints 7:e28002v3 https://doi.org/10.7287/peerj.preprints.28002v3
Abstract
Background. Despite a fifty-year failure of paleontologists to find a viable connection between geomagnetic polarity reversals and evolutionary patterns, recent paleobiology databases show that the early appearance, radiation, and diversification of Paleozoic vertebrates tends to occur during periods having frequent collapses of the Earth’s geomagnetic field. The transition time during the collapse of the Earth’s protective magnetic shield can last thousands of years, and the effects on biota are unknown. Solar and cosmic radiation, volcanism, climate alteration, low-frequency electromagnetic fields, depletion of ozone, the stripping of atmospheric oxygen, and increasing production of Carbon14 in the stratosphere have been proposed as possible causes, but previous studies have found no effects.
Methods. Using published databases, we compiled a spreadsheet showing the first appearance of 2104 genera with each genus assigned to one of 8 major taxonomic groups. From Gradstein’s Geologic Time Scale 2012, we delineated 17 Paleozoic zones with either high or low levels of polarity reversals.
Results. From our compilation, 727 Paleozoic vertebrates represent the initial radiation and diversification of individual Paleozoic vertebrate clades. After compensating for sample-size and external geologic and sampling biases, the resulting Pearson’s correlation coefficient between the 727 genera and geomagnetic polarity zones equals 0.8, a result that suggests a strong relationship exists between Paleozoic vertebrates and geomagnetism.
Discussion. The question: is this apparent connection between geomagnetism and the evolution of Paleozoic vertebrate due to environmental or biologic factors. If biologic, why are vertebrates the only biota effected? And after an indeterminate period of time, how do vertebrates become immune to the ongoing effects of polarity reversals?
Author Comment
Primarily, this is an update of paleobiology.org data, as of Dec 10, 2019. Also we shortened the major clades from 11 to 8. We used a single source for paleomagnetism, and found additional methods for calculation Pearson's Correlation. We added a chart for visual clarification.
Supplemental Information
Chart A: Phylogeny
Each genus is listed alphabetically and placed in a major clade, numbered one to eight, as shown by paleobiology.org (black font), Benton (brown font), Zhoa and Zhu (green font), and Sepkoski (blue font).
Chart B: Chronology
Chart B shows the chronology of our 2104 genera.
Chart C: Proportional dating
Proportional dating is a method to compensate when the end-date of a geomagnetic zone falls between the estimated date for when a fossil is deposited. For example, if the genus is dated between 410 and 390 million years ago, and the geomagnetic zone is dated at 400, then the genus would be 50% in one zone, and 50% in the next. Dating by paleobiology.org is in black font; by Benton is brown, by Zhoa and Zhu is green; and Sepkoski is in blue font.