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?