A simplified correlation between vertebrate evolution and Paleozoic geomagnetism

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?


Introduction 7
Geomagnetic polarity reversals occur randomly at a rate of about two or three times per 8 million years (Gradstein, 2012). The transition between the collapse of the Earth's protective 9 magnetic shield and its subsequent regeneration can last thousands of years, and any effects on 10 biota during this interim are unknown.

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In 1963, Uffen raised the possibility of polarity reversals increasing extinction rates due to 12 harmful solar and cosmic radiation. Others pointed out the Earth's atmosphere is our primary 13 shield despite a potential loss of ozone (Crutzen, 1975). Secular variations of a weakening 14 geomagnetic field intensity show enhanced cosmic-ray production of 10 Be, 36 Cl, and 14 C in the 15 stratosphere (McHargue, 2000). Reinforcing this view, age-dated Greenland ice cores show 16 relatively high concentrations of these isotopes during polarity excursions (Raisbeck, 2006). 17 Despite active repair mechanisms, DNA is susceptible to 14 C decay (Sassi, 2014), and Van Huizen

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(2019) showed weak magnetic fields can directly alter the regeneration of worms. Volcanism 19 (Courtillow, 2007), climate alteration (Harrison, 1974), low-frequency electromagnetic fields 20 (Liboff, 2013), depletion of ozone (Huang, 2017), and the stripping of atmospheric oxygen (Wei,   In our previous study (Staub 2018), we showed a strong connection between geomagnetic 28 activity and the initial twenty-million-year evolution of 27 separate clades. In this study, for 29 simplicity and reproducibility, we will compare only major phylogenetic groups. Instead of a 30 twenty-million-year limit, we will use a replacement approach, where the early radiation of a 31 clade's evolution ends at the intervention of a subsequent phylogenetic group. For example,

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Cambrian conodonts are considered early-phase, whereas Ordovician and later conodonts are late 33 phase. The difference: the two phases are split by the appearance in the Early Ordovician of the 34 pteraspidomorphs with their protective scales and armor. Likewise, the jawless fish are early-35 phase until the appearance of the gnathostomes; jawed fish until the osteichthyans; bony fish 36 until the sarcopterygians; lobe-finned fish (including lung-fish and tetrapodomorphs) until the 37 Upper Devonian tetrapods; the tetrapods until the amniota (Reptiliomorpha); followed by the 38 reptiles and pelycosaurs until the therapsids. The early-phase genera represent the early evolution 39 and radiation of their respective clades. They will be used to correlate vertebrate evolution to  Parareptilia, Eureptilia, and Diapsida. 10) Pelycosaurs. 11) Therapsids. See Table 2. "min_ma" dates. From these occurrences, we found the earliest appearance of 1668 genera.

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A genus is often dated entirely within the range of an LPZ or HPZ. But when the "max_ma"       Table 2 shows the 17 high (red) and low polarity zones (blue), their range and duration (Ma), number of 125 polarity reversals, reversals per million years, and distribution of total genera in each polarity zone 126 showing early-phase genera (EP), total genera, and percentage found in each polarity zone. Note that the 127 Reversals per million years and percentage of genera are used to calculate Pearson's correlation 128 coefficient using Social Science Statistics.  Any genus not listed in the four main sources was ignored. With duplicate genera, Sepkoski 164 had the lowest priority. Otherwise, we chose the earliest, most precise date (Zhao and Zhu's 165 dating appears to be excellent). We removed synonyms and uncertain genera. Imprecise dating 166 >20 Ma was ignored, unless those dates were placed entirely within a single LPZ or HPZ. 167 Paleobiology's "max_ma" and "min_ma" dates were entered directly into our spreadsheet 168 (in our previous report we used Gradstein and Ogg for dating purposes). 169 Dolichopareias, an early amphibian, is not Tournaisian. It is Upper Visean (the fossil, dated 170 Visean, was discovered in 1927-a book written soon after made the dating error-see 171 paleobioDB).

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The paleobiology database does not divide the Visean into sub-stages, therefore, we used 173 Benton's dating.  The Cambrian presents a unique problem. There are 15.74 genera in the Early Cambrian 178 HPZ-1, followed by 7.88 genera in LPZ-2 (See Table 2). This distribution is positive to our 179 hypothesis, but when we divide the 7.88 genera by the total (7.88), the results still equal 100%.

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To compensate, we add the 15.74 genera from HPZ-1 to the 7.88 genera from LPZ-2 and divide