THE MYSTERY OF THE DINOSAURS: THE EARTH’S ELECTROMAGNETIC FIELD
MAY EXPLAIN THEIR GIANTISM AND EXTINCTION
Tsutomu Nishimura1*, Kaneo Mohri2,3, and Masanori Fukushima1
1
Translational Research Center, Graduate School of Medicine, Kyoto University,
Shogoin Kawahara-cho 54, Sakyo-ku, Kyoto 606-8507, Japan
Phone: +81-75-751-3397; Fax: +81-75-751-3399
E-mail: t246ra@kuhp.kyoto-u.ac.jp
2
Aichi Micro Intelligent Corporation, Wanowari 1, Arao-machi, Tokai, Aichi 476-8666 Japan
3
Nagoya Industrial Sciences Research Institute, 1-13 Yotsuya-dori, Chikusa-ku, Nagoya, Aichi
464-0819, Japan(Received August 06, 2008; Accepted February 20, 2009)
Abstract
Why dinosaurs became so large and why they
became extinct are two of the great mysteries of
biology. However, no theory has yet succeeded in
explaining the biotic transitions adequately. In aprevious meta-analysis, we found that exposure to an
extremely low frequency electromagnetic field(ELF-EMF) was associated with an increase inanimal body weight. In the present paper, we proposethat the large body size of the dinosaurs was caused
by ELF-EMFs generated by natural phenomena:
geomagnetic storms, volcanic activity, earthquakes,
or Schumann resonance. To support this hypothesis,
we researched long-term data on changes in theseprocesses. We found that there was a high level ofcrustal change during the age of the dinosaurs. We
propose that Ultra-low frequency (ULF) /ELF-EMFs
produced by widespread earthquakes and volcanism
caused the dinosaurs to become larger, then whenthese phenomena were no longer so prevalent, thedinosaurs became extinct for a number of reasons,among them the loss of ULF/ELF-EMFs.
(Keywords)
Bergmann’s rule, Rensch’s rule, Cope’s rule,magnetic field, ELF, body size, dinosaur, extinction,
giantism
1. Introduction
Why dinosaurs became so large and why they
became extinct are two of the great mysteries of
biology. The Cretaceous-Tertiary extinction, during
which the dinosaurs died out, ranks as one of the fivelargest extinction events of the Paleozoic. At the time,the earth was undergoing changes in global climate
and sea level, and was subject to events such as
massive volcanism and bolide impacts. Many causes
have been hypothesized for the mass extinction,
including bolide impacts [1-3], massive volcanism[2-4], sea level change [2,3], and climate change [2,3].
However, no theory has yet succeeded in explaining
the biotic transitions completely.
In a previous article [5], we focused on therelationship between extremely low frequency(3-3000 Hz) electromagnetic field (ELF-EMF)
exposure and animal body size, given that
Bergmann’s rule stipulates that organisms will tend to
be larger at higher latitudes, where the earth’s
geomagnetic field (typically around 50 µT, range
20-90 µT) is more than twofold stronger than atlower latitudes. In that article, we reviewed four

Viva Origino 37 (2009) 7-9ⓒ 2009 by SSOEL Japan-7-

papers in which animals exposed to ELF-EMFs andanimals that were sham exposed were compared overa period of 2 years. Meta-analysis revealed that
ELF-EMF exposure had a statistically significant
positive association with weight in males (p =0.0007), but not in females (p = 0.25). Thus,
ELF-EMF seems to cause an increase in body weightin males but not females, which might explain
Rensch’s rule, which states that in many animalgroups, when the male is larger than the female,sexual size dimorphism (the ratio of male to femalesize) increases with body size, but in groups in which
the male is smaller than the female, sexual size
dimorphism decreases with body size). At higher
latitudes, the earth’s geomagnetic field is more than
twice as strong as at lower latitudes, which would
explain Bergmann’s rule (the tendency towards size
increase with increasing latitude). Similarly, astrengthening of environmental electromagnetic or
magnetic field (MF) over evolutionary time might
possibly explain Cope’s rule (the tendency towards
size increase within phyletic lineages). In theabove-mentioned article, we mainly focused on therelationship between the earth’s geomagnetic fieldand Bergmann’s and Rensch’s rules.
Ultra-low frequency (ULF) (0.03-3 Hz) and
ELF-EMFs are generated by geomagnetic storms [6],volcanic activity [7], earthquakes [7], and Schumann
resonance [8]. The human brain uses a range of
frequency patterns, which can be detected using
electroencephalography; The frequency range of theelectroencephalogram rhythms coincides with thefrequency range of the Schumann resonance signal(0–45 Hz) [9]. Thus, ULF/ELF-EMFs may have aneffect on evolutionary processes in animals, at least
with respect to animal brains [9]. So, in the present
study, we focused on a possible relationship between
Cope’s rule and ULF/ELF-EMFs. Recent studies
suggest that Cope’s rule holds for a variety of taxa,
including Cenozoic mammals [10-12] and dinosaurs[13]. Therefore, we researched the relationshipbetween giantism and ULF/ELF-EMFs in dinosaurs.
2. Materials and Methods
It was not possible to obtain long-term data on
Schumann resonance, because it is caused bythunderstorms. Therefore, we obtained long-term
data relating to geomagnetic storms, volcanic activity,and earthquakes. For geomagnetic storms, we
obtained data relating to solar activity, because thearrival of high-speed solar plasma and the associatedViva Origino 37 (2009) 7-9
generated by volcanic activity and earthquakes, canpropagate over long distances [17] and animals seemto be most sensitive to electromagnetic fields below
10 Hz [6,18,19]. Therefore, it seems likely that lower
frequency ULF/ELF-EMFs would have the greatest
effect on the body weight gain of animals.
Regarding the mechanism of weight gain, it isinteresting that mild increases in plasma thyroid
hormones (e.g., thyroxine) [20] and prolactin [21]have been found in pregnant lactating dairy cows
exposed to ELF-EMF. Thyroxine is known to play
key roles in growth, metabolism, reproduction, andsomatic differentiation in developing and adultanimals [22]. Also in pregnant lactating dairy cows,
exposure to the electric component of these fields
alone (10 kV/m) did not affect either prolactin or
thyroxine [23]. It is possible that MFs exert an effecton body size via plasma thyroxine and/or prolactin.
In fact, injections of prolactin and thyroid hormones
have been found to promote weight gain in malereindeer [24].
It is also possible that EMFs exert an effect onskeleton size via alteration of the proliferation andactivity of bone cells. In support of this hypothesis,
pulsed EMF stimulation has been used clinically formore than twenty-five years for the treatment ofpatients with delayed fracture healing and non-unions[25]. Furthermore, a substantial number of in vitro
studies have shown that EMFs have positive effects
on the proliferation and activity of bone cells [25].
Yamashita and Saito demonstrated that 100 mT
static magnetic fields have an effect on mitochondria;
they found that energy activity and cell respiration in
mitochondria that were exposed to a MF increased byfactors of 1.5 and 1.3, respectively, compared withthe sham control group [26]. It seems thatmitochondria are activated by MF and thereafter
provide more ATP to some organelles in the cells ofan organism [26]. Promotion of ATP synthesis by a
MF would provide the energy to maintain a larger
body size. That is, organisms would be able to use
magnetic energy as well as other forms of physicalenergy.
There is a theory that high atmospheric O2 caused
insects to become larger in size during theCarboniferous period and low levels of atmosphericO2 caused the dinosaurs to become larger in size
during the Cretaceous [27]. The same source also
proposed that the primary reason for the dinosaurs’endothermy adaptation was not to maintain a constanttemperature but to increase efficiency in a
low-oxygen environment [27]. However, plants werealso larger during the Carboniferous period [27]. For
plants, high levels of atmospheric O2 are harmful, so
conditions of high atmospheric O2 could not havecaused the plants to become larger. Thus, the O2
theory does not explain the giantism of both insects
and plants, but ULF/ELF-EMF does explain thephenomenon: several studies have suggested that
ULF/ELF MF may modify plant growth anddevelopment [28]. Furthermore, vascular plants
adhere to Cope’s rule [29].
The volume of volcanic materials created was also

shock wave near the Earth causes geomagnetic
storms [6]. We identified potentially relevant papers
by performing a search of the Web of Science
database (1990–December 2007). The search terms
used were ‘Cretaceous’ and ‘sun’, ‘Cretaceous’ and‘solar’, and ‘Cretaceous’ and ‘volcanic’, and thesearch was restricted to papers in English or
Japanese.
3. Results
Well-documented variations in the 15N/14N ratio inlunar surface samples are apparently the result of
secular increases in that ratio in the solar wind during
the past few billion years [14]. In the age of thedinosaurs, the 15N/14N ratio was at a high level;
however, the material has been determined to be
non-solar N [14].
During the late Carboniferous (∼250 million years
ago, Ma), continents were assembled in a single unit
called Pangaea, surrounded by a global ocean named
Panthalassa [15]. This configuration remained quite
stable for about 70 million years, but 190–180 Ma,
the super-continent Pangaea began to rift apart toform the central Atlantic Ocean, with North America
rotating away from Africa [15]. As Pangaea brokeapart, the tectonic plates of the earth moved against
each other, causing earthquakes and volcanic activity.
The high level of geologic activity at this time isreflected in the volume of volcanic rocks produced,
increasing from 250 Ma and then slowing downaround 70 Ma, when dinosaurs were dying out (Fig.
1) [16].

Figure 1. Long-term changes in the volume of volcanic
material produced on earth [16]4. Discussion
In our review of the literature, we found thatcrustal changes were at a high level in the age of thedinosaurs. Crustal changes such as volcanic activity
and earthquakes generate ULF/ELF-EMFs. So, wehypothesize that the ULF/ELF-EMFs generated byvolcanic activity and earthquakes caused thedinosaurs to become larger.
Lower frequency EMFs, especially the ULF-EMFs-8-

Viva Origino 37 (2009) 7-9
high in the Carboniferous period, as well as in the
Cretaceous period. During the Carboniferous period,
animal gigantism is known to have existed.
Carboniferous gigantism was most evident among a
number of diverse lineages of flying insects, but wasalso present in other arthropod taxa, such as
millipedes and arthropleurids, and among theterrestrial labyrinthodont amphibians [30]. Although
insects are heterothermic animals, if the airtemperature is high, their body temperature iscorrespondingly high. During the Carboniferous
period, the air temperature was high [31], so they
could have been subject to the effects of
ULF/ELF-EMF. We believe that ULF/ELF-EMF
may have affected a particular biological reaction that
requires high temperatures to proceed.
Although the Cretaceous-Tertiary extinction is
generally thought to have been caused by a
combination of factors [2], we believe that a
reduction in the prevalent ULF/ELF-EMF is one
important factor. Turtle, lizard, and snake species
were little affected by the Cretaceous-Tertiary
extinction [32] and, correspondingly, they do notadhere to Bergmann’s or Cope’s rules. If these
species are little influenced by EMF or MF, thiswould support our theory.
We propose that ULF/ELF-EMFs produced byintense earthquakes and volcanism caused thedinosaurs to become larger in size. Plants exposed to
ULF/ELF-EMF also became larger, providing more
food for dinosaurs. However, the prevalent level of
volcanic activity lessened in the late Cretaceous (Fig.
1), meaning that dinosaurs were no longer subject to
ULF/ELF-EMF, and, together with other changes inthe environment, the loss of the ULF/ELF-EMF led
to their extinction.

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