The Gravity Theory Of Gigantism and Extinction by John Stojanowski 1/20/07


This document is the third in a series entitled “The Rise And Fall Of The Dinosaurs.” Parts I and II describe a new theory that explains the gigantism of dinosaurs during the Mesozoic Era and how it related to their eventual extinction. The theory posits that a gradual reduction in the Earth’s gravitational field occurred as the terrestrial continents coalesced to form the super-continent of Pangea over 200 million years ago. The subsequent gradual breakup and drifting apart of those continental land masses was accompanied by an increasing gravitational field. This increase in gravity led to the extinction of many land and sea animals, especially the dinosaurs. The dinosaur/mammal equilibrium was disrupted, allowing the mammals to eventually displace the dinosaurs. This document supplements the prior two and introduces an additional factor to explain how the gravitational field strength could have been altered during the period in question.


Others have also come to the conclusion, based on the megafauna of the Mesozoic, that gravity must have been different during that time. Some have suggested that a large celestial body could have been in proximity to the Earth during that period and thereby acted to counter the gravitational field of the Earth. Some have suggested that the gravitational constant (the “G” in Newton’s Universal Law of Gravitation) had changed. They suggest that it instantaneously decreased prior to the advent of the dinosaurs and then increased around 65mya.

The Expanding Earth Theory, initially proposed by Samuel Warren Carey in 1956,1976 was also used as a basis for a gravitational change. Carey hypothesized that because the continental outlines seemed to mesh, the Earth must have been much smaller, with an expansion of 33% since 200mya. Those who supported this theory, in its relation to reduced gravity, attempted to explain dinosaur gigantism on the basis that a smaller Earth would entail weaker gravity. Since Alfred Wegener’s theory of continental drift has been almost universally accepted and explains the profile matching of the continents, the Expanding Earth Theory has been discarded by most scientists.

The theory described in this and the other two prior documents mentioned earlier offers a different explanation. And, that explanation is directly related to the formation and breakup of the super-continent of Pangea due to plate tectonic activity. Could the consolidation of the continents cause a substantial change in the surface gravity on Pangea? Since there doesn’t seem to be another adequate explanation for the anomalous size of the Mesozoic fauna , one has to explain how the gravitational change could occur. One explanation was given in the prior two documents. Further study has added another factor to explain the gravitational change. The following section addresses that subject.


The shift of the Earth’s solid inner core or both the solid inner core and the liquid outer core must be considered. With the consolidation of the continental land masses on a relatively confined surface area of the Earth, a shifting of the core away from Pangea within the equatorial plane could account for a lowering of the surface gravity of Pangea.

The shift of the core would act to maintain the rotational center of mass (not the center of mass) of the Earth at its axis. Figure 1 below is a representation of this situation. A rough estimate of the change in the gravitational force can be made using Newton’s Universal Gravity Law:


W=weight of an object of mass “m” on Earth.
M=mass of Earth
r=distance from center of core of Earth to
location of “m” on Earth’s surface
G= a constant

The resulting percentage decrease in gravitational force based on core-shift is, as shown in Fig. 1:

(Current radius of Earth) squared
(Distance from shifted core to surface) squared

Using a core-shift of 1000km would result in a ratio of about .75 (i.e. the weight of an object with the core-shift would be 75% of that without it at the equator) ignoring other factors. Again, this is only a crude estimate because the assumption being made is that the Earth’s mass is all concentrated at a single point. A shift of 1000km of the inner core would represent a distance less than half of the inner core’s diameter.

Note that:

Inner core diameter = 2400km

Outer core diameter =7000km

A shift of the inner core (and possibly outer core) would reduce the net surface gravity of Pangea. A core-shift would also help to explain another apparent anomaly described in the following section.


When studying sauropods, one is struck by a certain pattern which is hard to explain. The relevant literature states that dinosaurs inhabited every continent. Yet when one studies sauropods, there seems to be a high occurrence of sauropods in areas which were in lower latitudes (i.e., closer to the equator) during the Mesozoic Era. The literature also states that during the Mesozoic, tropical conditions existed on all land masses. South America, Africa, mid-western United States, mid to southern Europe, India and southern China are places where abundant sauropod fossils have been found. Places like Canada, northern Europe and Asia, Greenland, Siberia and Antarctica seem to have a dearth or even complete absence of sauropods although other dinosaur remains have been found in those locations.

Is it possible that insufficient searching of those areas is the reason? Is it possible that conditions in those other areas were not conducive to preserving their remains? If that is not the case and there is no other reasonable explanation for their absence in the higher latitudes, then this would support the core-shift explanation embodied in the theory presented in this document.

It can be seen from Figure 1 that the distance to the equator, with the core-shift, is greater than the distance to both of the high (north and south) latitudes on Pangea and therefore the lowest gravitational values would be on land masses closest to the equator.

Figure 2 is a representation of Pangea during the late Jurassic Period. The small circles drawn on that map represent locations where sauropod remains have been found including prosauropods. It is only a partial list of sauropods but it serves to illustrate the point being made. The sauropods represented by the small circles are listed on the page following Figure 2.

SAUROPODS (and prosauropods) USED IN FIGURE 2

Isanosaurus SE Asia (Thailand)
Antetonitrus South Africa
Euskelosaurus South Africa (Lesotho, Zimbabwe)
Blikanasaurus South Africa (Lesotho)
Plateosaurus Europe (France, Germany, Switzerland)
Lessemsaurus South America (Argentina)
Riojasaurus South America (Argentina)
Camelotia Europe (England)
Melanorosaurus South Africa
Amargasaurus South America (Argentina)
Nigersaurus Africa (Niger)
Cedarosaurus USA (Utah)
Sauroposeidon USA (Oklahoma)
Malawisaurus South Africa (Malawi)
Agustinia South America (Argentina)
Phuwiangosaurus SE Asia (Thailand)
Chubutisaurus South America (Argentina)
Saltasaurus South America (Argentina)
Rapetosaurus Africa (Madagascar)
Jingshanosaurus China (Lufeng Province)
Yunnanosaurus China
Massospondylus South Africa (Lesotho,Namibia,Zimbabwe)
Kunmingosaurus China (Yunnan)
Kotasaurus India
Vulcanodon South Africa (Zimbabwe)
Barapasaurus India
Omeisaurus China
Shunosaurus China
Mamenchisaurus China, Mongolia
Datousaurus China
Cetiosaurus Europe (England, Portugal),Morocco
Amygdalodon South America (Argentina)
Patagosaurus South America (Argentina)
Giraffatitan South Africa (Tanzania)
Lusotitan Europe (Portugal)
Camarasaurus USA (N. Mexico to Montana)
Diplodicus USA (Colorado, Utah, Wyoming)
Supersaurus USA (Colorado)
Seismosaurus USA (N. Mexico)
Barosaurus USA (S. Dakota, Utah), Tanzania
Apatosaurus USA( Colorado,Wyoming,Utah,Oklahoma)
Brachytrachelopan South America (Argentina)
Eobrontosaurus USA (Wyoming)
Dicraeosaurus South Africa (Tanzania)
Turiasaurus riodevensis Europe (Spain)
Erketu ellisoni Mongolia (Gobi desert)
Suuwassea emilieae USA (Montana)


A possible explanation for an additional, and probably more important, source of a reduction in the Mesozoic gravitational force on Pangea could be due to a shift of the Earth’s solid inner core, and possibly the liquid outer core as well. The breakup of Pangea and drifting apart of the continents would have been accompanied by a shift of the core(s) to a more Earth-centric position, thus increasing the terrestrial gravitational force.

The abundance of sauropod fossils in lower latitudes (i.e., closer to the equator) and their scarcity or absence at higher latitudes would be explainable by a shift in the Earth’s core(s) prior to the Mesozoic Era.

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