The Permian Extinction, the greatest extinction of all time, opened many new niches for exploitation. An explosion of new species, including the dinosaurs, grew to dominate the drier Triassic period which followed the extinction. The rise and fall of the dinosaurs is intricately tied to the wax and wane of the energy of lunar tidal heating dissipated by the close approach of the Moon. A Close Approach Lunar Model tells the story of the dinosaurs as it explains the dramatic environmental changes that paved the way for the dinosaurs to inhabit the earth, while these same forces continued to work on the environment and bring about the dinosaurs’ ultimate demise.
At the Permian-Triassic boundary a dramatic change in the style of plate tectonics occurred. Prior to the boundary, tectonic activity was slowing. However, after the boundary the modern plate tectonic regime that we know today began. As the dynamics of a closer Moon produced heat which was dissipated into the interior of the Earth, it re-energized the convection currents of Earth’s interior. From the minimal pre-boundary rates prior to the Permian-Triassic boundary to sometime in the Jurassic when plate motion reached a peak, plate motion dynamics made a major shift. (The Ring of Fire)
This major shift not only brought about the break-up of Pangaea but also caused changes in the atmosphere. As plate motion became more rapid and subduction increased, the rate of volcanic activity increased as well. Volcanic activity pumped the atmosphere full of CO2 and the atmosphere became highly concentrated with green house gases.
The atmosphere eventually became seven times the density of Earth’s current atmosphere.
The Rise of the Dinosaurs
During the age of the dinosaurs, the creatures of the Earth obtained gigantic proportions, some weighing as much as 70 tons, and all forms of life averaged two to three times the size and four to nine times the mass of today’s equivalent life. The fact that the physics of this size does not meet with the current physical laws of the Earth has remained one of the major mysteries surrounding the dinosaurs.
A dilemma of dinosaur size is the question of what gave dinosaurs the ability to pump blood to the head when raised to their full height. It does not seem to be anatomically possible, by today’s standards, for the heart of the dinosaur to pump blood to its brain. It is also not known how the large dinosaurs seemed to defy physics and generally withstand the crush of gravity. Plants too did not have the wood structure that today’s plants have developed in order to stand erect against gravity.
The elevated levels of CO2 created a buoyancy capable of “floating” the great dinosaurs. (Dr. Octave Levenspiel, (2001) personal communication). Carbon dioxide levels peaked during the Jurassic and it is no coincidence that the Jurassic is the time of the greatest dinosaurs. “This denser atmosphere, it was claimed, also helped the ungainly pterosaur (some with wing spans of up to eleven meters across) stay airborne.” (43) The by-product of this building atmospheric density was increased temperatures, thus the Jurassic was a hot tropical time on Earth. Coral reefs extended as far as latitude 60 degrees (today it is about 23 ½ degrees) and dinosaurs lived within 5 degrees of the poles. Even though seasonality was increasing as the axis of the Earth tilted, the effects were hidden by the dense atmosphere of the Jurassic period.
This sets the stage for the Cretaceous, the last of the three Mesozoic periods. The Cretaceous is known for very high sea levels. Plate motion, fueled by tidal heating of a closer Moon, caused the emergence of mid ocean ridges. These rising mountain chains, which grew down the central suture of the ocean basins, as they still do today, displaced large volumes of sea-water. The displaced water then rose and submerged low coastal continental shelves. The encroaching seas covered more than a third of the continental surfaces resulting in the flooding of all the low lying continental shelves including the Great Plains of North America. Sea levels reached their peak during the mid-Cretaceous.
The Decline of the Dinosaurs
As the Moon retreated and plate movement and flood basalt activity waned there was a decrease in concentrations of atmospheric CO2 and consequent decrease of atmospheric pressure, fueling the downsizing of the large dinosaurs.
The Cretaceous sees the continents assuming their more modern positions, a slowing of plate tectonics, and a lessening of the associated output of volcanic greenhouse gasses. This is because the solid body tide created a negative feedback, in the sense that the energy loss through this action would cause the Moon to slow. As the Moon slowed it retreated. This retreat lessened the gravitational pull and thus slackened the tidal effect that fueled the plate motion. The result was a trend toward a distinctly cooler environment, as plate tectonics slowed and the atmosphere became less dense.
The high sea levels of the early Cretaceous masked the increasing seasonality by moderating the global temperatures. But, beginning in the late Cretaceous, sea level fell and, after a series of oscillations, assumed its present relatively low level. Global cooling in high latitudes and increased seasonal contrasts in temperature culminated in polar glaciation during the mid-Tertiary and mid-latitude glaciation during the Quaternary. (37) Today we are experiencing the warmth of an interglacial period which is actually a rather rare thing.
What Killed the Dinosaurs?
Some scientists feel that sea-level changes played a large role in the extinction of the dinosaurs. Those who correlate mass extinctions with marked eustatic drops in sea level point to a variety of environmental changes that would ensue. Seasonal extremes of temperature would adversely affect terrestrial animals. Marine organisms would suffer from more variable water temperatures and drastic reduction of habitable area (37,38,39). Wiedmann also appealed to changes in sea level as the cause for what he considered to have been the gradual decline of large invertebrates, such as ammonites and belemnites, towards the close of the Cretaceous. (40) Sea level was a factor in mass extinctions but no single factor was completely responsible.
Van Valen of the University of Chicago proposed that it was the shift from subtropical to temperate vegetation, rather than the cold itself that killed the dinosaurs. He suggested that the dinosaurs could not stomach this form of vegetation; furthermore, the increase of deciduous trees which shed their leaves, made less food available in winter. (41).
The great restriction and final disappearance of the epeiric seas at the end of the era, the rise of highlands from Alaska to Patagonia, a sharp drop in the temperature accompanying the Laramide uplift, the vanishing of the swampy lowlands and the vastly changed plant world, have all been invoked to account for the extinction and the consequent rising of the weak and lowly into new kingdoms.
While all these factors played a role, it was seasonality brought on by the close approach of the Moon that sealed the fate of the dinosaurs. An asteroid impact at the K/T (Cretaceous/Tertiary) boundary may well have been responsible for local extinctions and the loss of the marginal species around the world. But the impact theory cannot account for the millions of years of the dinosaurs’ decline prior to the meteorite impact. Thus the so called K/T boundary may have been a time of an asteroid strike, the commonly accepted “nail in the coffin” theory of the demise of the dinosaurs, but the ultimate stroke was the orbital disaster brought on by the Moon’s alteration of the Earth’s spin dynamics. The close approach of the Moon created a temporary environment that was ideal for the development and rise of the dinosaurs but it was just that, temporary. As the Earth adjusted to its new set of circumstances the conditions changed, ultimately bringing about the demise of the dinosaurs.
The Close Approach Lunar Model provides a comprehensive picture of the rise and fall of the dinosaurs that is intricately tied to the energy of a closer Moon and its subsequent retreat throughout the Mesozoic period.