Extinction Theory and Its Impact in Contemporary Society The apparently sudden mass extinction of Dinosaurs marks the boundary between the Cretaceous and Tertiary periods. This catastrophic event has also triggered a large amount of interest in both scientific and general communities. Many speculations have thus been made regarding the reasons for the death of the dinosaurs. These include extreme changes in the global climate and sea levels, and supernova explosions.

During the 1980's notable new theories emerged regarding the mass extinction of dinosaurs. There has also been a concentrated effort to research these theories in terms of possible dangers to the human race. Luis Alvarez for example originated the idea of an asteroid striking the earth to cause the catastrophic demise not only of prehistoric reptiles, but also of most of the life forms present on the earth of the time.

According to the Alvarez theory, the environmental consequences of the alleged impact include a massive and catastrophic chain reaction. The asteroid striking the earth caused dust to cover the atmosphere on earth, resulting in continued darkness. This is referred to as "impact winter." The chain reaction involved the initial demise of plants, then of the animals depending on the plants for life, and finally the predators depending upon other animals. Other elements added to this theory...

This theory is more in keeping with the current anthropogenic environmental problems experienced by the earth today.
In contrast to the Alvarez theory, the volcano-greenhouse theory is less cataclysmic and sudden in its impact. According to this, the mass extinction of a species is the result of the interaction between earth processes and the consequent evolution or indeed demise of life on the planet. The premise is that the earth and its revolutions on its own axis and around the sun directly affect bioevolution and extinction. Thus rather than seeking the reasons for extinction in extraterrestrial causes, McLean search for them within the earth itself. Rather than resulting from accidental causes, extinction, according to this theory, is the result of natural evolutionary processes. Thus McLean's work focuses on a link between Deccan Traps volcanism and the extinctions occurring during the Cretaceous period. This link further included variations in the earth's climate and its direct effect on the population dynamics of vertebrates. At the same time McLean is willing to incorporate all theories, including the impact theory, into his investigations.

The belief is thus that variations in the carbon cycle are linked to a physiological mechanism, and population dynamics are influenced by this system. This theory has far-reaching consequences for scientists and biologists during the 21st century. What McLean terms the "Mammalian Population Collapse Mechanism" and the "Vertebrate Physiological Killing Mechanism" are directly linked to events that are evident in the ecological dynamics of the world today.

Of course there is also the fact that dinosaurs were largely the victims of their world. They did not consciously manipulate the world to make life easier for themselves. Instead they were forced to adapt to whatever physiological changes their environment underwent at the time. Whether these were due to natural mechanisms or to the sudden impact of a an asteroid makes little difference to the extent of the reptiles' ability to continue life. Human beings today…