101 CRAZY THEORIES ABOUT DINOSAUR EXTINCTION

Possible Theories

Many of these theories have some element which makes them in some way reasonable. However often they can only be related to a specific types of dinosaur, such as herbivores or carnivores, or to those which lived in a certain habitat.

Changes in the atmosphere

High levels of Carbon Dioxide destroyed dinosaur embryos.
The 'breathing stimulus' of warm blooded dinosaurs was removed by low levels of Carbon Dioxide.
The oceans became stagnant due to high levels of Carbon Dioxide. Stagnant conditions mean that there would be no oxygen for the any of the species living in the oceans, therefore there would be no food. However this theory assumes that the dinosaurs all lived in marine environments.
Atmospheric changes due to extensive volcanism and dust formation, which change the climate and light levels. There could also be the release of poisonous substances such as selenium, which could have been fatal, and also thinned the shells of the dinosaur eggs.
Cataract blindness. If the dinosaurs couldn't see, there was no way of knowing where they were going or how to find food.

Changes in climate. Changes in the minimum and maximum temperatures could have imposed stresses upon the dinosaurs that they could not adapt to in sufficient time. Every possible change in climate appears to have been suggested for the downfall of the dinosaurs. Also try Climate change page!

Too much Carbon Dioxide in the atmosphere due to the decrease of oxygen producing algae, making the climate too hot. This could have resulted in changes to the weather systems and rainfall patterns. A warmer climate would also effect the female:male ratio of hatchlings, as sex is determined by incubation temperature There could also be a decrease in the number male sperm produced, due to a warm climate which could reduce population size. Finally a hot climate could have caused the dinosaurs to become overheated in the summer if they were endothermic.
Climate too cold, which meant embryo development was inhibited, reducing dinosaur numbers. Furthermore if the dinosaurs were cold blooded, they would not have been able to survive through very harsh winters, as they were too large to hibernate and were unable to keep their body temperature at an appropriate temperature.
Climate too wet.
Climate too dry, making the environment arid and inhospitable.
Nearby supernova explosion could heat the upper atmosphere, but also disturb the ozone layer and produce large ice clouds in the high atmosphere, ultimately cooling the environment.

Competition with other animals. Much of North America was invaded by Asian mammals, however this explanation is only relevant to a specific part of the world.

There has also been a suggestion that caterpillars ate all the plants, leaving nothing for the herbivores to munch.

Changes in the DNA of dinosaur cells. A variety of genetic mutations could have resulted in weird and wonderful creatures being created, which could not survive.

A metabolic disorder relate to thinning of egg shells during incubation due to variations in certain hormones. The embryos would die, as the shells would be unable to protect them from predation and dehydration. Therefore within a very short space of time all the dinosaurs could have died out if no infants survived.
Also related to shell defects, is the idea that multi-layer egg shells formed, with two or three shells on individual eggs, which would suffocate any embryo. This idea is based on studies of French and Spanish dinosaur eggs found in the Pyrenees.
Increasing Entropy , resulting in less order and the eradication of larger organised life forms.
Epidemics of disease, however it is unlikely that a single epidemic could effect worldwide populations. Also, an epidemic sufficiently large to wipe out the dinosaurs would also effect other animal groups, but there is no evidence of such an effect.

Floral Changes. There are numerous related theories, due to the increase and dispersal of angiosperms towards the end of the Cretaceous.

Flowering plants are very efficient at producing oxygen, which will increase the rate of metabolism in animal tissue. If this rate is too high, especially in large animals, they may not be able to eat sufficient food to survive. As Schatz proposed, 'The dinosaurs may have well burnt themselves up, or out!' With increasing oxygen the atmospheric pressure may have changed such that the dinosaurs could not survive.
There was a rapid evolution of fungi, especially poisonous species, which may have contributed to the demise of the dinosaurs.
As the plant life changed, there was a loss of habitats, especially marsh land. Open land was also lost as forestation took place. Without the specific ecological environments dinosaurs could not compete and survive.
Flowering plants may have disagreed with the digestive system of the herbivores, as they produce alkaloids, which are toxic.
With the increase and diversification of plants that lose their leaves seasonally, such as deciduous trees, there would have been less food available throughout the year for the herbivore dinosaurs. If the herbivores died out, the carnivores would also have nothing to eat, resulting in their death also.

However a weakness with many of these floral theories is that the main diversification of the plants took place about 40 million years before the end of the Cretaceous. The rise of these plants was also accompanied by a diversification of the herbivores, hence they would have adapted to the changes in their diet. Furthermore, the rise of the angiosperms would have been a relatively slow process, and therefore vegetarian species would have had time to adapt to changes in their diet.

Sudden heating of the atmosphere by the entry of a meteorite.
Wobbling of the galactic plane. If the angle of this plane varies, dust and meteorites can be swept into our Universe, and there are more impact events than usual. There is some evidence that extinction events occur approximately every 26 million years. Wobbling of the galactic plane occurs on a similar frequency, and therefore the two events have been linked together with limited success.
A cumulation of infections, arthritis, bones fractures and caries.
Impact of an asteroid, perhaps the most widely accepted theory at the moment. It is suggested that a meteorite hit the earth at the end of the Cretaceous, causing huge quantities of material to be thrown into the atmosphere, reducing the light, decreasing atmospheric temperature and preventing plants from photosynthesising. Without food herbivores would be unable to survive, and consequently the carnivore dinosaurs would no food to eat, hence their extinction.
For more details try Meteorite Impact
An interstellar dust cloud, effected the atmosphere, by reducing light penetration.
Ionising radiation. This could
Mental disorders, including a decrease in brain size resulting in stupidity. There is evidence that many of the large dinosaurs, must have had very small brains in comparison to their total body size, possibly as small as a kitten's brain. With such small brain capacity responses to the surrounding environment would have been so slow that they could not compete with faster thinking animals.
An alternative is that there was a lack of consciousness and ability to change behaviour patterns.

The moon was extracted from the Pacific Basin, which would upset the atmosphere and climate.

Changes within the oceans. If ocean sizes and distributions change, therefore habitats are also affected. If the dinosaurs were could not to adapt to these changes, they would have been unable to survive.
- Drainage of lakes and swamps, removed important habitats.
- Flooding destroyed habitats.
- Changes in the distribution of the oceans due to mountain-building.
- Spillage of fresh Arctic water into the oceans, resulting in lowered temperatures and changes to weather systems.
- Reduction in the area of suitable terrestrial habitats due to increased sea-level.
- Regression , caused extinction on the basis that all dinosaurs were marine creatures! Perhaps not applicable to flying dinosaurs.
- Transgression caused the bottom of the oceans to become stagnant and lacking oxygen, which is essential for breathing.
Overpopulation, could have resulted in severe competition, rivalry and warfare amongst the dinosaurs. However animal groups also alive at that time, such as birds, somehow managed to avoid such problems.
The effect of parasites, such as lice, worms and flies. They could have overwhelmed the dinosaur population.
Predation from mammals which ate the dinosaur eggs preventing new generations surviving.
Over-predation , especially by the carnosaurs, who overkilled their prey, and hence had nothing to eat.
Overactivity of the pituitary gland, leading to excessive growth of bones and cartilage . This would hinder the movement and efficiency of the dinosaurs.
Alternatively the pituitary glands may have malfunctioned, which lead to overgrowth of frills, horns and spines, and such features impaired their ability to feed and move.
Poisoning by uranium, which was leached form the soil.
Racial old-age and over-specialisation. This includes evidence of enormous size, loss of teeth and spiney growths.
Reversal of the magnetic poles this would have created a temporary failure of the magnetic shield, causing genetic damage and eventual extinction. However there have been numerous reversals of the poles which do not have a corresponding extinction event.
There was a decrease in sexual activity, and not enough dinosaurs were born.
Slipped vertebral discs. This lead to severe back-ache, loss of mobility and the inability to compete for food.
Sunspots, these could have effected the climate and the atmosphere, to the detriment of the dinosaurs.
The explosion of a nearby supernova increased the radiation levels and cosmic ray penetration.
Volcanism. There is evidence that the formation of the Deccan Traps in India, took place at the same time as the dinosaur extinction. Excessive volcanic activity can have significant effects on the climate. The Deccan Traps erupted on a very large scale, and therefore could have had a major impact on the atmosphere at that time. This theory is the main alternative to a meteorite impact, and it can explain many of the associated observations. This includes the shocked quartz and the glassy spherules, see The Impact theory for details of these observations.
Increases in ultraviolet radiation due to destruction of the protective ozone layer by solar flares .

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