*dispersal of angiosperms >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.
*Asteroid > A nine mile wide asteroid hit the earth in the Gulf of Mexico.
*Brain Functions> Dinosaurs became endangered from the world evolving unlike their brain functions.
*Hitting Asteroids > Two large asteroids colliding created hundreds of smaller fragments to touch the earth and moon.
*High levels of carbon dioxide > High Levels of Carbon Dioxide Destroyed Dinosaurs Embryo.
*Cataract Blindness> Mass blindness is one theory that would've caused the extinction of dinosaurs.
*Caterpillers > Insects that reproduced at an alarming rate causing a shortage of vegetation.
*Stress > Over generation to generation dinosaur eggs became thinner and thinner from over stress causing the survival to go down.
*Increasing Entropy> Entropy id a measure of the disorder of the molecules in substances. Large organisms are seen to be more ordered than small organisms. If this would have increased that is would result in less order and the eradication of larger organized life forms.
*Fungi > A rapid evolution of fungi, especially poisonous species, which may have contributed to the demise of the dinosaurs.
*Greenhouse Effect> Too much carbon dioxide in the atmosphere causing a greenhouse effect.
*Lack of Sexual Activity > Over-Predation and Decrease in Sexual Activity, the Cause of Extinction of Dinosaurs
*Mass Flooding > Mass flooding may have destroyed important dinosaur habitats causing extinction.
*Mental Disorders> 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 that have evolved in the Cretaceous period.
*Metabolic Disorder> 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.
*Ozone > Ozone later was disrupted causing death from harmful UV rays.
*Supernova > A star exploding causing a supernova.
*Uranium > Poisoning by uranium, which was leached form the soil.

Dinosaur Extinction Theories
It is predicted that all dinosaurs became extinct around the date of 61 million years ago which is shortly past the Cretaceous Period. No one really knows for sure on how exactly dinosaurs became extinct but there is much evidence showing a sudden stop as opposed to the dinosaurs slowly dying off. With this strange mystery comes many theories on the possible reasons to what happened to stop their species. Click to the top links to read about the different ideas. Some are not very realistic as many are just suggestions, and are not backed up with proof. The theory on the Chicxulub crater is pretty much what most scientists think caused the end of prehistoric animals and dinosaurs.>>>>click here
http://www.dinosaurfact.net/dinoextinct.php