Stress on the dinosaurs is a possible solution for their extinction. This theory was first thought up by Heinrch K. Erben when he found that the shell thickness of a certain type of dinosaur species decreased as time went on. It was thought that the warm climate and good habitats in the Cretaceous period could have caused over population of dinosaurs, thus an increase of stress on the dinosaurs would develop. Stress is known to cause hormonal imbalances in modern day birds and lizards, so this could have happened to female dinosaurs. An increase of estrogen in the dinosaurs would have caused the females to lay eggs with shells too thin. If this happened it would greatly reduce the chances of the young to be hatched and live to adult hood.
Caterpillars which were believed to have evolved late in the Cretaceous period could have stripped plants of their leaves, a valuable food to the plant eating dinosaurs. If the caterpillars were able to strip all of the leaves from trees, then the plant eaters would not have anything to eat and would die. If the plant eaters died then the meat eaters would die from lack of food. However this theory is thought to be extremely unlikely for caterpillars would have to strip all of the trees around the world of their leaves at virtually the same time.
A supernova is an exploding star. It can blast material huge distances into space. Some scientists think cosmic radiation caused by the explosion would cause extremely high rates of deadly cancer among the dinosaurs. Others believe the radiation reacted with the Earth's atmosphere and destroyed the ozone layer. Without the ozone layer to filter out dangerous radiation, once again high rates of cancer could have occurred within the dinosaurs. Only small animals and plants, whose homes were sheltered from the harmful radiation, would have survived.
Continental drift and disease:
This has also been mentioned as a killer of the dinosaurs, due to continental drift, which would cause all the earth’s plates to move and join new land masses, this would then cause dinosaurs to be more adventurous and move to new places where they will not be able to survive there and possibly cause them to die off. But also if dinosaurs are moving to different land masses, the diseases which they are immune to could be carried to new areas where dinosaurs will not be protected, thus killing off more dinosaurs.
Another theory supporting that disease wiped out the dinosaurs, is the one, not just of dinosaurs killing wiping out dinosaurs but of the smaller species such as insects, it was known that in the period of when the dinosaurs were wiped out, that the climate was very warm,...