Over-Predation and Decrease in Sexual Activity, the Cause of Extinction of Dinosaurs
One of the theories put forward to explain the extinction of the dinosaurs is that of the reduction in their sexual activity and over predation. The sex determination in dinosaurs is considered to be temperature dependent. In this the incubation temperature of the egg is the determinant of the sex of the hatchlings. The study shows that a 2 to 4 degree change in the incubation period can result in all male or all female hatchlings. The study conducted on crocodiles and alligators the closest relative of dinosaurs, today supports the view.
There are evidence in support of the change in the climate and temperature at the end of the cretaceous era. Thus, a variation in the temperature might have resulted in a progeny that were all male or all female. This would have changed the breeding pattern of the dinosaurs drastically and may have driven them towards extinction.
However, it is difficult to test this theory in the lack of available data as the dinosaurs are extinct now. However, a few of the scientists are of the view that this theory should be accepted in light of the data collected from the living reptiles.
There are also arguments to suggest that this would not have happened due to a moderate shift in the sex ratio as there is evidence to suggest the monogamous nature of the dinosaurs. In case of a situation when all the offsprings that were produced in a herd were from a few males and they interbred, knowledge of modern genetics clearly states the inherent dangers. The reduction in the genetic variability would have produced a gene pool of dinosaurs which were less in their ability to respond to changes in environmental conditions.
Over predation is also cited as one reason in which the dinosaurs have been said to have over predated on their prey leaving nothing to eat and ultimately starved to death.