The Dominance of Angiosperms May Have Caused Wiping Out of Dinosaurs
The major theories doing rounds about the extinction of the dinosaurs is that of the extraterrestrial impact and the massive volcanic eruptions. However, it is obvious that it would have been a result of more than these two reasons. One of the factors that may have contributed to the extinction of the dinosaurs is the gradual climate change.
The dinosaurs belong to two groups the herbivores and the carnivores. The herbivores ate plant and flora whereas the carnivores ate the largest prey they can find. Giant herbivores were found during the cretaceous and Jurassic period. The cretaceous period was the period of change. During this period the climate cooled and the angiosperms radiated which resulted in the decrease in the number of ferns, cycadophytes and gymnosperms which were the main food for dinosaurs. Some of the species like that of Bennettitales became totally extinct.
Another reason which might have led to their extinction is that the flowering plants release lot of oxygen which in turn increases the metabolism and in case of large animals they may not have been able to eat sufficient food to survive. Also the change in the atmospheric pressure due to increase in oxygen may have contributed to their demise.
Some people are of the view that the dinosaurs should have switched to the habit of eating gymnosperms. However, the evidence from the fossilized stomach of the dinosaurs does not suggest this and shows that they selectively ate conifers even in the area that was dominated by angiosperms. There is a possibility of a few of the dinosaurs eating angiosperms but it is evident that most of them do not. The angiosperms radiated too rapidly to allow the dinosaurs to make changes in their eating habits. Thus, the dinosaurs would have perished due to lack of sufficient food to sustain them.