What caused the Demise of the dinosaurs ?

What caused the demise of the dinosaurs ? The demise of dinosaurs started in Pangia, The demise of dinosaurs happened because of multiple reasons , for example Mammals became bigger and competitive, drifting isolated continents touched each other, new diseases spread, the climate was getting colder, increased volcanic activity, acid rain. The demise of dinosaurs happened because Mammals became larger and the mammals became very competitive against each other. The continents that drifted touched each other and that also made the animals more competitive and they had to share food. New diseases spreading made the animals sick and they would die. The climate getting Cold , but the Mammals needed warm weather. Increased volcanic activity effected the sun light, without the sun light that would also effect the plants. The acid rain made the air hard to take in and breath.