Scientists say that 65 thousand years ago , the last of the non avian creatures called dinasours went extinct. There are many theories related to their extinction bit i have tried to gether those ones which you havent heard of already..
High Levels of CO2 destroyed their embryos
There has been a suggestion that caterpillars ate all the plants leaving nothing for dinasours to eat
Maybe the evolution of fungi , poisonous fungi that may have contributed to demise of the dinasours
Overpopulation may have resulted in severe competition, rivalry and warfare amongst the dinasours
Predation from mammals which ate the dinasours eggs preventing the survival 9f new generations
Thanks @sirknight for giving me a chance to write this..Hope you enjoyed reading this post.. UPVOTE if you liked it..