So basically the dinosaurs had 54 million years to evolve and adapt to their environment. Animals alive today have been evolving over millions of years but the environment is changing too quickly now for them to be able to adapt and survive.
Afaik scientists reckoned CO2 levels also rose fairly quickly then. In total the Dinosaurs were around for 179 million years. There were lots of different evolutionary stages of Dinosaurs as well and over time various species either died out or evolved and continued on. They were only finally wiped out 66 million years ago by a Asteroid impact in the Yucatan peninsula. Bit of a buger that tbh....
Imo the difference this time is humans. Many species of wild animals are already under increased pressure from all forms of human activities.