I saw an interesting science programme recently. The dinosaur extinction theory revolved around the meteorite impact in the present GOM area / Yucatan peninsular. Massive heat blast from molten mantle material released by fracture of earth's crust - 'volcano' BBQed everything within about 600 mile radius of impact site. Tsunami wave effect damaged local coast line of mega continent of the time - Pangea or Gondwanaland. Embarrassingly, do not remember the name even though IU studied mining and petroleum geology for my first degree. The dust plume / fragments of earth crust rose high into the atmosphere and spread out, creating reduced light levels and temperature drop: silica particles acted like tiny mirrors, reflecting sun light back into space etc.. This created a 'nuclear winter' effect globally.
So, big dinosaurs begin dying off, eh / ph of sea and rivers changes killing sea creatures, as plants begin dying and temperatures drops. the food chain is disrupted, so dinosaurs begin dying off. So far so good.
BUT, and this is where I have additional thoughts. It is now thought the dinosaurs were warm blooded, not cold blooded. Creatures that size would have to sun bathe a lot just to shuffle around. Not efficient and would not give them enough time to eat each other etc.. So, they would have been able to deal with some temperature variation and migrate somewhere where things were better.
Also, if the 'nuclear winter' killed the plants, which starved the herbivore dinosaurs which, in turn, killed of the T Rex type beasties, how come the little mammals and insects survived - insects to pollinate plants, little creatures eating the insects, plants and each other if it was polar conditions everywhere? I am thinking the continent wide effect, away from epicentre might have been 10 years worth of wet,mild summers, like England but then things would gradually turn around. There are precedents for this Santorini and Krakatoa volcanoes creating weather disruptions. Additionally, the geological records show a number of distinct extinction episodes.
I would hazard a guess the dinosaurs were too specialized / adapted to their environment and when this changed over time, began dying out. The magnetic poles have flipped a number of times through geological history (from my studying memory), earth's precession / wobble on earths axis and slightly elliptical orbit around the sun played a part in ice ages. which have occurred at different times in the geological history as well, as shown by the lithological / stratigraphic record.
