That some of them might have died in the Flood, but that the vast majority died earlier, thru catastrophes or other occurances. If you search the CDRom, you will find some special issues of Awake! covering the topic of dinosaurs not THAT long ago, 10 years or so, and the question of when and how they died was also covered. I do not have it at hand right now. There was a picture of a long-necked dino on the front.I don't think there are any ideas about co-existence between them and man. Apart from a funny picture or two on some covers, as shown.
Voltaire or Rousseau - I do not remember which one, but one of them it was - dismissed the whole idea of fossils, and thought the bones found were leftovers from previously held lunches; so not everyone has always been quite up-to-date :-)
Schroeder of the GB told me they made huge food reservoirs for other animals when they died individually, and that of course is correct, but does not relate to the dying out - question.