Interesting hypothesis. There were probably many reasons for their demise. Now that the newness has worn off "Chixchilub", Paleontologists/ecologists are starting to once again look for credible reasons for the Meso extinctions.
Personally, I think that the rise of the Angiosperms and outgasing associated with the Himmalayian Orgeny is what weakened the Class to the point that one catastrophic event led to their extinction.
An even bigger mystery is the Permian extinctions at the end of the Paleozioc. 95% of all species were wiped out.
HERE is a link to a short video that presents an exciting new hypothesis for the event that opened the way for the Dinosaurs to evolve.
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