Doc, Is The Dinosaurs’ Extinction Contagious?

(Still) doing research for my book, I fell on this really interesting article that explores several possibilities for the dinosaurs’ extinction.

The one (and only) possibility that had been floating around in my head since I first heard of dinosaurs was of a Huge Catastrophe: imagine meteor crashing down on earth, causing supervolcanoes to erupt around the world, starting wave after wave of tsunamis and earthquakes…

I much prefer the ending of The Land Before Time

But “What Killed Dinosaurs?” brings up a good point: 

“Extinction is not a simple event; it is not simply the death of all representatives of a group.  It is the cessation of the origination of new species that renders a group extinct.”

So... what if it wasn’t Huge Catastrophe that came a knocking but instead, oh, I dunno, Massive Epidemy?  If so, what kind was it?  Dinosaur Flu?  Or something so far out there it could’ve come from outer space…  like global radiation from gamma rays that destroyed their reproductive organs, pretty present from our Galaxy’s Ever-Generous Center?

And if the latter, could we catch it too?