Actually, there isn't necessarily such a thing as "gravitational waves" - they've never been detected, although theoretically they should exist. But it's not true that it would take 100,000 for a black hole's gravity to affect us because it's 100,000 ly away - gravity affects all bodies in the universe - you're pulling on that black hole an infintesimal amount right now, but it has little effect because it's so far away and you're so much lighter. Gamma rays, on the other hand, are a form of light, and if by "black hole rupture" you mean a black hole exploding in Gamma rays, that could be, but if it's 100,000 ly away, it's very unlikely to have any significant effect on us, and as Shalmanese said, we wouldn't know about the Gamma rays until they hit us. But that assumes that black holes are the source of Gamma ray bursts, and there's no definite evidence that that's the case.
As for the actual question of what killed the dinosaurs, most of the scientific community believes the meteor story - PowerEngineer mentioned the Yucatan crater, and there's also the fact that most geological evidence shows a layer of dust (with a little bit of stuff that appears to be made of the same stuff that's in meteorites) that settled all over the world around the same time. And it's happened before in the Cambrian (I think) - an asteroid impacted and around half of all life was wiped out, and maybe more times.
And yes, if you've seen the movie Jurassic Park, you know that dinosaurs may be related to birds 🙂 but there's really no way to be sure if Dinosaurs had feathers - the last article I read on the topic seemed to suggest that some of the later dinosaurs had feathers, and the rest were more lizard-like.
