"I am not sure. My current understanding, subject to change as evidence warrants, is this. I think that dinos evolved from birds, and maybe reptiles, or whatever as well."
Well, you got it half right but ass backwards. You're doing much better than usual!
"I doubt they were created as such."
You're not the only one.
"After all, as the world changed they ceased to exist."
Having a rather large meteor land on you tends to do that.
"If they were a kind, they would be on the ark!"
Would one of you goofy bastards please define "kind" in some meaningful, rational and preferably scientific manner?
"That means they would have been here after the flood, 4500 years ago."
There was no flood 4500 years ago. At least not the one you're talking about. I'm sure there were many, just not yours.
"Don't think so, at least not most of them. "
Which is it? They all died in a flood or most of them died in a flood? You can't have it both ways.
"Also subject to evidence is the time of the flood in the strata record,"
No, the evidence pretty well sets your flood right around never.
"which I put somewhere near the KT boundary time. (as I say, subject to evidence, but so far, it seems to be a reasonable choice)"
Reasonable based on what? You don't even know what the KT boundary is, do you?
"Why would giants or dinos die out before the flood?"
Because a fucking ginormous meteor fell on their heads.
"Not sure, maybe man and creatures spreading out from Eden took over the food supply, etc."
Yeah, that's it. Humans, who didn't exist, or other "creatures" took over the food supply of the dominant life forms on the planet. Sure. That's a particularly grand accomplishment seeing as how humans wouldn't exist for another 65 million years or so.
"Or, maybe the dinos were killed in the flood?"
Or maybe, just maybe, there was no fucking flood and the dinosaurs died out from a mass extinction event.
"If they were no kinds, that would be OK biblically."
Trust me, dinosaurs weren't "kinds".
"If water came down from space, and up from deep below the earth, one would expect Iridium!"
One would? Why exactly?
"PS...intelligent man would likely tend to avoid them! I would. Unless I wanted a big omlette or something."
Intelligent or not, humans would have become extinct quite quickly if they existed at the time of the dinosaurs.