What traits might they have (if you consider, for example, present homo sapiens vs. our predecessors)?

That's an adorable question, and I'll refer you to Fermi's Paradox to explain why dinosaurs existing much past the development of high technology would have been effectively impossible.

effectively impossible if Fermi's paradox were valid?

It's too easy for me to be cynical. To use a super nerdy gaming analogy, every time a species fxcks with something that can end it, it rolls a die. A certain sequence of outcomes will trigger game over, and on a long enough timeline statistical probability guarantees a whammy.

If it wasn't so much easier to destroy things than create them, there might be a contest. As it stands, positing any sort of long-term game plan for any species just clever enough to destroy everything it touches is pure science fantasy.

that's not a bad argument but it supposes that the whammy always precedes the galactic spread of the species. maybe most of the time it does, and maybe not, but it's a lot of galaxies in the universe.

True enough. I am making a lot of (admittedly biased) assumptions. My intuition tells me humanity is playing chicken with its own extinction on a near day to day basis. It feels optimistic to give us decades, much less centuries, and geologic time is on a whole different scale. Tbh my earliest existential fear is humanity managing to stave off its own destruction long enough to spread itself outside of our solar system. Better to contain the malignancy before it spreads any further.

But to address the spirit of your querry, it's possible nothing would have changed at all. Horseshoe crabs still look the way they did 65 million years ago, and at that point in history they'd already been around for almost 400 millions years. Unless environmental factors put preasure on a species to change, it likely won't.

Another answer would be that if none of the dinosaurs had gone extinct they'd look like birds, because that's what happened to the ones that evaded exinction 65 million years ago. Big, burly birds. 🐦

there's good and bad in people. we won't evolve to a better species before the current crisis is resolved, so the question seems to me to be whether we can act based on intelligence and the good of the planet rather than selfishness, and then maintain that philosophy.

your point about 65 million years tacked on to 400 million is excellent. some species wouldn't have changed much at all. but evolution has an inevitability to it overall. genes are going to mutate. those 400 million years weren't static, so whether any species would have made a brain-power (or tool-manipulation, or other) quantum leap in the next 65 million without the meteor is an unknown.

my adorable question wasn't really meant to elicit the requested predictions so much as this kind of thoughtful consideration of mechanisms and time frame and pressures. i'm sneaky like that ( :

Lol, well played sir. As to the endgame of humanity, since nothing lasts forever an even more pessimistic take would be that anything we do merely delays the inevitable. I love hearing about good and bad. My riposte is the few bad apples analogy, except I frame it in terms of a turd floating in a jug of drinking water. An optimist might say it's less than 1% turd, which means it's still 99% clean water. I'd say as long as anyone has the mind to shit in the water supply, our collective long-term prospects are pretty grim.

i don't know. with a 65 million year jump on us, hopefully they'd have done better.

don't forget the daily struggle to eat and not be eaten. we've only gotten this far once the dinos were removed from the balance. if they were still here, we might be the extinct ones.

If SimEarth is correct, yes they would.