The dinosaurs were dominant 250 million years ago. If humans had come first instead of dinosaurs and built von Neumann probes at that time, our probes could be

The dinosaurs were dominant 250 million years ago. If humans had come first instead of dinosaurs and built von Neumann probes at that time, our probes could be saturating scores other galaxies--not stars, galaxies by now. That's with only a 250 million year differential in technology emergence. It isn't hard to imagine the emergence of technology varying by even more than that. https://en.wikipedia.org/wiki/List_of_nearest_galaxies https://en.wikipedia.org/wiki/List_of_nearest_galaxies