A few post extincition dinosaur like fossils have been found and he birds are all flying dinosaurs.
But thats not the mystery. The mystery is why almost all of the top predators stopped hunting on two legs and started hunting on four.

We havnt got any conclusions as to the rise of farming communities but we have plenty of clues.
One of the big ones is that the warmer world made more land suitable for cultivation.
Another one is that the mammoth, the giant sloth, and numerous other giant ice age mammals were unable to cope with the warmer climates and died out, leaving the nandartals wihtout a food source, so they had to take to farming.
But even then the question remains. Why did a species, apparently more suited to farming than hunting, die out, right when farming was getting started?