Actually one of the most interesting things in plant evolution is that they evolved into fruit producers to protect themselves from large herbivores. Primates l

Actually one of the most interesting things in plant evolution is that they evolved into fruit producers to protect themselves from large herbivores. Primates likely served as an ample defense against skittish herbivores. There's trees that host nests of ants that will drive away a giraffe, and what do the ants get in return? Fruit of course. Even if Dinosaurs hadn't been killed in a mass extinction, trees had already begun evolving their countermeasure and it's the fruit production which is directly attributed to the spread of primates. So we would have likely evolved in some form even if dinosaurs were still around. I mean there's some extremely weird things in the world that give an insight into what would have happened in a world with dinosaurs. The most common thing we think of is snakes, crocodiles and alligators eating large pray animals and being rather successful. However the smallest mammals seem able to defend their territory from reptiles. I've heard of adult rabbits killing snakes, which is rather contrary to what you'd think. I've seen a Hare eating a grass snake before. Meerkats will chase off puff adders (that can kill humans), baboons will torments and kill crocodiles. The thing that really illustrates what primates would have done against the predominantly land based dinosaurs is that a gibbons will defend their territory from tigers. I saw it on National Geographic IIRC, and it's quite amusing to watch because the gibbon will grab at the ears, pull on the tail and just outright kick and slap the tiger while swinging from the trees. If it's nothing for a gibbon to fight off a tiger, then imagine what it would be like for any dinosaurs that are ambush predators.