Genesis 3:17-18
And to Adam he said, “Because you have listened to the voice of your wife, and have eaten of the tree of which I commanded you, ‘You shall not eat of it,’ cursed is the ground because of you; in toil you shall eat of it all the days of your life;
thorns and thistles it shall bring forth to you; and you shall eat the plants of the field. 19 In the sweat of your face you shall eat bread till you return to the ground, for out of it you were taken; you are dust, and to dust you shall return.”
I think maybe thorns and thistles evolved later maybe after the dinosaurs. Maybe, when man was in paridise he was a small furry rodent, and the dinosaurs also came later as part of that curse?
So I guess being less appealing to herbivores has nothing to do with the whole thorns and thistles thing?