That's what I was wondering - are they saying they are surprised because this particular dinosaur apparently was a herbivore? Or are they surprised it lived in Utah? Or are they surprised it existed? Humans and other animals eat plants and meat so I'm not sure what the big story is here. Someone help me out.
They're surprised because it lived in Utah and it was monogamous.
I think the surprise was that this dinosaur was an omnivore, while other, later, members of this species or genus were strictly herbivores. Also, these fossils were found in an area where fossils of this particular animal have not been seen.