To unlock Site B you have to beat all of the missions, it's cool because you make the dinosaurs and watch them run wild on your little island paradise.
How to impress Dino nerds
Dino nerds are the hardest visitors to impress. A good way to impress them is using Dinosaurs from the same time period AKA late cretaceousthat are mixed Herbivores & Carnivore.They may also get a kick out of Carnivore taking down a Herbivore.
If you don't have any dinosaurs from the same time period,use Dinosaurs from the same place of discovery.AKA Arizona or China