The Gallery of Natural Science is the part of the museum that covers all around the rich flora, fauna and minerals Skyrim have. It's entrance is in the Main Gallery in the same wing as the Hall of Oddities. Instead of going straight to the Oddites Room, you have to turn to the right and go downstairs. In the stairs there around X Paintings marking the place.
The main attractions of the Gallery of Natural Science are the dioramas you can find that are built by the Dragonborn himself via the recolection of some materials depending of what will show on it. They are, from right to left, below this. If you wanna check the materials you need for the specific Display or Diorama just click on the respective image.