I still think if these following dinosaurs are missing from this game or any of the expansions, that Frontier has a serious dislike for the creature, as they are pretty popular and unique, I don't understand if you make a dinosaur game that you would leave out any of these for ANY reason, and then start adding things like Aerchornithomimus and Metriocanthosaurus...
1) Therizinosaurus
2) Deinoncheirus
3) Gigantoraptor
4) Oviraptor
5) Protoceratops
6) Psittacosaurus
7) Lambeosaurus
8) Shantungosaurus
9) Lesothosaurus (The small herbivore version of the Compy)
10) Elasmosaurus
11) Quetzalcoatlus
12) Tapejara
13) Liopleurodon
14) Camptosaurus (The most vanilla dinosaur out there, but that makes it special)
15) Tenontosaurus = The ideal prey for smaller carnivores like Deinonychus.
16) Saltasaurus or another armored sauropod
17) Shunosaurus
18) Miragaia
19) Minmi
20) Eurhinosaurus = the only ichytosaur that is actually cool and special
21) Archeolon
22) Concavenator / Irritator
23) Crylophosaurus
24) Plateosaurus
25) Wuerosaurus
26) Hypsilophodon
27) Theselosaurus
28) Scelidosaurus
29) Scuttelosaurus
And of course the likes of Tanystropheus and Dimetrodon, but that will probably not happen anyway...