Protoceratops are dinosaurs confirmed to appear in Additional Creatures: Endemics.
Protoceratops, meaning "First-Horned Face" is a ceratopsian dinosaur that lived in Mongolia during the Late Cretaceous, 75 million years ago. Protoceratops is one of the most common dinosaurs from its habitat and region which, along with its size, has given it the nickname "Sheep of the Cretaceous". Due to the high amount of remains, Protoceratops was one of the first dinosaurs to have its ontogeny (life cycle) fully understood, with Protoceratops caring for small offspring whose head and crests got more complicated and larger with age. Sexual dimorphism also could exist in Protoceratops, due to two distinct 'morphs' in the species, but it's still contested. There was even a protoceratops discovered locked in combat with Velociraptor, the only fossil of its kind.
Protoceratops is known to be added to Additional Creatures: Endemics, but it's unclear of what it's role will be.