Juvenile Dakotaraptor RPRing a ornithomimid, being surrounded by other ornithomimids and Pachycephalosaurus
Raptor Prey Restraint (also known as RPR) is a gameplay mechanic exclusive from Dakotaraptor. This technique is something that is practiced by raptors, like Dakotaraptor and even Acheroraptor. The player can practice RPR if it jumps to a suitable creature, where it will hopefully latch to it with its foot claws.
Immature Triceratops being RPR'd by a Dakotaraptor
RPR is effective to kill prey of around the same size or larger than you, by jumping to the back or to the sides of the prey and using LMB to bite and RMB to flap the player's wings and keep balance. At the bottom of the screen, a white line is displayed with a cursor that moves to the left or to the right, according to the player's balance. If the player is unbalanced, the cursor will move to the sides, turning the line into a red color, but if it is balanced, then the cursor will remain around the center, keeping the line white coloured. If the cursor gets out of the line, the Dakotaraptor will jump out of the animal, after loosing balance. When the prey dies, the Dakotaraptor will normally jump out of it too.
Concept art of Dakotaraptor RPRing a Pachycephalosaurus
RPR is useful to damage prey, with fewer risks of being injured in any way, although some animal species can step on the player's tail or bite some zones of the body and cause damage. When the player latches on to the back of the prey, the player is safe from most damage as long as they remain balanced. If the player looses equillibrium, it will jump off the prey item. Usually, adults have more experience with RPR than subadults or juveniles, due to their increased stamina and durability, and also because most of their viable prey items are usually about their size or smaller.
Raptor Prey Restraint is available in every stage of development of a Dakotaraptor, except as a hatchling. Therefore, RPR is only practiced from the juvenile stage forward. Juveniles will start practicing RPR in small animals and, although you can attack any bigger animal, the damage will be insignificant or you will easily loose balance. Juveniles are adapted to use this technique on small animals, like Acheroraptor, though they can already start practicing on killing Thescelosaurus and Pectinodon, though those get easier in future life stages. Subadults will have a wider range of prey with this technique, being able to take down Thescelosaurus and Pectinodon, but closer to the adult stage, they start being able to take down ornithomimids and immature Triceratops, albeit with caution. For adults, almost anything worth RPRing (with the exception of Tyrannosaurus) can be latched onto by the player. Pachycephalosaurus and immature Triceratops start becoming more reliable prey by this time. Although adult Triceratops, Anatosaurus, Denversaurus and Ankylosaurus are very difficult game to pursue, an old adult could try to take one down.
You can RPR every dinosaur in-game, with the exception of the DePalma's Ornithuran, the Tyrannosaurus, the Dakotaraptor, and the Acheroraptor, the latter only incapable of being RPR'd by an adult Dakotaraptor. RPR in crocodylomorphs is perfectly possible, although it is not efficient, as it still deals damage in the player when in that position. You also cannot RPR Quetzalcoatlus, Champsosaurus, Basilemys, Chamops, Palaeosaniwa, Mosasaurus, Didelphodon and Lepisosteus.
Triceratops cannot RPR, but they themselves can suffer from Dakotaraptor attacks. As a Triceratops player, the best you can do to avoid Dakotaraptor RPR is to move around to promote imbalance in the predator, or use your herd as a valuable protection against the attacker.