Suchomimus Edit: I refrained from saying this because I wasn’t sure, but probably Allosaurus, as some people pointed out. I would be a lot more satisfied with this answer.
Edit (again): Hard to see in the trailer, but looks like there will be another ceratopsian making a debut in this film. Looks like either Styracosaurus or Sinoceratops, but my money is on Sinoceratops, looks much closer to this animal than a Styracosaurus. Also, there are a couple small dinosaurs in the cliff shot that could be Stygimoloch, a pachycephalosaurid, which also is confirmed to make an appearance because of leaked animatronic shots
Lady helix, I'd really like for you to talk to me about rampardos
Well, Rampardos and it’s pre-evolution Cranidos, are based on Pachycephalosaurid (Pachy = thick, cephalo = headed, = saurid = lizard) dinosaurs. These are of course the famous headbutting dinosaurs, but how well does the design and behaviour of these Pokémon match up to what we know about these dinosaurs?
First of all, lets talk about Pachycephalosaurs. This is a clade (taxonomic group) within the Ornithischian dinosaurs, which is one of the two major dinosaur groups, containing other well known clades including the Ceratopsians (e.g. Triceratops - and Bastiodon), the armoured dinosaurs, or Thyreophora (e.g. Stegosaurus and Ankylosaurus) and the Ornithopods (e.g. Iguanodon and the Duck billed dinosaurs). Long necked dinosaurs (Sauropods) and the bipedal carnivores that would give rise to T.rex, velociraptors, and of course, birds, are placed in the other major dinosaur group, the Saurischians, but that is a story for another time.
Back to Pachycephalosaurs. They include about 16 fossil species, and are united by a distinctively thick skull roof, often surrounded by bony spikes. In some species, in particular, the most famous species Pachycephalosaurus wyomingensis, the skull roof is domed and inches thick, and it is this characteristic skull and species that the skull fossil and thus our Pokémon in question are based upon.
Pachycephalosaurs were relatively late on the Dinosaur scene, arising between 90 million years and 65 million years ago in the Late Cretaceous, with P. wyomingensis being one of the very last dinosaur species before the KT mass extinction, living between 70mya and 65mya ago. This is the first discrepancy with the description of our Poké Pals, as many of Cranidos’ pokedex entries state that it lived 100 million years ago, placing it towards the early end of the Cretaceous.
Now, both Cranidos and Rampardos are described as The Head Butt Pokemon, and indeed many of their pokedex entries describe head butting behaviour, either at obstacles, for hunting prey (even though pachycephalosaurs, as well as most Ornithischians were herbivores, so this is discrepancy #2), and of course, for head on collisions with each other, a nod to what P. wyomingensis is best known for, or at least what we thought we knew about them.
First of all, it may be that not all P. wyomingensis had domed skulls. Flatter headed Pachycephalosaur species, such as Dracorex hogwartsia (which is the coolest fucking name, it literally means dragon king of hogwarts, and the palaeontologist who discovered it says he visualised it as “a slightly less pyromaniac Hungarian Horntail”) have now been proposed to be juvenile and female P. wyomingensis, with the domed skull only developing in adult males, a sexual dimorphism, just as antlers would develop in male deer, to be used in intra-specific competition, i.e. male/male combat for females later in life as we see in many modern animals, such as deer.
If this is true, then this could be discrepancy #3, as Cranidos and Female Rampardos shouldn’t have domed heads (though to be fair, DP was released in 2006, and this theory was proposed first in 2009)
We do think that the domed skull was used for combat. The bone type is a special kind of bone, called fibromellar, which contain cells that specialise in wound healing and new bone deposition. Furthermore many skulls have been found with not only lesions, but evidence of healed osteomyelitis, a type of bone infection that results from trauma. The presence similar injuries in many specimens that in most cases heal is a pattern found in modern species that undertake such combat.
However, could these guys have fought via head-on collisions, a behaviour most commonly shown in popular media, including our Pokédex entries? Unlike modern animals who fight in this way, such as mountain goats and musk oxen, domes are not the best structures for hitting against each other, as the rounded surface means a reduced surface area for hitting, and any impact would be deflected and glanced off the other dome. We also know that the structure of the neck vertebrae mean that these dinosaurs would have held their necks in an S or U shaped curve. Goats and musk oxen can lock their head, neck and body in a horizontally straight position in order to transmit stress to the head, concentrating the power of the blow to this point and avoiding neck injury etc., however no known dinosaur, including any Pachycephalosaur could straighten their neck in this manner. Furthermore it is argued that the skull still would not be thick enough to protect from head on impact with another skull. Thus, discrepancy number #4, head on collisions, plus ramming through objects such as trees and buildings as described in the Cranidos and Rampardos pokédex entries would have been unlikely.
It is now thought that they may have used side on, flank butting swinging and ramming their spiked heads into the side of their competitor (supported by the relatively wide and sturdy build of the body which would have helped protect internal organs from such blows).
A dex entry for Cranidos mentions that it uses it’s head to fight against Aerodactyl, and indeed it is suggested that Pachycephalosaurs would have used their spiked and thickened heads to defend against predators too, as well as male/male competition, as would many modern herbivores with such weaponry, such as horns. Also, many of the dex entries for Rampardos mention a small brain, and indeed, Pachycephalosaurs, along with many other Ornithischians would have had relatively tiny brains.
TO SUM UP:
Cranidos and Rampardos are described as Pokémon who lived 100 million years ago, and used rock hard domed skulls for head on collisions with others of their species, for ploughing through obstacles such as trees, for defending from predators, and for hunting prey.
In reality, the dinosaur they are based on, Pachycephalosaurus wyomingensis, lived between 70 million and 65 million years ago, is unlikely to have been able to sustain head on head butts (with other P. wyomingensis, and as an extension, large objects such as trees) but would still have used their heads as weapons for fighting each other and predators, and they were herbivorous. Furthermore, we think only adult males would have had domed heads. Like Rampardos however, they did have tiny brains.