Introduced in Fallen Kingdom, we see this relatively small therapod running alongside the gyrosphere as Claire and Franklin speed away from the volcano. That one presumably doesn't make it as it's struck by volcanic debris and presumably overtaken by ash, but we see another later on, escaping from the facility beneath the Lockwood estate.
Allosaurus existed during the Late Jurassic period, approximately 150 million years ago. It reached lengths of up to 28ft and heights of just 16ft. Evidence suggests that Allosaurus may have worked with others, though this is a topic of debate among experts, the reason being that fossil damage revealed that Allosaurus fed on large sauropods, which, if not scavenged, would have been difficult for an Allosaurus to take down without a pack.
Returning from Jurassic World, this dinosaur is seen among the stampede on Isla Nublar. We see several Ankylosaurus throughout the film, most of which perish beneath the cliffs of the island. Some are captured and auctioned off and some escape from the Lockwood estate at the end, free to roam and probably cause a fair amount of property damage with their tails.
This armored creature existed toward the end of the Cretaceous period, some 66 million years ago. It possessed a club-like tail which was likely used in combat against would-be predators, as we saw in Jurassic World, when one fought against the Indominus. Ankylosaurus was the largest of its kind, measuring roughly 20ft in length and almost 6ft in height.
Introduced by the cast and crew as the Stygimoloch, we see this dinosaur several times, but it's given special attention in one of Fallen Kingdom's more memorable scenes in which Owen and Claire are essentially rescued from their cage beneath the Lockwood estate by what we'll refer to (we'll explain why in a bit) as a young pachycephalosaurus that, later on, ends up terrorizing the cruel auction above.
Pachycephalosaurus was a herbivorous dinosaur generally believed to have used its hardened skull to butt heads with rivals. It existed during the Late Cretaceous period and was one of the last non-avian dinosaurs that existed before the KT-extinction. It spanned roughly 15ft in length and could reach heights of up to approximately 10ft. It was previously believed to have been the largest of the pachycephalosaurids but fossils belonging to dinosaurs formerly believed to be relatives-- stygimoloch and dracorex-- are now generally believed to have belonged to pachycephalosaurus in various stages of growth.