In "Day of the Predator", these Unknown Dinosaurs are the primary antagonists. These creatures are extremely intelligent and are capable of mimicking noises produced by other creatures. The creatures Liam and his group had to face were led by a male known only as "Broken Claw". These creatures are unlike any dinosaur species ever discovered, being smarter than any known dinosaur, even Troodon.
These creatures are best described as a cross between a small theropod species and a hominid, seeing as they have features of both species. They are incredibly thin, and extremely agile, although the downside to this is that they can be killed extremely easily by larger predators if they are caught out in the open. The creatures' most prominent feature is the shape of their skull. Instead of remaining small, their skull is the shape of a hotdog, a feature not found in any dinosaur/reptillian species on this earth. The creature lacks the muscle mass of the larger predators, but more than makes up for it with its advanced intelligence and weaponry, with four-inch long claws on its feet, which can deal massive damage to both prey and predator.
The reptilian species is not a solitary hunter. Rather, it hunts in packs, much like the dromeaosaurids living in the Creataceous period. Its methods for hunting creatures are extremely different: the creatures only hunt under the cover of Cretaceous foliage, and one creature in the pack would mimic the sounds of a wounded youngster in order to lure its prey over. As the prey lumbered over, the pack would leap onto the prey and slash at its sides. Unlike dromaeosaurids, however, one member of the pack (in this case, Broken Claw) would attempt to hack at the prey, in order to reach its heart. Broken Claw would then slash at the heart, killing the creature so his pack can feast. Broken Claw and his species are also capable of hindsight, as the creature realizes that the reason its hunting grounds are depleted is because his pack killed too many species, leaving the jungles nearly barren. It is unknown what prey Broken Claw and his pack go after, but one surprising detail is that Broken Claw's species is intelligence enough to go after even Tyrannosaurus Rex, or Many-Teeth, as Broken Claw calls it. The same method used for luring prey to the pack is used here to great effect, and with Many-Teeth lured into jungle instead of open ground, it is unable to move properly. The pack is then able to leap onto its side, and eventually slash at its heart, killing Many-Teeth.
This species prefers to live in tropical jungle, as evidenced both 65 million years ago and in 2001. The species hunts prey well in this habitat, but is nigh-on useless out in open terrain, where it can be easily be crushed or eaten. It is possible that this species is nomadic, as it is revealed Broken Claw and his pack have exhausted the amount of prey in their hunting grounds, indicating they may have to move on.
These creatures display a pack hierarchy quite like the other theropod species did at the time. The main difference is that, instead of the strongest alpha male being in charge, it is the individual with the most wisdom, the most experience than can be passed down from generation to generation that is in charge.
In Day of the Predator, Broken Claw and his pack learn from Liam and the students trapped in the Cretaceous period. The creatures learn how to use basic tools, even how to build a bridge, and it is believed that this knowledge is what allowed them to survive the K-T Extinction Event, allowing this reptillian race to flourish soon after. Instead of Homo sapiens becoming the dominant species, it is this reptillian race that become top dog. However, they show no sign no technological advancement, as in 2001, Maddy notes that they only have basic infrastructure & transport, along with rudimentary tools such as spears. It is possible that the species plateaued, that they evolved to the best they could possibly be, and then simply stopped, as there was nothing which required them to evolve any further. It is unknown whether the creatures ever reached the technological capabilities of mankind, or whether they managed to achieve the same breakthroughs as man. It is possible, that as the continents began to drift, this species could have made its way across the world, but given the harsh cold of the North, and the cold-blooded nature of reptiles, it is doubtful that this species ever made it to the Eurasian landmass. Perhaps humanity evolved separately on the Afro-Eurasian landmass, whilst the reptillian hominds remained in the Americas, possibly moving downwards to the more tropical South America.