Utahraptor

Utahraptor was a large dromeosaurine dromaeosaurid from the Early Cretaceous of Utah.

Characteristics
Utahraptors are quite robust animals, far more so than similarly sized animals such as Crylophosaurus or Kaprosuchus, covered mostly in a heavy coat of feathers on everything but their lower legs and head. The length of the leg feather distribution varies from the hips to the ankles in the various subtypes, as Nigredo, Rubedo, Raja and Caudopavonis subtypes have feathers that stop at the ankle, while Citrinitas subtypes have feathers that give way to bare skin at the knee for increased speed while running and Albedo Utahraptors have feathers extending onto the toes to keep their feet warmer. While the feathers on most of their body are more akin to the fur-like feathers of emus, their backs, wings, and tail fan are closer to flight feathers. Their most notable weapon is the enormous sickle claw on their second toes, which can be used to disembowel prey. Coloration tends to vary per region, with multiple subtypes popping up and spreading when environmental needs arise.

Most Utahraptors live in large colonies, formed around a communal nesting ground. The packs are formulated around alpha males and females, with all females and beta males staying behind to raise and protect the young while alpha males go out in groups of four to find prey. Some subtypes like Albedo and Raja are more solitary and prefer to hunt and live alone. In at least two variants, their feathers are used to camouflage as plants found within the environment when buried within foliage. Once the prey is caught, it is either taken alive to the nests or eviscerated and only the organs taken to the nests. If prey escapes the initial attack but had lost blood before escaping, the hunting party will track and hunt it down until they have been killed. The presence of a hunting party will cause any small animal in the area to become quiet and agitating larger ones that are too big to hide from the predators.

Utahraptors are extremely intelligent, with some individuals learning how to open doors and even recognizing individual human faces after observing them enough, seeking out revenge against those that injured them. In spite of their aggression towards most other species, Utahraptor colonies have been observed getting along fairly well, using friendly gestures to calm each other down. Some colonies have even been observed working together with colonies of different subtypes when one of their nesting grounds' was encroached upon by Zosimus and Andrei Wynn. Their method of establishing hierarchies between subtypes is similar to bonobo chimpanzees, as well as ravens, crows and other corvid bird species, and dominance is generally resolved without violence in such cases. Once the subtypes establish who has dominance, they readily engage in friendly body contact as a way of welcoming each other and have been seen to admire each other's colorful plumage.

Nigredo:
The original subtype, these are jungle-adapted animals mostly found in Southeast Asia. They are highly social and live in large colonies.

Albedo:
A white and black subtype found within the Himalayas and taiga forests, they have a denser coat of feathering to help deal with the cold climates. This subtype is generally more solitary than most other variants.

Rubedo:
A dark-feathered subtype with red spots found in desert-mountains, adorned with a distinctive mohawk starting above the eye and ending at the start of the neck head.

Citrinitas:
A yellow and black-striped subtype found in Africa, they are the fastest variant helped because they have feathers which stop at the base of their legs that allow them to run unimpeded, similar to an ostrich. The Citrinitas subtype also is a carrier of the deadly virus Dromaeosaurid Mutagen. They are highly social and mix well with other social subtypes such as Nigredo, as the Citrinitas subtype's alpha, Xipetotec, was a Nigredo subtype Utahraptor.

Caudapavonis:
The only Utahraptor subtype not descended from the population brought over by the first collider incident, instead brought from the one sabotaged in Angola. They are covered in iridescent blue-green feathers with eye spots in the center of each feather on their neck. They are quite social and readily will mix with other subtypes, as they were delighted at being reunited with the Citrinitas subtype after the two packs established a peaceful hierarchy.

Raja:
A subtype that is antisocial and solitary, with feathers of golden brown, red and white. Stalker Force does not know of its existence due to their elusiveness.

Ammit:
A subtype that is mostly black. They are sexually dimorphic, as the males have iridescent, blue feathers used for mating displays and in hunting. They are largely nocturnal.

Initial Discovery
Utahraptors were among the many animals originally released by the failing of the first USSR Particle Collider into Vulture Valley in Vietnam. However, the species wouldn't be discovered by Andrei Wynn until months after the incident and his subsequent abandonment by Borodin, when he encountered an individual he would later name Sobek when it fought a Kaprosuchus. Although he managed to kill his opponent, the Kaprosuchus' jaws kept their hold on Sobek's head and its limp body still held him down. Once Sobek began screaming in pain, the rest of his hunting party returned and helped remove the corpse and forcibly released its grip, leaving several teeth embedded into Sobek's skull and jaw.

The Arrival of Vulture Squad
A year after their initial introduction to Vulture Valley, the colony there attacked a platoon of Green Baret that had been sent by General Jericho to find the second Russian Compound, whittling the group down over a week before eventually killing them all. A few weeks later, Vulture Squad was sent to find the Green Beret. On their first night, they were stalked by a Utahraptor, the silence causing them to panic and run to get away from it. When their leader Captain Ryan Baker accidentally got ahead of the rest of the squad, the dinosaur attacked and dragged him off, but managed to do little more than tear up his boots and break the skin of his foot before being scared off by the rest of the team shooting at it. The hunting party would later come across a group of Russian soldiers, The Dogs of War, and killed Aleksandr.

That day, the alpha of the pack, the Cyclops, attacked Gerald as he was fighting off a pack of Deinonychus, scaring off the smaller dromeosaurs before simultaneously suffocating and disemboweling Gerald. When the rest of Vulture Squad caught up to their position, the Cyclops attempted to curl up and use his camouflage to hide from them while waiting for Gerald to die. Gerald, meanwhile, managed to pick up his knife and drive it into the predator's chest, causing it to jump up and screech in pain, giving up their position away to the rest of the squad. Recognizing it was outnumbered, The Cyclops attempted to run off with its quarry, only being stopped when Logan Stovall jumped onto it and wrestled it, including driving his own knife into its eye, long enough for the rest of the Squad to drive it away with their gunfire and force him to drop Gerald.

The Cyclops quickly regrouped with his hunting party and followed Vulture Squad to Andrei's research station. While there, the pack left one of their members at the fence to distract the soldiers, while the rest of the pack jumped on the roof and attacked from the windows. After multiple unsuccessful attacks at the windows from the originally seen member and another animal, The Cyclops and the remaining individual began attempting to break through the glass on the pyramid roof of the building, while the other two began attempting to break down the door instead. Realizing the glass wouldn't hold them for long, Ryan opened the door to the station and had Leon Varnes shoot the pair with a rocket launcher, sending the, flying back as the other pair crashed through the ceiling, the group running before the pack could recuperate. Once Vulture Squad briefly stopped to signal their helicopter, The Father Vulture, the hunting party caught up and attacked them, cutting Leon open and attempting to drag away the still alive Gerald. Logan was forced to shoot Gerald and let his corpse go so the Utahraptors would stop chasing them and not eat Gerald alive.

The Destruction of the Collider
The following day, a hunting party of Utahraptors attacked and killed a group of Con Nhen's Viet Cong that had been sent out to ambush Vulture Squad. That night, most of Cyclops' colonies' males scavenged carcasses from a Russian Compound after an attack by a pair of Tyrannosaurus. Some of these animals attacked the Black Ops, killing all three of them before moving back to scavenging, with the pack moving off to bring all the carcasses they were able to carry back to their nesting site. Returning to the compound, Cyclops' hunting party discovered Vulture Squad, Wynn, Jericho, and Sergei Medvedev within the Collider Laboratory, eventually following them inside. The pack did not locate the group within the building until Leon called out, unaware of the dinosaurs. The hunting party attacked, three eating Sergei alive while Cyclops faced off with Ryan, ending in both of their deaths. When the rest of the men made it to the roof, the rest of the Utahraptors returned and began attacking their rescue helicopter The Father Vulture. Once the helicopter lifted up in spite of the attacking raptors, Sergei pulled the pin of a grenade and set off a series of explosions which killed much of the pack within the compound. Over the night, the surviving hunting raptors continued life as normal, catching Grigory Borodin as he was hiding from the Tyrannosaurus at day break. Borodin would be taken to a communal nesting site, where he would be placed in a nest and eaten alive by a clutch of Utahraptor chicks.

The Hunting of Stalker Force
Nesting Site A, as it was later deligated, would later be discovered by the newfound Stalker Force, and would become heavily monitored for the following three months. During one of these expeditions, the colony had been found to have moved out of Vulture Valley, leaving several fledgling families and a single small colony behind. Over the span of the next year, over competition and tactical elimination by both Stalker Force and a mated pair of competing Yutyrannus would take an immense toll on the Utahraptor population within the valley.

Trivia

 * Though Utahraptor is known in the book series which occurs from 1968 onwards, the species wasn't known in reality until 1975 when it was discovered as fragmentary fossils by paleontologist Jim Jensen, then again in 1991 from more complete material by Carl Limone, James Kirkland, Robert Gaston, and Donald Burge in 1991 before being described in 1993. It can be assumed that in-universe for Primitive War, Utahraptor fossils were discovered much earlier due to the fact Andrei Wynn was able to describe the species to Vulture Squad during the events of the novel.
 * The color scheme of the Citrinitas Utahraptors in Animus Infernal is a homage to the featherless Utahraptors seen in BBC's Walking With Dinosaurs series.