ARISTOSUCHUS

Aristosuchus pusillus

Etymology: Small bravest crocodile

Nickname: "Risty"

Classification: Neocoelurosauria, Compsognathidae

Diet: Carnivore

Size: 2 meters long

Provenance: Wessex Formation, England, UK - Early Cretaceous, Barremian stage, 125 - 123 million years ago

Movie appearances: The Lost World: Jurassic Park (1997); Jurassic Park III (2001); Jurassic World: Fallen Kingdom (2018); Jurassic World: Dominion (2022); Jurassic World Rebirth (2025)

Aristosuchus pusillus is an extinct species of compsognathid neocoelurosaur that lived in the United Kingdom during the Early Cretaceous period. Aristosuchus is a genus with a long history, and its validity was historically challenged. For instance, its type species was historically assigned to the Jurassic Poekilopleuron and later even regarded as a synonym of the contemporaneous Calamospondylus too, but this was changed when it was revealed that Calamospondylus was based on a different specimen than the Aristosuchus holotype. It is covered in feathers, a trait shared by some of its assumed compsognathid brethren, such as Sinosauropteryx and Sinocalliopteryx (though these could also sit outside of Compsognathidae, all the same).

Aristosuchus lives on a diet of mostly small animals, such as insects and lizards, but it doesn't say no to scavenging, if given the chance, but its teeth appear to be surprisingly robust for a compsognathid, indicating a more prepared approach to deal with tougher prey, such as mid-sized or larger vertebrates.

Aristosuchus appear to be rather erratic animals that startle at the slightest unexpected offense; a single electric shock can deterr even an aggressive Aristosuchus, which causes repercussions in the actions of the whole flock. However, they're not necessarily skittish, and they may take their time to regroup in larger packs to resume hunting of a challenging large prey, which can be as large as an adult human being. Their curiosity is persistant, and if they have interest in hunting a human, they will follow them for a long time. The expected outcome is for the Aristosuchus to finally launch their attack on the large prey, once their movements are fully appreciated and predicted. Although these pack hunting behaviors are best documented in the populations that lived in Isla Sorna, in Isla Nublar they also exhibited such a behavior towards humans too. If a large dinosaur is trapped or incapacitated, even if its a dangerous predator, like a Deinonychus, the Aristosuchus may seize their chance to take it down. Otherwise, in a normal circumstance, Aristosuchus would quite simply flee from a dangerous healthy large predator like this. Aristosuchus curiosity is also translated to its habit of biting a lot of strange objects, and it has been observed that this dinosaur has an awfully bad habit of biting and chewing wires.

When Aristosuchus was resurrected, scientists discovered that this animal had strange chemical agents in its saliva that serve as anticoagulants, which has been tentatively compared to a form of venom. The dinosaurs were held in Isla Sorna, and after Hurricane Clarissa, in 1993, they would be roaming around free in the island; in 1997, a pack of Aristosuchus attacked a young girl, named Cathy Bowman, who was on vacation in the island with her family, that led to the firing of InGen's CEO John Hammond, leading to the succession of his nephew, Peter Ludlow, who aimed to capture the dinosaurs from Isla Sorna and bring them to an idealized version of Jurassic Park located in San Diego. In the same year, Dieter Stark, one member of a team sent by Ludlow to capture dinosaurs, was being hunted by a pack of Aristosuchus; one scout of the pack was sent to investigate the human, a first action that would eventually lead the rest of the pack to follow suit. Once Stark got lost in the woods, he was repeatedly attacked by the dinosaurs, and although he initially managed to scare them away, the pack would return in strength to finish him off, marking the first confirmed human death caused by Aristosuchus.

In 2001, Aristosuchus were observed still thriving in Isla Sorna, first being witnessed by some humans who were stranded on the island, where the compsognathids were fleeing from a fight between a Spinosaurus and a Tyrannosaurus rex. Later Alan Grant refuged in Eric Kirby's hideout when a pack of Aristosuchus passed by, but the theropods instead were content in feeding on some insects that were nearby.

In Isla Nublar, after the end of Jurassic World, in 2015, Aristosuchus were living as wild animals in the island, and often proved a nuisance to some of the humans who were surviving there. By 2018, Aristosuchus still proved to be living in the island, up until the eruption of Mount Sibo. A collection of these dinosaurs was captured before the island erupts, and brought to Lockwood Manor, where they were meant to be sold at auction, before Maisie Lockwood releases them, and the other dinosaurs, to the californian wilderness. The Aristosuchus were seen feeding on Eli Mills' remains, after he was killed by a Tyrannosaurus rex.

Surviving in the wild meant that the Aristosuchus cunning opportunistic instincts could manifest in a whole new environment, and rightfully so, as the increase of human made food products led these dinosaurs to bleed into civilization just to feed on leftover food. The DPW (Department of Prehistoric Wildlife) had several encounters with these dinosaurs, sometimes saving some that were injured in man-made contexts. Aristosuchus therefore is one of the feral dinosaurs that people had the most interactions with. Aristosuchus increased contact with humans led to them being handled with a sense of bigger familiarity, reducing their potential danger to people.

FILM vs. REALITY

DISCLAIMER: Aristosuchus does not appear in the Jurassic Park films, being instead, here, serving as a plausible replacement to the films' Compsognathus. The real life Compsognathus is distinct from its films counterpart by a collection of traits. In the films, the genus is assigned with the species triassicus, but that isn't a known species of Compsognathus, but it is a species of Procompsognathus, a genus of coelophysoid from the Triassic period. The type species of Compsognathus is Compsognathus longipes. The film's counterpart is sometimes depicted with just two fingers on its hands, but Compsognathus actually had three fingers. In opposition to the real life counterpart, the film's Compsognathus are depicted actively hunting large prey, such as adult humans, but the teeth of Compsognathus were small and pointed, indicating a diet of small vertebrates and invertebrates, making them wholly unfit to hunt large vertebrate prey.

The real life Aristosuchus differs from the films' Compsognathus by being considerably larger, with an estimated length of 2 meters. Based on other coelurosaurs that could potentially be related to it, Aristosuchus would likely be covered on simple feathers, unlike the naked Compsognathus we see in the films. There is not a lot of skeletal material known from Aristosuchus, such as its skull and tooth shape, so whether or not it would have been a fitting hunter of large vertebrates, like the films' Compsognathus, is up to speculation, but Aristosuchus is known to have long phalanges, which indicates some relatively long hand claws. The large size of Aristosuchus, however, does point to a much more manageable likelihood to hunt large prey, in case these dinosaurs were pack hunters.

The exact phylogenetic position of Compsognathus and other presumed relatives, such as Aristosuchus, is hard to assess, as they could sit outside Coelurosauria, be basal coelurosaurs, part of the tyrannosaur group, or sit somewhere in the Maniraptoromorpha group, and that could influence how its integument is arranged; this interpretation assumes the position of Aristosuchus and Compsognathus as basal maniraptoromorphs. The pack hunting skills depicted by Compsognathus in the films could still be speculated for Aristosuchus, as pack hunting is sometimes described in reptiles, including birds, and the range of intelligence of sociality of dinosaurs is hard to fully assess based on fossil evidence alone, so it is not impossible. The presence of venom in these dinosaurs is a bit more controversial, as there is no evidence that any dinosaur would be producing venom, but anticoagulant properties in the saliva of some predators not traditionally seen as venomous can be observed, so although it is speculative, it is not impossible.