PASCUALGNATHUS

Pascualgnathus polanskii

Etymology: Polanski's Pascual's jaw

Nickname: "Pascu"

Classification: Synapsida, Traversodontidae

Diet: Herbivore

Size: 40 to 60 centimeters long

Provenance: Río Seco de la Quebrada Formation, Argentina - Middle Triassic, Anisian stage, 247 - 241.4 million years ago

Movie appearances: Jurassic World: Dominion (2022)

Pascualgnathus polanskii is a species of herbivorous traversodontid therapsid synapsid from the Middle Triassic period. It belongs to a lineage of very interesting successful herbivores that thrived throughout the Triassic period.

Pasculgnathus, upon resurrection, were revealed to be very aggressive creatures, having been observed killing small dinosaurs, like Aristosuchus and Ojoraptorsaurus with little provocation. They're also very territorial, fighting other members of their species, sometimes to the death.

In 2022, a Pascualgnathus named Leonard was owned by Kayla Watts who kept it in a cage to be sold at the Amber Clave Night Market in Malta. Leonard was later pitted against a juvenile Carnotaurus, but the fight was interrupted by Owen Grady and Rainn Delacourt who fell into the pit to fight themselves. Rainn was defeated and fell, with the Carnotaurus biting his right hand and Leonard biting his left hand, clamping it long enough for Owen to interrogate Rainn, before he is ultimately mauled by a juvenile Baryonyx.

FILM vs. REALITY

DISCLAIMER: Pascualgnathus does not show up in the Jurassic Park films, and it is instead, here, meant to be a plausible substitute to the films' Lystrosaurus. The films' Lystrosaurus is mostly similar to its real life counterpart but there are notable differences. Lystrosaurus is depicted by having what appears to be a small frill coming back of its skull, vaguely resembling that of a primitive ceratopsian, however the real life animal didn't have that. The head of Lystrosaurus was very distinctive in terms of shape and appearance, having the eyes sit on top of the head, and having a more rectangular and bizarre appearance. The jaws of Lystrosaurus were also not the most appropriate for crushing, and although they could probably be quite strong to a degree, they wouldn't be so well designed to cut or slash the wrist of a human or the head of a sizeable dinosaur. The films' Lystrosaurus is however accurately portrayed with a more splayed limb posture and what appears to be the lack of ear holes (this last detail is ultimately not known for sure, but it would be plausible).

Pascualgnathus is a different kind of synapsid species that was also herbivorous and had characteristic fangs, though its jaws were very well adapted for mastication, so their jaw musculature probably delivered a stronger and consistent bite, which, in theory, could be more devastating if applied against an animal. Additionally, it had two pairs of very large fangs, one coming from the upper jaw and the other coming from the lower jaw, an arrangement that could be make it more prone to slash the head of a dinosaur, in theory. Unlike the films' Lystrosaurus, both the real life Lystrosaurus and Pascualgnathus likely lacked hairs. While well preserved mummies of Lystrosaurus show that they had naked hairless skin, paleontologists agree that the appearance of hairs only occured by the time mammal ancestors lost their pineal foramen, which is a feature present in the Lystrosaurus and Pascualgnathus lineages, indicating these were likely totally hairless.