Jurassic Park Wiki

Gillicus was a medium sized fish from the late Cretaceous, it was probably a food source for large predators like Tylosaurus, Xiphactinus and sharks. Gillicus fed on smaller fish or algae. There is a famous fossil of Gillicus after it was eaten by a Xiphactinus. The Gillicus was eaten whole which caused the Xiphactinus' death.

Wikipedia has a more detailed and comprehensive article on Gillicus

Jurassic Park Inspired Games

Jurassic Park: Builder

see Gillicus/Builder

Gillicus can be created in Jurassic Park: Builder. Though it requires dino-dollars purchase.

Jurassic World: The Game

see Gillicus/JW: TG

Gillicus was added as a new tournament cave in the game on June 13th, 2018.