Return to Jurassic Park is a mod for the 1998 PC game "Trespasser" set on Isla Nublar several years after the events of the first film. Running on an upgraded Trespasser engine, players will get to explore the abandoned facilities through nine expansive levels covering the entire island, while at the same time searching for weapons and supplies as well as solving challenging puzzles; encounter a wide range of dinosaurs, from the tiny compsognathus to the massive aquatic tylosaurus; and uncover a story unlike any previously presented in a Trespasser mod.
"Although you may not glimpse them at first, look carefully to the treetops on your left for our elusive population of segisaurus. One of the smallest dinosaurs in the park, segisaurus is an arboreal carnivore from the Jurassic period. Unlike our other carnivores, segisaurus hunts from the treetops, leaping down upon unsuspecting rodents and other bite-sized meals, making segisaurus one of the most agile predators in Jurassic Park."
Kinda reminds me of the Coelophysis from Walking With Dinosaurs.
Well, the two are quite closely related!