Allosauruses are T. rex’s Jurassic progenitors, while Pathfinder’s compsognathuses likely owe their venomous bites to Jurassic Park. Their ability to serve as animal companions and familiars, respectively, increases the likelihood of PCs encountering them.
Adolphus Mexartus is mounting an expedition to capture one of the famous indigo allosaurs of the Maar Jungle. Along the way, he will have to brave disease, vampire bat swarms, and the light-displacing zebrafolk of the plains.
No one noticed the mating pair of compsognathuses sneak onto the Santa Ilsia. Once their young hatched, the dinosaurs quickly overcame the crew. Now a ghost ship, the Santa Ilsia and its hungry passengers are soon to float into the harbor at Fort Marcos.
Not all dinosaurs are found in lost worlds and hidden valleys. Certain troglodyte druids raise allosaurus companions from the shell to protect their most sacred caverns. Feeding the beasts is an effort usually left to humanoid slaves.
—Pathfinder Bestiary 2 90