Gonza is a blue Tyrannosaurus marked by distinctive red eyelashes and a light triangular head marking. His tail bears a partial amputation, a lasting injury from an early encounter with Heart. Exhibiting curiosity and slyness, Gonza relentlessly pursues perceived truths, often to provoke reactions. Despite his antagonistic role, he adheres to a personal code of honor, evident in his final moments.

He first appears with his pack, led by Baku, hunting a Triceratops. Spotting Heart observing them, Gonza follows him into the forest. There, he pins down Light, Heart's adoptive herbivorous brother, attempting to force Heart to eat Light and awaken his predatory instincts. Instead, Heart attacks Gonza, biting off part of his tail. This act forces Heart to recognize his own carnivorous nature, causing him to flee. Gonza retreats, feeling betrayed.

Years later, Gonza and his pack attack Umasou, Heart's adopted Ankylosaurus son, in the outlands. Heart intervenes, defeating the pack. During this fight, Heart shoves a rock into Gonza's mouth, breaking his teeth. Though his teeth later regrow, Gonza appears noticeably thinner, likely due to temporary difficulty eating.

Gonza's final confrontation occurs when he blocks Heart and Umasou near Egg Mountain, demanding revenge. He declares their passage contingent on his death. Heart engages him in combat, inflicting a fatal throat wound. Before dying, Gonza attempts one last attack on Umasou and reveals Heart is not Umasou's biological father. Umasou acknowledges this but affirms Heart as his father regardless. Gonza then apologizes and dies.

His amputated tail serves as a recurring visual motif, symbolizing his repeated defeats and enduring vendetta against Heart. Gonza's actions directly catalyze pivotal developments in Heart's life: his initial acceptance of his carnivorous identity and his unwavering commitment to protecting Umasou.