Tartakovsky conceived the idea of this series while developing the last season of Samurai Jack (2017). Originally it was going to be a more kids-oriented story, with Spear written as a kid. When Pixar released The Good Dinosaur (2015), Tartakovsky shelved the project, until finishing Samurai Jack.
Spear's growls and roars are provided by voice actor Aaron Laplante. Tartakovsky first met Laplante when he was developing a new animated Popeye film, and Laplante was hired to record a temporary dialogue track for Bluto. Although the project stalled, Tartakovsky liked Laplante's work, and has cast him in several projects since.
Spear's design actually appeared in an episode of Dexters Lab where a caveman is transported to the present and becomes friends with Dee Dee.
According to art director Scott Wills, nature documentaries were a significant source of inspiration for Primal.
The first Cartoon Network Studios series to be entirely produced and aired on Adult Swim.