Originally named Jurasson in Japanese media, Jonathan is an android created by Rex Owen's biological parents, Dr. Ancient and Dr. Cretacia, prior to 2126. His primary function was serving as Rex's butler and protector, specifically tasked with safeguarding the infant from threats like Dr. Z and Seth.

During the Ancients' mission to the Mesozoic Era aboard the timeship Backlander, Dr. Z ejected Jonathan, Rex, and the Ancients into a time vortex. This event scattered them across different times and locations. Emerging from the vortex left Jonathan's head inverted, causing critical damage that resulted in complete memory loss and erratic functionality.

Throughout the first season, malfunctioning Jonathan appeared in various temporary roles: an airplane pilot over the Swiss Alps, a tour guide and dancer in Bali, an artist painting patterns on dinosaurs, a ninja race coordinator, and a world-renowned chef named "Johnny Cook." Later, in Moscow, he served as a train conductor before Seth tracked him down. Seth forcibly extracted data from Jonathan's memory banks using the dinosaur Tank. During this attack, Jonathan reactivated his protective protocols to shield Max, Rex, and Zoe from Terry's Volcano Burst attack, sustaining severe damage.

The D-Team brought him to the D-Lab for repairs by Reese Drake. Chomp accidentally spun Jonathan's head back to its correct orientation, triggering partial memory recovery. Seeing Rod and Laura, he recalled Seth's data theft and stole a jet to infiltrate the Alpha Gang's Zeta Point base. He defeated Spiny but retreated from Seth's Saurophaganax. His memories continued to return, and he later revealed the full backstory of the Alpha Gang and the dinosaur cards to the D-Team.

Jonathan assisted in the final battle against Seth, disabling Alpha Droids, repairing the robot Helga to free imprisoned allies, and delivering Secret Dinosaur cards to the climactic battle against the Black T. rex. He intercepted a Fire Scorcher attack meant for Rex during this mission, collapsing afterward. Drs. Ancient and Cretacia later fully restored him.

In the second season, Jonathan piloted the Backlander as the D-Team and Alpha Gang pursued the Spectral Space Pirates through time to rescue the captured parents and recover the Cosmos Stones. He navigated the ship across the Cretaceous Period, Ancient Rome, the pirate-age Caribbean, Ancient China, Ancient Japan, Ancient Persia, Renaissance France, the Jurassic Period, the Stone Age, and various points in the present day. His involvement was largely limited to ship operations.

During the final confrontation with the Space Pirates, a Gel Jark entity knocked Jonathan unconscious with Seth's lightning rod, causing the Backlander to crash. After repairs, he piloted the ship against the Dark Pterosaur until Seth commandeered it for a final attack. Jonathan then took control of the Space Pirates' ship to transport the Ancients, Alpha Gang, Seth, and all dinosaurs back to 2126 as the series concluded.

Jonathan possesses superhuman strength and agility, demonstrated by overpowering Spiny in combat and withstanding attacks from Alpha Droids and dinosaur moves like Fire Scorcher and Volcano Burst. His personality shifted from malfunction-induced cluelessness and eccentricity to fierce loyalty and unwavering obedience to the Ancients and Rex after repairs. He follows orders without question, even when conflicted, such as separating from the Space Pirates' ship to protect the Cosmos Stones despite leaving the D-Team's parents behind.

He is one of the few major characters not featured in the Dinosaur King Trading Card Game.