As the Diaclone toyline grew, the scope expanded beyond the standard fare of the highly popular Real & Robo to keep the series from getting stale. Capitalizing on the popularity of dinosaurs among young boys, Diaclone introduced the Dinosaur robo, such as Brontosaurus, a robotic Apatosaurus ajax.
Brontosaurus was designed by Koujin Ohno, the designer responsible for a great number of Diaclone toys, and later, Transformers. Early solicitations and catalogs show a prototype most similar to his final production version. However, either as a shortcut of the test shot, or an error of the airbrushing artist, the figure’s right toe (and the corresponding shape on the dinosaur’s back). The robot mode of the test shot uses a blue chest, and a simple red light or window in the center.
Brontosaurus’s dinosaurian mode depicts a robotic Apatosaurus (for which Brontosaurus is an antiquated synonym) with its tail dragging on the ground. It features a large amount of silver and gold chrome, including the tail, back, upper body, and inside the translucent head and neck. He is otherwise entirely silver plastic. His head is articulated at the top of the neck, and his jaw can open to reveal sharp triangular teeth. Its pilot is the second type of Diaclone pilot with a red torso and black limbs, featuring magnetic feet.
His transformation is rather unique, but shares some traits with Tyrannosaurus, such as the head flipping down to unlock the wing panels, and the rear of the dinosaur splitting to become the legs. The fists extend from the bottoms of the Apatosaurus forelegs. The robot mode is well-proportioned save for his comically wide stance. He has a red die-cast chest with a translucent door at the center for the Diaclone pilot. However, the door is inaccessible in dino mode. The robot can wield a combination of a gold chrome sword, black rifle, or a handheld rocket launcher with small gold chrome missiles.
Brontosaurus is relatively sturdy, and the only likely damage to a vintage sample would be missing translucent screw caps on his dinosaurian hips.
Brontosaurus does not have any production variants. However, a number of knockoffs such as “Dinosaur Robo” and “Ancient Animal” were released in the US and Europe. These were nearly identical to the Diaclone Brontosaurus, and loose samples only differ in very minor details.