The Dinobots were the first sub-group of Transformers, built by Wheeljack and Ratchet on Earth, after the Autobots discovered fossilsed dinosaur bones in a cavern in Mount St. Hillary. The first three Dinobots were Grimlock, Slag, and Sludge, and were deemed failures by Optimus Prime, and sealed up in that same cavern. When the Decepticons captured the Autobots shortly thereafter, Wheeljack and Ratchet were forced to reactivate the Dinobots, but managed to upgrade their mental programs so they accomplished the task of saving their fellow Autobots. Although they were allowed to remain with the Autobots, they were never truly accepted by them, until Megatron convinced them to join the Decepticons. Wheeljack and Ratchet constructed two new Dinobots, Snarl and Swoop, and sent them to battle the other turncoat Dinobots. When Optimus Prime risked his life to save Grimlock from an explosion, the three original Dinobots realised their true place was with the Autobots. Snarl and Swoop were accepted without question by the other three Dinobots. All the Dinobots have their own special abilities, as detailed below, and all of them have exceedingly thick armour in Dinobot mode, resistant to conventional Decepticon artillery.

GRIMLOCK

Leader of the Dinobots, Grimlock resembles a Tyrannosaurus Rex in Dinobot mode. In this mode he can generate intense bolts of laser energy from his mouth. In robot mode, he is armed with a double-barrelled missile launcher and a flaming energy sword.

SLAG

Slag resembles a Triceratops in Dinobot mode. In this mode, he can shoot condensed blasts of flame from his mouth wih pinpoint accuracy. His horns make powerful weapons, and have been seen on occasion to generate bolts of energy (ref: "S.O.S. Dinobots"). In robot mode, Slag is armed with a standard blaster.

SLUDGE

Sludge, perhaps the most slow-witted of the Dinobots, resembles a Brontosaurus in Dinobot mode. In this mode, he can create powerful tremors by stomping his feet, and take to water better than the other Dinobots. In robot mode, Sludge is armed with a conventional blaster, and also has great strength.

SNARL

Snarl resembles a Stegosaurus in Dinobot mode. In this mode, he gains his strength from sunlight, collected by the solar panels which decorate his spine. His spiked tail makes a formidable weapon. In robot mode, Snarl is armed with a standard blaster and a flaming energy sword.

SWOOP

Swoop resembles a Pterodactyl in Dinobot mode. In this mode, he carries two cluster missiles, one under each wing, and has excellent aerial ability. In robot mode, Swoop is armed with a standard blaster.

When Megatron built (?) the Constructicons, and sent them to destroy Teletran One while he battled Optimus Prime, the Dinobots defended the base. The separate Constructicons were no match for the ferocious Dinobots, but when the group of robots merged into Devastator, they only just managed to beat the Dinobots back. The arrival of the other Autobots turned the tide.

When the Autobots were dying of Cybertronium deficiency, the Dinobots were sent to Cybertron with Spike Witwicky and his girlfriend Carly, but Grimlock, Slag, Snarl and Sludge were captured. Swoop, Spike and Carly saved the day, by rescuing the Dinobots and recovering enough Cybertronium to repair the Autobots.

When Powerglide discovered a mysterious prehistoric island still populated by dinosaurs, the Dinobots were sent there to train, as they were proving too much of a liability at the Ark. When the Decepticons tried to steal energy from the island, the Dinobots and a herd of their dinosaur bretheren saw off Megatron's forces. This proed to Optimus Prime that the Dinobots were capable warriors, and he let them remain with the Autobots for good.

The Dinobots aided the Autobots whenever possible, and were used to counter Devastator in the Earth year 2005, who was being used as the primary weapon against Autobot City during the massacre. Snarl, however, was not present - why is unknown, but it seems he may have been involved in the debacle within Unicron, and possibly even died in Unicron's digestive system, although he was seen thereafter. It remains to be seen which of these reports is erronious. In any case, the Dinobots, without Snarl, crashed landed on the harsh planet of Quintessa along with Hot Rod and Kup, where they met the stranded Autobot, Wheelie, who aided them in rescuing Kup and Hot Rod from the clutches of the Quintessons. Their brutal instincts and skills overcame even the ferocious Sharkticons.

After accidentally chewing on some electricity cables, Grimlock recieved a massive electric shock, exposing his brain to an over-abundance of anti-electrons, making him super-intelligent. While he was in this state, he was able to take parts of Unicron's head, and build the Technobots to counter the Decepticon Terrorcons. Grimlock sacrificed his new-found intelligence to empower the Technobots' gestalt form of Computron.

During a great battle on Earth's moon, the Dinobots, along with all the other Autobot and Decepticon Primitives (those with animal forms), were mentally summoned by a being known only as the Assistant, to battle an energy creature known as Tornitron. Tornitron had been created by the insane immortal alien known as Primacron, who was also the creator of the monstrous Unicron, and proceeded to drain the energy of the Autobots and Decepticons, as the Primitives were briefed by the Assistant. Engaging Tornitron in battle, the Primitives were easily bested by the creature, leaving Grimlock alone to stop him. Like Unicron, Tornitron rebelled against Primacron, and almost destroyed him, until Grimlock, using his simple instincts, simply reversed the energy polarity of the machine which created Tornitron, causing him to shrink and cease to exist, discharging all the stolen energy, restoring the other Transformers to life. This was the last recorded appearance of the Dinobots. Their final fate following the restoration of Cybertron's Golden Age is unknown.