*After their defeat against Shockwave, the Dinobots were not only stranded on Earth but buried under tons of volcanic lava rocks. Locked in Stasis Mode for centuries, they were discovered by Skywatch, a human division of the US Army and reactivated as weapons ment to be used agains the Decepticons threat. Grimlock managed to escape but only to find out how desperate his current status was as he was caught right on the middle of a power struggle between Machination and Skywatch.
In the meantime, Abraham Dante aka Scorponok -head of Machination- is pulling the strings behind Skywatch, planning for take over this section and become the supreme ruler of the planet. But someone else is hot on his heels, and is no one else that Sunstreaker with the help of Hunter O'Nion who are willing to punish Machination for what they did to them.
*Source:comicvine.com