Some fossilized dino dooky made its way into the pet food supply, and all of the Gingham County critters who ate it have reverted back to their ancient selves. Merle's a sabre-toothed kitty, Paco the goldfish is now a dangerous Megalodon, Wiley's new pet lizard, Lupe, has become a snarling T-rex, and poor Nate Farkles, the town vet, is up to his ears in dinosaurs. If only Grampa hadn't mistaken a doggy biscuit for a gingerbread cookie, he and Wiley might've had a chance of taming the deadly dinos. But it's never over 'til it's over with this hilarious duo—Grampa may be ancient, but he's agile!