Megasaurus Rex was a giant dinosaur which roamed the region around Megakat City 65 million years ago.
The massive saurian had a row of bony plates down its back, rather like a Stegosaurus, and a mouthful of sharp teeth, making it a definate carnivore. Its most striking feature however, were its pointed head structures resembling kat-like ears.
At least one Megasaurus Rex was summoned through a Time Vortex by the Pastmaster in his first appearance, using a spell found in the Tome of Time. After crushing the Enforcer Sergeant’s Enforcer Sedan, the dinosaur picked the Pastmaster up and set him safely atop its head (as, like nearly all the creatures summoned through the Time Vortices by the Pastmaster, it was under the evil wizard’s control) and acted as his transport through the city en route to the City Hall clocktower, pausing only to knock the Turbokat through the still-open portal.
On the way, the dinosaur met opposition in the form of the Enforcers, who, on the order of Commander Feral, launched gas grenades at the huge reptile after their laser weapons failed to even phase it. Stunned, the Megasaurus Rex stumbled into the Megakat City Tar Pits and sank in up to its neck, forcing the Pastmaster summon a flock of Pterodactyls through a Time Vortex as an alternate mode of transportation.
Although the Megasaurus Rex was shown with its head still well above the tar, it is unknown if it finally sank under all the way. If not, it is also unknown what the city officials did with it. At least one more Megasaurus Rex was seen by the SWAT Kats in prehistoric times.