Thunderbreath

Thunderbreath is an extraterrestrial dinosaur kaiju created by Toho and appears as one of the two main antagonists (alongside Bolt) of The Dawn of Monster Kid: Origins, then returns as a major antagonist in The Dawn of Monster Kid and The Dawn of Monster Kid: Dimensions. He is a Spore Monster created when a Spore merges with the fossils of an extinct dinosaur.

Origin
Thunderbreath is an ancient prehistoric creature and part of an unnamed species of dinosaur that gets revived by a Spore.