Tyrantrum is a large, dinosaurian Pokémon, closely resembling theropods like Tyrannosaurus. It is predominantly brick-red in coloration, with scaly patterns on its skin and scattered orange highlights on some of the scales and ridges. The underbelly is gray with white borders, and it has a long tail with two orange spikes near the tip. Its small forelimbs have only two black clawed digits, but it has powerful hind legs with three sharp, black talons. Plated, armor-like ridges are found on the front of the legs and down the back and tail. Spiky, white "fluff", similar to the primitive feathers on many dinosaurs, extends into a cape-like fringe around the neck. Additional feathering forms a prominent beard on the lower jaw, which is otherwise gray in coloration. Its head is proportionally large, with a ridged snout and powerful jaws. The lower jaw is lined with pointed teeth, and the upper jaw features a number of tooth-like projections which are also highlighted orange. Its eyes appear to have black sclera with white irises. An orange, five-pointed crest extends from the snout above the eyes and point backwards, giving it the appearance of wearing a crown.
Before its extinction, wild Tyrantrum used to live 100 million years ago, when its powerful jaw conferred its status as an unmatched predator. Since it was considered invincible in the ancient world, it behaved like a king.
Tyrantrum seems to be based on the Tyrannosaurus, though it also shares characteristics, including the orange facial crest, with dinosaurs in the Carnosauria group. Considering its orange crest and white fringe upon its chin and neck, it may have also been based upon a king, with the crest acting as a crown while the white extensions are its beard and cape.
Tyrantrum may be a combination of Tyrannosaurus, tyrant, and tantrum.
Gachigoras may be a combination of ガチン gachin (banging noise) or ガチガチ gachigachi (teeth chattering), チゴラス Chigorasu (Tyrunt's Japanese name), and Tyrannosaurus. It may also come from がっちり gacchiri (stocky).
In other languages
Possibly from ガチン gachin, or ガチガチ gachigachi, チゴラス Chigorasu, and Tyrannosaurus