User blog comment:BannedLagiacrus/Monster Appreciation Week: Molten Tigrex/@comment-4702773-20160124053148/@comment-17735225-20160124115424

Yeah, prehistoric bugs 'arguably' managed to grow huge under large amount of oxygen because their respiratory system allow them to increase their oxygen intake infinitely (through body pores). Normally creatures with lungs can't grow like that because their lung generally has a limit to their capacity.

But from my interpretion the gene that comes from Ancient tigrex might just be 'grow big fast gene', and Molten just manage to have access to food to support its growth. I think more oxygen in this case just means more foods and Molten can afford to use more energy than its relatives.

Metallic claws and exploding dandruff? It does get more complicate than that. There are already some hints about Brute Tigrex's scales and hides being changed by spending too much time in volcanic areas. I think this guy is Tigrex species with really long history in volcanic area, or he might just have teostra's exploding scales and flint teeth(in its case, claws) gene.