(Capcom's primary storyline)
Later model Tyrants, such as the T-103 models were equipped with Power Limiters that prevented further mutation. However, these components were prone to being damaged during battle or by environmental hazards.
Once this occurs, Tyrants will mutate. The most noticeable change is that the Tyrant's upper body mass will increase substantially. Skeletal growth in the arms will form crude claws that the Tyrant will then use as weapons. The heart will also increase in size, often protruding from the body. Once mutated into a Super Tyrant, a Tyrant's speed, strength, and resilience to damage will increase.
It is unknown if this transformation causes a Tyrant to forget its programmed mission and act on pure instinct- most known Super Tyrants continued to chase their previously assigned target.