Regenerated, and dropping tails
Tegus regenerate their tails, tails break off when it is grasped by an enemy, and they can also drop their tails if they feel very threatened. When the tegu tail regenerates it does not replace the segmented vertebrae. Instead, there develops a long tapering cartilaginous tube within the trauma. The bones and vertebrae do not regenerate. Tegus make cells to build a new tail out of cartilage. Original tails are made of bony vertebrae. Regeneration can use up a lot of energy, and as tegu starts regeneration, their new tails actually become less colorful, and tegu tails usually grow back in one solid color. The tails usually no longer and have the banding they once had, or the length either. The regenerated tails are never as nice as they once were; the original tails are always much nicer looking.
Tegu tails play a role in locomotion, social and sexual interactions, and energy storage, is too valuable an organ for it to be dropped indiscriminately. They will not just drop the tail for no good reason, however they never drop them so high that is causes them to loose the whole tail. The upper tail close to the body is always saved to keep most of the needed fat cell resources. So even though a tegu might drop 3/4 of the tail, there is still one 1/4 of the tail left to hold the needed fat cells.
Tegu tails play a role in locomotion, social and sexual interactions, and energy storage, is too valuable an organ for it to be dropped indiscriminately. They will not just drop the tail for no good reason, however they never drop them so high that is causes them to loose the whole tail. The upper tail close to the body is always saved to keep most of the needed fat cell resources. So even though a tegu might drop 3/4 of the tail, there is still one 1/4 of the tail left to hold the needed fat cells.