Evolutionists have long propagated that presently living creatures, including mankind, possess what are called vestigial or âuselessâ organs which they claim to be carry-overs from evolutionary ancestors in whom they may have once served a function but no longer do in living descendants.
This claim has been thoroughly discredited, however, as it turns out that virtually every so-called vestigial organ does in fact have a function and a use more vitally important than previously thought for the survival and proper function of those living thing which possess them.
In the case of fossils, such as the small arms of the T. Rex, there is no knowing as to what their function might have been as no one in recent history has ever seen, let alone observed, the habits, functions, and behavior of a T. Rex. There have been many theories as to what function the small arms of the T. Rex might have served, but none that have been proposed have been able to provide a satisfying explanation. It is possible that the small arms may have served a purpose in the early stages of the life of a T. Rex but became useless as the animal matured.
https://www.app.pan.pl/archive/published/app67/app009212021.pdf