The word “prehistory” has been used for a long time to indicate all extinct organisms of the past, with dinosaurs occupying a center stage stimulating the imagination of a very large audience. Such erroneous use of the term prehistory is widespread even today, a word and concept originally referred to the period of human history which preceded writing, i.e. prior to documented history and embracing a time interval from about 2.6 million years ago to 4000 BC. Keeping in mind the crucial milestone of 'deep time' concept in geology the division of the extensive Earth history into only two sections of respectively 4.5429 billion years and 4000 years in our opinion is a misleading oversimplification. Over the past few centuries much effort has gone into the development of a hyper-detailed chronostratigraphic scale, substantiated by absolute dating, detailed biostratigraphy, and documentation of biological evolution. All this generation of knowledge, conducted by thousands of researchers over many years, is completely lost when, in a simplistic way the anthropocentric dichotomy is accepted.

Tyrannosaurus rex is infamous for its large body size and seemingly mismatched forelimbs, which are extremely small relative to body size. Since its first description by Osborn in 1905, the diminutive size of this attribute has fueled an arms race of sorts wherein specialists have advanced numerous theories seeking to prove a seemingly single-track use or non-use for the arms. While the overall debate on the evolutionary processes behind the small limb size are not addressed here, previous functional theories are reviewed within a functionalist perspective. This paper contends that Tyrannosaurus rex would have used its limbs for whatever purposes possible and that selecting one function to the exclusion of others is not a realistic approach to understanding the lifeways of the Tyrant King. Rather, a functionality assessment is suggested and tested using existing theories with the aim of providing a tool to assess future use case theories.