The first difference that many will notice about our new T. rex is that it lacks feathers. In 2017, Phil Bell & colleagues published a study on the skin covering of Tyrannosaurus rex . In this paper, Bell et al. presented evidence against the theory that all tyrannosauroids were feathered, a notion that us and many others had followed.
The paper had some fairly convincing evidence; most notably, the paper offered published skin impressions of Tyrannosaurus rex for the first time. These impressions came from multiple areas of the body (see graphic), all of which showed very small reticulate scales. This was in contrast to the giant tyrannosauroid Yutyrannus , described in 2012, which preserved only feathers.
It seems that giants, apparently, are hairless and featherless,
In addition to the physical evidence for reticulate scales, there is also a biomechanical argument to be made. One of our major consultants on this reconstruction, Scott Hartman, has been conducting physiological modelling on early dinosaurs and other reptiles, including quantifying thermal constraints (Hartman 2015, Hartman et al. 2016). He is not working specifically on T. rex , but his research has implications for its potential feathering. According to his research, depending on ambient temperature, animals stop receiving any benefit from dermal insulation at somewhere between 1 and 3 tonnes. Due to the costs of producing such integument, this may cause these traits to be selected against, as has occurred in many large mammals and fur.
So this is why elephants are bald. But what are we to make of mammoths, mastodons, and wooly rhinos?