[rkuykendall-com]

> Also, what animal has a leathery covering like that, rather than scales or supple skin?

Elephants! Which is apparently our closest approximation of Sauropod skin, which we actually have fossil impressions of.

I went down the same rabbit hole as you for the same reason, more Dinosaurs had more feathers than we originally thought, but not all. For example, the theropods out your window have lots of feathers, so other theropods like T-Rex and Raptors might have as well, though the bigger theropods probably had fewer than the smaller ones.