A lot of the feather hypotheses are re-creations based on wishful thinking and not fact.Many small theropods like the one you pictured did have feathers but larger ones of the Cretaceous may only have had feathers on the young. (sorta like chicks). T rex was one of those. They found one or two fossils of young tRex and they had like "goose bump" spicules and maybe fuzzy feathers for warmth. They probably lost their feathers as the got larger.
A smaller (and geologically separated member of the class ) called Quanlong wucaii
was seen in the late Jurassic and was the ancestor to the laterDilong liaoning ensis
(I think that was the species name), Quanlong did have feathers throughout the entire life of the dinosaur. They both looked like a crested T rex but were a bout 1/2 as big and had more useful "arms and hands". About 35 genera of feathered dinos were known . Most of them were the coelurosaurs
They were from a different linneage (the Dromeosaurs)than the baby T rexes and the Quanlong and Dilong critters.Sciuromimus
was one of the first found and it was found in bavaria by a guy from Rutgers. The fossil was like that of an ornithischian dinosaur (bird hipped species) and its name means "Squirrel tail mimic". It was a raptor and sported a feather coat but more like a "fuzz" than the darwing you presented. (A lot of the popular press stuff mixes up the genera and their ages )
The actual number of dinosaurs with feathers is still really not great but its enough to make the story of the development of feathers from dinos to birds a real observation and not bullshit.
"nature and Nat Geographic style Magazines started the bandwagon to spread the story that all dinosaurs were showing feathers and THATS just made-up stuff for the popular science press.
Many many dinos have been presented as "proving" that they bore feathers when it was later seen that the "spicules" were evidence of muscle attachments and not feathers.
But the dromaeosaurs (the raptors) , when they first appeared, began to show their arms to be sporting all kinds of nifty feather arms (almost wing-like) before the true birds appeared
The story about the true birds and their separateion from a common ancestor of dromaeosaurs probably happend as early as the mid Jurassic , (but we are alas, short of proof fossils). Bird evolution still remains speculation and needs more good evidence from the mid to late Jurassic. Its more problem with the environment of fossilization than an iissue with the validity of evolution
As much as the science hates it, archeopteryx still is a feathered bird-like lizard or is a lizard-like bird. Its almost our best example of the development and evolution of teh Aves