A bunch of melanosomes don't necessarily mean an animal is black

[Halichoeres]

Melanosomes preserve reasonably well in certain environments and are a reliable indicator of the dark pigment melanin. But that pigment isn't always in the skin, it can be in the intestinal tract or other internal organs. This study looks at living and fossil frogs and finds that melanin from the gut can look like it's from the skin if the carcass has been disturbed. Moreover, other pigments don't preserve as well, so sometimes you're left with just a strong black signal with all other colors drowned out. Caveat palaeontologus.

Open access: https://www.nature.com/articles/s41467-018-05148-x.pdf

[Faelrin]

So would this change how Archaeopteryx and Microraptor should be depicted? Possibly anything else out there?

[Halichoeres]

I suspect not, but I don't know enough about their specific taphonomy to say for certain. But I suppose if a heavily melanized gut got smeared all over their feathers during preservation it could affect our interpretation.

[Sim]

A heavily melanised gut wouldn't have had to be smeared all over the feathers of a Microraptor, it would have had to do this on every Microraptor specimen with well-preserved feathers that I've seen as they all have dark feathers.  The paper in the first post of this thread says this is unlikely:

Importantly, preservation of non-integumentary melanosomes
does not necessarily preclude preservation of original
integumentary colour patterning (Fig. 4c), especially where melanosomes
have not redistributed and in body regions where
redistribution is unlikely. The latter includes feathers that do not
overlap the torso, in particular where melanosomes are localized
to the barbules and are embedded in an organic matrix, i.e., the
degraded remains of the feather keratin.

Also, see Reply #1521 and the Dinogoss blog post linked to in it for more info on fossil feathers showing colouration they had in life: http://dinotoyblog.com/forum/index.php?topic=3573.msg173811#msg173811