Feathers on large ceratopsians?

[amargasaurus cazaui]

That is one possible interpretation of the  fossil, but it asks then...why do they all seem to have the exact same distance ,ending or origin location within the skin envelope....single file as well, in one line, and not even slightly mixed or distorted below the apparent skin ....
  If this is the product of taphony and is not as we can actually view it, shouldn't the beginning and entire sequence be more jumbled and perhaps less well symmetrical?
   I think it is an interesting possibility and has some potential....wish the specimen could somehow be studied from the other aspect with x ray or other methods to give a better view of the areas hidden within the rock.

[Dinoguy2]

If that were the case wouldn't we see the scales and pigments preserved on them the same we way we see them on the bones?

We do see that, on the bottom 4cm of quill that is being overlain by the body outline. Some people (including apparently the authors of the original 2002 paper) seem to be misinterpreting this as the quills being INSIDE the body. But there's no way this can be true (see below).

That is one possible interpretation of the  fossil, but it asks then...why do they all seem to have the exact same distance ,ending or origin location within the skin envelope....single file as well, in one line, and not even slightly mixed or distorted below the apparent skin ....
  If this is the product of taphony and is not as we can actually view it, shouldn't the beginning and entire sequence be more jumbled and perhaps less well symmetrical?
   I think it is an interesting possibility and has some potential....wish the specimen could somehow be studied from the other aspect with x ray or other methods to give a better view of the areas hidden within the rock.

Why would that be the case? If the quills are in a single file row emerging from the dorsal skin, and the dorsal ridge of skin is being overlain by the side of the body envelope (which it unquestionably is since the fossil is preserved in oblique ventral view), we should expect the quills to appear to emerge in a single file row behind the tail. Which is exactly what we see. I don't know what makes you think they should be jumbled. The Vinther et. al quote I posted states that compression fossils like this show minimal overall distortion, being basically a 2D translation of what was originally a 3D animal. The bones themselves are not jumbled other than the tail vertebrae being twisted inside the flesh envelope to a lateral view. In fact, if the tail vents are twisted, and the quills did anchor at or near the vertebrae, then you would expect them to have rotated at least partially with the vertebrae themselves when they became twisted, and be bent and jumbled out of shape, because they would have to have somehow twisted THROUGH the skin and muscle, which did not twist and is preserved in the same aspect as the rest of the body! (As evidenced by the location of the pubic callous and cloaca). It is far, far more likely that the quills anchor in the skin in a single row on the dorsal ridge of the tail, which is preserved behind the rest of the fossil. The only alternative I can think of is that Psittacosaurus had a single row of hollow quills that somehow grow from the muscle tissue (??) and stick out laterally, not dorsally, and apparently only on the right side of the tail!

For anybody who is having trouble following what I'm talking about here, imagine that the specimen had been wearing a conical birthday party hat when it died. The dead body rolled over on its back and got flattened by geological compression over time. When we dig up the fossil and see half a point sticking out above the head with the rest of the cone visible through the skin and bones of the head, which is more likely? That the hat got squished and is partly buried behind the head, or that the hat is actually growing from within the skull?

Edit: Here's a very quick and rough sketch in Photoshop which shows what is going on in the fossil according to Vinther et al. and how it translates to a "normal" side view of the dinosaur in life.

[Cloud the Dinosaur King]

That diagram is incorrect in many, many ways.

Psittacosaurus quills are not in any way related to the quills associated with early feathers, or the quills of Tianyulong. They are entirely distinct.

The quills of Tianyulong and "fluff" of Kulindadromeus may share a common physical ancestor with theropods, or that ancestry may be entirely genetic.

There aren't any filamentous feathers known from Megalosauroidea, I'm going to assume this a dated element rather than an extremely liberal assumption because Kulindadromeus is not included in the chart and it's probably the best evidence of a potential "feathered" ancestor within dinosauria.

See my post here:
http://dinotoyblog.com/forum/index.php?topic=5543.msg166530#msg166530

If you look at the feather of a bird, the middle shaft is a quill. Quills on ornithoscelidans are simply these feathers minus the parts that extend from the quill.

Quills = feathers lionfish are birds confirmed. Not everything called a damned quill is a feather shaft, the term is more literary than it is scientific.

They aren't related to feathers. These are morphologically distinct structures.

Lionfish quills are actually venom glands.

[Cloud the Dinosaur King]

Of course, porcupines are birds! What are you talking about?

Porcupine quills  are stiffened hairs, not actual bird feather quills.