Obviously I have covered feathers on dinosaurs here several times, so it’s about time we looked at non-feather integuments, or to be less jargon-y, skin. This picture is of a rather nicely preserved piece of dinosaur skin on display at the Geological Museum of China. Sadly they don’t list which taxon or fossil site it is from and I keep forgetting to ask them. However, based on its size (the small scales are only a couple of millimeters across), similarity of form to others in the clade and frequency of the specimens in the formation from which most of the museum’s specimens come, I suspect it’s a ceratopsian of some kind, quite probably Psittacosaurus.
I’m no expert on skin so I could be wrong, but the important point here is that a) it looks nice, b) it therefore shows off just how good evidence we have for what some dinosaur skin looked like, c) how good the fossil preservation is and d) what the actual pattern of the skin was like. Here at least you can draw a great deal of information on skin and scale pattern and structure. What you can’t do however is say exactly what animal it came from, or from what part of the body.
This piece is in isolation – it’s just a piece of skin on a rock. As such despite it resembling ceratopsians (to my eye at least, or even if we had a pretty much exact match to another known taxon) we really can’t say for sure what it came from. Nor do we know where on the body it would have gone – we can probably rule out the soles of the feet and the head but after that it could be leg, tail, back, even belly. This is important as of course there are significant variations in skin patterns not just in modern reptiles but birds too and also in dinosaurs. As such, it’s good, but hardly great, though still worth enjoying.
Dave Hone's Archosaur Musings 
Actually, this would be a post about dinosaur scales; not dinosaur skin. The skin would be under and between the scales, as exemplified by this snake eating an egg: http://thescienceexperts.com/wp-content/uploads/2008/11/snake-eats-egg.jpg
Sorry, but this has become a pet peeve of mine. Non-feathered dinosaurs weren’t naked. They were scaly.
I’m sorry but I don’t buy this. The scales are integral to the surface of the skin. If you were to ‘skin’ a lizard you would peel off the dermis, epidermis and the scales. Scales are a specialised part of the integument (as indeed are feathers, hair, glands and so on) but they are still part of it. According to my vertebrate anatomy (Kardong) book scales are “a fold in the surface edpidermis, hence, an epidermal scale”. It’s part of the epidermis and thus part of the skin.
To be less techy, there is more than just scales in that image, but also the spaces *between* the scales which would represent the underlying skin.
I have to disagree there. You can, theoretically, descale a lizard. The result might be a bloody mess, but there will be skin left over in the end. That scale formation tends to get simplified as “a folding of the epidermis” does not do justice to its complexities. There are certain reptilian pathologies that result in localized, and sometimes even full body, scale loss. There is skin left over when the scales fall off. There are even certain genetic mutations that result in snakes and lizards being born without any scales. They wind up with loose, wrinkly skin much like that of hairless dogs and cats.
For instance: http://media.photobucket.com/image/%252522scaleless%20snake%252522/GONESNAKEE/Pictures%20of%20others%20snakes/WeirdSnake.jpg
There have even been a couple of papers related to the subject.
Light, P. and Bennet, A.F. 1972. A Scaleless Snake: Tests of the Role of Reptilian Scales in Water Loss and Heat Transfer. Copeia 4:702-707.
Toni, M., and Alibardi, L. 1992. Soft epidermis of a scaleless Snake Lacks Beta-Keratin. European Journal of Histochemistry. 51(2):145-151.
But this does not stop the scales being *part* of the epidermis and by extension (and definition) part of the skin. Sure there is skin left over if you peel off the scales just as there is when you peel off own epidermis when you get a skin scrape – you are losing *part* of the skin. Just because you can breed an animal without scales does not make them not part of the skin, just as finding a lizard with missing toes say does not make them not part of the leg.
That’s more or less what Carnotaurus’ skin looks like, too. Small scales with haphazardly-placed osteoderms scattered about.
I’d say the larger scales were fairly evenly distributed here rather than ‘haphazard’, but that’s largely a quibble of language more than anything else.
”Small scales with haphazardly-placed osteoderms scattered about.” From the skin and scales I have seen that seems to the idea of dinosaur skin in general, what differs is the frequency of the extra large scales/osteoderms and the overall size of the scales in relation to the animal, Hadrosaurs having the smallest, sauropods and advanced ceratopsians having the largest.
In the bottom right of the photograph the scales look square-ish in shape. In a SVP abstract Bakker described some Triceratops skin that shows square belly scales. Maybe the skin patch is showing the side of the animal transitioning into the underbelly? Do those square scales carry on much further past the edge of the photograph?
No they don’t carry on really. I cropped that image to the maximum size I could but it basically overs the whole of the available specimen (only a few bits lie outside what you can see here).
Small scale pattern seems generally to indicate theropod dinosaur (granted I’m really only familiar with Hell Creek skin samples) but the large raised “scales” are reminiscent of other ceratopsian skin. If this is psittacosaur or some other relative I would not be surprised. Truly a beautiful piece of skin, I say skin and not scales because shape alone is not enough to determine the make-up of the dermal layer and what may have covered it. What’s to say, given their lineage, that what appears as scales are no more than modified feathers, I also then pose the inverse, what if modern feathers are nothing more than modified scales.