Preen Glands or Powder Down?

[ZoPteryx]

I've been reading The Unfeathered Bird by Katrina van Grouw (a must own btw!) and, amongst other things, I've learned just how freaky preen glands look.  Preen glands are those odd little bulbs under the skin at the base of the tail that secrete oils used to maintain a bird's feathers.  Powder down is downy feathers that are constantly disintegrating which produces a powder that is used for feather care in some other birds.  My question of coarse is, which system, if any, did are extinct feathered dinosaurian friends use?  Did they even have specialized mechanisms for feather care, or did they just rely on dust baths?  If they didn't use any sort oils, were their feathers not waterproof?  Do we know anything about this sort of stuff for certain?!

Thanks!

[wings]

...If they didn't use any sort oils, were their feathers not waterproof?  Do we know anything about this sort of stuff for certain?!

Just in case if you are interested,

"...a number of studies over the past century have shown that even aquatic birds like the Tufted Duck (Aythya fuligula) can apparently maintain waterproofed, well-groomed plumage if their uropygial glands are removed when they are hatchlings (Fabricius 1959)..."(Proctor & Lynch 1993)

References
Fabricius, E.1959. What makes plumage waterproof? Rep. Waterfowl Trust 10: 105-113. (you can find it here http://wildfowl.wwt.org.uk/index.php/wildfowl/article/view/107/107)
Proctor, N., and P. Lynch. 1993. Manual of Ornithology: Avian Structure and Function. Yale University Press.

[ZoPteryx]

I was unaware of that, thanks for sharing Wings!

[wings]

From reading the paper it seems like almost all feathers (perhaps except for bristle and filoplume) are waterproof (even feathers without barbules to hold its shape, like down and semiplume); as long as the overall shape is not broken...(trap air, provide insulation, prevent water to soak through)

Unfortunately having said this, it doesn't quite answer the original question which is about the function of this oil gland... is it completely pointless in having the gland? Probably not, since as you read on about the experiments by Hou, Madson or Elder that the birds with their oil glands removed would bite their feathers to the point which these feathers become "non-waterproof" (broken barbs, barbules and "shape").

[Dinoguy2]

As for fossil evidence, I don't think any fossil feathers are well-enough preserved (or studied well enough) to show evidence of powder down, though I do recall those Cretaceous non-neornithean feathers trapped in amber as showing evidence of waterproofing similar to those found in modern diving birds. But we have no idea what species these came from.

Oil glands, we may never find. Heck, we have yet to find non-bony evidence of a rectorial bulb, even in really good fossils of avialans we're pretty sure would have had one, and that's a huge mass of muscle surrounding the pygostyle. I wouldn't hold my breath for preserved evidence of glands.

[ZoPteryx]

Very interesting.  I guess our only hope is to find a tiny enantiornith preserved in amber.

[wings]

...Cretaceous non-neornithean feathers trapped in amber as showing evidence of waterproofing similar to those found in modern diving birds...

Oil glands, we may never find. Heck, we have yet to find non-bony evidence of a rectorial bulb, even in really good fossils of avialans we're pretty sure would have had one, and that's a huge mass of muscle surrounding the pygostyle. I wouldn't hold my breath for preserved evidence of glands.

Just curious to know, what evidence of waterproofing do we have from these feathers that you are referring to? Is it something structurally or chemically that is unique to diving birds' feathers that was shown on these preserved feathers?

Too bad there isn't a study on the association of the rectorial bulb and the uropygial gland; for now I suppose you probably can have one and/or another.

[Dinoguy2]

...Cretaceous non-neornithean feathers trapped in amber as showing evidence of waterproofing similar to those found in modern diving birds...

Oil glands, we may never find. Heck, we have yet to find non-bony evidence of a rectorial bulb, even in really good fossils of avialans we're pretty sure would have had one, and that's a huge mass of muscle surrounding the pygostyle. I wouldn't hold my breath for preserved evidence of glands.

Just curious to know, what evidence of waterproofing do we have from these feathers that you are referring to? Is it something structurally or chemically that is unique to diving birds' feathers that was shown on these preserved feathers?

IIRC it was something in the microstructure but i'd have to double check the paper.

[wings]

IIRC it was something in the microstructure but i'd have to double check the paper.

Hopefully you can list the paper though; would be an interesting read.

[Dinoguy2]

IIRC it was something in the microstructure but i'd have to double check the paper.

Hopefully you can list the paper though; would be an interesting read.

Looks like I had this backwards - the feathers have coiled basal barbules, which in modern birds is an adaptation to *absorb and retain*, not protect from it. Modern birds use it to transport water to chicks and to absorb water to help diving birds sink.

The paper is actually available online at the moment:
http://faculty.eas.ualberta.ca/wolfe/eprints/McKellar_Amber_feathers2011.pdf