2 questions...

[darylj]

im not sure if these have already been discussed on the site, but i cant find them?

what are peoples opinions on -
pre-dinosaur archosaurs have feathers of any kind? (ive not looked into this an awful lot, so there may be common knowledge regarding this)
and
the possibility of sauropods (and possibly all dinosaurs) possesing feathers of some kind? (in the way that all mammals posses hair, even if it is only very small amounts, like in elephants)

[Sharptooth]

As far as i know we don't have proof that archosaurs had feather-like integument; we know that rauisuchids, aetosaurs and such had an extensive covering of croc-like scales (afterall they were closer to crocs than dinosaurs), but what about silesaurids and all the other protodinosaurus? Is it really incorrect to guess that, maybe, hairy protofeathers developed among them? I wouldn't totally deny it, even if i wouldn't be totally sure of it...

About feathers in sauropods, well... I'm generally against it considering we know that, according to those titanosaurs' embryos found in South America, they were scaly since birth, but again, i wouldn't mind if we'll eventually discover that some of them had sparse "fuzz" poppin' out here and there (nothing too big or flashy, mind you; something like in elephants or even less).

[darylj]

I totally agree that i dont think (or want) sauropds to have had full coats of feathers / fur.
all im thinking is that - all mammals have fur... and even the mammals that no longer need fur have not fully lost it.

so if protodinosaurs had feathers and the first dinosaurs had feathers, then it would make sense that feathers in some sense were present in all dinosaurs?
the reason sauropods fascinate me in this topic is because of historical and present media, it is increasingly easy to imagine theropods, ceratopians, and even hadrosaurs with some kind of feather / fur features.
however, when you try and picture a sauropod, all that springs to mind is saggy or scaly skin.

im thinking that maybe a little bit of head gear in the way of display feathers is a major possibility

[SBell]

I totally agree that i dont think (or want) sauropds to have had full coats of feathers / fur.
all im thinking is that - all mammals have fur... and even the mammals that no longer need fur have not fully lost it.

so if protodinosaurs had feathers and the first dinosaurs had feathers, then it would make sense that feathers in some sense were present in all dinosaurs?
the reason sauropods fascinate me in this topic is because of historical and present media, it is increasingly easy to imagine theropods, ceratopians, and even hadrosaurs with some kind of feather / fur features.
however, when you try and picture a sauropod, all that springs to mind is saggy or scaly skin.

im thinking that maybe a little bit of head gear in the way of display feathers is a major possibility

We aren't at a point where early, stem-dinos had feathers. There are indications of early theropods with feathers, but the few structures found on ornithischians aren't really 'feathers'. So at this point, it is mostly unlikely that feathers would have shown up on anything other than theropods.

It is also possible, if the earliest stem dinos had feathers, that the feature coul dhave been lost entirely in the radiation of the saurischians into theropods and sauropods. In which case, until something incontrovertible (or at least highly definitive) shows up on a sauropod or prossauropod, it is probably less correct to depict any kind of feathering on a sauropod.  Even the 'scaly fins' on images such as the WwD Diplodocus are mostly speculative. But they look cool.

[darylj]

with the recent discovery of Yutyrannus along with feathered raptors and the therizinosaurs, it would seem that feathers originated somewhere before the common ancestor of all of these dinosaur lines.

I just think that... lets say for example, theropods. I am under the assumption that feathers evolved first, simply because if theropods had already started to become diverse and become the dominant land predators etc... then why would feathers begin to appear?

do people have opinions of why feathers would have originated in the first place?

It seems that since they first appeared they have not evolved again since, but merely continued to be passed on from species to species.

[SBell]

with the recent discovery of Yutyrannus along with feathered raptors and the therizinosaurs, it would seem that feathers originated somewhere before the common ancestor of all of these dinosaur lines.

I just think that... lets say for example, theropods. I am under the assumption that feathers evolved first, simply because if theropods had already started to become diverse and become the dominant land predators etc... then why would feathers begin to appear?

do people have opinions of why feathers would have originated in the first place?

It seems that since they first appeared they have not evolved again since, but merely continued to be passed on from species to species.

Given that therizinosaurs, tyrannosaurs and maniraptors are essentially in the same lineage as birds (a derived theropod lineage), it's not much of a stretch. They are essentially one group within the theropod lineage.  Trying to extend back to sauropods or all dinosaurs (or even all theropods) is a much bigger cladistic leap until we have some kind of supporting physical evidence.

To illustrate, this image:
http://theropoddatabase.blogspot.ca/2012/05/amazing-new-tetanurine-paper.html


The lineage labelled Coelurosauria is where pretty much all of the feathered dinos come from.  Not exactly a dinosaur-wide feature. Unless we find, say, a spinosaur or Herrerrosaurus with feathers (or something like them). As it is, the only one I am immediately aware of is quill knobs on the arms of Concavenator--still not dinosaur-wide, and still not going to have much bearing on sauropods, but indicative of an earlier presence within theropods.  If the Psittacosaur (ceratopsian) and Tianyulong (ornithopod) quills can be demonstrated to be feathers or related, then it would very likely indicate an early dinosaur connection--although sauropods could still be a lineage that lost them as they evolved from prosauropods; until positive evidence is found, the question could go either way.

Of course people have opinions on why feathers evolved. People have opinions on everything.  But there is a pretty well-documented body of research on what some of the selective pressures were. I'm not going to go into it, as a simple google search will find lots (beware the BANDits though).

[darylj]

good response... enjoyable read. appreciate that.
and I like the image... its very helpful seeing it broken down like that.

I often google theories / ideas... and seem to come across an increasing ammount of... lets say.. garbage. lol.

the ceratopsian feathers / quills does interest me.. more now youve mentioned it.
but then so does the thought of a feathered spinosaur. (it really could have been a giant heron!?!) lol.

[Sharptooth]

By the way Sbell, i recently re-read the original description of Tianyulong, and it surprised me that it doesn't really talk about "fuzz", but more of quills similar to the Psittacosaurus' ones; and someone here on this forum (Griffin, if i remember well) mentioned that maybe Psitta's quills could have been elongated scales... Maybe Tianyulong was like an "echidna-saur" of some sort?

[Metallisuchus]

As far as I know, feathers didn't exist until sometime during the Jurassic Period. I think they probably evolved in a single species and branched out from there, though I don't know much about this, admittedly.

With that said, I wouldn't imagine sauropods to have had feathers as they weren't descendants of any feather-bearing dinosaur that we know of.

[Gryphoceratops]

Yeah as far as I know the "quills" on psittacosaurus and tianyulong were highly modified thin scales rather than actual feathers or feather quills.  I gotta see if I can get the source for this information still.  Did tianyulong actually have a fuzzy covering on the rest of its body or is that just what the artist decided to depict in that one illustration and everyone else just took it as fact and went nuts?

Last year there was an article in National Geographic about the history of feathers.  They said that the origin of feathers starts a lot earlier than when they previously thought.  I remember the line from the article was something like "its not about how feathers were gained in theropod dinosaurs but rather how feathers were lost in other archosaurs."  You should be able to hunt it down on the internet fairly easily. 

Either way there are plenty of really well preserved specimens of ornithiscian dinosaurs like corythosaurus, triceratops and edmontosaurus with skin and other soft tissue with no evidence of any feathering of any kind.  There are also skin bits from theropods like carnotaurus and allosaurus showing no evidence feathering.  That being said until actual evidence is found its safest to keep the feathers off of most dinosaurs other than the coelurosaurs. 

[paleofreak]

By the way Sbell, i recently re-read the original description of Tianyulong, and it surprised me that it doesn't really talk about "fuzz", but more of quills similar to the Psittacosaurus' ones

They are also similar to the Beipiaosaurus ones. They seem to be a dense covering of the body (or a big part of the body). And their structure fits the stage-I protofeathers predicted in the Prum & Brush model of feather evolution. So, the most parsimonious explanation is that they are protofeathers, and not an independent re-evolution of unbranched filaments.

[Gwangi]

Yeah as far as I know the "quills" on psittacosaurus and tianyulong were highly modified thin scales rather than actual feathers or feather quills.  I gotta see if I can get the source for this information still.  Did tianyulong actually have a fuzzy covering on the rest of its body or is that just what the artist decided to depict in that one illustration and everyone else just took it as fact and went nuts?

Last year there was an article in National Geographic about the history of feathers.  They said that the origin of feathers starts a lot earlier than when they previously thought.  I remember the line from the article was something like "its not about how feathers were gained in theropod dinosaurs but rather how feathers were lost in other archosaurs."  You should be able to hunt it down on the internet fairly easily. 

Either way there are plenty of really well preserved specimens of ornithiscian dinosaurs like corythosaurus, triceratops and edmontosaurus with skin and other soft tissue with no evidence of any feathering of any kind.  There are also skin bits from theropods like carnotaurus and allosaurus showing no evidence feathering.  That being said until actual evidence is found its safest to keep the feathers off of most dinosaurs other than the coelurosaurs.

I'm pretty much on board with all of this. One thing no one has mentioned yet is the pycnofibers on pterosaurs which I believe adds some evidence to the notion that even if a body covering was not present on the first archosaurs it may have been present on the first Avemetatarsalia (the group containing both dinosaurs and pterosaurs). Either that or pterosaurs, coelurosaurs and ornithischians all evolved some sort of body covering independently of each other which would be equally as shocking I think.
There is an old Tetrapod Zoology post that discusses possible evidence for feathers on Dilophosaurus (or similar animal) which I find interesting but am still skeptical about. Also of interest is the theory that rather than feathers evolving from scales perhaps scales (scutes actually) evolved from feathers. Here is an interesting article about it but it is a bit dated. It adds support to the statement "its not about how feathers were gained in theropod dinosaurs but rather how feathers were lost in other archosaurs."

[darylj]

The pterosaur point really interests me. This would suggest a very early origin for feathers.
I find merit with every post so far, but i still wouldn't be shocked if tomorrow we doscovered that sauropods had 'feathery manes'... 

Are there any other theories regarding pterosaurs? like for instance ideas about them being more closely related to certain lines of dino?

[SBell]

The pterosaur point really interests me. This would suggest a very early origin for feathers.
I find merit with every post so far, but i still wouldn't be shocked if tomorrow we doscovered that sauropods had 'feathery manes'... 

Are there any other theories regarding pterosaurs? like for instance ideas about them being more closely related to certain lines of dino?

Pterosaur aren't dinosaurs at all--if they were closer related to one group than another, they would be dinosaurs.  As for the integument, it is not feather-like at all.  It turns out that a reptilian scale has a lot of potential variation.

[Sharptooth]

And what if... (not saying it's how i see it, bear in mind)... pterosaurs are just another type of dinosaurs as Bakker suggested in '86?

[darylj]

yeah thats more what i was thinking. im well aware that pterosaurs are not dinosaurs... but... what if they are another line of dinosaur?
thats all i meant be - has there been any theories on pterosaurs bearing any resemblance or any signs of a potential common ancestor with any dinosaur lines?

[SBell]

And what if... (not saying it's how i see it, bear in mind)... pterosaurs are just another type of dinosaurs as Bakker suggested in '86?

No. Absolutely not.  If a conversation is going to be taken seriously, I wouldn't recommend invoking Bakker hypotheses.  For every hit he had (keeping in mind, most of those were really other people's work that he was just much better at publicizing) there is a lot of way-out insanity in his 'theories'.

This article has a pretty succinct explanation of why it couldn't work (or why we would need to expand the meaning of 'dinosaur' to ridiculous extremes, I suppose):
http://blogs.smithsonianmag.com/dinosaur/2010/11/why-a-pterosaur-is-not-a-dinosaur/

[Horridus]

And what if... (not saying it's how i see it, bear in mind)... pterosaurs are just another type of dinosaurs as Bakker suggested in '86?

I don't think anyone takes that idea seriously anymore, if they ever did. You'd have to redefine the Dinosauria to be much broader...and a name for such a clade already exists.

[Gwangi]

Yup, Avemetatarsalia unites the two groups together well enough as it is, there is no need to re-classify pterosaurs as dinosaurs. Still though, the two groups are related. Pterosaurs are the closest relatives to the dinosaurs and I think that some sort of body covering could have arisen before the two groups split. This is not a notion I'm sold on (but I really like). I don't really know enough about feathers and integument to formulate an opinion. There is a good write up titled "Plucking at the idea of feathered dinosaurs" on the blog Reptilian Rants. I would read it with a grain of salt, there are certainly some thing I personally don't agree with but he makes some good points. The most interesting part of the article would have to be where he discusses three hypothesis for the evolution of archosaur integument. He mentions all the groups for which we have scale impressions rather than feathers and it is a big list. Ceratopsians, hadrosaurs, ankylosaurs and some theropods like Carnotaurus for example. If some sort of fuzzy integument were a plesiomorphic trait (not feathers mind you as pterosaurs did not have feathers) for Avemetatarsalia then that means that this integument was lost at least 7 times as opposed to convergent evolution evolving fuzzy integument 4 times in the groups that we know had them. In the end it could go either way but I don't think there is enough of a consensus one way or the other. This is a case where you just need to read the conflicting evidence for yourself and decide from there how you feel about the issue until more evidence is found.

[Horridus]

"To put it another way, the chances of a scaly dinosaur with a feathery mohawk, are extremely unlikely."

Hear that, toy manufacturers?

Much as I like the quote, the comment thread is worth a read on that article.