dino news: mummified dinosaur tail found in amber. Has ACTUAL 3D FEATHERY FEATHERS

faetal on 13/12/2016 at 20:36

I'm with Vivian on this. Not seeing feather-like structures at heat exchangers at all.
They're nothing like large ears morphologically either, so no idea where that comparison comes in.

Pyrian on 13/12/2016 at 20:47

Quote Posted by faetal

Not seeing feather-like structures at heat exchangers at all.

Okay. Why not?

Quote Posted by faetal

They're nothing like large ears morphologically either, so no idea where that comparison comes in.

Insert Dumbo joke here. Really, you're going to have to elaborate, because I think I've made my point clear and I don't see either where you've missed it or where you're disagreeing with it.

Vivian on 13/12/2016 at 21:51

So you're mooting that feathers first evolved in multi-tonne theropods as blood-filled fan structures that they used to dump heat. Coelurosaurs don't start as giants, and there haven't been any large-bodied dinos found with feathers really at all. What you got in support?

SubJeff on 13/12/2016 at 22:02

Interesting debate.

Where do you stand on the "should we clone/raise from extinction" Viv?

faetal on 13/12/2016 at 23:18

Quote Posted by Pyrian

Okay. Why not?

Because they are really quite awful at heat exchange. If they weren't, eiderdowns would be awful to sleep under.

Quote:

Insert Dumbo joke here. Really, you're going to have to elaborate, because I think I've made my point clear and I don't see either where you've missed it or where you're disagreeing with it.

Elephant ears aren't branched and filamentous. Probably because if they were, they'd trap in too much heat. One of the most important aspects of heat exchange is rapid diffusion away from the site of heat exchange. Elephant ears are great because the entire plane of heat exchange is touching nothing but vast empty space, whereas with feathers, your heat would be exchanging in a billion different directions at once due to the lack of rigidity and a good amount of your heat would be heading straight back to where it came from, or transferred to an adjacent filament. The problem being that heat exchange works both ways, so you actually conserve heat that way (not infinitely, but probably would lose it more slowly than just having skin there). The best way to get rid of heat is to have a panel which sends it all off into general diffusion with the surrounding air, which allows for a better gradient for subsequent heat loss. Of course, a homeotherm like an elephant will also have some nice crafty mechanisms like vasodilation / vasoconstriction to determine how much heat exchange is going on in those ears. I doubt (will probably need Vivian to confirm) them dinos had such sophisticated stuff going on.

It's all sounding a little specious at present. First up - what is the temperature data (cyclical if possible) for the region the animal was believed to be living in? Secondly, which feathered structures are still present for the purposes of exchanging heat with air?

faetal on 13/12/2016 at 23:26

Here is a simple list of things feathers are useful for: (https://askabiologist.asu.edu/content/23-functions-feathers)

Note that cooling down is only mentioned in the context of moving extremities out of feather coverage.
This raises an interesting point which I guessed at earlier (though worded it atrociously). If dinosaurs were living in generally hot areas but they grew cold by night (which as anyone with a decent understanding of physiology can tell you, always hits the little guys harder due to the the surface area-to-volume heat loss dynamic), it would certainly be of benefit to have some insulating material which could be used in a specific posture to slow heat loss. In fact, the more I think about it, the more it's obvious that if it was a pressure to lose heat, the little dinosaurs would have less need of it than the bigger competitors, so that thought pushes me even farther in that direction.

Vivian on 14/12/2016 at 11:07

Quote Posted by Pyrian

Bird lungs are fascinating, but it's a lot easier to see how they could have evolved from the need to supply a great deal of oxygen to a very large body, than to see how they could have evolved from a heat-dispersal capacity. The cross-current is more suited to heat retention. From a thermodynamics perspective, a captive air supply just isn't a good place to try to radiate even more heat into.

Not the lungs, the air sacs. Big big surface area, tidal flow (the bit with the monodirectional flow is only the lung itself). Also, the air isn't captive, it definitely gets dumped into the environment (thats what the whole breathing out thing entails...). Air sacs = cooling is something I learned as dogma, I will admit, but the physics stacks, and here's some old data on pigeons (interesting actually, suggests they route air away from the actual lungs when they hyperventilate for cooling purposes, to avoid excessive CO2 loss): (http://www.pnas.org/content/55/4/750.short)

So, you've got a cooling system that exists in modern dinosaurs (the air-sac system) and that there is also convincing evidence for in most theropods ((http://www.nature.com/nature/journal/v436/n7048/full/nature03716.html)), and you've got an insulation system that exists in modern dinosaurs (feathers) that there is also convincing evidence for in many theropods (probably all coelurosaurs at least), and you're suggesting that the air-sac system didn't do cooling, and that the feathers didn't do insulation, instead they retained their developing form throughout their use-life, and they acted as radiators. Both of those are not parsimonious hypotheses. And then there is the whole volume/surface area problem and the lack of extreme feathering in big theropods. I think you've got something that's more of a speculation than a hypothesis, to be honest.

I also can't find anything on heat loss from developing feathers, what you basing that on?

Vivian on 14/12/2016 at 11:40

Quote Posted by SubJeff

Interesting debate.

Where do you stand on the "should we clone/raise from extinction" Viv?

For what, non-avian dinosaurs? There's Jack Horner's chickenosaurus thing (which is proper mad science, I'm not sure I agree with it: (http://www.livescience.com/50886-scientific-progress-dino-chicken.html)), but otherwise it's not going to happen. For mammoths and stuff, I dunno - it's an interesting idea, and part of me thinks why not? But I'm dubious, there's loads of epigenetic stuff you'd miss... this is more neontology stuff really - Faetal, what's your take?

Vivian on 14/12/2016 at 11:45

Quote Posted by faetal

Of course, a homeotherm like an elephant will also have some nice crafty mechanisms like vasodilation / vasoconstriction to determine how much heat exchange is going on in those ears. I doubt (will probably need Vivian to confirm) them dinos had such sophisticated stuff going on.

eesh, no evidence in extinct guys for anything like skin vascularisation patterns (that I know of). But see above, living dinosaurs control heat loss by adjusting the ventilation rate of selected parts of their pulmonary system, which is sort of equivalent in terms of fluid flow control?

demagogue on 14/12/2016 at 13:13

Well while we're on the topic, I have a question that I'm sure I could answer with a 20 second Google search but I'm trying to rekindle this whole human contact thing so here goes...

A few years ago I recall a popularish article that reported on a small tree-bound rat monkey-like creature which was important because it was right in the neighborhood of the line that would go on to become hominids, I don't remember how far back but it was in the millions to 10s of Ms of years ago, which was a humbling thing to read about since usually we're only told about past homo lines or at the furthest when humans and great apes separated, but we're almost never told about really ancient lines leading up to humans. So my question is, if I were to follow my ancestors back, what kind of creature might I run into say in the Jurassic Era? Doesn't have to be exactly, but in the ballpark. Is that kind of thing something we know anything about?