How colourful were dinosaurs.

[Darwin123]

Even if his back yard does include alligators and crocodiles, they are still not as closely related to dinosaurs as are birds.

My mistake. I meant to say:

Unless your backyard includes alligators or crocodiles, the birds are not as closely related to them as non avian dinosaurs.

Suppose that his yard contains a lizard, a snake, a turtle, a bird and an alligator. Both the bird and the alligator are closely related to some non avian dinosaur. The lizard, the snake and the turtle are not so closely related to the same non avian dinosaur.

Crocodilians definitely have some sort of pigment. I saw an albino alligator at my local aquarium a few years ago. She had pink eyes and translucent scales. The advantages of pigment were quite obvious in her limitations.

Oleander the Alligator would have died in the wild. The aquarists had to light her tank with a special type of light which did not contain any UV. She situated to ambush some turtle. She stuck out like a white thumb. Normal alligators look like logs.

So very obviously pigment must have evolved long before there were dinosaurs or birds. Pigment doesn't have to be present in feathers, but the animal will die without it. Skin pigmentation could have migrated into feathers. It would only be a matter of the genes for pigmentation being turned on and off at the right times.

Iridescence requires microscopic features. So iridescent colors in feathers had to evolve after feathers had evolved. Structural color in feathers had to evolve separate from the pigmentation. Lizards may have iridescence in their scales, but feathers did not emerge from lizard scales.

The theory that feathers are modified lizard scales has largely been disproved. Feathers and lizard scales evolved from different basal structures. So structural color in lizards could not have eve evolved in structural color in birds.

 

[Jrrarglblarg]

Is there anybody who doesn't think we need to start cloning dinosaurs?

*raises hand*

Uh, actually, I have this business plan involving herds of Parasaurolophus in Argentina?

 

[Rincewind]

Is there anybody who doesn't think we need to start cloning dinosaurs?

But... Don't you remember what happened when Hollywood did that?

 

[Roboramma]

My mistake. I meant to say:

Unless your backyard includes alligators or crocodiles, the birds are not as closely related to them as non avian dinosaurs.

Suppose that his yard contains a lizard, a snake, a turtle, a bird and an alligator. Both the bird and the alligator are closely related to some non avian dinosaur. The lizard, the snake and the turtle are not so closely related to the same non avian dinosaur.

Again, birds are more closely related to all dinosaurs than any dinosaur is to crocodiles:

http://en.wikipedia.org/wiki/Avemetatarsalia

Avemetatarsalia (meaning "bird metatarsals") is a clade name established by British palaeontologist Michael Benton in 1999 for all crown group archosaurs that are closer to birds than to crocodiles.[1] It includes a similarly defined subgroup, Ornithodira. An alternate name is Pan-Aves, or "all birds", in reference to its definition containing all animals, living or extinct, which are more closely related to birds than to crocodiles. Members of this group include the Dinosauromorpha, Pterosauromorpha, and the genus Scleromochlus. Dinosauromorpha contains more basal forms including Lagerpeton and Marasuchus and more derived forms including dinosaurs, which according to most modern scientists the birds belong to as members of the theropods. Pterosauromorpha contains Pterosauria, which as far as is known were the first vertebrates capable of true flight.

There are some dinosaurs that birds are more closely related to than other dinosaurs, but there is no dinosaur that is more closely related to a living non-bird than it is to a bird.

 

[Varanid]

Here's my favorite XKCD comic germane to this thread. It's literally my favorite one ever. I still chuckle every time I read it.

https://xkcd.com/867/

It would be interesting to investigate the link between visual acuity, color perception and the color development for sexual selection.

Birds have quite good eyesight, but most non-avian reptiles do not. However, many lizards rely on color-coded social cues.

 

[Dinwar]

If my understanding is correct, dinosaurs and crocodilians came from different groups of archaeosaurs (I may be off here, as recently I have focused on mammals). Birds ARE dinosaurs, which means it is retry hard (but not impossible) to be outside the Dinosaurian and be more closely related to things inside the Dinosaurian but not birds then the dinosaurs are to birds. The very earliest dinosaurs my fit the bill, but that would be about it. Modern crocs are FAR more distantly related to dinosaurs than birds.

As for why Horner picked emus, it was for specific physiological reasons. He is not allowed to bring them to full term (federal laws prevent it), so aesthetics are irrelevant. Plus, what constitutes a good-looking critter differs from person to person. Borophagus is not, to most, an attractive animal, but I would get mauled while looking at it (happened in Skyrim first time I saw a mammoth....).

As for cloning dinosaurs, we can't. Too many gaps in the DNA we have. What we can do is create monsters that sorta look like dinosaurs. Plus, many were communal, living in packs, small family groups, or herds. Even if we get the genetics right. (There is no way to know) we cannot reproduce the behaviors that the young would rely upon, or the behaviors of the adults. It would be akin to having a dog and trying to raise him as a chicken, then trying to learn about dogs that way. The laws of taphonomy be a harsh mistress.

 

[Dinwar]

So according to he book I have with me on the evolution of vertebrates, crocs are the only surviving archosaurs (again, paleontologists of necessity accept para phyletic groupings). Dinosaurs evolved from a different group, but the relationship isn't exactly clear. So while we can say they share a common ancestor, and that said common ancestor would have been an archosaurs, stating any greater detail is premature (unless someone has a better reference, which I doubt given the difficulty in finding material of the appropriate time).

 

[William Parcher]

I think I have read that bird coloration is often related to bird vision and their visible spectrum which can include ultraviolet. Many of the flashy colors are especially vivid in the ultraviolet range and are attractive to potential mates or are significant to rivals. I recall reading something about raptors using UV vision to see rodent urine as a way to find prey.

Dinosaur vision may be related to dinosaur coloration.

Question: was the full sunlight spectrum the same back then as it is now?

 

[Dinwar]

Probably the light hitting Earth's surface was. The ozone layer was well in place, and while portions of the planet were more humid,others were arid, and both contained dinosaurs, so the water vapor wouldn't play more of a role than it does today.

Again, though, we cannot rule out ecology. Hadrosaurs fill a niche more akin to zebras than birds, so similar selection pressures are likely. Tyrannosaur is were not flying above Mesozoic forests; they were hunting within them.

 

[William Parcher]

Again, though, we cannot rule out ecology.

Who would do that?

 

[fuelair]

How colourful were dinosaurs?

Depends on how P.O.ed they were at the time. I am given to understand they could get very colourful when they had a snoot/snout/nostril full!!!!!

 

[Roboramma]

Who would do that?

We all keep talking about comparing dinosaurs to birds and noting that birds are colourful, so, since birds are the closest living relatives of the dinosaurs who's colouration we're curious about, we might suspect those dinosaurs to have been colourful as well.

Dinwar's point is just that while that may be a meaningful point, ecology is also an important factor: colouration or lack thereof may have more to do with the ecological niche that an animal inhabits than it's place on the tree of life.

I think it's a good point, but it requires us to examine the question more on a species by species basis than the apparently simple "how colourful were dinosaurs".

 

[Dinwar]

Who would do that?

What Roboramma said.

Words are tricky things, and paleontologists learn early on (at least, those trained the way I was) that saying the things everyone is thinking is vital. The unsaid tends to get forgotten remarkably quickly. Even those who are supposed to know better can all to easily fail to consider something that everyone, allegedly, knows so well it need not be said.

I think it's a good point, but it requires us to examine the question more on a species by species basis than the apparently simple "how colourful were dinosaurs".

We pretty much need to do that anyway. Dinosaurs are too diverse to treat as a whole for most purposes--what may be true of one group may not for others. Even the presence of feathers likely isn't universal among dinosaurs; some had more primative structures, some likely had more advanced structures that diverge from feathers, and so on. Ceratopsians had structures that really can't be called feathers, for example. Plus, dinosaurs were around for some 190 million years; things clearly changed through that time--so even in the same lineage the question of coloration may have changed dramatically over time. I mean, look at apes and how diverse OUR coloration is. And that's not 1/3 of the time that dinosaurs had to diverge!

 

[Varanid]

Dinosaurs are too diverse to treat as a whole for most purposes

Pardon my snip for brevity.

This cannot be said enough.

 

[macdoc]

That's a little bit of a "duh" comment.

We assume "birds" and "fish" come in a wide range of colours...to name a couple of simple categories.

NOW we can assume that "dinosaurs" did too....that is a change that has gradually emerged over time.
That will change the illustrations, how we percieve them as a widely diverse and successful group and how many disciplines studying them will try and tease out behaviours.

It also brings the dino/bird relationship into a clearer view.

We can pretty safely transform the Age of the Dinosaurs from dull green to multi-hued....and perhaps wildly so....that's a change in perspective.

Forest and trees comes to mind.

Noticing the forest has leaves is a start.

Hey we are still teasing out the gaits.

 

[Dinwar]

That's a little bit of a "duh" comment.

When I was in school, a professor had us look at the Silica Shale Fauna. This is a concentrat lagerstaaten right next door; I have spent far too much time out there collecting fossils (been sun burned AND frost bit on those outcrops, but not on the same day). So had everyone else. It was easy: shallow marine fauna, right?

Then he made the "duh" comment: These organisms were predominantly filter feeders, with the few exceptions being nectic predators. There was precisely ZERO indication of depth from these creatures. We had just always been told that these were shallow fauna, so we accepted it.

The answer to this riddle was to examine the stratigraphy (and, I learned later, the morphology of the bryozoans--but that requires DETERMINING the morphology, and good luck with that; imagine putting together a jigsaw mixed in with a few hundred others and they're all of a blue sky....). We spent a fair amount of time discussing exactly how to figure these issues out using those two sets of clues, and how the two played off each other. But the important thing for this conversation is that a room full of paleontologists--all of whom had degrees already--completely missed this trivially obvious fact.

It really drove the message home: we must ALWAYS be cautious about things we think are trivially obvious. We must ALWAYS check our assumptions, even the ones we know to be accurate. We must ALWAYS remind each other of the obvious, because the stuff that's obvious doesn't get discussed and the stuff that doesn't get discussed gets forgotten.

That's just one example. There are too many to count; this is the punchline to many, many stories we tell.

We assume "birds" and "fish" come in a wide range of colours...to name a couple of simple categories.

"Fish" is simple? I have three textbooks that attempt to address this issue. It's like "reptile"--something that is so obvious that it must be real, but when you actually dig into it is pure fiction. There is no group "fish". At best, there's "chrodates with hard skeletons that aren't terrestrial and that haven't been terrestrial in their clade's history", but even that doesn't do that group justice. Which isn't tangential, really: fish are a bad comparison, because the taxonomic issues inherent in such a paraphyletic group are not going to have any analogy in the Dinosauria. Birds are better, but they are completely inadequate in terms of ecology. For that, mammals are better--but the best examples are extinct and we are completely inadequate in terms of taxonomy.

That will change the illustrations, how we percieve them as a widely diverse and successful group and how many disciplines studying them will try and tease out behaviours.

More or less, yes. Understanding both the taxonomic and ecological issues involved in coloration (as well as others; the Dinosauria is pretty unique and will have unique issues) will necessitate changes in artistic renderings and studies of behavior. I have posted this link before, but the lessons in this paper are both relevant and well worth remembering when dealing with paleontological reconstructions: http://palaeo-electronica.org/content/2014/917-commentary-state-of-the-palaeoart

 

[Roboramma]

That's a little bit of a "duh" comment.

We assume "birds" and "fish" come in a wide range of colours...to name a couple of simple categories.

NOW we can assume that "dinosaurs" did too....that is a change that has gradually emerged over time.

On the basis of relatedness alone? I don't think so. There's an argument to be made that while birds are dinosaurs, the dinosaurs living, say, 100 million years ago were more similar ecologically to modern mammals than to modern birds (in that they filled the niches that are currently filled by mammals). Of course this is also a huge oversimplification, because A) the niches were different. B) Some types of dinosaurs filled some of the same niches as are now filled by birds.

Of course there will be traits that have been carried over into birds (or adapted to other purposes) based on relatedness alone, and thus we will expect major similarities and perhaps can make some predictions about dinosaur traits based on traits we see in modern birds. On the other hand we can also make some predictions based on ecological considerations.

So were dinosaurs colourful? Just the fact that modern birds are decentdants of some dinosaurs doesn't tell us conclusively.

 

[Varanid]

This seems as good a place as any to leave this:

Flight without Feathers

 

[Dinwar]

This seems as good a place as any to leave this:

Flight without Feathers

Odd, but not terribly surprising--this is the common pattern seen in evolution. That said, I always give any discovery from China six months before I even tentatively accept it; too many frauds.

 

[Damien Evans]

When I was in school, a professor had us look at the Silica Shale Fauna. This is a concentrat lagerstaaten right next door; I have spent far too much time out there collecting fossils (been sun burned AND frost bit on those outcrops, but not on the same day). So had everyone else. It was easy: shallow marine fauna, right?

Then he made the "duh" comment: These organisms were predominantly filter feeders, with the few exceptions being nectic predators. There was precisely ZERO indication of depth from these creatures. We had just always been told that these were shallow fauna, so we accepted it.

The answer to this riddle was to examine the stratigraphy (and, I learned later, the morphology of the bryozoans--but that requires DETERMINING the morphology, and good luck with that; imagine putting together a jigsaw mixed in with a few hundred others and they're all of a blue sky....). We spent a fair amount of time discussing exactly how to figure these issues out using those two sets of clues, and how the two played off each other. But the important thing for this conversation is that a room full of paleontologists--all of whom had degrees already--completely missed this trivially obvious fact.

It really drove the message home: we must ALWAYS be cautious about things we think are trivially obvious. We must ALWAYS check our assumptions, even the ones we know to be accurate. We must ALWAYS remind each other of the obvious, because the stuff that's obvious doesn't get discussed and the stuff that doesn't get discussed gets forgotten.

That's just one example. There are too many to count; this is the punchline to many, many stories we tell.

"Fish" is simple? I have three textbooks that attempt to address this issue. It's like "reptile"--something that is so obvious that it must be real, but when you actually dig into it is pure fiction. There is no group "fish". At best, there's "chrodates with hard skeletons that aren't terrestrial and that haven't been terrestrial in their clade's history", but even that doesn't do that group justice. Which isn't tangential, really: fish are a bad comparison, because the taxonomic issues inherent in such a paraphyletic group are not going to have any analogy in the Dinosauria. Birds are better, but they are completely inadequate in terms of ecology. For that, mammals are better--but the best examples are extinct and we are completely inadequate in terms of taxonomy.

More or less, yes. Understanding both the taxonomic and ecological issues involved in coloration (as well as others; the Dinosauria is pretty unique and will have unique issues) will necessitate changes in artistic renderings and studies of behavior. I have posted this link before, but the lessons in this paper are both relevant and well worth remembering when dealing with paleontological reconstructions: http://palaeo-electronica.org/content/2014/917-commentary-state-of-the-palaeoart

Indeed. A Lungfish is more closely related to a Tiger (or any other land animal) than it is to a Trout, for example.