The Coloration & Integuments of Extinct Animals

[Derek Sohoza]

I wanted to dispel a statement I came across on Brian Engh's blog (dontmesswithdinosaurs.com) in the hopes that others will not follow this same train of "logic."
The statement comes from someone by the name of Matt, and it goes as follows:

"If you go bold, you won't be right; whatever you dream up is not going to the same as whatever outlandish structure the animal actually had. On the other hand, if you don't go bold, you'll still be wrong, and now you'll be boring, too."

Now I don't know if you've seen his illustration of brachiosaurs with "elaborate display structures" (http://dontmesswithdinosaurs.com/?p=471), dinosaurs with ridiculously vibrant colors that don't even seem plausible, images of every ceratopsid with quills because a couple species within the entire family have them, or pictures of every theropod with enough feathers to stuff a mattress, but I feel like some of you guys are getting out of hand.

As paleoartists, we hold, whether we like it not, a fair bit of influence on those who don't readily know about dinosaurs and other extinct animals. How we portray them makes a difference in how other people see and imagine them. For this reason I find being inaccurate as unacceptable as teachers incorrectly giving history lessons to their students.

You have to understand that the coloration and integument of every living thing is a product of evolution in some form, and if you know a fair bit about evolution, you'll know that mutation is the key driving factor here. And to give you an idea of what I'm talking about, I'll give you some modern-day examples.

Zebras exhibit a simple but striking pattern of stripes that help individuals in the herd escape predation. They did not evolve to have this pattern and by coincidence it helped them to survive. At some long period in their evolutionary line, the mutation for this striped pattern arose within various members of their populations and they survived to pass this onto their offspring. Members of the populations who did not possess this mutation died before passing on their genes, were soon dominated by the genetically different genes of other members, or both. And if you've seen the different species of zebra, you can see how the gene for these stripes continued to mutate, or had mutated around the same time to establish different species with similar but different stripe patterns.

Also, there's the elephant, which has no distinct coloration at all. For around 5,000 years, elephants and its ancestors the mammoths have been large, successful herbivores with large tusks providing a formidable defense. As its climate changed, they no longer needed their wooly coats of fur, but as far as extreme coloration among animals goes, they had no need for it. They were the largest things walking around with tusks and herds for protection, so they had no need to evolve vivid color patterns for camouflage or warning. If a mutation were to arise among elephant populations that gave it more color (or with albinism, a lack of color) those individuals could easily be singled out by predators. And for those who were not previously aware, elephants do have predators. Lions on occasion do bring down elephants.

Lions, cheetahs, leopards, and jaguars are another example. Closely related species, each with a coloration or pattern which has enabled them to sneak up on unsuspecting prey. I'm sure there's some of you familiar with white lions, which are always seen in captivity. A mutation like this would make them very unsuccessful predators in the wild. Among the faded yellows and slight greens of the savanna, a white lion could easily be spotted by potential prey. Then there's the case of the black panthers, which are not their own species, but in fact jaguars or leopards with a melanistic mutation. Although they aren't common, they have the chance to pass on this mutation because in the darkness of the forests, being a darker color isn't always such a bad thing, especially for nocturnal hunting.

Feathers also hold true to this genetic survival-of-the-fittest. Male peacocks over a long period of time evolved their elaborate tail feathers and developed their fan-out courtship display to attract mates. Males with less impressive feathers over this period of time did not impress the females and so they did not reproduce to pass on their genes. Also, one cool thing I learned about birds recently is that not only do birds have the ability to see UV light (not discernible to our own eyes), but feathers also look different under UV light. So when you see a bird, you aren't seeing that individual as other birds would see it. This brings evolutionary colorations and integuments to a whole lot of other possibilities that are hard to even imagine since we aren't able to view other species in this way.

My main point is that every color, integument, and structure in nature is not the result of haphazard occurrences. Whether it be for plants, animals, or even fungi, all these things have come to be as they are (or were, if we're speaking of extinct species) because of evolution. They all serve some purpose in one way or another.
So my advice to you is, when re-creating dinosaurs or other extinct animals, look to their descendants, their ancestors, and their relative species. Look to animals of the same size, animals with similar structures like horns or long necks. I'm sure your vivid imaginations could come up with some truly wild things, but if you really want to recreate these animals as they were, your best reference is the natural world they left behind.

[Gryphoceratops]

So basically in a nutshell you just said that paleoartists should choose the colors they do for their extinct dinosaur subjects based on logic and not what looks cool? 

I think that's what most of us do.  Its just that not everyone has the same exact vision (which is a healthy thing in my opinion).

[Gwangi]

We know many theropods had a full coat of feathers. Why not infer that others did as well? Likewise with ceratopsians, if we've found quills on some why not infer that others had them? Do we evidence that they didn't? I admit I am taken back by all the quills handed out these days to ceratopsians (especially when they're localized just above the tail) but it does not seem unreasonable to assume that it was a trait passed on to other lineages.

You're making a mistake if you're assuming dinosaurs had coloration similar to that of mammals just because they occupied similar niches. Mammals evolved from nocturnal animals with mostly poor color vision. Dinosaurs are reptiles, related to birds. These are typically diurnal animals with good color vision and it shows when you look at the diversity of color and patterns in extant reptiles (and birds). You're on the right track with the peacock analogy but suggesting that large dinosaurs weren't colorful because elephants and rhinos aren't makes no sense. Mammals have undergone different evolutionary pressures than what the dinosaurs did. It is completely feasible to me that sauropods might have brightly colored displays...why wouldn't they?

As for white lions, I do believe they occur in the wild. I have a book I have not read yet called "Operation White Lion" and I know there is another book on the subject as well. Unfortunately I don't know much more than that on the subject.

[Gryphoceratops]

White lions do exist in the wild but they are different from the leucistic ones in captivity.  Its simply a less common phenotype amongst African Lions that is much more pale.  Lots of animals have more than one naturally occurring color phases. 

  https://www.youtube.com/watch?v=HvtUFOxV_28

[Derek Sohoza]

We know many theropods had a full coat of feathers. Why not infer that others did as well? Likewise with ceratopsians, if we've found quills on some why not infer that others had them? Do we evidence that they didn't? I admit I am taken back by all the quills handed out these days to ceratopsians (especially when they're localized just above the tail) but it does not seem unreasonable to assume that it was a trait passed on to other lineages.

That would be a one-integument-fits-all theory, which I don't think is scientifically supported. It seems to me that integuments and attributes might start with ancestry and lineage, but end at adaptation. If elephants died around the same time as mammoths and we couldn't find a well-preserved specimen, would we hypothesize that they had thick coats of fur as well? They're more closely related to each other than psittacosaurus and triceratops. And if psittacosaurus's quills were for display alone (which seems to be the most likely answer), why would it be passed on to larger ceratopsids who evolved much more useful display structures that could also act as a defense mechanism? And if the evolution of feathers started for use as insulation and/or display, why would larger theropods who lived in much warmer climates have them? And this is also a long stretch of time when feathers have started to evolve. That concept alone should decrease the number of dinosaurs we so freely add feathers to. When reptiles began the slow evolutionary process that came to produce mammals, they didn't all start growing hair or fur. Not all theropods directly evolved into birds. And not all species in a suborder share a simple display structure - not all lizards dewlaps, not all birds have wattles, etc. And in just the same way that we know there are plenty of dinosaurs that had feathers, we also know there's some that didn't. The two hadrosaurid dinosaur "mummies" with multiple well-preserved skin impressions that didn't reveal a single feather imprint.
It's like they're connecting dots that are too far away from each other to even be reasonable.

You're making a mistake if you're assuming dinosaurs had coloration similar to that of mammals just because they occupied similar niches. Mammals evolved from nocturnal animals with mostly poor color vision. Dinosaurs are reptiles, related to birds. These are typically diurnal animals with good color vision and it shows when you look at the diversity of color and patterns in extant reptiles (and birds). You're on the right track with the peacock analogy but suggesting that large dinosaurs weren't colorful because elephants and rhinos aren't makes no sense. Mammals have undergone different evolutionary pressures than what the dinosaurs did. It is completely feasible to me that sauropods might have brightly colored displays...why wouldn't they?

I was not saying they had similar colorations. I was using the development of their colorations as an example. The same concept applies to reptiles, birds, amphibians, etc. Even crocodilians and komodo dragons, the largest lizards, have no vivid coloration. Neither do emus, ostriches, or rheas. Cassowaries do, but the coloration is contained strictly to the head and neck, and doesn't involve their feathers.
You're asking the wrong question. You shouldn't be asking "why wouldn't they?" - you should be asking "why would they?" You're using inductive reasoning, which isn't scientific or logical. That line of questioning you're using begs to assume that evolution plays no part in their integument or coloration, but we know that it does, because there isn't a single single species that shows otherwise.

[Gryphoceratops]

That would be a one-integument-fits-all theory, which I don't think is scientifically supported. It seems to me that integuments and attributes might start with ancestry and lineage, but end at adaptation. If elephants died around the same time as mammoths and we couldn't find a well-preserved specimen, would we hypothesize that they had thick coats of fur as well? They're more closely related to each other than psittacosaurus and triceratops. And if psittacosaurus's quills were for display alone (which seems to be the most likely answer), why would it be passed on to larger ceratopsids who evolved much more useful display structures that could also act as a defense mechanism? And if the evolution of feathers started for use as insulation and/or display, why would larger theropods who lived in much warmer climates have them? And this is also a long stretch of time when feathers have started to evolve. That concept alone should decrease the number of dinosaurs we so freely add feathers to. When reptiles began the slow evolutionary process that came to produce mammals, they didn't all start growing hair or fur. Not all theropods directly evolved into birds. And not all species in a suborder share a simple display structure - not all lizards dewlaps, not all birds have wattles, etc. And in just the same way that we know there are plenty of dinosaurs that had feathers, we also know there's some that didn't. The two hadrosaurid dinosaur "mummies" with multiple well-preserved skin impressions that didn't reveal a single feather imprint.
It's like they're connecting dots that are too far away from each other to even be reasonable.

People keep using the elephant analogy to justify large featherless theropods.  The problem with this idea is that mammalian fur is different from feathers.  Yes, the elephant has a sparse coat because it lives in a hot environment.  But you will notice that modern birds all have feathers much denser than that in all kinds of environments, including hot ones.  Feathers are a very adaptable body covering.  They can be used for insulation but then can also aid in cooling the animal's body off, in addition to display.  Ostriches don't have any thick, insulating feathers but they still have a healthy amount on most of their bodies.  They even have small ones on their heads and necks if you look closely. 

This past September I went down to Maryland and got to meet Dr. Thomas Holtz and was lucky enough to spend a good part of the day with him and pick his brain about dinosaurs.  I remember one of the first questions I asked him was what he thought about the idea of feathers or feather-like structures on Hypsilophodontids and other not as obvious candidates as coelorosaurs for that sort of thing.  I think my exact words were "What do you think they were covered in?"  His response was word for word I remember "I think they should be covered in question marks.  Because as of now feathers or just scales are each a valid idea".  That's the beauty of this field.  You can apply as much harsh logic as you want to something we don't know much about but at the end of the day nobody knows for sure, even the pros.  Also, there can in fact be more than one logical answer!  Then one day someone might make a new discovery and all that we thought we knew about it because we applied our harsh scientific logic to it is completely off!  I'm not saying to abandon all logic and go crazy but its probably healthiest to keep an open mind about what could be considered logical for an animal that we only know from fossils. 

[Gwangi]

That would be a one-integument-fits-all theory, which I don't think is scientifically supported. It seems to me that integuments and attributes might start with ancestry and lineage, but end at adaptation. If elephants died around the same time as mammoths and we couldn't find a well-preserved specimen, would we hypothesize that they had thick coats of fur as well? They're more closely related to each other than psittacosaurus and triceratops. And if psittacosaurus's quills were for display alone (which seems to be the most likely answer), why would it be passed on to larger ceratopsids who evolved much more useful display structures that could also act as a defense mechanism? And if the evolution of feathers started for use as insulation and/or display, why would larger theropods who lived in much warmer climates have them? And this is also a long stretch of time when feathers have started to evolve. That concept alone should decrease the number of dinosaurs we so freely add feathers to. When reptiles began the slow evolutionary process that came to produce mammals, they didn't all start growing hair or fur. Not all theropods directly evolved into birds. And not all species in a suborder share a simple display structure - not all lizards dewlaps, not all birds have wattles, etc. And in just the same way that we know there are plenty of dinosaurs that had feathers, we also know there's some that didn't. The two hadrosaurid dinosaur "mummies" with multiple well-preserved skin impressions that didn't reveal a single feather imprint.
It's like they're connecting dots that are too far away from each other to even be reasonable.

Sticking to theropods (because I never suggested feathers for hadrosaurs), for just about every species where feathers can be preserved, they have been preserved. Even in dinosaurs are large as Yutyrannus or as distant from birds as Sciurumimus. To the best of my knowledge there are more examples of feathered theropods than there are featherless and so in my opinion it is almost irresponsible NOT to include feathers on any theropod. No, not all theropods directly evolved into birds but feathers are not nor need to be unique to birds. They could have arisen at the base of the theropod group (and the evidence is suggesting that) or even earlier in dinosaur evolution. On what evidence would you not include feathers on a theropod? Everyone is saying "oh, feathers cannot be on this or that" and then evidence turns up that they are. Surely you see the logic here.
Also as Gryph pointed out, hair and feathers are two very different body coverings. Also, mammals and dinosaurs two very different groups of animals. You compare elephants and mammoths but like so many others neglect the fact that elephants do in fact have hair. It's spare but it is there.

I was not saying they had similar colorations. I was using the development of their colorations as an example. The same concept applies to reptiles, birds, amphibians, etc. Even crocodilians and komodo dragons, the largest lizards, have no vivid coloration. Neither do emus, ostriches, or rheas. Cassowaries do, but the coloration is contained strictly to the head and neck, and doesn't involve their feathers.
You're asking the wrong question. You shouldn't be asking "why wouldn't they?" - you should be asking "why would they?" You're using inductive reasoning, which isn't scientific or logical. That line of questioning you're using begs to assume that evolution plays no part in their integument or coloration, but we know that it does, because there isn't a single single species that shows otherwise.

Komodo dragons may appear dull in coloration but if you were to go to Australia and look at their largest lizard (the perentie) you would see some very bold markings on an 8' lizard. You're mistaken, I am asking "why would they" and my answer to that is "why wouldn't they". As I pointed out, dinosaurs seem to have been dirunal, visual animals with color vision. Many had elaborate displays and their closest relatives are among the most colorful animals on the planet, their next closest relatives are the remaining reptiles, the vast majority of which are boldly marked, colorful or also have elaborate displays. Everything we know about dinosaurs points to them being similar in this regard. I agree, evolution plays a part, that is why I agree with feathers on theropods and visual displays...because that it what the evidence suggests. So yes, I ask the question "why wouldn't they" because there seems to be no reason to assume otherwise. I'm not suggesting we just toss unrealistic colors and displays on dinosaurs just for the fun of it. Of course I want an artist to look to modern animals to infer what dinosaurs were like and make an educated guess but...those animals shouldn't be mammals. So if an artist wants to look at a komodo dragon or an emu and depict their dinosaurs similarly that is fine but there is also nothing wrong with looking at a Tokay gecko or a peacock for inspiration as well.

[Balaur]

Everyone is saying "oh, feathers cannot be on this or that" and then evidence turns up that they are. Surely you see the logic here.

I think one example I can think of is with Velociraptor. Scientists where pretty sure Velociraptor probably had feathers, but had no evidence, until the discovery of quill knobs on a Velociraptor forelimb in 2007.

The best example is Yutyrannus. Everyone was saying that "because they are so big, large tyrannosaurs could never have had feathers". Then Yutyrannus came along (though I should note that Yutyrannus lived in a colder climate than other tyrannosaurs)

Now I think that our speculation that feathers are on most or all coelurosaurian is pretty logical, because of those two examples.

I just wanted to put in my two cents.

[Gryphoceratops]

Everyone is saying "oh, feathers cannot be on this or that" and then evidence turns up that they are. Surely you see the logic here.

I think one example I can think of is with Velociraptor. Scientists where pretty sure Velociraptor probably had feathers, but had no evidence, until the discovery of quill knobs on a Velociraptor forelimb in 2007.

The best example is Yutyrannus. Everyone was saying that "because they are so big, large tyrannosaurs could never have had feathers". Then Yutyrannus came along (though I should note that Yutyrannus lived in a colder climate than other tyrannosaurs)

Now I think that our speculation that feathers are on most or all coelurosaurian is pretty logical, because of those two examples.

I just wanted to put in my two cents.

Agreed.  Remember it wasn't THAT cold where Yutyrannus was at the time though.  It was seasonally cooler but its not like this was the arctic or anything like that.  Even so modern birds, including the large flightless ones, that live in extremely hot environments still have plenty of feathers so its safe to say its likely the other Tyrannosauroids had them in some form on their bodies as well until a discovery is made that explicitly tells us otherwise.