The Dinosaurs of my childhood: Slow, stupid, tail dragging swamp dwellers. The great thing about that image of the Mesozoic was that it made it easy for all my bipedal dinotoys to stand up by balancing on their tails. The long sharp teeth typical of most dinosaur depictions were tremendously exciting to us children. We usually wanted them hanging out on full display, preferably stained red for extra terror. Their overall coloration was usually pretty dull though, mostly uniform grays and greens. In the decades since, there have been tremendous advances in our knowledge of how Dinosaurs looked and sophisticated guesses about how they acted. There is an ongoing effort made by paleoartists to improve the accuracy of their paintings and sculptures in line with the latest scientific discoveries. Careful study of anatomy and reconstructed skeletons provide opportunities for talented artists to open exciting windows into the distant past with ever improving clarity.
One of the first advances in Dinosaur reproduction came when we realized that tails were for balance and not support. Almost overnight, Dinosaurs tipped forward and became agile to align with evidence from trackways. Their relationship to birds started scientists thinking that Dinosaur vision probably was sensitive to color. As many birds and reptiles are spectacularly colorful, we began to consider Dinosaurs as great canvases for a technicolor past. Wild hues spread over heads and necks to attract mates and repel rivals. Fantastic camouflage patterns spread over backs and sides. Now there are even feathers in tufts and crests sprouting from formerly scaly skin. Another recent assertion is that proper interpretation of their skulls proves that Dinosaurs didn't have lips. It has become as difficult to have the most cutting edge Dinosaur on your mantle as it is to keep the newest and fastest computer on your desk! All of this has been in the name of scientific, museum quality accuracy. Still, those teeth are hanging out, dripping saliva and drenched with blood.
The depiction of Dinosaurs certainly allows a lot of latitude in how an artist decides to make the rendition. I have seen many artists defend their colorful and flamboyant view of the past by pointing out that nobody really knows what anything in that era looked like, so their artistic vision is as valid as any other. This would be fine except for their accompanying claims of being the most scientifically accurate and up-to-date with the distant past. If we can't really be certain how well our current crop of sculpture and paintings depict reality, I think we can still predict how well they portray real animals living real lives. Let's look at these trends and ask how likely they really are.
First, both careful analysis of bone articulations and trackway studies provide pretty persuasive evidence for the teeter-totter posture that almost all bipedal dinosaurs are now displaying. The only problem that I often see is a rather unlikely balance of back and front. A look at most theropod sculpture shows that there is a tendency toward a huge head and body with a fairly thin tail. Of course most of these need to be pinned to their base so they don't tip over. We now believe an important function of the tail is providing a counterbalance for the front of the beast so it balances on the fulcrum of its pelvis. It seems from the usual appearance of the sculptures I see that they are very front-heavy and those tails must be full of lead. Maybe the tail vertebrae are supposed to be already fossilized as stone is a lot heavier than native bone. If they are merely flesh and blood, those tails must have been a lot longer than they usually appear or a lot bulkier. Otherwise, to be accurate these sculptures need to start showing skid plates on their chins. This might explain the mystery function of the tiny arms on Tyrannosaurs. They would have been perfect for grabbing the tail of another Tyrannosaur and keeping it from toppling. Then they would have hunted as bonded pairs. A larger aggregation could have formed a linked loop whirling across the countryside in search of prey; the original vicious circle. But I digress...
Colorful Dinosaurs? Smaller members of the group may well have had interesting colors and patterns. It would have helped them blend into their environment, although that would probably have confined them to greens, yellows and browns. The larger Dinosaurs were probably mostly browns and grays, much like almost all large animals today. Obviously I have no proof of this, but coloration is important for camouflage. Predators don't want to be seen and neither do prey. Bright colors may as well have been applied in concentric circles as any other patterns. Otherwise most animals pretty much share their colors with their surroundings. Complex patterns are rare in large animals, perhaps because of the energy involved in forming and maintaining them. Seasonal changes in color may have occurred for mating but they would have to balance attractiveness to members of the opposite sex with visibility to members of the opposite dietary preference. I have to admit that giraffes have pretty amazing coloration for a large animal, so prominent patterns on Dinosaurs certainly aren't impossible. Still, it is hard to think of any other beast weighing over a ton that isn't brown or gray; why would we really expect Dinosaurs to be different?
Downy Dinosaurs?? They may have been fairly closely related to birds and a lot of experts now say they were birds. Even if that is true, by the mid-Jurassic they were probably 50,000,000 years apart. That's enough time to develop some pretty prominent differences in covering. Some feather-like structures have been found on some small theropods, but a lot of them are more fibrous than feathery and actually subcutaneous in location. So, were Dinosaurs totally covered with feathers? There is no real evidence in the fossil record for this, so why the rush to feather covered pictures and sculptures in the name of scientific accuracy? Birds need aerodynamic feathers for flight and fluffy feathers for heat retention. Dinosaurs were too big to fly and at their size heat dissipation would have been a greater concern. Looking at recent sculptures and paintings I have seen raptors with punk crests and a lot of Dromaeosaurs with fully feathered "wings"; for what purpose? It takes a lot of energy to make feathers. These animals were not structurally adapted for flight, so why waste hard-to-get protein on frivolous plumage? I see others covered with the hairy feathers typical of modern ratites. If they had to have feathers, I suppose that is how they would have looked, being ground dwellers. They didn't have featherless bird beaks, but all the feathered depictions I have seen look like bald-faced vultures. Why doesn't the face ever get feathered? Why is it that most of these look as if they were conceived by Dr. Suess?
Do Dinosaurs deserve a lot of lip? Most sculptures and paintings of carnivorous Dinosaurs emphasize the mouth more than any other part. It is almost always shown open with huge gleaming teeth displayed as a picket fence of gory glory. Lips are usually pulled back to accentuate those ferocious fangs. Recently I have heard that some experts have stated that Dinosaurs did not have lips, their teeth occupying the outer edges of their jaws. I'm not sure whether they are saying this because it makes their favorite Dinosaurs look fiercer or if they really have any scientific basis for their claims. It's unlikely that a lot of fossilized soft tissue will ever be found to prove this contention one way or the other, but I don't think it makes a lot of sense from an evolutionary standpoint or even from the fossil evidence that does exist. First and foremost, lips keep moisture in. Ever since the earliest terrestrial vertebrates began their invasion of the land, the most important adaptations that allowed them to do so involved conservation of water. Once eggs and skins were sealed against water loss there was only one other large surface left to lose vital liquid and that was the mouth. If you don't believe this, try sleeping with your mouth open. All land-dwelling vertebrates have lips to seal their oral cavities. If they don't, they dry out too fast and don't reproduce. Crocodilians may not have lips, but then they do live in water. Birds don't have lips either, but their whole oral structure is somewhat different, lacking teeth and gums in particular. While there may be a link between birds and Dinosaurs, it obviously isn't expressed in the structure of the mouth. Every other vertebrate group has lips, so it stands to reason that Dinosaurs did too. There has been some "qualification" on this issue. The no-lip faction does feel that there would have been a row of scales to seal the edges of the mouth but since they weren't muscular and fleshy, they weren't really lips. I never felt they had to look like Mick Jagger, but if they look like lips and act like lips, they are lips and Dinosaurs should not be depicted with naked teeth.
Now just how far did those teeth really stick out? Was a row
steak knives on display each time a theropod snarled or cracked a
Most reptiles actually have pretty gummy looking mouths.
the extremely long sharp teeth of snakes and large lizards are usually
hidden in a mass of pink tissue, felt but not seen. I
this has something to do with the supporting structures needed for
self-replacing teeth. The only good reason to depict Dinosaurs as
having a markedly different oral appearance from all other
reptiles is that it looks better that way. I have recently seen a
lot of Dinosaur depictions that show a row of fangs hanging over the
lip. This seems to have been inspired by some Tyrannosaur skulls
with major metamorphic distortion in which the maxilla was partially
over the mandible. This has resulted in a trend toward depicting
theropods as prehistoric Goofys.
Aside from the obvious problems in water conservation arising from
around with their overhanging teeth, Dinosaurs that looked like that
have shredded their lips with every bite. Besides, their upper
lower teeth worked together to rip meat. If their uppers were
outside their lower lips, they would have been unable to slide along
lower teeth. That would be analogous to trying to cut a piece of
meat with a fork in each hand, one above and one below. Face it,
if those Dinosaurs wanted to be successful, they would have had to push
their gums back and get some orthodontia.
To be honest, I like the way the way most paleoartists today
the past. Most of my models of carnivores showcase a set of
sized slicers and dicers. I am just calling for caution in trying
to keep up with the latest speculation in the field. In another
years we may look back on this era of Dino-art with the same bemused
we now apply to the creatures of Hawkins' Crystal Palace.
Where the Dinosaurs
Tyrannosaurs: a Call to Arms
THE OLD BONE ODORI
My Dinosaur Tale
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