Sunday, October 7, 2012

Part 4: Pteranodons / Hatchling Sketches

(Continuing the Pteranodon series) I've often preached at art schools about how you should do plenty of research, and then do lots of preliminary sketches and not get too attached to any of them, because the idea is going to change.

Today's post is about me taking my own medicine.

With the first painting completed, the goal of the second illustration for the Pteranodon article was to show a hatchling Pteranodon. If some dinosaurs nested in protected colonies, wouldn't Pteranodons, too? I reasoned that they would be so vulnerable after hatching that they would need to be looked after by their parents.

I did five little sketches of Pteranodons in a nesting colony. Here are my notes to the art director:
A. Tender scene with warm colors showing female with downy chick in nest built of dried ferns and sticks. The rest of the nesting colony visible out of focus behind.
B. Looking a bit upward at the female sternbergi on a mud nest. Edge lighting from sunrise.
C. Variation of B with front lighting and the single chick protected by drooping wings.
D. Closeup of heads and faces of both mother and chick.
E. Female guards hatchling. Communal nesting colony could be visible behind. Golden lighting from behind.

Unfortunately all these sketches were based on wishful thinking and a lack of evidence, something one has to guard against in science. I did more reading about pterosaur hatchlings in David Unwin's 2006 book "The Pterosaurs From Deep Time." The book described three major discoveries of fossilized pterosaur embryos in recent years, which is remarkable, since there hadn't been any comparable finds for 200 years.

The new finds showed that the eggshells were probably soft and leathery, and they gave no support to the idea that the young were altricial (requiring nourishment), as opposed to precocial (active and mobile at birth).

I did a new set of sketches. Here are my notes to the art director:
"The hatchling picture is vignetted so it will fit in the lower corner of the page. I gave the egg the appearance of a soft reptilian-type eggshell, and made the hatchling comparatively precocial. I followed David Unwin's summary of the recent pterosaur hatchling fossil discoveries, which suggests they probably didn't need much if any altricial parenting. Also, apparently they could fly quite soon after hatching. This affects the way I paint the little guy. I'll make sure to make him look more flight-ready than he appeared in the sketch."

Now that I had taken it as far as I could with book and internet research, it was time to show the sketches to a scientist in the field. I received the assistance of Christopher Bennett, one of the most knowledgeable experts on Pteranodons, especially their ontogeny.

Dr. Bennett replied with many helpful suggestions:
"I have marked up the babies drawing. Yes, they look very birdy, and they shouldn't other than the rounded skull and the goggle eyes. First off, there would be no trace of a cranial crest. I erased the crests on the left two babies and X-ed out the crest on the right one. The crests did not begin to develop until large and size and the beginnings of sexual maturity were attained. Jaws should not have tip hooks so, I have just drawn straighter lines. I think that the body posture of the right baby is spot on. I have added lines to indicate a bigger hand with three walking fingers in addition to the flight finger. The last problem is the biggest and birdiest of them all. The lower left baby has a pelican head-neck-trunk posture, and there is no way a pterosaur could do that. Yes, there could be a bit of an angle between the front end of the neck and the head, but the neck could not be bent back on itself at all. What I would suggest is replace the pelican neck and trunk with a lizard neck and trunk."

Tomorrow I'll show the final picture incorporating these corrections.

Part 1: Pteranodons / Thumbnails
Part 2: Pteranodons / Maquette
Part 3: Pteranodons / Step by Step


Kessie said...

Ouch! That's some critical feedback! I kind of like the idea of them being good parents, but again, these are reptiles we're talking about. Reptiles aren't usually the mothering types (although there are alligators and crocodiles).

I like the sketch of the mama and baby heads. It's very sweet.

Anonymous said...

I think this has more to do with the psychology of the artist than the science of pterosaurs.

James Gurney said...

Anonymous, there's not much direct evidence about Pteranodon nesting behaviors, so speculation is inevitable if you want to reconstruct hatchlings. Let's hope paleontologists find more direct evidence, as they have done with hadrosaurs. Birds and crocs serve as modern analogues for a variety of styles of parenting, but in the post, I try to explain the risks of such extrapolation. As for psychology, it's impossible to be neutral or objective with such speculative work, for any choice is grounded on some sort of assumption.

Kessie said...

The sad thing is, we have a flying analogue in every other animal classification (fish, birds, mammals), but no flying reptiles (not gliders). We lost our flying reptiles a long time ago. So we really don't have anything to compare them to.

Zubin Erik said...

From what I've read and watched, young pterosaurs hatched fully developed and ready to fly (I got this mainly from Flying Monsters 3D with David Attenborough).

I could very well be wrong.

Anonymous said...

The close up of chick and parent does reach the heart.
Looking forward to seeing how your corrected sketches turned out. - MP

Tom Hopp said...

Of course, you're sort of stuck with the experts' interpretations of fossil evidence.What if they're wrong?

James Gurney said...

Tom, that's a very interesting point. Every artist must think independently and be ready to question any authority, and any good scientist will welcome ideas and will welcome respectful challenges from artists, who often look at things differently from their scientific colleagues. You can solicit the opinions of various scientists, too. I almost always defer to the top paleontologists because they have studied this stuff for a long time and can marshall the evidence. But fundamentally, you have to look at the evidence and judge for yourself. Paleontology and paleoart are partners in a way, one stimulating and guiding the other.

David J Teter said...

I love all these little studies and the finished art.

I actually think it is OK to 'be wrong'. I don't mean you personally, I mean all of us.
Science is an inexact science. ; ) (sorry scientists)

It evolves and changes over time, like anything else, as we discover new things and technology advances.

So even though you want to be as accurate as possible with current science data, it may be different tomorrow.

These are a reflection of what we know now.

Lida said...

James, not sure if you came across this in your research, but I think this is relevant (taken from the 'Evolution' facebook page):

"Reptiles, known as egg-layers, form their eggs and it completes its embryological development outside the body of mother. However, some species are not following this pattern. A lizard species, yellow-bellied three-toed skink, forms the egg and keeps it inside of the body until baby lizard almost completes its embryological development. The level of this development inside the body changes depending on altitute and temperature. As altitude gets higher and temperature gets lower, these lizards almost gives birth to live babies.

This change in birth style creates some problems and solution to these problems. The main problem is about nourishment of the embryo. The egg shell gets thinner to make breathing of embryo possible, then, the amount of calcium stored in the egg shell lowers. Since thin shell stores less calcium, baby lizards may have some health problems. James Stewart, a biologist, explains how lizards are evolving to solve this problem :"Now we can see that the uterus secretes calcium that becomes incorporated into the embryo—it's basically the early stages of the evolution of a placenta in reptiles"