Showing posts with label crocodile. Show all posts
Showing posts with label crocodile. Show all posts

Wednesday, June 20, 2007

Dragon Skin

While drawing Draconians, we started discussing how crocodile skin is textured. Crocodiles are (mostly) covered in non-overlapping "scutes" like dinosaurs, turtles, bird legs, and lizard faces, but different from the overlapping diamond-shaped scales on the bodies of snakes and lizards.

Crocodile faces are actually smooth, without scales, but they do have ridges, bumps and short horns. They have no lips, so the skin of a crocodile's head is pulled tight over it's skull. The skin over the jaw-closing muscle toward the back of the mouth is wrinkled or scaly with the main creases parallel to the jaw and the bottom of the skull. The jaw is faintly scaled (you can barely see the creases) and the throat skin under the jaw has scales arranged in a neat rectangular grid.

Two prominent ridges on a crocodiles face run from the top of the skull, over the eyes and toward the nostrils. Similar ridges are found on other archosaurs, sometimes enhanced with crests like Dilophosaurus or horns like Carnotaurus. The only living dinosaurs - birds - don't have lips or scaly faces, so it's tempting to imagine how dinosaur faces might resemble crocodiles, but Carnotaurus had scales on it's face, and the jury is still out on dinosaur lips (and cheeks.)

The scales on the crocodile's neck, body and tail follow this neat rectangular pattern, as if the crocodile were divided into short segments (rows) like a worm and each segment was divided into the same number of scales lined up in neat columns running from the head to the tip of the tail. These columns are pinched above the shoulder near the top of each leg as if the columns were pushed apart to make room to insert the front and back legs. The scale pattern is also pinched at the back of the jaw. Irregular areas are filled in with smaller scales.

The scales of the back are combined into armored plates which are twice the width of a normal scale, with the creases aligned to every other row of smaller scales. Some of the columns of armor scales have a raised ridge in the middle of each scale. Two rows of ridged scales, starting just over the back legs, have higher and higher ridges, sometimes resembling a pair of fins.
The scales of the side are bumpy and there may be one or two more columns of large, ridged scales on the side, alternating with small bumpy scales. The scales of the belly are smooth.

The scales of crocodile limbs are not neatly parallel and perpendicular to the central axis of the limbs. Instead the main segments seem to run through the limbs like slices in the direction of water flowing around the limbs bent at natural zig-zag angles from the body (so the limb bones are 45 degrees one way or the other from the axis of the spine.) The scales of the hands and feet are similar to the pattern seen on birds.

(Images from the Flickr pages of liquidindian and hiyori13 shared with the Creative Commons Attribution-Sharealike license.)

Saturday, June 16, 2007

Draconian

Squawk Draconians are intelligent crocodilians with short snouts, strong legs that allow them to walk bipedally, and short powerful arms with opposeable thumbs. The strange long-snouted creature in the lower right with extra arms is a genetically modified (chimaeric) draconian. Draconians are comfortable both on land and in the water. When they wear clothes, they prefer garments that minimize drag while swimming.

My intelligent crocodile is a strange idea, but there were real crocodile relatives who ran around on long legs, climbed trees, looked like ichthyosaurs or sharks, had short snouts (and ate plants) and even a giant crocodilian filter feeder who caught tiny prey like a baleen whale.

Here are some more Draconians I scanned in recently. My earlier draconian drawings were more anthropomorphic with shorter bodies and longer arms than they should have.


Friday, June 15, 2007

Enter the Dragon

In the Squawk role-playing game, "dragon" is a common name for four-legged predators. Because the big predators in Squawk are archosaurs, most dragons have a classic "reptilian" shape like the crocodile above, and many of them are equally at home in the water or on land.
I like to call this critter the "catoplebas". The forelegs are probably much too long compared to the back legs. Most archosaurs have longer hind legs and higher hips than shoulders. (Obvious exceptions would include high-shouldered sauropods like Brachiosaurus, and some birds.)

Strange as it may seem, crocodiles are more closely related to birds than to lizards. Birds are dinosaurs, and some dinosaurs have toothy snouts, long tails, and scaly armor like crocodiles, but it's still hard to see the bird-crocodile connection because (modern) crocodiles are specialized for living in water (a bit like archosaurian otters.)

It's easier to see the kinship between crocodiles and dinosaurs (including birds) when we look at the different ways that crocodiles move. Like lizards, crocodiles can crawl on their bellies, but when crocodiles need to walk a long distance, lift their bodies off the ground or move quickly, they can use the "high walk" and "gallop", which are very different from the ways lizards walk and run. (This video was posted on YouTube by crocodilian.com.)