Someone asked me: What are you? Science Guy or Artist?
Leonardo da Vinci said: “I don’t understand a thing ‘till I draw it.” When you draw, your finger tips teach your brain what’s important.
Cleaning Bones & Feeling Dinosaur Muscles
Most fossil-cleaners are good artists. As they chip away the rock, their finger tips record each bump and hole, every place that’s smooth, every place that’s rough. Expert fossil-cleaners dream about the fossil – they see it rotating, turning every which way.
Let’s say we have an ankylosaur skeleton, fresh from the field. We clean off the rock slowly. Every time we have a square inch clean, we paint thin glue on it (so it doesn’t crack and fall apart). As we do, we make sketches of the bone. That helps plan the complete cleaning. It’s X-ray vision, sort of. As we sketch the bone we can draw in the parts of the specimen that are still buried in the rock.
For instance: let’s say we have the upper left arm (humerus). And we have the elbow end cleaned, but the shoulder end is still in the rock. A sketch will help us imagine where the bone is and how to chip the rock off so we don’t break anything accidentally.
Putting Muscles and Ligaments Back On
|Fossils from a Dimetrodon hip bone.|
Texture of fossil bone is important:
Rough spots full of squiggly ridges are where tough ligaments and tendons attached to the bone.
Smooth spots are where soft muscle attached.
Bones with big pits are armor plate – in life the pits were filled with a thick layer of finger-nail like skin.
At the Zoo with Brachylophosaurus
Now let’s shift to Leonardo, the Brachylophosaurus, the dino-mummy now visiting the Houston Museum of Natural Science. I wanted some drawings of the critter, and to prepare I spent a lot of time watching live animals.
I sketch live critters in the zoo all the time. And I make diagrams of the heads, bodies and legs of skeletons from species that are still alive today. I can’t imagine a live Brachylophosaurus or any other dinosaur without studying rhinos and elephants, ostriches and cassowaries, giant tortoises and water buffalo.
Tweensy Gator Hands
Most plant-eating dinos have hands like the one in the little vegetarian dinosaur Hypsilophodon. There were five fingers in this animal and most other herbivores. Carnivores sometimes have three, as in Velociraptor, or two as in T. rex and all members of the rex family. In all dinos, meat-eater and plant-eater, only the inner three fingers had claws. In herbivores the claws are blunt and hoof-like. Carnivores tend to have sharp-tipped claws. In all dinos, the outer two fingers had no claws at all.
The five fingers/three claws is standard equipment for most ancestors of dinos too.
|photo credit: James Jordan|
Who has this five/three hand in a zoo today? Only in one clan – gators and crocs. Lizards and turtles have claws on all five fingers. Crocs & gators have three claws, five fingers, no claw on outer two. Watch out when you draw dino hands – a lot of books make the mistake of giving a dino four or five claws. Even the movie “Jurassic Park” makes that error with the Triceratops. Don’t YOU do it! Remember: five fingers but only three claws in most plant-eating dinosaurs.
No Bowling for Duck-Bills
Duck-bill dinos have a puzzling variation on the basic veggie-saur hand. The outer two fingers are fine – no claw or hoof. But there are only four fingers in total. Which is missing? The thumb. Duck-bills are the only dinos without any thumb. That’s strange because the thumb is usually one of the strongest fingers in all other dinosaurs. Even T. rex has a thumb. There’s a predatory dino with just one finger – Mononychus – and that single finger is, you guessed it, the thumb.
One result of being thumb-less is that when you’re choosing a bowling team, you don’t want a duck-bill. They can’t hold the ball.
The duck-bill hand has three fingers held tightly together, so only the finger tips would touch the ground when walking. The three digits look sort of like a ballerina’s hind toes in a ballet slipper. Footprints of duck-bills show a big, wide hind-paw and only a tiny little track where the hand touched down.
Duck-bill fingers in general are very long – and our Brachylophosaurus has exceptionally long digits. Plus the forearm is very long and slender. Put arm and fingers together, and you have the longest front limb of any dinosaur.
Modern Dance – 77 Million Years Ago?
The super-elongated arm & fingers don’t make sense for merely walking. But they would be useful in signaling. Imagine “Leonardo” gesturing to his Mom: he raises his body, puts all the weight on his hind-paws, and swings his arms and hands in a graceful arc. Adult brachylophs could use hand gestures as part of the mating dance.
Our brachylophs lived side-by-side with small butting-head dinos (pachycephalosaurs).
Compared to body and hind-legs, the butting-head dinos had tiny harms and hands, tinier than any other veggie-saur family. Why? No one knows yet. Horned dinos had big hands, as did dino-tanks (ankylosaurians).
Chicken Thighs & Toe-Walkers
Duck-bill dinosaurs have standard dinosaurian hips, knees and ankles. The over-all design was close to what ground-birds have today. The upper hip bone was wide so the thigh muscles were wide too. The top half of the shin had a big bulge of muscle, a dinosaurian drumstick. Don’t draw your dino with a skinny upper shin. Or fat lower shin. Give your dino a drum stick.
Butt-head dinosaurs had the most primitive hind foot for veggie-saurs. The arrangement was like a bird’s: three big toes, with the center one the longest. Plus there’s a smaller toe on the inside. T. rex has a similar hind foot, except the inner toe was even smaller. Triceratops had a big inner toe. The inner toe was used to prop the foot when walking on soft, muddy ground. And so…it looks like Triceratops liked mud better than T. rex did.
Only a few specialized dino-herbivores had only the three big toes with no inner toe at all. Duck-bills are that way. That should mean that duck-bills avoided soft, squishy terrain.
The toe joints in duck-bills show that the hind paws were not flat-footed. They walked with their heels high off the ground, just as big birds today walk. Fossils footprints show the same thing. All dinos of all species walked and ran in high-heels. Remember that when you draw a dino. No Flat-Foots!
If you’re careful about drawing toes and shins, you can figure out what dinosaur ran the fastest.
|photo credit: Paraflyer|
Go back to a zoo. Draw legs c a r e f u l l y. Who has short shins and short ankles? Elephants. Who has the longest shins and ankles? Deer and antelope. Who’s fastest? The deer and antelope.
It’s an anatomical rule. To run super-fast, you need long shins and long, thin ankle bones (what we call metatarsals). Even big, heavy critters can be medium-fast. Draw a rhino and draw an elephant. Who’s faster? Rhinos – they can go 33 mph. Elephants top out at 23 mph. Who has longer ankles? Rhinos.
Who has longer shins + ankles – a Brachylophosaurus or a T. rex? The rex – it would be faster. So would all members of the tyrannosaur family. How ‘bout butting-heads? They’re medium-fast – they have longer shins + ankles than a duck-bill but shorter than a rex. T’tops and the other horned dinos have shorter shins and ankles than do duck-bills.
Flex Zee Knees
Ski instructors from Austria tell you “Flex zee knees!” Pay attention to knees and ankles. Elephants have straight knee and ankles, like the ones we humans have. That means we can walk long distances with a slow, even, smooth stride. But we’re pretty slow.
|photo credit: BrianScott|
Now check out rhinos and buffalo – there’s a bend at the knee and at the ankle too. The bend gives the animal a bounce when it runs, and the bounce makes for higher speed.
Ok – let’s sketch some dino joints. Long-Necks (sauropods) like Diplodocus, have elephant-type knees and ankles. The joints are almost straight. But Triceratops and T. rex have bent knees and ankles. Therefore, we can conclude, that T’tops and the rexes were bouncier and faster than the long-necks. The butting-heads had bent joints too.
When we pay attention to ankles, shins and joint angles, we get the results of a dino race:
Diplodocus is slowest.
Triceratops and other horned dinos are medium-fast.
Duck-bills are faster.
Butting heads are faster still.
T. rex and other tyrannosaurs are the fastest multi-ton dinos.
For the fastest dino of all, check out the “ostrich-mimics”, like Struthiomimus. They’re mid-sized, only 300 pounds or so. But you’ll be amazed at the shins and ankles…
Duck-bills are gutsy. Their stomachs and intestines were HUGE! The ribs curve outwards very strongly – that means the stomach and intestines were bulgy and huge, much larger than a tyrannosaur of the same length would have. Plus, duck-bill intestines go further back along the body than almost any other land animal.
Observe the skeleton of a tyrannosaur. The intestines have to end at the pubic bone. Since the pubic bone goes straight down from near the hip socket, the guts can’t go any further back than the hip socket. So we have to say that a tyrannosaur was a gut-less wonder.
Duck-bills and butting-heads and horned dinos pull an anatomical trick: they swing the pubic bone backwards, so the lower end is way behind the hip socket. Now the guts can be enlarged. Intestinal chambers can extend very far back. Birds do the same trick (it’s called the “bird-hipped-condition;” ornithischian-condition if you want the technical term).
Duck-bills go to even greater extremes in gut-expansion. The lower hip bones (ischia) are made extra long and point backwards. The gut can go all the way to the tip of the ischia, and so the intestines are even larger than those in a butting-head dino or a horned dino.
Why would duck-bills need huge guts?
To digest tough plants, that’s why. Check it out in a zoo. Lions eat meat, and lion guts are small, because meat is easy to digest. Zebras and rhinos eat tough grass and branches, and their tummies are big and bulge out. Inside the bulgy tummies are chambers with water and micro-organisms that make the juices that digest the plants. Butting-head guts are so large that they must have eaten lots of vegetation every day.
When I put duck-bill neck bones together, they didn’t go in a straight line, front to back. Instead, the neck had a lovely S-curve – sort of like what you see in a swan or goose but thicker. It turns out that ALL dinosaurs have S-shaped necks. T. rex has a sharp curve. Brachylophosaurus has an even sharper curve. Triceratops has a gentler curve. Remember that when you draw your dino.
Dinosaur necks come in several strengths: super strong; strong, and weak.
|photo credit: Paul J Everett|
The tyrannosaurs have super-strong necks. The neck bones are tall and wide and had big prongs to attach the muscles. The back of the skull too is tall and wide, so the neck muscles that attached here were thick. A tyrannosaur could bite down hard and then twist and shake its victim, the way a pit-bull or a croc does.
Triceratops and the other horned dinos have stiff necks, because the front vertebrae are all grown together. The muscle attachments on the head were very wide, so these dinosaurs could swing their heads sideways and up – a good way to fight with their horns.
Butting-head dinosaurs had thick strong necks too, with muscles arranged like a musk-ox. Musk-oxen today ram each other; butting-head dinosaurs probably did too.
Duck-bill dinosaurs have beautiful, long, graceful necks. There are more separate bones than usual – up to fourteen vertebrae in the neck. Tyrannosaurs, butting-heads and most other dinosaurs had only 9. And the duck-bill neck was designed to move quickly in every direction – up, down and sideways. Thick muscles get in the way of fast neck movements. The duck-bill neck bones are arranged for thin muscles. The neck vertebrae are very low – they don’t have the thick, tall bony prongs that stick up in tyrannosaurs and other dinos. Those prongs are for muscles. Low prongs mean low, thin muscles and and without them duck-bills couldn’t have powerful neck movements. They could use their thin, pencil-necks to move the head all around as the critter searched for just the right leaf or branch to eat.
There was a trade-off, though. To get quicker-acting necks, duck-bills had to give up muscular strength.
Duck-bills had to be careful. But when a meat-eater attacked, the duck-bill had to protect its head and neck.
|Leonardo the mummified brachylophosaurus. Check
out the curvature of the neck bones.
Today, most antelope and deer are pencil-necks too. A lion or puma tries to grab its victim by the neck and throw it to the ground. Sometimes a lion uses a swipe from its big front paw to break the neck of a gazelle. Wild cats often grab the neck in their jaws – they kill antelope and deer by holding on and throttling their prey.
When I sketched the head/neck muscles that would have made the bones move in a duck-bill, there was a surprise. Leonardo and all other duck-bills were pencil-necks. Their neck bones were thin and weak.
Take a look at how Leonardo’s neck lies in the rock. X-rays show the usual strong curve – the neck goes down from the shoulders and then up.
It’s YOUR TURN!!!
That’s the dino-art lesson for today. Go to your zoo and study legs and guts, necks and tails, front paws and hind paws. Then go back to the museum and draw two dinosaurs and analyze them scientifically.