Fun with Fossils
Critter of the Month: Hybodus
Meet Chum. He would love to go for a swim with you, especially if you have any treats! 🙂
The shark cruised the turquoise water, sunlight rippling through the waves to the soft sand below. A small school of silvery fish stirred up a cloud in the warm, shallow waters by the reef, but the shark turned away from them.
Critter of the Month: Ceratosaurus
Meet Bowser. Those horns may look intimidating, and his toothy grin can be downright fearsome. But you know what they say about books and their covers… 😉
Crouched in the dappled shade of a gnarled cedar tree, Bowser inhaled a long, slow breath.
The bitter tang of oily sap that bubbled from a gash in the tree’s trunk.
The dusty heat from sun-baked rocks and chalky, clay-hardened soil.
The earthy spice of charcoal and wood smoke…and a sweetness so tantalizing he could almost taste it as the scent filled his sinuses. Continue reading
Critter of the Week: Allosaurus
Meet Alfred. The lion of the Jurassic! The prince of the Mesozoic! The…oh, there he goes after another butterfly. All he needs to be happy in life is his food, his chew toy, and a nice long nap.
Looks like Alfred has found something to chase. Continue reading
The Art and Science of Alfred
Hello there! Alfred is super excited to see you, and look at how curious he is. Do you own a cat or dog? Because he seems to think you smell good. (stay back Alfred, be nice). Here we go, I’ve got a nice ball of cheese and bacon here. He’ll love it. Here Alfred, go get it!
While Alfred gets the ball, I can share this lovely disclaimer. Que elevator music…
I do the best I can with research, but I definitely don’t claim to be an expert. I try my best to keep up to date, and all my illustrations reflect this. (thank you internets, and to all hard-working paleo-nerds who are kind enough to make your papers open source!) 😀
That said, all the drawings in the A&S post series are quick doodles to illustrate a point, with not as much reference as I usually use, so there are plenty of inaccuracies for you to point out for me. 😉
Thank you disclaimer, you can go bother someone else now. 😛 Elevator music fades out…Oh and here comes Alfred! Looks like he wants more…
There we go, good boy Alfred!
Now Alfred here is an Allosaurus. He’s young, so only about 12 feet long so far, but he’ll grow to be a lot bigger. Not as big as his wild cousins though, a few of them could be as big as T-rex! (very few, gotta be old to get that big, and most dinos have a live fast, die young policy)
1. On Scaly Skin vs. Feathers
So you see Alfred here has these lovely bright yellow and forest green scales, the colors of youth. (They’ll mellow out a bit when he gets older, like monitor lizards do)
Also like a monitor lizard, you’ll notice that most of Alfred’s scales are quite small, with a rather pebbly texture. They get a bit larger and thicker on his back, which is good since adult Allosaurus tend to get into quite a lot of tussles with each other. But most of his scales have that nice cobblestone look to them.
Like this guy, remember him from last week’s post on feathers and scales?
Short answer as to why Alfred has scales…there’s a young Allosaurus with preserved scales somewhere on it’s body. (Unfortunately the report didn’t say where)
Long answer was so long I made a post out of it…To Feather or Not to Feather Your Dinosaur, That is the Question. (The komodo dragon above was laying around in that post. So was this gal, she’s a monitor lizard. 🙂 )
2. Getting Comfy…
Looks like Alfred’s all worn out from chasing after that giant, cheesy bacon-ball. He hasn’t quite grown into his adult silhouette yet. He’s still young enough to think he can chase after stuff, but he’s starting to get to an age where it’s getting hard to make those quick turns.
When he fills out his more barrel-chested adult figure, he’ll be spending quite a bit of his leisure hours (think energy-efficient) laying around. Since his body is a bit taller than it’s wide (more lanky cat than double-wide gator), it’s more relaxing to be lounging on his side.
Of course, that doesn’t mean he can’t do other things to relax, even things that may surprise us (ever seen a large horse roll? It’s hilarious 😀 ).
Oh, and here’s that horse… 😀 I can totally picture some “duckbill” dino doing this.
3. Where are His Teeth?!
I hear ya, I wondered the same thing when I looked up pictures of Komodo Dragons and monitor lizards. But wait, what does that have anything to do with it?
Pete will help us out here. I know Alfred looks a little awkward, but he’s actually quite comfy. Ah- I’ll let Pete tell you the rest…
“Thank you. Yes, Alfred is quite at ease here. I’m not heavy to him at all, and he weighs at least a good 300 pounds at this age. So he doesn’t mind a bit.
I’m tilting his head back very gently- show us your teeth there Alfred, that’s it, nice and easy.
See this is the biggest difference between a domestic Allosaurus like Alfred here and a wild one. Look how completely relaxed he is. He’s not fighting me at all, and even his eyes are closed, look at that. (Alfred makes a gurgly, kinda purring sound in his throat)
Anyhow, I’m holding onto his lips here so I keep my fingers out of his mouth. My fingers can look a bit like treats, so I’ll be sure to keep them right at the edge here, at the gums.
All this, the lips, the gums, the saliva- it all keeps his teeth nice and moist. Dinosaurs have a healthy coat of enamel on their teeth, same as your teeth, and the key to healthy teeth is to keep them moist. Even better if you can give your teeth a constant bath of saliva.
Yes, drool is essential to healthy teeth!
Now Alfred will lose his teeth and grow new ones, just like crocodiles and alligators do, but if you look closely at these teeth-they’re serrated. They’re like steak knives- not like the cone-like teeth of crocodiles.
Thank you Alfred, you’ve been quite patient. Here’s some jerky.
But crocodiles don’t need serrated teeth. They’re eating different things, they have a different habitat, and different diet, they’re eating in a completely different way. Alfred has teeth like a bone saw.
Ever cut a roast turkey with an electric knife? That’s what Alfred’s teeth are doing when he eats, so they need to stay sharp, and they need to be strong in his mouth. So the gums hold his teeth, and his lips keep them nice and moist so they stay strong and don’t get brittle.”
Thank you Pete, and Alfred. Just for comparison, here is a crocodile monitor lizard.
My first thought, “Where are the teeth?!” Then I noticed those sharp white triangular things inside the lip. Also interesting is that it looks like there are pockets for the bottom teeth to slip into. 🙂 Here’s the skull of the same animal…
They look quite different from the other picture don’t they? Almost, shall I say, dinosauresqe? Take a look at an Allosaurus skull. 😀
The one and only skull I could find that doesn’t have its teeth halfway falling out of their sockets (it happens when the dead critter decays). Jason has many more pictures of the Allosaurus mounts at the American Museum of Natural History, and I’d highly recommend you check out his blog post. You’ll also discover all my errors and where I need to fix Alfred. 😀
Quick Question: Help me find what I need to fix! If you wouldn’t mind checking out this blog post on Allosaurus, you’ll get to see some great pictures of excellent mounts, and you’ll see what I have to correct in my illustrations of Alfred.
I’d love to hear from you in the comments! I’ll be posting a comment on how many I find, and let’s see if we come up with the same ones or more. 😀
P.S.- You can always hop over the the A&S page to pick out who you want to see next! 🙂
The Art & Science of Terry
Hi there! Terry is here with us today, a rather odd looking critter isn’t she? If I asked you to tell me what she is, what would your answer be? Flying dinosaur? Terradactyl? Pterosaur?
If you said Pterosaur then clearly you’ve done your homework. If not, don’t feel bad (I’m not pointing fingers), because the sad fact is that most books, movies, toys, and pretty much anything to do with dinosaurs always lump Terry and her many relatives into the same pile.
Terry is a Pterosaur (Don’t mind the P there, it’s confusingly silent), a group of flying reptiles closely related to dinosaurs. To be specific, her wild cousins are Pterodactylus kochi. Pterodactylus is the pterosaur, where we get the name for the whole group. So now you know she’s special. 😀
1. Is that…fur?
Terry, like all pterosaurs, is covered in a fuzzy layer of pycnofibers. They’re made of the same keratinous proteins as our hair and fingernails. But they appear to be hollow inside, which makes them much more like feathers than fur.
I say “appear to be”, because not everyone agrees. Most of the fossils are a bit squashed, and even the 3d fossils can be hard to tell if what fills the space inside was part of the living animal or just more of the fossil (or a part of decomposition after the critter died, but before it fossilized).
Last week we saw the basic structure of a feather. If pycnofibers are indeed hollow, then that could mean that they are similar in structure to feathers.
Terry and her many relatives are related to dinosaurs in the same way that crocs are related to dinosaurs (They are all Archosaurs). A bit like a great aunt.
Since many dinosaurs are known to have feathers of various kinds, it would be pretty significant if pterosaur pycnofibers are determined to be feathers as well.
How significant? More fluffy dinosaurs! It’s possible that the earliest dinosaurs had a coat of fur-like feathers. 🙂
2. Hard Beak or Fuzzy Snout?
Now I’m not quite sure where I first heard of the idea of hard-beaked pterosaurs…I think I remember Petrie from The Land Before Time had a beak. Come to think of it, I guess there are plenty of interpretations with beaky pterosaurs, but I’m not sure how many are based on fossil evidence.
So why does Terry have a soft, fuzzy snout?
The fossils don’t have a beak. In fact, in several beautifully preserved ones we see only soft tissues, complete with a soft crest and that lappet on the back of head. There’s a lovely diagram showing how clear the fossil is over at Mark Witton’s wonderful blog. I’d highly recommend you check it out, because he’s an excellent artist, and an expert on all things pterosaur. 🙂
Terry’s friend on the left is a Rhamphorynchus (that’s a mouthful, sorry, let’s call him…Ron). Some illustrate Ron and his wild relatives with just the toothless tip of his snout with a beak, but I’ve based mine off of Mark Witton’s lovely illustration.
Honestly, it’s hard to imagine those crazy teeth with any kind of soft tissue, and that seems to be the argument for a hard beak over the bone.
3. The original pole vaulting masters
Pterosaurs had powerful wings, but their legs weren’t really strong enough to jump up to fly like birds. So does that mean they’re helpless on the ground?
Not at all, look at Terry scamper around!
Pterosaurs were Earth’s first pole vaulting masters. Their powerful wing-arms were strong enough to push their bodies (even the biggest ones) up into the air. Mark Witton proposes that even the largest, giraffe-sized pterosaurs could lift off from the ground. Many could probably take off from the water!
Helpless? I think, not. 🙂 Here’s a quick video so you can see it in action. 🙂
How is it possible?
Unlike birds, pterosaurs have most of their muscle dedicated to their wings. Birds need enough muscle in their legs to jump up before flapping, while pterosaurs pole vault into the air with the same power they use for flying.
So no need to jump off a cliff or wait for warm updrafts of air. 🙂
Quick Question: Ah, the nostalgia of so many movies and documentaries…I must say I still rather like the leathery, cliff-clinging bats in Fantasia (so many great retro-saurs in that one). Are there any pterosaurs from books or movies that have colored how you see these animals? 🙂 I’d love to hear your answer in the comments!
P.S.- You can always hop over the the A&S page to pick out who you want to see next! 🙂
The Art & Science: Steggy
Hello there Steggy! She’s followed me here because she wants the bucket of tasty fern balls I’ve brought with me. That works out nicely, since she’ll stay here and munch while we point and chat about her for a few minutes. Just like when we talked about Ajax last week, I’ll stick with 3 research tidbits for now, to keep things short. 🙂
1. Soft or hard-shelled turtle?
Steggy’s a bit smaller than the average wild stegosaurus, but she’s still quite a bit taller than we are. If you reach up on your tip-toes you might be able to touch the biggest of her plates, the one right above her hips there.
There’s been some speculation in recent years on if these plates were hard and covered in keratin- like a turtle’s shell or cow’s horn- or if the plates were soft and covered in scales or skin.
I did a bit of digging (research wise), and came across this lovely gem of information written by Darren Naish. He cites a paper provided by Christiansen & Tschopp (2010), who reported a continuous sheath-like covering on one of the plates they referred to another spiketail known as Hesperosaurus.
So there you have it. Hesperosaurus is a very close cousin of Stegosaurus, so in the realm of phylogenetic bracketing that makes it more likely that Steggy had a smooth, hard sheath of horn on her plates and spikes.
2. Armed to the teeth.
The same Hesperosaurus described had another very rare insight on spiketails- fossil skin. As you can see on Steggy here, most of her body is covered in small, non-overlapping scales, called tubercles. They look a bit like pave stones don’t they? Now look up here, a bit higher up on her side. Interesting isn’t it?
Steggy has some pretty tough scales. These large oval scales are called osteoderms, just like the large, hard scales on the backs of crocodiles. They’re covered in keratin, like our fingernails, and they do a pretty good job as armor. I’m sure Alfred‘s wild relatives had a tough time munching on wild stegosaurus. 🙂
- thick skin with larger, armor-like scales (also useful for prickly plants) You can find the abstract for the paper describing the skin here.
- Large, horn plates protect the spine
- Bony neck armor protects neck from predators and prickly plants
- Muscular tail that’s flexible enough to jab at hard-to-reach places, like between a predator’s legs. Just take a look at this article about a time the allosaur lost the fight…And check out this article on exactly how lethal a blow from this kind of tail can be (using a different spiketail cousin as a model)
- Short front legs can bring head lower to the ground (harder to reach) and spiky end up, or push the body up to swivel on powerful hind legs. Awesome for quick, sharp turns. No way a hungry predator can get to anything soft and vulnerable if that spiked mace is always between it and the stego.
3. She might not be the sharpest rock, but she’s one tough cookie.
Steggy might have a brain the same size as a dog’s, but she’s not nearly as dumb as movies and the media would have you think. (I’m looking at you Spike, in The Land Before Time). I think most encounters would not have ended up like the stego in Disney’s Fantasia (which is totally what inspired my love for them in the first place 🙂 )
With all that armor, and tons of fossil evidence with some serious dino damage on Alfred‘s wild relatives, it looks to me that spiketails had an attitude to match their prickly array of spikes and plates.
Because of that, I’ve given Steggy a bright warning pattern. Someone told me it reminded her of a skunk, and that’s exactly what I’m going for. Steggy’s color is something that says “stay away!”
Good thing Steggy is a calm and peaceful pet then, a domesticated spiketail. Domestic spiketails have a tendency to be nervous, and spook easily (like horses), but Pete works with her a lot, and hardly anything bothers Steggy now. (horses can be trained like this too)
Just for fun, here’s my reasoning on why Steggy may not be as dumb as you think. A quick check on Youtube brings up plenty of smart tortoises. Yep, after discovering that it couldn’t fit through the pet door, this one figured out how to open a sliding glass door.
Quick Question: Animals do all sorts of crazy things we wouldn’t expect. Do you have a story about an animal or pet that did something unexpected? I’d love to hear your answer in the comments!
P.S.- You can always hop over the the A&S page to pick out who you want to see next! 🙂
The Art & Science of Ajax
First up is Ajax (hi there Ajax! Give’em a smile), because really he’s the first critter of the lot I ever drew, and he shows up in my sketch book a lot. Plus he’s just an all around friendly guy, and anyone knows a brontosaurus (ahem, Apatosaurus) when they see one. 🙂
So what’s science and what’s art? To keep this post short, I’ll cover three main points (there are always more, but we can save those for later). All drawings in these posts are quick doodles to illustrate a point, with not as much reference as I usually use, so there are plenty of inaccuracies for you to point out for me. But I do have this great
toy model replica to look at when I’m clueless as to how something looks at certain angles. 😉
1. Toothy grin, or soft smile?
For starters, let’s talk about Ajax’s smile in the picture above. There’s a lot of discussion on dinosaur lips- did they have a toothy grin like crocs, or closed lizard-type lips?
On one hand there’s the study by Ashley Morhardt (unfortunately I can’t find it, so I’m relying on 3rd party sources). She compared the skulls of prehistoric and modern animals, and looked at the clues left behind by beaks, lips, etc…and her study suggests that sauropods like Ajax had a face more like a crocodile’s than the fleshy lips of mammals.
This article by Duane Nash on the giant canine teeth of saber-tooth tigers (smilodon & relatives) gives some food for thought. The blog post has all sorts of cool info of what makes a tusk vs. a tooth. 🙂
Ajax’s teeth, like most dinosaur teeth, have a pretty healthy coating of enamel, the same stuff that coats our teeth and makes them hard. Enamel does best when it’s bathed in saliva 24/7, which is why mostly all animals that have enamel-rich teeth have mouths sealed shut by lips of some sort.
Anyway, Ajax eats whatever he can get a hold of. He does replace his teeth every once and a while (unlike our permanent set of adult teeth), but still, it takes a while to get a replacement tooth, so he needs to use each set for as long as he can.
With that in mind, I’ve decided to reconstruct Ajax and the other sauropods with closed, lizard-like lips.
It’s one of those things that we can’t know for sure, because even a mummy can’t give you a perfect picture, anymore than a raisin can tell you what a grape looks like.
2. How far can he stretch?
Oh boy, paleontologists have gone back and forth on this one for over a century. First thin, graceful necks like swans, then BBC’s Walking With Dinosaurs comes out and shows the fruit of research claiming that Ajax & Dippy held their necks out like suspension bridges. They held their heads and tails in almost a straight line, and were unable to lift their heads higher than their shoulders.
More recent work has pointed out that if you add space for cartilage between the bones, then the necks of many sauropods had the flexibility to loop in a complete circle. The brilliant minds behind the SV-POW! team over at svpow.com (always enjoyable to read, but definitely more on the technical side) helped rekindle my love for the long-necked giants by holding their heads high again, and regain neck flexibility by taking soft tissues into account.
My latest research just today, I come across a paper studying ostrich necks, and what that means for how far Ajax can stretch.
In short, we don’t really know. But Ajax would probably have a great deal more flexibility than Walking With Dinosaurs would have you believe. The bendiest part would be the middle of Ajax’s neck, with the ends less flexible.
I always think that animals are more capable than we usually think, so one of Ajax’s buddies has reached back to scratch at an itch on his leg. 🙂
Oh, and those two in the back with the puffy necks…that’s entirely speculative. Something weird was going on with Ajax’s neck though, that’s for sure. 😉
3. I think we need some bigger horseshoes…
Feet, especially the front feet, are usually drawn very, very wrong when it comes Ajax and his relatives. Many artists will slap elephant feet on them and call it a day. But take a look at one of Ajax’s tracks…
Ajax’s legs are like solid pillers, and all the finger bones are wrapped together to form a fleshy, padded, hoof-like structure. Only the “thumb” has a claw, which has some limited mobility depending on the species. Ajax can move his thumb claw up and down a little bit. 🙂
Scientists disagree on how much Ajax could move his wrist. So how far he has his front foot bent at the wrist is a bit speculative.
I’ve done a terrible thing and made his wrist flexible based on an elephant’s range of movement. 😛
Quick Question: Is there anything in the popular media you can think of about Ajax and other sauropods? What common misconceptions do movies like Jurassic Park and The Land Before Time give about Ajax and his cousins? 🙂 I’d love to hear your answer in the comments!
P.S.- You can always hop over the the A&S page to pick out who you want to see next! 🙂
Uncharted Waters (all about the big picture. No animal lives on a blank sheet of paper)
Let’s revisit our friend Mr. B from the first post of this series on fossilization (Who’s Mr. B? Refresh your memory here). We’ve dug up his bones, put them together, figured out all the soft stuff like muscle and skin, and we’ve got a pretty good idea how he lived…but he didn’t live all by himself on a desert island, or on a blank white sheet of paper (ahem, I’m looking at you, boring sideways diagrams).
So how do we figure out about the big picture? Where does Mr. B fit in?
First let’s take a look at old Mr. B…what do we know about him?
- We know he’s a Brachiosaurus.
- We found it in Colorado while digging at the Morrison Formation.
- He’s a very large mega-herbivore, and rare in this particular formation.
This isn’t a lot to go on, aside from the fact that Mr. B would need plenty of plants to eat and water to drink, and lots of space to roam.
Who’s in the neighborhood? It would be tough to figure out what makes a Savannah with only a giraffe to look at, so let’s take a look at some of Mr. B’s neighbors.
- There were also all sorts of other non-dino critters, like flying pterosaurs, several small land and water-loving crocs, all sorts of insects (including termites that built 90ft-tall mounds), fish, frogs, turtles, lizards, crayfish, clams, and even a few egg-laying mammals no bigger than rats.
Now we’re getting somewhere. We know that this environment has to support several very large herbivores and carnivores, along with a very diverse population of smaller dinosaurs and other animals. We’ll have to assume that many small and delicate animals were not preserved.
What we can’t really figure out from looking at all these animals is…what where all those giant plant eaters eating?
The Green Stuff. Of course, plants are essential to any ecosystem, and in the Morrison Formation we find stuff kinda like this…
Horsetails can live just about anywhere so long as there’s a river- even deserts.
Ferns in the desert! Notice how grass-like the “dead” one looks.
Dirt isn’t just dirt. Sand, mud, ash, sediment at the bottom of the ocean or a lake…they all turn into different kinds of rock. So what kind of rock a fossil is buried in can tell us a lot about plants, which can then tell us a lot about the local weather.
The Morrison Formation is made of layers of mudstone, sandstone, siltstone and limestone, and is light grey, greenish gray, or red in color. Most of the fossils occur in the green siltstone beds and lower sandstones.
To translate into plain English, this means that the area was an area laced with a few rivers, and had seasons of drought and flood. Since the area was relatively flat, it would flood and turn into swamp in the wet season, but have dry Savannah during the dry season.
But there was no grass or flowering plants in the Jurassic, so what sort of plants would there be in a Mesozoic Savannah?
Take a look at modern ecosystems. In areas that have no grass or flowering plants, what is the primary groundcover?
Let’s take another look at those desert ferns…
Dead looking and dry during the long months of drought, but give it a little water and it transforms. The grassy-looking brown fern further up does the same thing. Dead and brown when it’s dry, lush and green when it rains.
Another ground cover…biological soil crust.
Biological what? (my thoughts when I first read that)
Biological soil crust, or cryptobiotic soil, is a community of bacteria, moss, and lichen that holds moisture, prevents erosion, and provides valuable nutrients for plants (and possibly dinos 😀 ). It looks all brown and crusty during the dry season, but like the ferns, turns green when it rains.
One last picture, and here we have something that is probably very similar to what the Jurassic Morrison habitat was like. Only instead of the flowering shrubs we see here, imagine many different shapes of cycad and bushy areas of dried out ferns waiting for rain…closer to the river we get horsetails, ginkgoes, and giant, more water-loving ferns and tree ferns.
The padded feet of dinosaurs, like camels, kangaroos, and ostriches today, doesn’t break the slow-growing crust underfoot.
Quick Question: Now that we have a more complete picture, how do you think Mr. B fits in now? My guess is as good as yours, so it’s all fun speculation. I’d love to here your answer in the comments! 🙂
Fleshing out the Bones Series:
- Part 1: The Miracle of Fossilization (the crazy hard obstacle course from death to museum)
- Part 2: The World’s Toughest Jigsaw Puzzle (making a mounted skeleton out of bits and pieces)
- Part 3: Here’s the Easy Part (figuring out muscle and other fun anatomy)
- Part 4: Let’s Put Some Skin on That (how much we know, and don’t know, about the soft stuff)
- Part 5: Time to Get Wild! (how we can guess about behavior, and how crazy it can get!)
- Part 6: Uncharted Waters (all about the big picture. No animal lives on a blank sheet of paper)