They say the dead tell no tales…Obviously whoever coined that phrase never studied the bones of prehistoric animals, because the fossils of dead critters sure say a lot.  Dry bones all kinda look the same, but take a closer look and you can see the clues left behind.

 

Last Monday, we went through a basic rundown on how paleontologists can figure out how to put the bones together.  How they take the bits and pieces they find in the field and build up the skeletons you see in museums.  Now before we move on to the soft stuff I just want to make one thing clear.

Unless it’s something totally new, most dinosaurs don’t have as much guesswork as I implied in my post.

Take Allosaurus, for example.  Tons of bones, from many different animals, gives us a good overall picture of the species and its growth cycle.  So for many dinosaurs, the difference from one skeleton to another is pretty small for the average enthusiast like myself.  And honestly, the skeletons of lions and tigers are almost identical.  We wouldn’t have a clue how obviously different they are without everything on top of the bones.

But I’m getting ahead of myself now.  We’ll come back to the lion and tiger example next Monday. 🙂

So what can bones tell us about an animal?

• A skull can tell us about how the animal sensed the world around it.  The size and shape of its brain, how good its sense of smell, if it had binocular vision like we do…all that good stuff.

• Teeth and special adaptations in the skull can give us clues to diet and wacky feeding habits.  Take a quick look at woodpecker skulls and you’ll see what I mean. 🙂

• The shape of the joints, and points of muscle attachment, can show us how the animal might’ve moved.  It also gives us a basic silhouette to work with.

• Bumps on the forearm, called “quill knobs”, show where large feathers where attached.  As well as other marks of soft tissue like where crests might attach.

 

These are just a few things bones can tell us, and how can we know this?

Take a close look the next time you eat a chicken drumstick or turkey leg.  The bone is not perfectly smooth, and it has a very specific shape.  There are ridges, bumps, little divets on one side…these are all marks where the muscles and tendons attached.

The chicken drumstick is actually a great example, because the bones of birds and crocodilians can be a sort of Rosetta Stone for translating dino bones.  Birds and crocs are the closest living relatives of dinosaurs, and birds are now classified as a group within dinosauria.

Long story short, the bones of living relatives like birds and crocs are a good starting point for figuring out dinosaur anatomy.  Not perfect, since crocs aren’t dinos, and modern birds fit into a specific niche inside the huge and diverse group of animals we call dinosaurs.  But crocs and birds can help fill in a few places that we would otherwise be clueless about.

• How much muscle?  Crocs and birds have a different structure to their muscles than mammals.

• So we know the shape and size of the critter’s brain, but what does that mean?  Crocs and birds today can give us clues.

• Other soft bits like organs, and how dinos metabolisms worked…looking at birds and crocs can help figure out mysteries in the bones, like how dinosaurs got so big.

But now we’re heading into squishier territory than even muscles.  Bones are pretty solid (for the most part).  Muscles and soft tissue directly attached to the bone is just a matter of translating the markings correctly…but next Monday we’ll dip our toes into the mud and find out how much we know, or don’t know, about the soft outsides.

 

Quick Question: Take a moment to notice all the little bumps, ridges, and dimples in this skull.  Notice that triangular dip at the back of the lower jaw, and the high ridges that make that triangle shape.  Powerful muscles to close the jaw attach here and go through that “loop”, where they attach to the back of the neck and head. This is one powerful critter!  Can you guess what it is?  

Hint: those teeth will tell you it’s not a dinosaur or reptile. 😉 I’d love to hear 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)