Whole-Hole Catalogue: The Horned Meat-eater Ceratosaurus

Here’s the skull and life portrait of the carnivorous dinosaur Ceratosaurus, from the Late Jurassic of Colorado, Wyoming and Utah.  It’s the only meat-eater with a tall, sharp-edged horn on its nose.

(And it’s my very favorite dino of all time – isn’t it just lovely?).

Check out the holes in the skull and the organs that fill the holes in life.

The nostril is no surprise, it’s the oval slit up front.

The eye is in the third big hole from the front.

The very big hole between nostril and eye is for the complex air chambers connected to the throat – birds have these chambers too.

The triangular hole behind the eye was filled with jaw muscle.

The eardrum was located far aft, behind the muscle hole, tucked under a little ledge made by the skull.

Who had a stronger bite, Ceratosaurus or Tyrannosaurus? Compare the size of the holes for jaw muscles……..

Interested in learning more about dinosaur skulls? Check out my previous blog.

Skull Slushies – What’s inside a dinosaur’s skull?

We get so many great questions through our blog, and every now and then we can turn those responses into a blog post. One our readers favorite posts is “What would YOU ask a paleontologist?”

Last week we got this question from Britt:

“ok so, if dinosaurs, for the most part had tiny little brains, and giant heads, what filled up the rest of their head if not brain? like some kind of brain slushie or what?”

Dr. Bakker, curator of paleontology here at the museum wrote this in response:

Skull Slushies – What’s inside a dinosaur’s skull?

Skull
Creative Commons License photo credit: Lord_Alex

Darn good question. You’re asking about the fundamental architecture of a vertebrate head. And to understand the skull, you must discover that there are really two skulls in your head, one inside the other.

The outer skull is a shell of bone that makes your eye-socket, the hole for your nostrils, your cheek and upper jaw with its row of teeth. Same for T. rex or a Triceratops or a cocker spaniel…….  Komodo Dragon, man-eating Nile Crocodile, etc., etc.

Inside the outer shell of bone is the cranial inner sanctum – the braincase. Yep – the braincase houses the brain. There are holes in the braincase to let out nerves and sense organs. The eyeball really is a big nerve. It comes out a hole in the front of the braincase and then goes into the eyesocket. The nerve for your sense of hearing goes out a hole in the braincase located further aft. This auditory nerve goes out sideways and ends up inside a ball of bone at the base of your ear.

The spinal cord is a huge bundle of nerves that goes out the biggest hole – we label it the foramen magnum. The spinal cord continues to the rear through holes in the vertebrae.

The outer skull and the braincase are attached to each other a couple of places at the top, sides and rear of the head.

Brains and only brains fill the braincase. Fine. Now what is between the outer skull and the braincase?  Slushies? Packing peanuts? Old newspapers wadded up? Receipts from Buckey’s?

Nope. More important stuff – muscles. The muscles you use for chewing are packed between the outer skull and braincase. Try this: get some tasty beef jerky and chew. Put your fore-finger on the side of your head, just behind your eye-socket. There’s a hole in the outer skull here. You can feel your jaw muscle bulging as it contracts each time you chew.

That chewing muscle is your temporal muscle. The hole in your outer skull is a temporal fenestra (temporal “window”). Now trot out to our dinosaur display and check out the T. rex. skull. There are lots of holes in the outer skull. The tall oval hole is for the eye. To the rear it has a hole shaped like a w turned on edge. That’s a temporal fenestra. Look through this hole, You’ll see the braincase.

In animals with mid-sized brains, like T. rex, there’s a lot of space between the braincase and the outer skull at the temporal window. All the space was filled with muscles. So the jaw muscles were thick and strong.

We humans are the opposite of a rex. We have a giant, bulgy braincase chock full of brain. We’re the thinkiest species on land (porpoises give us competition in water).  But we are wussies when it comes to chewing. There’s only a thin space between braincase and outer skull. Check out a human skull. It’s humbling. We just can’t chew hard.

Now, every time you see a skull on exhibit, try to judge how much room there was for chewing muscle between the outer skull and the braincase. Hyenas are particularly intriguing……

If you have any questions you would like to ask any of our bloggers or curators, send us an email at blogadmin@hmns.org.

Dead Man’s Party – Dia de los Muertos

Dia de los Muertos artwork by one of our hmns bloggers!

Halloween is this Saturday and everyone is scrambling to put together their costumes and figuring out what parties to go to Friday and Saturday. But what are your plans for Dia de los Muertos on November 2nd!?

The education department here at HMNS offered an encore event to last year’s very popular Dia de los Muertos Educator Overnight and teachers came from all over the greater Houston area to learn about this incredible holiday and how to do some activities with their own students so that they may learn more about the culture. If you want to learn how to make sugar skulls check out this guide online – it has some great tips on how to make some incredible shaped sugar treasures!

Above you’ll see an artwork that references La Calavera Catrina, an etching done by Mexican printmaker Jose Guadelupe Posada in 1913. La Catrina and some of Posada’s other artwork is reproduced and can be seen around town available on book bags, t-shirts and in jewelry – especially around Dia de los Muertos. This piece pictured here is composed completely out of dyed eggshells by one of our very own hmns bloggers!

Below are some of the fun hands on activities and projects the teachers did at the Overnight this year and don’t worry – we’re already thinking up some cool ideas for “Dia de los Muertos II – the Overnight Sequel for Educators” – next October! Drop me a line if you want to receive notice when we start accepting registrations for this Overnight in 2010 – overnights@hmns.org.

Decorating sugar skulls
Decorating sugar skulls
Calacas puppet in progress
Calacas puppet in progress
Cigar box altar
Cigar box altar
This tiny clay skull is perfect for a tiny cigar box altar table!
This tiny clay skull
is perfect for a tiny cigar box altar table!
Completed sugar skulls!
Completed sugar skulls!

Mystery Skeleton – Update 3

Cavity

After a few days of soaking the bones in the hydrogen peroxide bath, I took the skull out and dried it off.  According to Lee Post, if a bone still has fats inside it, there will be spots on the bone that are darker and still look wet even after it is totally dry. Taking the skull out gave me the opportunity to identify the bones and see how much more of a soak it would need.

I picked the skull because it is the bone that most readily identifies an animal.  In this instance I began by asking Dr. Bakker what he thought.  From the pictures I showed him, he said dog. 

I already knew it was a canid, so it wasn’t surprising that it was a dog.  At first, I wanted to determine what type of dog it was, but I quickly realized that was kind of dumb on my part.  It was probably a wild dog.  I wanted to check it out anyway however, just to make sure.  It was going to be fairly crucial to the articulation to make sure I have the right critter, so I went to Skulls Unlimited to see what they had for comparison.  Except for specialty breeds, like pugs, my skulls and their skulls are a pretty close match.

As I said in the original post, my parents live on a ranch.  Around their ranch are several packs of wild dogs. It is not uncommon for people to shoot at the dogs because they will hunt livestock, fight with working dogs and are occasionally rabid.  To think that this was a wild dog that was shot isn’t too far fetched (no pun intended).

Broken Teeth

I took a look at my vat o’ bones and considered this theory.  All the major bones seem to be there – leg bones, pelvis, shoulder blades.  None of the spinal column bones or the ribs seem to be shattered like a bullet hit them.  So what this tells me is that this theory might be faulty.  The skull is smaller than Millie’s would be.  She is a 60 pound dog, so she is good sized but not huge.  I imagine this dog being more in the 35 to 45 pound range.  The dog would have been more compact, a small target.  It seems logical to conclude that the shooter would have gone for a body shot, and it seems nearly impossible that, from several yards away, he or she wouldn’t have hit the dog and shattered several bones.  So if it wasn’t a bullet, what was the cause of death?