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Learning about Tyrannosaurus


I've had a lot of T-Rex action this week. I was planning to write this post anyway, but while I was away on holiday there was this tyrannosaurus skeleton nearby (above), and my brother Sam bought a model of a T-Rex skeleton as well - and I saw Jurassic World at the cinema today ! 

 Tyrannosaurus is the biggy - one of the largest land predators ever known, one of the most studied (because lots of specimens have been found), and the best known dinosaur. Bone evidence is often the only way to understand how they lived - but this week's blog post is about something I've always found a bit weird about them.

Tyrannosaurus lived around 68-66 million years ago, at the late Cretaceous Period. They were therapods - and were apex predators, which means that they were at the top of the food chain. They weighed around seven tons, could grow up to 40 ft long and 13 ft high. at the hips. Here's the model from the Natural History Museum when I visited two years ago.

I say "at the hip" because until about 1970 it was believed that T-rex stood pretty much upright with the tail on the ground, and so would have been much taller. Here's a drawing from 1905 which shows what people believed then:

Archeologists Paleontologists in 1905 weren't stupid, and that wasn't a bad guess at all.  That's because it's pretty hard to imagine an animal so huge designed like a see-saw, balanced on one set of legs. Think of a large male African elephant. Now imagine it balanced on two legs. Weird, isn't it ?

Weird stance ?

Up until last week, while I understood that Tyrannosaurus walked that way, I thought it looked a bit ridiculous. I thought about it while on holiday, which was next to a park. I mean, could you imagine an animal that had a huge body, long neck, with one set of legs in the middle ? Then a peacock walked past.

But the peacock has working wings, not silly little arms, and it can't run very fast. I mean, can you imagine an animal that had a huge body, long neck, three toes on each foot, and with one set of legs in the middle which had silly little arms which didn't do anything, yet could still run extremely fast ?

Then about twenty yards away from the peacock was this.

Oh yes. An emu. Which can outrun a leopard.

But a peacock's head is tiny compared to its body, and a emu's is tiny and fragile as well.  Tyrannosaurus's is huge. What's happening there ? 

The skull

Here's the problem. How did  Tyrannosaurus end up with a huge heavy body which is balanced in the middle,  but with a massive weight - a skull that was up to 5ft long - at one end ?

You would think that if the legs are in the middle of the body, and there is a heavy skull at one end, that it would struggle to walk. Well, its long tail balances it out, with its 40 caudal vertebrae.Well, the Tyrannosaurus has very strong neck vertebrae. It also has but the skull also has holes in it to reduce weight, as well as doubling as muscle attachments.

The skull is also V-shaped, with a narrow snout, but much broader at the neck, to merge with the strong neck and have space for the massive jaw muscles - it had an incredibly strong bite - as well as giving Tyrannosaurus's eyes clear vision forward for hunting. 

And having such a massive, heavy skull also helps explain why the arms evolved to be so short: if it killed with the jaws, it had less need for arms when hunting prey

The legs and feet

The Tyrannosaurus' legs are huge ! They bear all seven tons of the Tyrannosaurus, so they have loads of muscle attachment. The feet have three sharp toes each, just like modern birds. They are really spread out to help to support the weight.

How did Tyrannosaurus run ? Was it slow or fast ? Scientists use a lot of clever guesswork, but even they don't know. Most think it could run at 25mph - but some think it could go at almost twice that.

One of the things scientists look at is whether the tibia (shin bone) is longer than the femur (thigh bone). In deer - which are fast runners - the tibia is longer. 

All of these pictures ( except from the top two ) are from the Tyrannosaurus skeleton at the National Museum of Scotland which you can read about here.

Here is a time lapse of the Tyrannosaurus skeleton being assembled at the National Museum of Scotland :

Tyrannosaurus is one of the best known and best understood dinosaurs - but even so, there is still a lot that scientists are trying to learn about it. One of the problems is that for modern animals, you can look at other animals which are very similar - but no human has ever seen a dinosaur move, walk or hunt, so scientists make smart guesses based on the bone evidence. I still have a lot to learn about Tyrannosaurus, but it's good to know the scientists who are making the discoveries are helped by looking at the bones of modern animals in order to learn what is similar and what is different.

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Nasia said...

Very nice post Jake. Just a small correction though, archaeologists have nothing to do with the study of dinosaurs, at least today. I am not sure whether there was a distinction between archaeology and palaeontology in 1905 but nowadays are two separate fields.

Jake said...

Thanks ! Have changed it now.

Simone Ross said...

Hi Jake
I am an osteopath and love bones! I have bought your book for my daughter and am impressed by what you have put together. The study of bones and anatomy is a great subject and I hope you continue on with your studies. You have an impressive collection. I am wondering whether you have looked at how the different shapes of bones work with the different functions of the body. If you havent get someone to show you. It is a brilliant part of anatomy. As an osteopath we only study the human body but some of the bones are very similar. Anyway, I have a 7 year old daughter who has found 3 skulls so far in the woods. We went to an otter park today in Cornwall and found a skull of a bird of prey - I think! They have birds of prey there and we found it in one of their show boxes. But we have no idea what it is Can we send you a photo of it? Many thanks

Bessie said...

Hi Jake i am a 13 year old naturalist willdlife photographer and lover before i read your great blog i had never thought of writing one but i have just started photographingdabblingducks@wordpress.com thanks for the great idea,

Jake said...

Of course ! Email it to jakesbones@gmail.com

Jake said...

Brilliant, good luck ! I think your URL got mangled, though: https://photographingdabblingducks.wordpress.com/. You might also find this post useful: http://www.jakes-bones.com/2012/08/my-top-ten-tips-for-other-child-bloggers.html

Bessie said...

Thanks great tips for blogging

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