Thanks to Brilliant for  supporting this SciShow video!

As a SciShow viewer, you can keep  building your STEM skills with a 30-day free trial and 20% off an annual premium  subscription at Brilliant.org/SciShow. Sauropod dinosaurs – the ones  with the really long necks – are some of the most famous and instantly  recognizable of all ancient animals.

Their most outstanding feature has  got to be those incredible necks. These included the very  longest necks in Earth history, with some growing more than 12 meters long! So with this being one of the most  iconic features in all of evolution, you’d think we would know what it did.

And…you’d be wrong. [♪ INTRO] If you look at dinosaurs in books and movies, you’ll see that those necks have been  depicted in many ways over the decades. Sometimes they’re held straight upward  from the body, sometimes straight out front, and sometimes they’re  all wiggly like a cartoon snake. And here’s the fascinating thing:  we don’t know which way is correct.

Well, it’s probably not  the wiggly cartoon version. But paleontologists have been debating  over sauropod neck posture for decades. It’s a surprisingly hard question to answer.

It’s not as easy as just putting the  bones together and seeing how they fit. For one thing, we have almost  no complete sauropod necks. Even the best-preserved sauropod skeletons are usually missing a few neck vertebrae.

This is partly because they’re just so darned big. To get a fossil you generally need  the body to be buried quickly, and with something that big it’s just  not likely to happen to the whole thing. Another problem is that we’re  also missing soft tissue – cartilage, tendons, ligaments, the kind  of stuff that doesn’t often fossilize.

And these are key factors in the  flexibility and length of an animal’s neck. Plus, strange as it sounds, the neck  might not be the only important part of understanding the posture of… the neck. Some researchers have examined the  shape of the dinosaurs’ inner ears, which can help us understand how they held  and moved their skulls atop their necks.

And others have estimated the position  of sauropod shoulders and hips. Tall shoulders, for example, might  have been key for providing support for lifting the long neck. And on top of all that, it can be  really hard to tell the difference between what an ancient animal  could do, versus what it did do.

Like, if you looked at my skeleton, you might say, this person was fully capable of going  for a ten-mile run every morning. But I don’t do that. Because I don’t want to.

So, with all this in mind, you  can start to see why this question has been debated so much: we’re  working with limited information. But there’s another thing you might be wondering: why do we care so much how these  dinosaurs held their necks anyway? Well, for one thing, it’s just plain fascinating.

Some published estimates  suggest that if these dinosaurs could hold their necks vertically,  some species might have been able to raise their heads twenty meters  in the air standing on their tippy-toes. If that’s true, that’s awesome. So, we want to know if it’s true!

But besides that, our interpretation  of sauropod neck posture also affects our understanding  of how they used them. Sauropods were the biggest animals in  just about any ecosystem they lived in. And like any large animals, they would have had a huge  impact on the environment.

The better we understand what they were doing, the better we’ll understand how  their entire ecosystems functioned. Two main factors are thought  to have driven the evolution of these super-long necks: food and sex. On the one hand, long necks are  obviously good for accessing food, but different neck postures  are good for different diets.

A tall neck would be great  for reaching high plants that no other herbivores could access. While a horizontal neck might be  good for quickly and efficiently sweeping a whole area of low vegetation. It might seem like a simple distinction, but it has all sorts of implications  for the lifestyles of these dinosaurs.

The quality of their food,  and their ease of access, would affect how much they had to eat,  how far they had to wander to find food, how well they helped plants disperse, and more. That’s a lot of valuable information that  comes down, in part, to neck posture. And then on the other hand,  extraordinary structures in evolution often function as tools for attracting  mates and intimidating rivals.

Long-necked animals today often  use those necks for showy displays, courtship rituals, or even for fighting rivals. If we understood what sauropods were  doing with their necks, it could help us better understand how they interacted  with each other, whether they waved their necks slowly during courtship or violently  smashed them together like giraffes. Seriously, just watch a pair  of giraffes fighting sometime.

It’s terrifying. And it’s also ridiculous. And just to complicate the whole thing,  there probably isn’t a single correct answer.

More likely, there are many. Sauropod dinosaurs were extremely diverse. There were loads of species living  in habitats all over the world for over a hundred million years.

The answers to these neck questions  might be as numerous and diverse as the dinosaurs themselves. So, for now, the debate is far from over. But the more we explore this topic, and  the more we analyze the amazing anatomy of dinosaurs, the more we  understand about the ancient world… even if there are some things we might never know.

It’s easy to get stuck in a single  train of thought that supports your original hypothesis, like the idea  that long necks are also tall necks. But good scientists are able to keep an open mind and let the data tell them how the world works. That’s the whole idea behind hypothesis testing, which you can learn all about in the  Brilliant course dedicated to the topic.

This course teaches you how to use  the power of statistics when testing a hypothesis, proving a point, and  understanding the world around you… or the way the world used to be. You can unlock all of those answers  with a great dataset and the stats in this course, from making sure  your sample size has enough power to running a linear regression that  helps you analyze your results. And Brilliant will show you how.

Brilliant is an online learning platform  with thousands of lessons in math, science, and computer science available  when you type Brilliant.org/SciShow into your search bar or go to the  link in the description down below. That link also gives you a  free 30-day trial and 20% off an annual premium Brilliant subscription. Thanks to Brilliant for  supporting this SciShow video! [♪ OUTRO]