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How Did Sauropods Sleep? Plus Comparisons to Present-Day Animals

If you don’t get a good night’s sleep, you tend to feel like a dinosaur when you wake up. Otherwise, though, you’ve never stopped to think about the sleeping habits of dinosaurs. You’re sure that clades of dinosaurs like sauropods slept, but you have no idea about the logistics. How did sauropods sleep?

Although experts aren’t quite sure, they believe that sauropods and other four-legged dinos like them probably slept standing up. Interestingly, T. Rexes likely laid down to sleep just like we do!

Now that you’ve begun pondering how sauropods slept, you’re eager to learn more. You’ve come to the right place. In this informative article, we’ll examine what research and fossils tell us about how sauropods slept. Keep reading! 

Did Sauropods Sleep Lying Down? How Fast Could They Stand Up?

Without fossils, we wouldn’t know nearly as much as we do about sauropods and other dinosaurs like them. Yes, dinosaurs did sleep, although fossils tell us less about this than about facts such as how many teeth a Diplodocus had or the shape of its beak.

How-did-sauropods-sleep-AdventureDinosaurs

Some fossil evidence has emerged that could paint a picture of how dinosaurs slept. Smithsonian Magazine details one such fossil in a 2012 article. The fossil talked about in the article is even older, from 2004. It was uncovered by Mark Norrell and Xing Xu and was called Mei long, a dino from the Early Cretaceous Period.

Mei was recovered in a fossilized form in what appears to be repose. Its skeleton was almost completely intact, a rarity when finding fossils. The tiny dinosaur, which measured about a foot, had its arms folded and its tail draped over its torso. 

A second Mei fossil was recovered in China after the first, and it too was preserved in the same position. The experts believe that the Mei dinosaurs died this way.

The Mei long fossils are certainly fascinating, but they do raise a lot of questions. Since the Mei dinosaur died in this particular position, we can’t say for sure whether it was sleeping at the time of its death or was perhaps defending itself. 

After all, based on its skeleton, it looks like Mei was cozily reclining, but could it also have been shielding itself from a predator? It’s hard to say. 

Plus, the Mei is admittedly a small dinosaur. These species would have had much more versatility in how they slept. They could easily sleep lying down because they could jump back up. A larger dinosaur like the sauropod couldn’t get up immediately due to its sheer size and the fact that it was sluggish, so it couldn’t afford to be vulnerable for long. 

According to a Science Focus piece, their experts believe four-legged dinosaurs probably didn’t lie down to sleep. Instead, sauropods and their fellow four-legged brethren would remain upright.

The assumption is that doing this would make it easier for a sauropod to respond to predators quickly. 

Now, the real question is, what did sauropods do with their long necks when they slept? Did they allow their neck to drop to the ground so their head had a nice place to rest, or did they keep their necks upright?

That’s information that we just don’t have, so we can only guess!  

Sauropod Sleeping Habits – A Comparison with Modern-Day Animals and Birds

Since so much of a sauropod’s sleeping preferences are guesses, we can look at animals and birds that came from dinosaurs to understand better how sauropods could have slept. 

Let’s examine some common threads.

YouTube Video About How Lizards Have REM Sleep

YouTube video by Science Magazine which discusses lizards and their REM sleep cycles and how it relates to mammals – AdventureDinosaurs

Crocodiles

Crocodiles look reminiscent of dinosaurs, and it’s proven that they came from dinosaurs that lived millions of years ago, especially the crocodilians. So how do they sleep? Well, crocodiles are already on their bellies, so it makes sense for them to stay there while they drift off.

What’s interesting is that crocodiles keep their mouths open when asleep and that they might begin panting as well. 

Ostriches

The ostrich is akin to sauropods in a lot of ways. Both creatures have very long necks and small heads. Ostriches are known for sleeping standing up. Experts are aware that the bird can enter rapid eye movement or REM sleep, but eerily, it looks awake when the ostrich is in its first wave of sleep, known as slow-wave sleep. The bird’s eyes are open and everything.

In slow-wave sleep, the ostrich keeps its neck upright and stays on its feet. By the time the bird enters REM sleep, the ostrich closes its eyes, and its neck starts to sway, but the ostrich remains upright. 

Experts believe that dinosaurs might have entered a state of REM sleep as well, although we obviously have no way to confirm this claim. If that were the case, then that would mean that dinos too would have slow-wave cycles first. 

Would a sauropod have swayed its neck when entering REM sleep just like today’s ostriches do? It’s certainly possible! 

Snakes

Ostriches aren’t the only animal that can sleep with their eyes open. Snakes never close their eyes, even in REM sleep. Instead, their brain activates the snake’s sleeping mechanism, and the animal begins recovering. 

To predators, it looks like a snake is always watching even when it isn’t. Could dinosaurs do the same? Possibly! To determine how we only have to look at the Mei long fossils. Experts believe the sleeping dino had one eye open, supposedly so it could keep watch over its surroundings.

If the Mei dinosaur were truly sleeping when it died and wasn’t cowering defensively, that would suggest that dinosaurs could sleep with their eyes open as snakes can. 

Tuatara Lizard

The tuatara lizard is a New Zealand reptile that’s not your average lizard. The tuatara prefers cooler rather than warmer climes and lacks external ears. Still, it’s technically a reptile, so let’s see what we can learn from how it sleeps.

For one, tuataras are nocturnal. They also like to burrow so they can sleep without danger. Burrowing would certainly be a viable option for smaller dinosaurs, although it would never work for sauropods. They were too large, so obscuring themselves would be nearly impossible.

The sleeping habits of the tuatara lizard do bring up an interesting thought. Were dinosaurs nocturnal, or did they sleep at night like we do today? 

A 2021 study from the journal Science suggests that dinosaurs had night vision. 

What would a dinosaur need night vision for if it was asleep once the sun went down? Maybe dinosaurs didn’t sleep at night, at least not all. If that’s the case, then therapods would be among them. The Science study, after all, examined theropods, specifically the Haplocheirus sollers, and determined it had night vision.

If one theropod was gifted with night vision, we could assume that most were. That would mean theropods would sleep during the day rather than at night. 

How Could Sauropods Stay Safe from Predators While Sleeping? 

If anything, sleeping in daylight is even riskier than at night. Predators and prey alike can clearly spot a theropod, and they’d be able to tell very quickly whether the dinosaur was moving or not. If the theropod stayed in one place, it’d be easy prey.

How did theropods prevent themselves from becoming a midnight snack? 

Well, we already talked about one such way that theropods were smart when they slept. They didn’t lie down. Since they’d already been upright, even if a predator tried to attack a theropod, it would be awake and ready to defend itself much faster than if it had to pick itself up off the ground.

YouTube Video About Strange Animal Sleeping Habits

YouTube video by SciShow that discusses eight interesting habits that animals have when sleeping – AdventureDinosaurs

Theropods were also known to live in herds, and there’s strength in numbers. Even if a predator could take down one sleeping sauropod, attacking a herd is too risky. If the other dinosaurs woke up, the predator would quickly become prey.

It could be that the theropod herds took turns sleeping, so at least one dinosaur was always awake to keep watch. It, too, could detract predators very quickly.

Plus, remember, we don’t know whether theropods slept with their eyes open. A group of theropods could be sleeping, and if their eyes weren’t closed, a predator would be unable to tell if the dinosaur was asleep or awake. Chancing it would be too risky.

Paleontologists also believe that dinosaur herds traveled in packs, which dinosaur trackways can deduce. If a dinosaur never stays in one place for too long, a predator can’t learn its sleep-wake cycle and plan an attack. 

Conclusion 

Sauropods were believed to have slept standing up rather than lying down due to their sluggishness in getting their large bodies off the ground. Although we can’t say for sure, there’s fascinating evidence that suggests that sauropods were nocturnal and that they might have slept with their eyes open.

One thing’s for sure, asleep or awake, prey would not want to cross a sauropod! 

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