Nemegtosaurus

## NemegtosaurusNemegt Lizard

***Nemegtosaurus*** (Nemegt Lizard) is a genus of titanosaurian sauropod dinosaur that lived in the Nemegt Formation in Mongolia, 70 million years ago, during the Maastrichtian stage of the Late Cretaceous Period.

## Description

### Size and Physique

*Nemegtosaurus* is only known from a single skull, which has the long, low profile and pencil-shaped, chisel-tipped teeth of diplodocoids, an unrelated group of sauropods which went extinct more than 20 million years prior to its existence. Given the lack of sufficient remains, not much is known about this titanosaur, which is estimated to be around 12 meters (40 feet). It is not known what plants *Nemegtosaurus* would have preferred to eat (flowering plants, ferns, and conifers were common at the time, indicating its options), neither is it clear whether they were high or low browsers, as the animal's neck is yet to be found, and several titanosaurs are known to have either short or long necks, making it difficult to simply base *Nemegtosaurus* off of its relatives.

### Eyes

While little is known about *Nemegtosaurus*, its skull does preserve the sauropod's sclerotic rings, bony rings that support the eye which can indicate the animal's overall eyeball size, and therefore, their lifestyle. Small sclerotic rings indicate that the animal is diurnal, those with larger rings had larger eyes fit for nocturnal activity, and those with medium-sized rings are likely cathemeral, active in short, irregular intervals throughout day and night. The preserved sclerotic rings of small animals that lived in the various Mongolian formations indicate that they were either cathemeral like *Protoceratops*, or nocturnal like *Velociraptor*. While significantly larger, compared to modern reptiles and birds, *Nemegtosaurus* also has proportionally medium-sized sclerotic rings, suggesting that this large animal was also cathemeral, which isn't too surprising given how even large, modern-day animals from ungulates to elephants evolved to live a cathemeral lifestyle.

### Identity

At one point, it's been theorized that *Nemegtosaurus* is nothing more but the head of another titanosaur in the Nemegt Formation, *Opisthocoelicaudia*, which is known from a well-preserved skeleton lacking a neck and skull, though the idea that they are one and the same animal cannot be confidently confirmed since the poor remains of *Nemegtosaurus* don't show enough similar characteristics for comparisons to be made.

## Habitat

*Main: Nemegt Formation*

Main: Nemegt Formation

*Nemegtosaurus* lived 70 million years ago in the Nemegt Formation, an area that would one day become the Gobi Desert in Mongolia. The formation shows evidence of a rich, humid environment with large river channels, tidal flats, and forests. However, the area is also known to have undergone periodic droughts, and there is precedence for arid regions much like the Gobi Desert today existing in Mongolia during those times. *Nemegtosaurus* remains were also believed to have been found in the Subashi Formation, an area within the Xinjiang Autonomous Region of western China, though these fossils have since been considered dubious.

## Behavior

As with most sauropods, *Nemegtosaurus* is shown exhibiting herding behavior, grouping not only with themselves, but also with larger titanosaurs like *Mongolian Titans*. Even smaller animals, like *Prenocephale*, may also choose to travel alongside these behemoths for protection (at the small risk of being trampled underfoot). Given their size, they likely require a lot of sustenance to sustain their massive bodies, hence, in both their appearances on Prehistoric Planet, *Nemegtosauruses* are shown seeking out great sources of water, even if it means traveling vast distances and navigating through narrow canyon mazes that are barely wide enough for them (where, despite their size, even titanosaurs as big as them are left wary of danger, as shown when a herd of them end up panicking and stampeding due to the mere presence of a trio of *Tarbosaurus* in Badlands).

## Appearances

### Deserts

#### Segment 2

The second segment of Deserts takes place in Asia. In the simmering heat of the desert, where the temperature rises to 60 degrees Celsius (140 degrees Fahrenheit) at the height of summer, lizard, only a few inches long, runs around to find a meal, pursuing a fly across the rocky wilderness.

***“ This immense carcass could be promising. A dead sauropod, a potential feast for many. But strangely, all is quiet. ”***

― **David Attenborough**, *Deserts*
The lizard eventually comes across a rotting sauropod carcass. While the identity of the carcass remained unconfirmed, given its size, it is likely a *Nemegtosaurus*. Above the carcass, five azhdarchids circle overhead, but are unwilling to land and begin scavenging the corpse, for sleeping around the carcass is a group of four large theropods.

***“ Tarbosaurus. The equivalent in this desert of T. rex. They keep everyone else away. But for the lizard, they might bring an opportunity. If there is one thing that attracts flies more than a carcass, it's a sleeping Tarbosaur that has been feeding on that carcass. Time to be bold. ”***

― **David Attenborough**, *Deserts*
Seeing the number of flies attracted to the carcass and the smelly faces of the tyrannosaurs that fed on the carcass, the lizard sees the good feeding opportunity, and musters some courage to go after some flies, running on and around a *Tarbosaurus*, trying to catch some of the flies that gathered around its face, taking caution not to awaken the large theropod.

***“ A Velociraptor. Time to be careful, because Velociraptors often hunt... together. ”***

― **David Attenborough**, *Deserts*
Just then, a *Velociraptor* rushes in and snaps up another lizard in the area. A second *Velociraptor*, eyeing another lizard in the area, rushes at the little creature, but the lizard manages to run away in time. Carefully, the *Velociraptor* sneaks around the sleeping *Tarbosauruses*, seeking out more lizards to eat. Finding another one, it goes after it, the lizard rushing under a sleeping *Tarbosaurus*, causing the *Velociraptor* to bump into the bigger theropod, waking it up. Not happy to be disturbed, the tyrannosaur reaches out in an attempt to snap the *Velociraptor*, which rushes off with its companion as the *Tarbosaurus* gets up, causing the other *Tarbosauruses* to also wake up.

***“ The Tarbosaurs move on. And now the pterosaurs can come down and claim a share of the carcass. For the little lizard, the opportunity is gone. ”***

― **David Attenborough**, *Deserts*
The tyrannosaurs decide to leave the carcass, which has not that much left on it anymore, allowing the azhdarchids flying overhead to finally come down and feast on what little remains of the sauropod. The opportunity to feed gone, the little lizard scampered away from the area, running across the desert once more to look for food.

#### Segment 4

***“ When rain does fall, it can seep into the land and travel great distances underground, until in some special places, the water rises to the surface and creates an oasis. Open water attracts desert animals of every kind from many miles away. Some dwarf everyone else... ”***

― **David Attenborough**, *Deserts*
In the fourth segment of Deserts, a temporary oasis attracts several animals from many miles around, among them, *Nemegtosaurus*, which appears to be the biggest animal in the area until the arrival of the 70-tonne Mongolian Titans, which dwarf every other animal in the area.

### Badlands

In the second segment of Badlands, beyond a maze of canyons where a family of *Velociraptors* reside, a temporary oasis has formed. The presence of this watering hole attracts a herd of Mongolian Titans, *Nemegtosaurus*, and *Prenocephale*. As they navigate their way through the maze of canyons, an obstacle in their path to satiating their thirst, the herd ends up sensing the presence of large predators, worrying even the Mongolian Titans, with two individuals accidentally swinging their necks against each other. Soon, the hunters, a trio of *Tarbosauruses*, make themselves known, causing the entire herd to panic and stampede (with one *Nemegtosaurus* stepping off a low ledge, causing it to fall and die in the process). With the protection provided by the titanosaurs now a hazard for them, the *Prenocephale* run up the canyon's steep walls, where they, now no longer under the protection provided by the presence of the sauropods, are ambushed by the *Velociraptors*, which successfully ambush and kick one of the pachycephalosaurs off a cliff. Eventually, the herd has left the canyon maze, leaving behind a *Nemegtosaurus* that fell and died during the stampede. The frantic travel, though not too disastrous for the herbivores, did leave feeding opportunities for the carnivores, with the *Tarbosaurus* trio feeding on the fallen *Nemegtosaurus* and the *Velociraptor* family feasting on the freshly-slain *Prenocephale*.

## Trivia

It is unknown how exactly dinosaurs drank water. Prehistoric Planet chose to depict various types of dinosaur drinking water in different ways, with sauropods like *Nemegtosaurus* and the Mongolian Titans shown simply sucking up water in the fourth segments of Deserts, using their great size and long necks to simply drink water bypass the other animals around and in front of them. By contrast, hadrosaurs like *Barsboldia* are shown lapping up water with their tongues, while theropods like *Mononykus*, *Therizinosaurus*, and *Tarbosaurus* are depicted as scooping up water with their lower jaws.

## References

1. ↑ 1.0 1.1 Holtz Dinosaur Genus Appendix
2. ↑ Nocturnality in Dinosaurs Inferred from Scleral Ring and Orbit Morphology
3. ↑ Elephants and Human Color-Blind Deuteranopes Have Identical Sets of Visual Pigments
4. ↑ Rediscovery of the type localities of the Late Cretaceous Mongolian sauropods *Nemegtosaurus mongoliensis* and *Opisthocoelicaudia skarzynskii*: Stratigraphic and taxonomic implications