Secernosaurus

## SecernosaurusSevered Lizard

* Adult
* Juvenile

### Temporal Range

* 83 - 70 million years ago, Campanian - Maastrichtian Stage, Late Cretaceous Period (*Secernosaurus koerneri*)
* 85 - 66 million years ago, Santonian - Maastrichtian Stage, Late Cretaceous Period (*Huallasaurus australis*)

## Characteristics

### Diet

Herbivore

***“ These dunes are so dry that living here is almost impossible, yet some dinosaurs manage to do so. Secernosaurus, a type of small hadrosaur. ”***

― **David Attenborough**, *Deserts*
***Secernosaurus*** (Severed Lizard) is a genus of austrokritosaurian saurolophine hadrosaurid dinosaur that lived in the Lago Colhué Huapí Formation, Argentina, 83 - 70 million years ago, from the Campanian to the Maastrichtian stage of the Late Cretaceous Period.

In 2022, the specimens the *Secernosaurus* of the show were based on were reclassified as a new hadrosaur, *Huallasaurus* (Duck Lizard), which lived in the Los Alamitos Formation, Argentina, 85 - 66 million years ago, from the Santonian to the Maastrichtian stage of the Late Cretaceous Period.

## Description

By hadrosaur standards, *Secernosaurus* is small, a mere 5 meters (16 feet) in length, though the maturity of the specimen is unknown. As with most animals related to *Kritosaurus*, it likely bore a rough, rounded crest formed by bones that rose from the nose, reaching above and between the eyes before folding back over. This crest may have also housed air sacs to help the animal amplify its voice like most other hadrosaurs. Prehistoric Planet depicts *Secernosaurus* with an orange-brown coat and a creamy-white underside. Its nasal crest, eyebrows, and the top of its head come in vibrant yellow and blue.

## Habitat

***“ It's not just extraordinary bizarre animals that live in the deserts of the Prehistoric Planet. There are strange, otherworldly landscapes too, such as here in South America. This may look like a dusting of snow, but these great dunes are composed, not of sand, but of gypsum. Gypsum is a fine, white mineral that dissolves in water so easily, it can only exist in solid form in the driest areas on Earth. ”***

― **David Attenborough**, *Deserts*
While the animal featured on Prehistoric Planet is now considered as a new species, *Huallasaurus* of the Los Alamitos Formation, this information was not yet known by the time, so Prehistoric Planet depicts this hadrosaur within the known habitat of *Secernosaurus koerneri*, the Lago Colhué Huapí Formation, which, as theorized in a 2016 paper based on gypsum deposits and desiccation cracks, was an extremely arid area, ironically set before and after ages of balanced wet and dry seasons. *Secernosaurus* would not have been alone in this desert, for various titanosaurs, a megaraptoran, turtles, crocodyliformes, and even fish lived in the area.

## Behavior

***“ Although they can survive on a poor-quality diet, every decade or so, this area dries out so extremely, that almost all the vegetation shrivels and dies. With young to care for, this can be the end of the herd. But some of the older, more experienced individuals may remember other potential sources of food and water, and they know that the way to survive is not to try to leave the desert, but to continue traveling across its baking dunes. ”***

― **David Attenborough**, *Deserts*
*Secernosaurus* are depicted as social herding animals that provide their young parental care to an extent, like most hadrosaurs are believed to be. Fittingly, given their harsh habitat, *Secernosaurus* proves to be a resilient animal, able to subsist on even just a few dry shrubs and desiccated branches. However, even desert-dwellers have limits, hence, in times when conditions become unbearable, the hadrosaurs resort to seeking proper sustenance, ensuring their survival in the vast, barren wastelands by exerting energy in places and times that would cause the least amount of stress, be it during the darkness of the night, or under the shade of a tall dune.

***“ With high winds and shifting sands, the desert is always on the move. And that makes navigation tricky. The herd prefers to travel at night. It's not only cooler, but also reveals a map that could enable an animal to find its way through the featureless - yet everchanging - desert. A map in the sky. Like many migrating animals, hadrosaurs can recognize celestial signposts. ”***

― **David Attenborough**, *Deserts*
Prehistoric Planet demonstrates *Secernosaurus* relying on the position and movement of the stars and other celestial objects to help determine both their current position and the location of their destination. While this is not something that can be proven by fossils, many animals in the modern day, even less complex creatures like insects, have been known to utilize the night sky as a means of orientation and navigation. Additionally, with their acute sense of hearing, the *Secernosaurus* are able to hear low-frequency sounds that would not be detected by most animals, like the waves of a distant coast.

## Appearance

### Deserts

The sixth and final segment of Deserts takes place in a vast gypsum desert in South America, one of the driest places on Earth. Within a rocky area of long-dead trees, a herd of *Secernosaurus* wander around, exposed to the harsh sun. One individual feeds on the few remaining dried-out shrubs it can find before attempting to chew off one of the low-hanging branches of a shriveled-up tree. However, it is clear that there is nothing left for the herd to subsist on, with the only reminder of sustenance being the shimmering mirage of an oasis flanked by vegetation.

Determined to survive rather than simply waste away in the middle of the desert, the herd decides to set out and find true food and water. As they travel in the darkness and coolness of the night, they navigate the desert by relying on the stars overhead.

***“ By day, the blistering sun still beats down from overhead. Even if they can find shade, this, for some, can be journey's end. But there is something else that may help them. The deep, rumbling sound of waves crashing onto the distant shoreline travels for miles through the dunes. The sound is so low that many animals cannot hear it, but hadrosaurs can, and so are able to find their way towards the coast. But this desert still has one more obstacle that must be overcome. Giant, coastal dunes block their path. Steep, unstable sand saps energy with every step. ”***

― **David Attenborough**, *Deserts*
After what may be one or several days, the herd is next seen resting behind a dune, taking refuge from the heat of the sun. There is a noticeable glimmer of hope in the change of scenery, yellow sand as opposed to the blinding white gypsum lands they came from before, indicating that the environment is less arid than before, even if only by a bit. Eventually, the herd comes upon a tall dune, the last obstacle between them and the sea, where their salvation might be. The climb proves difficult, and one juvenile calls out to its mother, exhausted, though the mother calls out to her calf and manages to convince it to continue just for a little longer.

***“ They have made it, and their first award is to lick droplets of water that condense on their skin from the fog that forms where dunes and ocean meet. And this fog also nourishes a rich, coastal paradise. This is enough to feed the herd for now, but once it runs out, they will be forced to move on, and once more endure the trials of life in the deserts of the Prehistoric Planet. ”***

― **David Attenborough**, *Deserts*
Finally, the herd reaches the top of the coastal dune, being greeted and coated by a salty fog that they lick off their skin, serving as their first taste of water in a long time. This same coastal breeze also allowed lush green shrubs to flourish on the shore. At last, the herd has found a sufficient amount of food that can keep them and their young alive for the time being, sustenance that, until the day it runs out, will bring them relief from the inhospitable gypsum deserts of Argentina.

## References

1. ↑ 1.0 1.1 Naish, Darren (@TetZoo) (May 26, 2022) on Twitter, confirming that the *Secernosaurus* in Deserts is now *Huallasaurus*
2. ↑ 2.0 2.1 A new hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous of northern Patagonia and the radiation of South American hadrosaurids
3. ↑ 3.0 3.1 Coria, Rodolfo A (2015). "South American hadrosaurs: considerations on their diversity". In Eberth, David A.; Evans, David C. (eds.). *Hadrosaurs*. Life of the past. Bloomington and Indianapolis: Indiana University Press. pp. 332–339.
4. ↑ Ordenamiento y Caracterización faunística del Cretacico Superior del Grupo Chubut, Cuenca del Golfo San Jorge, Argentina
5. ↑ From dung beetles to seals, these animals navigate by the stars