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),[1][DN 1] 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.
By hadrosaur standards, Secernosaurus is small, a mere 5 meters (16 feet) in length. Initially suggested to be a subadult, it has been proposed that it may have been more mature than previously thought.[2] 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.
Paleoecology[]
Paleoenvironment[]
South American hadrosaurs may have descended from North American immigrants, exposing them to new opportunities, but also new challenges
“ 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. ”
Most hadrosaurs are known to live in North America and Asia. However, others have ventured to other places, as proven by species in Europe (e.g. Arenysaurus), Africa (e.g. Ajnabia), and Antarctica.[3][4] South America also has its share of these very successful ornithopod dinosaurs. It is believed that the ancestors of South American hadrosaurs such as Secernosaurus, Huallasaurus, and Kelumapusaura came from a temporary land bridge that formed between North and South America during the Late Cretaceous Period, allowing a biotic interchange to occur (with Alamosaurus possibly being an example of a North American animal that evolved from South American immigrants).[5][6] An alternate theory is that this land bridge is not an unbroken strip of land, but a series of islands, so hadrosaurs may have also needed to rely on rafting, riding on large, floating pieces of land that broke away and drifted elsewhere (a means of dispersal that titanosaurs cannot rely on as easily due to their significantly greater size).[5] Whatever the case, it is for this reason that Secernosaurus got its name, "severed lizard"; in migrating to the far south of Gondwanaland, it became greatly separated from its Laurasian relatives. In setting foot on South America, hadrosaurs can explore and come across new opportunities to thrive, but they will also have to survive and adapt to new challenges, like habitats more arid than their regions of origin.
The gypsum dunes of the Lago Colhué Huapí Formation
“ 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. ”
While the hadrosaur featured in the sixth and last segment of Deserts is now considered as a new species, Huallasaurus of the Los Alamitos Formation, this information was not yet known by the time the show's first season was being made, so Prehistoric Planet portrays 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.[7]
Secernosaurus feeding on the branches of a dead tree
“ 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. ”
Fittingly, given their harsh habitat, Secernosaurus proved to be a resilient animal, able to subsist on even just a few dry shrubs and desiccated branches, serving as an example of hadrosaur toughness, adaptability, and overall success in thriving all over Earth. 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.
Social Behavior and Parental Habits[]
From the example set by the older members, the young Secernosaurus within the herd learn that journeying through the desert is the key to finding their salvation from it
“ 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. ”
Secernosaurus are depicted as social herding animals that provide their young parental care to an extent, like most hadrosaurs are believed to be. This may allow for the passing down of basic knowledge through several generations. By seeing how the elders deal with the desert's dangers, the younger hadrosaurs can eventually learn that even the barren landscape of their home has an end, that the seemingly unremarkable world around them has secrets that can lead them to where they need to go, and that braving the heat and the towering dunes of the wilderness is necessary to reach the key to their continued survival.
Navigation[]
A herd of Secernosaurus traveling through the desert during the coolness of the night, with the stars in the sky serving as their navigational guides
“ 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. ”
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.[8] Additionally, with their acute sense of hearing, Secernosaurus are able to hear low-frequency sounds that would not be detected by most animals, like the waves of a distant coast.
Setting Lago Colhué Huapí Formation, Golfo San Jorge Basin, Argentina
Filming Location Namibia
The Secernosaurus herd subsisting on every last patch of vegetation they can find
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.
The Secernosaurus herd takes a break behind the shade of a tall desert dune
“ 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. ”
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.
At last, the Secernosaurus herd reached their destination, a shrub-covered paradise where the desert ends and the sea begins
“ 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. ”
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.
Gallery[]
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↑ 2.02.1Coria, 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.
