Shamosuchus (Sand Desert Crocodile) is an extinct genus of paralligatorid neosuchian crocodylomorph that lived in the Djadochta Formation of the Gobi Desert (in Mandarin Chinese, "shā" means "sand", "mò" means "desert", and, combined, "shāmò", means "sand desert" or simply "desert"), Mongolia, 83.6 - 72.1 million years ago, during the Campanian stage of the Late Cretaceous Period. Prehistoric Planet depicts Shamosuchus as living in the obscure, lacustrine Songliao Basin of China.[PhP 2]
The animal depicted on Prehistoric Planet is actually meant to be Paralligator (Near Alligator), which is known from the Nemegt Formation (which overlies the Barun Goyot Formation, the immediate successor of the Djadochta Formation), 70 million years ago, during the Maastrichtian stage of the Late Cretaceous Period. Both Shamosuchus and Paralligator have been considered one and the same by some studies in the past,[2][3][4] though it is now believed that, while closely related, they were distinct from one another given their differences, like the significantly shorter snout of Shamosuchus.[5] While both Shamosuchus and Paralligator lived slightly before Prehistoric Planet's mostly Maastrichtian setting, it is still reasonable enough to believe that some of them did persist a bit longer past the time range indicated by their fossils.[DN 1]
Shamosuchus is a paralligatorid neosuchian crocodylomorph that reached lengths of 4 - 4.6 meters (13 - 15 feet).[PhP 1] Its actual mass is not known, but based off of modern crocodiles of equivalent size, it might have weighed around 300 - 600 kilograms (661 - 1300 pounds).[1] However, it should be noted that paralligatorids may not have had the exact same proportions or mass as modern crocodylomorphs, and thus may have been lighter or heavier than them. In truth, while paralligatorids may superficially resemble crocodiles, they are different enough that they cannot simply be portrayed, live-acted, or substituted by modern-day crocodilians.[DN 2]
The eyes and nasal openings of Shamosuchus, unlike those of modern crocodiles, were not raised above its short skull, meaning that it would need to raise its head completely out of the water to breathe. This indicates that, unlike modern crocodiles, Shamosuchus is not an ambush predator, with this, coupled with teeth suited for crushing, suggesting that it was a durophage, going after shelled aquatic invertebrates like bivalves or gastropods.
Paleoecology[]
Paleoenvironment[]
The Songliao Basin in northeast China
“ The vast swamplands of northeast Asia. Within this low-lying, flooded territory, there are countless islands. Each of them is surrounded by slow-moving waters. And that makes them potential sanctuaries for new life. ”
Shamosuchus lived 83.6 - 72.1 million years ago in the Djadochta Formation of the Gobi Desert in Mongolia, which underlies the Barun Goyot Formation, which is in turn found under the Nemegt Formation. While the area was, for the most part, a semi-arid desert resembling its current state, occasionally, bodies of water form,[6] providing Shamosuchus with shelter, albeit temporarily.
However, Prehistoric Planet does not depict Shamosuchus in this arid desert environment. Instead, it depicts Shamosuchus as living in the river deltas and swamps of the lacustrine (lake-filled) Songliao Basin in China. Most of what is known about the region is based on one particular area within it, the Nenjiang Formation, which does hold crocodylomorphs, molluscs, fish, amphibians, turtles, mammals, as well as dromaeosaurs, troodontids, and a possible tyrannosaur (all of the aforementioned dinosaurs are only known from teeth, however).[PhP 2][7] The region dates back to the Santonian and Campanian stages of the Late Cretaceous Period, being approximately 83 - 85 million years old, but a comment made by Dr. Darren Naish, Prehistoric Planet's lead consultant, implies that the segment Shamosuchus appeared in is still meant to take place during the Maastrichtian stage of the Late Cretaceous, around 72 - 66 million years ago, indicating that this particular section of the Songliao Basin is much younger than its other parts.[DN 1]
Thermoregulation, Hunting Tactics, and Feeding Preferences[]
Most (but not all) crocodylomorphs like Shamosuchus are poikilotherms (equivalent to the outdated concept of "cold-bloodedness"), reliant on their surroundings to regulate their body temperature since they cannot generate their own heat, with slow metabolism to match. For this reason, crocodylomorphs that lived similarly to modern-day crocodiles rely on ambush, patiently waiting for prey to approach their location, to conserve effort and energy. The crushing teeth of Shamosuchus indicate that it was a durophagous carnivore that fed on tough, armored prey like bivalves and gastropods, but Paralligator, the crocodylomorph that Prehistoric Planet actually depicts in the first segment of Swamps,[DN 1] may have hunted in this manner.
The Shamosuchuses are shown to be opportunistic and persistent as any other predator, alerted by newly-hatched juvenile azhdarchids trying to fly over their waters and taking advantage of these easy meals, with some leaping out of the water to grab low-flying pterosaurs, while others would go so far as to get up on land and chase some of the newborn pterosaurs. Such behavior can be seen in crocodiles today, which would throw their heads sideways out of the water in an attempt to grab or at least collide with bats flying overhead.[DN 3]
The slow metabolism of most crocodylomorphs does have its benefits, as it allows them to go for long periods without food, the amount of time between meals depending on the size of the prey they consume. Given the size of the juvenile azhdarchids they were depicted hunting, each Shamosuchus must consume several of the pterosaurs until its hunger is fully satiated.
Greenfield Lake Park and Black River, North Carolina, USA[PhP 2]
Okefenokee National Wildlife Refuge, Georgia, USA[PhP 2]
“ A young pterosaur. An azhdarchid just a few hours old. Being on an island means that she's able to take her first tentative steps in safety. Having found her feet, it's time to try out her wings. Getting them to work properly will take some practice. ”
In the first segment of Swamps, on the islands of vast swamplands in northeast Asia, are newly-hatched juvenile azhdarchids. One female, only a few hours old, takes her first steps and practices flight within the safety of the hatching grounds. To feed, however, the young azhdarchids need to fly out of their sanctuary and make their way to the forests past the swamps, with the light breeze of the day providing some help with extra lift. One youngster flies off, but, with insufficient strength, it loses lift and lands in the water. As it resorts to just swimming all the way to the forest on the other side of the swamp, it is grabbed by a Shamosuchus. Sensing an incoming feast, several more Shamosuchus emerge from the mangroves, closing in on the island of the youngsters.
“ If their takeoff isn't perfect, it's difficult to gain height. And this is not high enough. Some of the stronger fliers have almost reached the safety of the forest. Others have still to make their attempt. ”
More hatchlings attempt to fly for the forest, but some fly too low and get grabbed in midair, while others splash into the swamp and become easy pickings either way. Some of the stronger fliers were close to reaching the forest, while others are still hesitant to take off. Staying on the island is not an option, however, as one Shamosuchus clambers up onto land and begins chasing the female juvenile from earlier. Left with no choice, she runs for the edge of the island and take flight. Appearing to be successful at first, the juvenile slowly loses height, but still seems to be close to her destination. Suddenly, a Shamosuchus springs out of the water and almost grabs her, the impact causing the juvenile to plummet into the water, forcing her to swim the rest of the way to the forest, the Shamosuchus right on her tail. Upon reaching land, the crocodilian continues to go after her, but she manages to run off and finally evade her pursuer by taking flight once again, going further inland before landing on a rock, safe at last.
“ A near-miraculous escape. And now, the chance to collect her rewards. In these rich swamp forests, there's all the food she needs. ”
Seeing a lizard scampering across the roots of the trees, the young azhdarchid pursues it and snaps it up. In this forest, she and the rest of the survivors will grow, with plenty of food around them. The feeding opportunity over, one Shamosuchus, flies buzzing and walking atop its head, submerges back to the depths of the swamp.
↑Efimov, M. B. (1983). "Review of fossil crocodiles of Mongolia". Transactions of the Joint Soviet–Mongolia Paleontological Expedition. 24: 76–95.
↑Rozhdestvenskiy, A. K. (1974). "History of the dinosaur fauna of Asia and other continents and questions concerning paleogeography". Transactions of the Joint Soviet–Mongolia Paleontological Expedition. 1: 107–131
↑Storrs, G. W.; Efimov, M. B. (2000). "Mesozoic crocodyliforms of north-central Eurasia". In Michael J. Benton; Mikhail A. Shishkin; David M. Unwin; Evgenii N. Kurochkin (eds.). The Age of Dinosaurs in Russia and Mongolia. Cambridge University Press. pp. 402–419
