Though not big enough to stop the flow of rivers, when this beast wades through the murky waters of Ryl Madol, the other animals are sure to feel its presence. With the shoulder-height of an elephant, it is among the largest herbivores of the island.
Moschoposeidon pachyostosteus (pronounced “mos-kho-poseidon”) is a tapinocephalian therapsid that feels at home both on land and in water. In some ways it reminds one of a hippopotamus, with its bulky body and smooth skin. Also like a hippo, its feet and toes are large and broad, allowing for good grip on muddy ground. However, its long neck allows for a far greater range in diet. In water it can easily lean down and pick up various algae and aquatic plants, while on land it can reach for tall tree canopies. Its teeth are simple, mainly made for raking off vegetation and less so for chewing. Instead, the food is masticated with the use of stomach stones (gastroliths). If swallowed in great numbers, these may also help with buoyancy.
The idea that the long neck primarily evolved as a snorkel to breathe when the animal is fully submerged in deep water has proven to be incorrect. Even with the robustly built ribcage, the water-pressure at such depths would be too much for the lungs to be able to greatly expand. It is probably for this reason why these animals prefer to wade only through shallow water, with their bodies being only half-submerged.
Moschoposeidon appear to be surprisingly calm when approached by humans, but that does not mean they cannot act aggressively. Giving live birth, the females can be angered very easily if they feel any source of potential danger coming near their child. During mating season, males can also be observed fighting over access to females with necking-duels, which are simple pushing matches similar to those of elephant seals. The closely related Ceratocephalus exhibit a similar behaviour, but use ossicones growing from their heads to hit each other like giraffes.
The beasts defend themselves by using their great bulk to trample foes to death. If a predator proves to be too formidable or too large to be defeated or intimidated, Moschoposeidon will try to flee into water. Unfortunately, many of the larger carnivores descend from amphibians and so can follow them there.