South American Elasmosaur

## South American ElasmosaurIndeterminate Species

***“ The river water is now approaching the sea. A taste of salt in its waters is already detectable. At high tide, visitors come in from the open sea to explore these channels. Elasmosaurs. These are true ocean-going reptiles. But some come to estuaries to explore the brackish waters. ”***

― **David Attenborough**, *Freshwater*
Present on Prehistoric Planet is an **unnamed elasmosaur** plesiosaur that lived in South America during the Maastrichtian stage of the Late Cretaceous Period. It is possible that this species is *Kawanectes* (Kawas Swimmer), a small elasmosaur that lived in the Allen Formation, Argentina, 72 million years ago, during the Maastrichtian stage of the Late Cretaceous Period.

## Description

Not much can be assumed regarding this elasmosaur, given how its identity remains unconfirmed. Assuming it is intended to be *Kawanectes*, this animal would have measured merely 3.8 meters (12 feet, 6 inches) long and weighed around 140 kilograms (310 pounds).

Prehistoric Planet depicts this animal with an almost-bleached skin color and its dark Turkish stripes, though it is otherwise very similar to *Tuarangisaurus* in appearance save for its stripes, which are slightly more prominent.

## Habitat

***“ Now, the millions of tons of sediment carried here by rivers is finally delivered into the sea. The river water takes time to mix with the ocean, and, for a while, the two waters flow side by side. Nonetheless, great shoals of fish find plenty on which to feed in these waters. ”***

― **David Attenborough**, *Freshwater*
The unnamed South American elasmosaur is depicted living in the rivers and estuaries leading into the Kawas Sea, an ancient extension of the Atlantic Ocean that covered most of Patagonia during the Late Cretaceous Period. If the animal is indeed *Kawanectes lafquenianum*, it would have lived in the Allen Formation of Argentina, a semi-arid environment heavily eroded by winds (partly due to large storms in the region), with landscapes that range from estuaries and tidal flats by the coastal regions to lakes and rivers further inland.

## Behavior

Like most of their relatives, these plesiosaurs are depicted as being primarily piscivorous, using their needle-like teeth to grip fish as well as other types of suitable prey like cephalopods. Though plesiosaur necks are rigid and thus incapable of flexibly whipping around to snap up prey from any direction, it is believed that plesiosaurs evolved their long necks so that their heads could ambush and grab fish right before their prey can be alerted by the sight and pressure exerted by their massive bodies. With large eyes directed relatively upward and a strong sense of smell, the elasmosaurs are able to close in on their prey even in murky waters.

## Appearance

In the sixth and final segment of Freshwater, in the forests of South America, elasmosaurs journey down a river flowing through a mangrove, with a *Quetzalcoatlus* watching them curiously. The elasmosaurs continue on to where the river widens, where more inhabitants of the forest (namely, what appears to be a juvenile *Quetzalcoatlus* and an *Austroposeidon*) take an interest in the peculiar presence of the normally ocean-dwelling creatures. The elasmosaurs eventually end up where the murky waters of the river meet and mingle with the sea. There, they pursue great schools of fish, circling around them to agitate and pin them right where they want them to, leaping out of the water to catch mouthfuls of fish as they try to jump and escape.

***“ The clouds of sediment conceal the fish if they're any distance away. But the elasmosaurs don't hesitate to swim into the murkiest of water to pursue their prey. There is no escape for the fish, even above the water. These elasmosaurs collect the last of the river's gifts before its traces are finally lost in the oceans of the Prehistoric Planet. ”***

― **David Attenborough**, *Freshwater*
The elasmosaurs are seen diving in and out of the clouded boundary between river and ocean, catching as many fish as they can, and the segment ends with one last view of Patagonia from space.

## References

1. ↑ 1.0 1.1 Naish, Darren (@TetZoo) (May 27, 2022) on Twitter, stating that the segment starring the unidentified elasmosaurs in Freshwater is in fact set in South America