On Freshwater Turtles in Patagonia - Update

In a previous post earlier this year, I mentioned that the movie director Miguel Angel Rossi suggested that the "Lake Monster" of Lake Nahuel Huapi was probably a turtle and I listed different species found in Argentina, none of which live in Patgonia due to the low temperatures. However, looking into the matter I found several references on these animals in the Patagonian rivers.

In August 2016, (Source), a freshwater turtle was photographed swimming in the Rio Negro River at Paso Córdoba (Google map), Pablo Chafrat, from the Museo Patagónico de Ciencias Naturales, a museum in the neighboring city of General Roca said that it could be an "exotic" turtle that someone bought and then grew tired of it, discarding it in the river. Below is a picture of the animal.

Turtle, Paso Córdoba, Rio Negro.

An article published in May 2019 reported finding a turtle (Phrynops Hilarii) in the Plottier irrigation channel during works on it. This irrigation system takes water from the Limay River. After draining it, they checked for any fish that may have become stranded, to capture them and place them back in the Limay River. They found a turtle which was rescued ant taken to the local fish-stocking station. It is pictured below.

Lagoon Tortoise (Phrynops Hilarii), Plottier channel.

The director of the fish-stocking station of Plottier, Jorge Figuolo said that the animal was checked by a veterinarian to make sure it was healthy, adding that its habitat is the Paraná River basin, and that they would return it to that area as they don't believe it could adapt to the cold water in Neuquén. They couldn't understand how it found its way into the irrigation channel (see the location on google maps). This spot is 58 km (35 mi.) upstream from Paso Córdoba.

A second turtle was found by a fisherman in Dec. 2023, 15km - 9 mi. east of Plottier, in the waters of Duran Creek (Source, with video), it was also identified as a Phrynops hilarii specimen. This spot is not far from Plottier, and is actually a branch of the Limay River (Map with location). The same explanation was given: a pet that was returned to the wild.

Turtle, Durán Creek, 2023

In Dec. 2024, the media reported (see video) a turle at Paso Córdoba (was it the same one spotted in 2016?) and again the fact that it was an exotic animal was mentioned. The turtle in the video looks well adapted to its habitat! See its picture below.

Turtle, Paso Córdoba, 2024

The facebook page of the Reserva Ecológica Plottier (Plottier Ecological Reserve) mentions several sightings in the area, not only the one mentioned in 2019, but others: Jan. 2025, and the turtle was left where it was found. The post says that these animals are now part of the local fauna. It also has a picture from Nov. 2022, a sighting in 2018 and another at Santa Helena Lagoon in the Plottier botanical gardens.

So, are these native creatures that had gone on undetected until now, or were they brought to the Neuquén, Limay, and Negro rivers area as pets from another place outside of Patagonia, and then set free in the environment? By the way, they seem to be thriving in the area, despite the cold winter temperatures.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall © 

The 1922 Plesiosaur was probably a Turtle or Crocodile

Back in 1922, while the expedition was searching for the Plesiosaur that Sheffield had said he'd seen in a tiny lagoon close to his home near the Epuyen River, many looked on with a skeptic attitude.

Below is the text from an article published in the New York Times (HINT 'PLESIOSAURUS' WAS A HUGH TURTLE; Dr. Lucas and Washington Scientists Scoff at Tale of Finding Monster in Patagonia) published on March 8, 1922, mocking the expedition.

"Dr. F. A. Lucas, director of the Museum of Natural History, does not credit the report that a plesiosaurus, an amphibian of the Mesozoic period, generally believed to exist only in fossil form, has been seen alive in Patagonia.
'It is very unlikely that a plesiosaurus has been seen,' said Dr. Lucas yesterday. 'It is possible that something has been seen, but not a plėsiosaurus. It has been my experience that the nearer one goes to the source of such reports the less people seem to know about them. Nobody seems to know just how these wild reports start. Not long ago a report was circulated that a glyptodon, a genus of large extinct mammals of the order of edentata, related to the armadillos, had been seen in New Zealand.'
'As nearly as I can recall, no fossil remains of plesiosauri have been found in South America, but I know of no reason why they should not exist there. The most recent remains found in this country date from the Cretaceous period. It is barely possible that the animal seen was a large fresh-water turtle or a crocodile, though Patagonia is far south for a crocodile.'
WASHINGTON, March 7. - Professor Gilmore of the National Museum and N. Hollister of the National Zoological Park said today that they were of the opinion that such animals as plesiosauri vanished from the earth long ago.
'The last positive evidence of such creatures running at large,' said Professor Gilmore, dates back some 10,000,000 years. So far as scientists are aware, no such animal has been seen since that period. I would not hesitate in advising that the subject be dismissed.'"

Scientists

These men were authorities, and they made a good point.

Frederic Augustus Lucas, (1852-1929) was a naturalist, director of the American Museum of Natural History from 1911 to 1924, and honorary director until his death. He was an authority on vertebrate anatomy.

Charles Whitney Gilmore (1874–1945) was an renown paleontologist who worked with dinosarus during his career at what then was the United States National Museum (now the National Museum of Natural History).

Ned Hollister (1876-1924) was a naturalist, and between 1910 and 1916 served as Assistant Curator in the Division of Mammals, United States National Museum. Then he became the Superintendent of the National Zoological Park in Washington, where he worked until his death.

Comments

The New Zealand glyptodon is an interesting story, since there were no native mammals in the islands because it split from Gondwana before the first mammals appeared. It only had birds and reptiles, but no mammals. It is the first time I have read about it, but I have not been able to find any references to this sighting.

The suggestion that if there is an animal, it may be "a large fresh-water turtle or a crocodile" is reasonable. Nevertheless, Lucas points out that there are no known crocs in Patagonia. I agree with this possibility.

Plesiosaur from an article published in Buenos Aires in 1912.

The image above was published in 1912 ( Fray Mocho: semanario festivo, literario, artístico y de actualidades. (1912). En Busca de un Nuevo Monstruo. Argentina. Año 1, N° 11.) and its caption reads: "A plesiosaur, a species who mister König believes the mysterious inhabitant of Lake Pueyrredón belongs to."

This sighting at Lake Pueyrredón took place ten years before Sheffield's sighting.

Of course, Plesiosaurs died out 65 million years ago. The creatures, if real, were not plesiosaurs.

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall © 

Gigantic Turtles

Exploring the "giant turtle" option as an explanation for lake cryptids, I came across an article published in Science that mentions a giant sea turtle, the Atlantochelys mortoni

It was 3 meters from head to tail (10 feet) and looked something like contemporary loggerhead turtles. It swam in the oceans during the age of the dinosaurs some 70 to 75 million years ago.

Atlantochelys mortoni. Source

Read the article here: Nadia Whitehead (2014). Stitched-Together Fossil Reveals Giant Prehistoric Sea Turtle. Science. 25 March, 2014.

It was part of the Protostegidae family of giant sea turtles that thrived during the Cretaceous period. They were the largest turtles that have existed. Some had heads 39 inches long (1 meter). They were carnivores, and became extinct during the asteroid collision event that wiped out the dinosaurs and large reptiles.

Gigantic Amazonian Turtle

However, closer to Patagonia and closer in time, a new species was described in 2024, the freshwater turtle known as Peltocephalus maturin. It lived between 40,000 and 9,000 years ago. Its shell measured 180 centimeters long (6 feet) making it one of the largest freshwater turtles that have existed.

Currently the Asian narrow-headed turgle (Chitra chitra) is the largest one, and it is still alive! It measures 140 cm (4 ft. 7 in.). The largest freshwater turtle in South America is the freshwater tortoise in the Amazon is the Arrau turtle (Podocnemis expansa), with 110 cm (3 ft. 7 in.)

They must have been hunted by the Paleoindians who reached the Amazon area at least 12,000 years ago. If they harvested the turtle's eggs, they would have put it under pressure and eventually led to its extinction.

Peltocephalus maturin and capibara. Credit: Júlia d'Oliveira

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia Copyright 2009-2025 by Austin Whittall ©