Scientific American on the "Plesiosaur" of Patagonia

The July 1922 issue of Scientific American (Vol. 127 issue 1) included an article on page 21 titled "An Antediluvian Monster - Is the Argentine Plesiosaurus a Fake or a Scientific Marvel", by Leonard Matters.

Below is an image with the article.

An Antediluvian Monster. Scientific American

Below I quote it fully, just for the record, of course outlines the case and gives us the impression that Onelli's story was a indeed fake:

"Whatever may be the opinion in scientific circles —and it is one of scornful skepticism—the fact remains that the report of the existence in Argentina of a living specimen of a race of mammoth reptiles, supposed to have been extinct for millions of years, has excited intense interest. Every scientist of note has scoffed at the idea, but, headed by Dr. Clement Onelli, Director of the Zoological Gardens at Buenos Aires, there is a large body of Argentine public opinion strongly of opinion that a member of the plesiosaurus family will be discovered, alive or dead.
Dr. Onelli has disclosed to the press in Buenos Aires the fact that some time ago he received a letter from a American mining man down in Patagonia, reporting the existence of some monster, of a type well known to palentologists through fossil remains, but unknown to modern zoology. The American, a Mr. Sheffield, has been prospecting for gold along the Andes in the Tertitory of Chubut for many years, and Dr. Onelli says he knows him to be perfectly reliable. Mr. Sheffield wrote to the doctor stating that he had come across some enormous tracks near a lake. Bushes and undergrowth were trodden into the ground, and so deep were the tracks that they could only have been made by some living thing of ponderous weight. Continuing his account, Mr. Sheffield said: “I saw in the middle of the lake an animal with a huge neck like that of a swan, and the movement in the water made me suppose the least to have a body like that of a crocodile.”
Dr. Onelli has pointed out that Mr. Sheffield has given, for a layman, a remarkably accurate outline of the plesiosaurus, one of the mammoth reptiles that lived countiess years before the ice-age, and became extinct during that geological epoch in the world's history. Moreover, the report recalls more than one similar story of the existence in Patagonia of some strange feature, never yet clearly identified. Patagonia was undoubtedly at some time the habitat of mammoth beasts, and prehistoric man. Extensive fossil beds have been located, and scientific knowledge has been Widely enriched by the discovery of many kinds of extinct mammals and reptiles. Professor Frederic B. Loomis conducted an expedition through the Territory of Chubut in 1911, on behalf of Amherst College, and was successful in unearthing a petrified forest and, among other interesting fossils, the skull of a pyrotherium, an extinct elephantine creature.
There has long existed a romantic sort of idea that in the comparatively uninhabited parts of Patagonia, where certain forms of vertebrates are believed to have originated, a discovery would yet be made, of a nature that would stagger science—the finding of-the “missing link,” for instance, or more probably the capture of an actual living specimen of some supposedly extinct creature of antediluvian antiquity.
Palentologists and scientists in general have never been associated with such a belief, but nevertheless it has been a popular fancy, and has not lacked some degree of support among men whose opinion carries weight. In announcing the latest report to the public Dr. Onelli has recalled this interesting speculation. He was personally first attracted by the idea 25 years ago when he was down in Patagonia. On the shores of White Lake there then lived a Chilean farmer who declared that often at night a strange noise could be heard, as though a cart were being dragged over the pebbly shore. It was asserted that on moonlight nights a huge beast could be seen in the lake. It had a long reptilian neck which rose high above the water, but when disturbed it would at once dive and disappear in the depths.
Ten years after hearing of the apparition in White Lake, Dr. Onelli heard of the discovery made by a Norwegian engineer named Vaag, who was a member of the commission of demarcation of the boundary between Argentina and Chile. Mr. Vaag gave the name of River Tamango to a waterway flowing from the Andes, on whose banks he found the remains of some great beast, and the tracks of a creature that probably resembled the plesiosaurus. Later on, in a cavern, further south at Ultima Esperanza (Last Hope) there were found the remains of a hide and many bones of a great quadruped. The condition of the hide and the fact that the bones were conserved in a gelatinous condition, gave rise to the belief that it might be possible to find a similar beast alive. These interesting discoveries led to a number of expeditions, to which popular imagination at least attracted the objective of looking for a surviving specimen of the mammoth age, even if the scientists themselves had no such belief in the idea. These expeditions worked in different parts of Patagonia, and made interesting discoveries, though credence in the they found nothing to warrant any popular theory supposing the existence of zoological phenomena.
This, in brief, is the history behind the most recent report made on the authority of Dr. Onelli. Science in general utterly discredits the suggestion that a plesicsaurus, or anything like the extinct reptile, is still alive, and the many scornful comments on Dr. Onelli’s report leaves it doubtful whether scientists admit even the possibility of there being in Patagonia some unknown animal of large proportions. It has been hinted that the creature with the long swan-like neck is in the sume class as the sea-serpent, and is really born in a bottle. However, the refusal of scientists to take Mr. Sheffield’s story and Dr. Onelli’s theory as credible, has not prevented the doctor and the Argentine people getting deeply interested in a proposal to fit out an expedition for the capture of the creature, alive or dead.
So seriously has the idea been taken up that a rather amusing development has followed. Dr. Albarrin, President of the Society for the Protection of Animals, has demanded that the Minister for the Interior shall stop the expedition, under Law No. 2,786, which prohibits the hunting and destruction of rare animals. Dr. Albarrin urges that if there should still exist a plesiosaurus, then Argentina possesses a scientific marvel of immense value, and it should neither be killed nor captured, but should be allowed to enjoy to the full the liberty it has had over millions of years. The worthy doctor claims that it would be more humane and creditable to Argentine culture to leave the creature where it is and let it reproduce its species."

You can Read it online and see what this magazine looked like over 103 years ago.

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

The 1922 Plesiosaur Expedition

Caras y Caretas magazine in its issue 1224 of March 17, 1922 published two articles about the "Plesiosaur". One was written by Clemente Onelli ("Lo del Animal Misterioso" - "About the Mysterious Animal"), he was the Director of the Buenos Aires Zoo (see article here), and it included the famous letter written to him by Martin Sheffield, telling him about the plesiosaur he saw at a lake beside his hunting cabin.

About the mysterious animal by Clemente Onelli. From Caras y Caretas No. 1224.

The second article was titled "En Busca del Plesiosaurio" - "In Search of the Plesiosaur" (see the page here), can be seen in the image shown below, that included a cartoon of the expedition with the long-necked animal in the distance, captioned "how the author of Sarrasqueta sees the expedition that Mr. Onelli is organizing". There is a photograph of Dr. Vaccari, and the text says that Doctor Augusto Vaccari representing Caras y Caretas will go on this "risky and worthy exploring commission that will go to Patagonia in search of the plesiosaur, the famous animal of prehistoric origin whose fantastic appearance in a southern lake has stirred intense emotions in all social and scientific circles around the world. Whatever outcome the expeditionaries reach it is undoubtable that the risk of hunting it or not hunting it will duplicate the pictouresque value of the great adventure."

Vaccari and the cartoon. Caras y Caretas

Our next posts will look into this extravagant expedition chasing a non-existent plesiosaur

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

The "real" Plesiosaur lake at Epuyen

 

View of Lake Chulta y Plesiosaur Lagoon(?). From Google Earth

The Plesiosar Lagoon is located in the Epuyén River Valley, Chubut. And according to several sources, it is set on the western shore of the Epuyén River. It is barely larger than a pond and there is a bog between it and the river. It is closed in on the west by Mount Pirque. The lagoon is close to where the Pedregoso Creek joins the Epuyén River.

In the map above, I marked it with a red circle.

Today I read an article [1] about the area's geology and in it found the following:

Lagoon de las Mercedes (also named Chulta, Shulten, or of the Plesiosaur).[1]

Chulta Lagoon is the Plesiosaur Lagoon?. Copyright © 2010 by Austin Whittall

The Plesiosaur

I have already posted about the Plesiosaur at Epuyen so I will just summarize the story below:

An American gold prospector and otter hunter named Martin Sheffield wrote a letter in 1922 to the Director of Buenos Aires' Zoo, Clemente Onelli. He wrote that he had seen an enormous animal with the head of a swan and a crocodile body in "the lagoon where I have set up my hunting place".

Sheffield had met Onelli when he worked for him on the Argentine-Chilean Border Committee in the early 1900s.

Onelli told the press and caused a media uproar, an expedition was quickly organized and sent. After scouring the area it found nothing.

Sheffield's family's home was apparently built close to the Plesiosaur Lagoon (red circle above), but, could Sheffield's hunting shack be located at Chulta Lagoon?

Lake (or Lagoon) Chulta or Las Mercedes

This Las Mercedes or (de las Mercedes according to another source) Lagoon laguna de las Mercedes is located close to the village of Epuyén: from there you should take National Highway 40 north towards El Hoyo, and take a right turn on the junction with Provincial Highway 70 taking the climb towards El Maiten. The road is set on the slope of Mount coihue and after 8.5 km (5 mi.) you should take the road that branches to the left. 3 km (2 mi.) ahead is the Las Mercedes or Chulta Lagoon. Which is private property.

It is a small lake of the "Precordillera" at 580 m (1,900 ft) above sea level and it has a surface area of 80 ha (197 acres). It drains into the Las Minas creek and from there through the Epuyén River, Lake Puelo and Puelo River into the Pacific Ocean.

Local historian Casamiquela called it “Lake Chalta” [2] and supposed that its name came from the Tehuelche word Chaltén whose meaning is not quite clear (some say it means "mountain or hill that smokes" in an erroneous allusion to its alleged volcanic origin or, perhaps due to the clouds that snag against its summit). It is a sacred place because the demigod hero of the Tehuelche, Elal was taken there by a swan that set him on the mountain's peak. [3]

It was mentioned for the first time by the Spanish explorer Antonio de Viedma in his diary (1782), who spotted the mountain after discovering the lake that now bears his name. Viedma said it was called Chaltel because that was the name the natives gave it [4]:



Chaltén is an impressive peak 3,405 m (11,164 ft.) high, located in the Southwestern corner of Santa Cruz province in the Los Glaciares national park, on the border between Chile and Argentina. It is also known as Fitz Roy. It is very far from Epuyén and Chubut province, which makes me doubt Casamiquela's comment regarding the lake's name.

Plesiosar Lagoon

The official tourism websites on Epuyén on the other hand say that the Plesiosaur Lake is another one (which I had enclosed in a red circle in my map), and they treat it as a different entity to Lake Chulta or Las Mercedes.[5]

Which is the real and genuine lagoon?

Where did the mix up come from? A mystery indeed. I will continue my research on this matter.

Bibliography

[1] Miro, Roberto, (1967). Geología glaciaria y pre-glaciaria del Valle de Epuyén Revista de la Asociación Geológica Argentina. Tomo XXII, No. 3, Jul. Sept. 1967. pp. 183.
[2] Casamiquela, Rodolfo. (1987). Toponimia indígena del Chubut. Gobierno de la Provincia del Chubut, pp. 52
[3] Runa : archivo para las ciencias del hombre, Vol. 3. Ed. El Instituto, 1950. pp 193 y 198
[4] Pedro de Angelis [Ed.] (1837). Colección de obras y documentos relativos a la historia antigua y .... Vol. 6. pp. 56.
[5] Sitio web del Gobierno de la provincia del Chubut.Laguna del Plesiosaurio y Epuyén

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Lea este post en español

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Patagonian Monsters - Cryptozoology, Myths & legends in Patagonia

2010 International Year of Biodiversity Copyright 2009-2010 by Austin Whittall © 

Plesiosaur at Lake Epuyen. The letter

 

At Bariloche, last Saturday, I had the chance to photograph several documents on exhibit at the Museo de la Patagonia “Francisco P. Moreno” such as a facsimil of the letter written by Mr. Martin Sheffield to Clemente Onelli regarding the “Plesiosaur” at Lake Epuyen (see my posts on this lake cryptid).

The following image shows the original letter:

Sheffield's "Plesiosaur" letter to Onelli. Copyright © 2009 by Austin Whittall

And this is its Spanish translation; click on the link for an English version of the letter, click Here.

Sheffield "letter" to Onelli. Copyright © 2009 by Austin Whittall

Copyright 2009 by Austin Whittall ©

Patagonian Monsters

The Plesiosaur at Laguna Negra (Plesiosaur Lake), Epuyen. Part 3.

 

This is the third and last post on this strange creature.

III. The expedition

To head the expedition, Onelli’s chose his friend Emilio Frey who had worked with him on the Border Commission. The team also included José María Cinaghi, the Zoo’s administrator, its taxidermist, Alberto Merkle; Associated Press correspondent, Mr. Estrella; freelance reporter of Caras y Caretas Magazine, Dr. Vaccari and Mr. Santiago Andueza, a champion target shooter.

On their way

They set out on March 22, 1922 and soon arrived at Bariloche, where they stayed for a while. It was there that Frey wrote about a creature seen at lake Huechulafquen (see our post on Huechulito Here):

many times I heard respectable neighbors of Junín de los Andes say […] that in the Lake Huachi-Lauquen, at dusk, an animal often appears on its surface, which has more or less the same features of the one that is said to have been seen in Esquel. Very long neck, lizard head, body that must be enormous, because when it submerges it produces a sort of “boiling” in the waters.[1]

After leaving Bariloche, they arrived at Sheffield’s cabin on April 21, where they met his wife and children but not him, he was absent, and would be so for the remainder of the expedition.

Eager to get started he had Sheffield’s son, José take them to the place where the beast had last been seen. The track was:

quite erased; it must have been 30 cm wide [1 ft]. There have been no tracks of the animal since then, which is strange, because according to a statement of the lady [Ms. Sheffield] only 20 days ago Juan had again seen the mysterious animal. [1]

They explored the tiny lake finding it was very shallow – not deeper than 5 m (16.4 ft.). They threw dynamite into it and found nothing, not even pejerrey (silverside) fish, abundant in Epuyén River. Could the beast have eaten all of the lakes’ fish? Had it moved on?

Frey believed that the animal had left the tiny lake and swam downstream to Lake Puelo via Epuyén River. They widened their search to explore them, finding nothing. Frey was not discouraged because the local people “firmly believe in the existence of this strange animal”.

Sheffield somehow got the news to the US where Professor Brewster Loomis, a paleontologist of Amherst College, who had been in Patagonia back in 1911, was quoted in the New York Times as skeptically stating that while in Patagonia he too had heard stories of monsters which he disregarded because “the imaginative native might see anything”.[2]

The lack of any positive results and the arrival of winter led the team to postpone further exploration until the following summer. It was then that Leonard Matters in the July 1922 issue of Scientific American concluded that the plesiosaur “if it ever existed, appears to have fled to parts unknown”.

The expedition officially called off at the end of the following summer, on April 23, 1923. Onelli remained Director of the Zoo until his untimely death in 1924.

IV. Aftermath

But, what did Mr. Sheffield actually see, that is, if he saw anything?

Actually, he saw nothing, just some tracks; it was his daughter Juana who saw the creature with her brother Teddy.

According to Juana, when she was 10 or 12 years old, she saw a “big creature” and told her father.[1] He too had seen the tracks close to the lake where they usually hunted ducks; “the tracks were wide, but it seemed that [the creature] had short legs”.[3]

In an interview back in the 1970s she added that it “did not have a head or a tail, it looked like a [tree] trunk”;[4] later, in 1995, aged 85, she gave a more detailed account and told that it was not her father, but she who first saw the creature’s tracks.

They resembled “cart tracks”, which surprised them as they were in the soft ground of a “mallín” (bog) by the lake. It seemed to them that something heavy had dragged itself through the plants. She believed that these were “paw marks” and that the creature that made them had a long body and short legs and “where it passed with its belly or body it squashed the small plants”.[5]

She recalled that by the lake something frightened their dog and they noticed tracks that went into the lake and surfaced on the other shore, she also saw something:

half red, half yellowish, nearly the color of leather sole. The animal’s fur was like hairs or feathers. They looked like hairs. We did not see its tail or head. We saw the part of its torso. It was lying there, sleeping in the sun […] That animal walked over a dead cow and did nothing to it; apparently it did not eat meat[5]

It was not restricted to the lake, because she later saw it on a backwater of the Epuyén River, it was hunting fish; she heard a sound like a howling calf and saw the beast: “on a cliff, […] and the fish boiled above in the water […] the noise came from there. The animal howled like a two year old calf”.[5]

Closing comments

This article is just a summary of my book’s chapter on this interesting subject. Considering it is a blog, I have tried to keep the post as short as possible.

After reading Juana Sheffield’s remarks on the beast, it is clear that the animal was a mammal.

Its physical appearance is very similar to other cryptids reported in the region (i.e. Colhue Huapi creature).

Long body and short legs are definitively otter-like. A large otter.
A scary one too (her dog was afraid of it).

Could it have been Muster’s water tiger? Its yellowish hair is similar to what Musters described as the tiger’s fur color.

What we can be sure of is that it was not a plesiosaur. Onelli was right, the creature was a mammal. Though I don't think that it was a surviving mylodon (Onelli's theory).

Part 1 of this post is Here.
Part 2 is Here.

Bibliography.

[1] Juárez, F. Historias patagónicas. Online.
[2] The New York Times, (1922). New York. US 11.03.1922.
[3] Gavirati, M., (2001). Galería de Personajes Patagónicos: Martín Sheffield. El gaucho yanqui. La Bítacora Patagónica, Año 4, N° 16. Invierno 2001.
Also: Gavirati, M. Patagonia Histórica. Martin Sheffield: el gaucho yanqui. Entrevista con Juana Sheffield, 11-1995.
[4] Juárez, F., (2000). La historia de la magia. La Nación. B. Aires, Argentina. 09.01.2000.
[5] Matamala, J., (2001). Martin Sheffield Sheriff en la Patagonia. Testimonios. Online.



Copyright 2009 by Austin Whittall ©

Patagonian Monsters

The Plesiosaur at Laguna Negra (Plesiosaur Lake), Epuyen. Part 2.

 

This is the Second part on the "Plesiosaur at Laguna Negra". In our previous post we mentined the background (Mr. Sheffield's letter to Clemente Onelli) and the media stir that it caused. While the expedition was being prepared, Onelli told the press that he had heard about the "creature" several times in the past, and he gave details:

II. Onelli’s “evidence” and previous sightings

Onelli’s remark about having heard about the creature “for the last thirty years” was repeated by him in an article published in the New York Times: “from 1890 to the present time there had been twelve places in Patagonia, between latitudes 38 and 52, at which mysterious creatures had been reported”.[1]

These twelve sighting are the following:

1. The fox-snake “Nguruvilú”
In 1875 at Lake Aluminé (39°14’ S, 70°55’ W), Mapuche chief Nahuelpi told “Dr. Nietsche”, according to Onelli, about the existence of a monster that the Indians feared.[2] It was the Nguruvilú (see my previous post on it Here).

2. The Aluminé beast
The second sighting was at Aluminé River; Onelli said that he had circumstantial evidence of the presence of a huge beast in the neighborhood, but he gave no additional information. This river flows from Lake Aluminé into the Limay River that drains the Nahuel Huapi.[3]

3. White Lake creature
A third sighting was reported at White Lake (Lago Blanco) (45°53’ S, 71°13’ W). It is a 14,4 km (9 mi) long and shallow body of water that flows west till it runs dry close to the Andean foothills. Apparently, in 1897, a Chilean farmer living there reported hearing the sounds of something heavy being dragged along the pebble beach near the lake; at night he sometimes saw a long-necked form in the water. Here Onelli is implying a creature with a plesiosaur-like neck.

4. Tamango River
Also known as Chacabuco River (47°04’ S, 72°10’ W) is just 10 km (6 mi.) north of Lake Pueyrredón -known as Cochrane in Chile- from which it is separated by a steep range of hills; it flows into the South Pacific Ocean. Here, in 1898, a topographer of the Argentine Border Commission, Juan Waag, “saw the fresh footprints of a huge animal”.[4]

5. Unnamed lake in Santa Cruz
Onelli revealed a fifth sighting which was very similar to Sheffield’s. It concerned “a similar beast seen in 1913 by an Englishman in a lake in the territory of Santa Cruz […] the creature was said to have a long neck and bulky body" (once again the plesiosaur-like neck).[5]

6. Lake Vintter
Known then as Lake General Paz (43°56’ S, 71°31’ W); the sighting involved a local inhabitant, but no details were given beyond the year (1900). We have already mentioned that Illing had visited the region in 1898 searching lucklessly for the mylodon.[2]

7. Chubut, unidentified location
This one involved Florencio de Basaldúa when he was the interim governor of Chubut Territory (1900); he organized an expedition that was purportedly attacked by an animal similar to a mylodon.

8. Lake Pueyrredón
Shared with Chile, where it is known as Cochrane (47°18’ S, 71°55’ W). The lake covers a total area of 173 km2 (67 sq. mi.) and is 154 m (505 ft.) above sea level; it drains into the Pacific. It is very close to both the famous unicorn paintings at Cueva del Indio and Chilean National Preserve, “Los Tamangos”, home to many Huemul. Without giving any details, Onelli said that in 1910 while swimming in this lake, a local, Alfredo Sepúlveda, saw an animal that he described as a “saurius”.

9. Strange puma
A repetition of an account printed in Prichard’s book (1900/1):

the administrator of the Braun and Blanchard store at Santa Cruz [town] gave him the description of a fur that the Indians had taken there, that even though it was not the fur of a puma, it was nearly as large as [a puma fur]”.[6]

10. Patagonia unspecified location
Onelli himself (1896); while camping in Patagonia, he was told by natives that they heard frequent noises resembling a cart rumbling over boulders. When he and his team investigated they “saw an enormous black shadow swimming away […] the creature craned its long neck several times and then disappeared” (plesiosaur neck again).[5]
He added that “prospectors about twenty years ago found the sekeleton of an enormous creature by the Chilean frontier”.[5]

11. Deseado River
In 1901 Mr. Ludovic von Plaaten Hallermund, a Dane expert working for the Argentine Border Commission reported that a mule had fallen down a cliff by the Deseado River. When on the following day his men climbed down to salvage the cargo, they found the animal on the edge of the water, half eaten and in its vicinity, strange tracks “like those of a puma, yet not those of a puma”.[6]

12. Senguer River “Iemisch”
Which we have already mentioned in a previous post Here.

Comments

Onelli’s repeated remarks regarding svelte necks and swan-like postures, implying that the beast was a plesiosaur, may have been part of his deceptive plan to mislead those who may try to capture the animal before he had the chance to do so. Bear in mind that he believed the creature was related to the Eberhard Cave mylodon.

My Book.

In my book, I analyze each of these sightings with more depth looking into some interesting hypothesis regarding the creatures that could have provoked them. I also mention other incidents at those lakes (between 1922 and 2009).

We will continue in our next post (Part 3) Here.
See our previous post (Part 1) Here.
Photographs of those involved in the expedition Here.

Bibliography.
[1] The New York Times, (1922). Andean 'Plesiosaurus' May Be an Armadillo Or Modern Megatherium, Onelli Thinks. New York, US 16.03.1922. pp. 18.
[2] Publicación electrónica Secretaría de Ciencia, Tecnología e Innovación Productiva. Año 4: N° 1. Online.
[3] Arment, C., (2004). BioFortean History: The Patagonian “Plesiosaur” Expedition of 1922. North American BioFortean Review v. 5, N° 2, Issue N° 15, 10-2004.
[4] The New York Times, (1922). New York. US 08.03.1922.
[5] New York Times, (1922). Expedition tu hunt live plesiosaurus. 09.03.1922
[6] Hesketh, P. Op. Cit. pp. 335-338



Copyright 2009 by Austin Whittall ©

Patagonian Monsters

Plesiosaur "expedition" - the people

 

These are the "heroes" of the Plesiosaur "expedition". We have mentioned them: Clemente Onelli, Martin Sheffield, Emilio Frey.

Martin Sheffield. From [1]

Clemente Onelli. From [2]

Emilio Frey (in his later years). From [3]

Sources.

[1] Image from Online source.
[2] Image from Online source.
[3] Image from Online source.


Copyright 2009 by Austin Whittall ©

Patagonian Monsters

The Plesiosaur at Laguna Negra (Plesiosaur Lake), Epuyen. Part 1.

 

Laguna del Plesiosaurio (Plesiosaur Lake). From [1].

The photograph above shows a panoramic view of the famous Laguna Negra (Black Lagoon), now known as Laguna del Plesiosaurio (Plesiosaur Lake). In the image, the hills at the back are towards the east. Between them and the lake runs Route 40 and the Epuyen River which flows north (right to left in the image) towards Lake Puelo. The trees on those hills were burnt in a large forest fire in 1987.

Below is a map of the area, showing lakes Puelo and Epuyén, Route 40. The inset detail shows an enlarged view of the area and the tiny Plesiosaur lake is marked with a yellow arrow. The scale bar is 1000 m (3,28 ft.). On the large map, the snow capped Mount Pirque can be seen right behind the lake (on the left).

New - 06.10.2010 I have found new evidence that indicates that the lake may be another one. Close to this tiny Lagoon. It could be the lake now known as Chulta or Las Mercedes.

Laguna del Plesiosaurio (Plesiosaur Lake) map of the area.
Adapted by Austin Whittall from [2].

Introduction.

Plesiosaurs (which in Greek means “close to a lizard”), were large aquatic reptiles that lived at the same time as the dinosaurs.

They were sea creatures that had a broad stocky body, a short tail and turtle-like flippers. Most had small heads and slender necks and measured between 3 and 20 m (10 – 66 ft.) long. As marine reptiles, plesiosaurs had a worldwide distribution and their fossilized remains have been found in northern and central Patagonia.

Though they became extinct together with the dinosaurs 65 Ma., in the early XX^th century, one was allegedly seen alive in Patagonia.
This is the amazing plesiosaur story:

I. Background

It all began with Martin Sheffield (ca.1863-1932), an American hunter and gold prospector. Neither an outlaw nor a bandit, he portrayed himself as a Texan Sheriff, who had migrated to Argentina around the end of the XIX^th century and settled close to what is now the Andean town of El Bolsón (41°58’ S, 71°17’ W).

Click on the link to see a photograph of Martin Sheffield.

There were many Americans in the region at that time, and it seems Sheffield was acquainted with the famous bank robbers Butch Cassidy and the Sundance Kid. These rogues after running away from the US when things got to hot for them, had set up their base of operations at Cholila, close to El Bolsón, a safe haven out of the reach of the law. But not for long: soon after they robbed a bank at Rio Gallegos and Pinkerton Agency detectives quickly picked up the scent, forcing the bandits to hastily decamp.

Sheffield later moved to Epuyén, where he married a Mapuche woman, María de los Santos Pichun who bore his children. He prospected gold for many years and true to his own spirit, met his death panning for gold at the Las Minas Creek.

It was Sheffield who on January 19^th, 1922 wrote a very strange letter to Buenos Aires Zoo Director, Clemente Onelli, telling him that he had sighted a strange creature.

Onelli (click to see a photograph of Onelli.) who had visited the region many times as a member of the Argentine-Chilean Border Commission, knew Sheffield; he had even mentioned him in his 1903 book as “Mr. Chefield [sic]”.[3]

Perhaps this previous acquaintance prompted Sheffield to write to Onelli. His letter said the following:

Allow me to bring to your attention the following phenomenon that surely will awaken your vivid interest because it deals with the possible entry to your zoo of an animal until now ignored by the world. I will narrate the facts:
For some nights now, I have been noticing some tracks in the grass close to the lake where I have set up my hunting lodge; the track is similar to the foot print of a very heavy foot, the grass remains squashed and does not rise again which leads me to believe that the animal that dragged itself through there must have an enormous weight; I have been able to see, in the middle of the lake, an enormous animal with a head like a swan and enormous size and the movement in the water makes me suppose a crocodile body.[4]

He also suggested that the animal could be hunted and detailed the necessary equipment (harpoons, boat and embalming materials).

The lake mentioned in the letter is the Laguna Negra (Black Lake), now known as Laguna del Plesiosaurio (42°09’ S, 71°24’ W). It is barely larger than a pond, roughly 200 m (656 ft.) long by 200 m wide; set at the base of the steep slopes of Mount Pirque (1.430 m – 4,690 ft.), it drains into the Epuyén River.

This river has its sources at Lake Epuyén (17,4 km² – 6.8 sq. mi.) and flows into Lake Puelo, which in turn empties its waters through the Puelo River into the South Pacific Ocean (we have already mentioned some of the strange creatures seen in this river in our post on Puelo River monsters).

An expedition is hastily organized

Once Onelli made the letter’s contents public, it caused a stir and an expedition was promptly organized to search for and capture the beast that was named “the plesiosaur” by the media.

The news traveled around the world –this was eleven years before Nessie (of Loch Ness fame) was first mentioned- and headlines in Europe and the US would report the progress of the expedition.

I have already mentioned (Plesiosaur Tango) the effect of this extensive media coverage.

Some say that Sheffield was inspired by Sir Arthur Conan Doyle’s (the author of Sherlock Holmes) book The Lost World, which had been published serialized in Buenos Aires in 1914; maybe he had read it in his isolated cabin at Epuyén.

Doyle’s book portrayed plesiosaurs as moving their necks with “graceful, swan-like undulations” and as having a “barrel-shaped body and huge flippers behind the long serpent neck”; very similar to the creature described by Sheffield.

We know now that it would have been impossible for a plesiosaur to adopt a “swan-like” pose or even lift its head and neck above the water’s surface. Its body would not allow such a feat.

Sheffield’s comments about the foot print of a very heavy foot could not have been made by a plesiosaur either; the creature’s flippers would not have left a “foot print”; instead, like a turtle track, its trail would seem to be made up of lots of shallow dips made by its back flippers as it pushed itself along the ground, if and when it ever went ashore.

To be honest Onelli knew that plesiosaurs had become extinct with all other large reptiles and dinosaurs 65 Ma. He hoped that it was something else. He went on record saying that he believed that the creature reported by Sheffield was not a plesiosaur but a megatherium (a giant ground sloth, relative of the mylodon), reviving the Patagonian mylodon once again. He even brought up Lista and his pangolin shooting incident by stating that the lake creature was a “huge animal of the family, of which ancient remains -not fossil, mark you- were found in Patagonia In 1897, and one of which was fired upon and hit by the explorer Ramón Lista in 1890 without hurting it”.[5]

In his “secret instructions” for the expedition, he stated that he had “let the general public believe that [Sheffield] had seen an exaggeratedly monstrous animal at the lake at Esquel”, which was another lake and not at the tiny Black Lake. He did this to throw any others who wanted to hunt it off the real track of the expedition.[6]

He was also very clear regarding his belief that it was a mylodon and not a plesiosaur; his instructions stated that the expedition was to verify “the possible existence of an animal disappeared in prehistoric times; probably an edentate very close to, if not the same as the domestic Cryopterioum [sic], whose excrement and dry hide and bones were found” at Mylodon Cave in 1896.[6]

He added that he believed (but with trepidation) in Sheffield’s story but that “I dismiss the squashed grass by the shore of the lagoon, because that place may have been a resting place for some huemul”.[6]

It is strange that he did not consider the huemul, a stout, distinctly stocky deer with a thick coarse brown fur as a likely cause of the tracks seen by Sheffield. We have already mentioned the huemul in connection to (Patagonian unicorns) and pointed out its ease at swimming and fondness towards water.

Huemul were relatively abundant in the Epuyén region where, nowadays, a Provincial Reserve protects the few that remain in the mountains just behind the Black Lake, at cerro Pirque.

Onelli also believed that he had pinpointed the monster’s habitat:

For the last thirty years we have heard about it, only in those parts of our territory that were once claimed by Chile, on the oriental side of the divortiuim aquarum. The animal’s legend is found only in the valleys on the west of this easily surpassable line of continental waters’ divide before transposing the, for it, insurmountable line of the real cordilllera. These are the only regions where a great edentate, an animal of the lowlands, could be […] because these forested and crooked valleys were never visited by the natives of southern Argentina […] [The] current habitat should be the relatively low regions, not higher than 800 m [2,624 ft.] and very likely in the forests’ clearings and not in the thick woods, because the southern forest does not allow life under it.[6]

He was convinced that it lived in the basins of rivers that drain into the Pacific Ocean, a region that was disputed between Argentina and Chile in the late XIX^th century. The boundary line between both countries according to an 1881 treaty was to follow the highest crests of the Andes that defined the watershed. However in Patagonia, the Cordillera is transected by many glacial valleys causing some drainage basins on the east of the divide to flow into lakes whose Atlantic outlet is blocked by the glacier moraines; these rivers then bend and flow west into the South Pacific. This alteration of the spirit of the original treaty nearly led to a war. To settle the dispute the matter was referred to the arbitration of Queen Victoria, and an amicable settlement was reached in 1902. War was averted.

Perhaps Onelli believed that creature was confined to these areas not only due to the lower altitude of these basins which ensured a fairer climate, but also to the fact that it may have been a resident of the dense Valdivian Rainforest which offered more food and a thicker foliage to conceal it than the other Andean forests.

His remark about the habitability of the forests and their lack of large animals was also pointed out by Prichard. Patagonian forest animals are mainly small rodent mammals or nocturnal marsupials. This may be due to the lack of grasslands within the woods to sustain large herbivores and also to the fact that they are an isolated habitat, separated by more than 1.000 km (620 mi.) of arid lands from the nearest forests. There is no other similar “forest island” of this size in the world that has large sized native mammals; these need large extensions of continuous habitat to be able to survive.

Furthermore the Southern beech woods provide few edible seeds or fruits; this means that the niche filled by the northern hemisphere squirrel is empty. Patagonia’s small mammals survive in the underbrush, not the trees. For these reasons, these forests have a very high diversity of small rodents in comparison to other forests around the world, but no big mammals.

We will continue the "Plesiosaur saga" in our next posts. It is a long story.

Plesiosaurs Part 2.
Plesiosaurs Part 3.

Bibliography.

[1] Camping y cabañas Pocho. Online Here.
[2] Google Earth.
[3] Onelli, C. Op. Cit. pp. 48.
[4] Fort, C., (1931). LO! New York: Claude Kendall. pp. 110.
For the original Spanish version of letter, see: El Plesiosaurio.
[5] The New York Times, (1922). Andean 'Plesiosaurus' May Be an Armadillo Or Modern Megatherium, Onelli Thinks. New York, US 16.03.1922. pp. 18.
[6] Rey, C., (2007). Nahuelito: El misterio Sumergido. Bariloche: Caleuche, 2007. pp. 8. More on this novel Here, despite being fiction, it includes transcriptions of Onelli's instructions to Frey.


Copyright 2009 by Austin Whittall ©

Patagonian Monsters