How the Patagonian plesiosaur of 1922 got its name

The letter that set off Argentina’s plesiosaur hunt never uses the word. Martin Sheffield, a hunter writing from Esquel on 19 January 1922, told the director of the Buenos Aires zoo about a trail through the grass and an animal in a lagoon with a head like a swan.¹⁸²⁹ The word plesiosaur came later, in a headline over a note that Clemente Onelli, the director, had sent to a newspaper himself.³ A party that included the zoo’s administrator reached Sheffield’s lagoon on 20 April and found that he was not there.¹⁰⁶¹¹

What Sheffield asked for

Caras y Caretas printed the letter on 18 March 1922, in a boxed panel inside Onelli’s own article, “Lo del animal misterioso”.⁸ Sheffield is not reporting a plesiosaur there. He is asking for money and equipment: a launch, which he says can be built at Esquel, harpoons, and embalming material in case the animal cannot be taken alive, with a firm in Esquel, Pérez-Gabito, to advance the means.¹⁴ The lagoon has no name in the letter, and the date line is the only place it gives.²

The rest of the animal is a trail like the track of a very heavy chata, a flat wagon, with the grass flattened and not springing back.¹ Onelli says in the same article that he met Sheffield in 1898 or 1899, when Sheffield was about thirty, tall and stout, wearing gaucho trousers and in the habit of firing his revolver between his horse’s legs as he rode away from visitors.¹⁵ Sheffield was North American, according to Perez, Toledo, Vizcaíno and Tonni (2024) and to a Caras y Caretas diarist, who calls him “el norteamericano que ha escrito a Onelli”.⁹ The whole letter is transcribed and translated.

A question mark in a headline

Onelli did not publish at once. Per Perez and colleagues, he sent La Nación a note printed on 6 March 1922 under a headline that ended “¿Será un plesiosauro?”; in it he said he had held the news back for a while to be first to mount an expedition, and had already told the director of the Museo de La Plata.³ The authors argue that the headline gave the animal its new identity.² On 18 March his article in Caras y Caretas called the plesiosaur “problemático” and said none of those beasts had been seen ni por el padre Adán, “not even by Father Adam”, who had no Kodak with him anyway.⁸¹⁶

The press took it from there. Caras y Caretas ran Redondo’s cartoons, and on 8 April a mock letter signed “El Plesiosauro”, written from Epuyén, addressed to the president of the animal-protection society and invoking law 2786.¹⁷ Tangos, cigarettes and a fashion brooch took the name.¹⁷ The governor of Chubut, Orestes Franzoni, decreed a ban on hunting the plesiosaur, per Perez and colleagues, and Onelli had to go to the minister to have it annulled.¹⁸ Frederic Loomis of Amherst College, who had collected fossils in Patagonia in 1911, told La Nación that the animal would be a water snake, probably an anaconda.¹⁹

The mock letter puts the animal at Epuyén on 8 April, although the printed letter names only Esquel.²¹⁷ How the place became public is not explained in anything we read.

The animal Onelli said he wanted

Onelli’s own answer to the plesiosaur question, as Perez and colleagues report it, was to disown the word. They quote him telling the New York Times on 16 March that “Plesiosaurus is a pseudonym the newspapers have given it”, and telling Mundo Argentino six days later that he had not declared it a plesiosaur at all; he expected an edentate, a form between anteaters and armadillos and a close relative of the giant ground sloth Megatherium.⁴

The idea was older than the letter. Florentino Ameghino had announced in 1898 that a ground sloth survived in southern Patagonia, and hunting parties went out over the next three years. Hesketh Prichard, who led one, wrote that he had found “no single scrap of evidence”.²⁰ Perez and colleagues conclude that Onelli’s purpose in 1922 was to keep that search going, and that calling the plesiosaur a pseudonym suggests he did not think it realistic.²¹ They also note that the party still looked into the evidence for a water animal.²¹

On 12 June the Star in Christchurch printed that Onelli was not sure of the monster’s scientific name but “certain of its existence”, and that the creature was covered with reddish hair and protected by horny plates, against which Remington rifles had proved useless; the same column describes a plesiosaur as an extinct marine reptile with four limbs developed as paddles.⁵ On our reading the two descriptions do not match. Perez and colleagues quote Onelli’s October 1922 article as saying the expedition also carried a programme for surveying the region’s resources, to curb a drain of more than 100,000,000 gold pesos a year spent abroad on raw material.²²

Epuyén, where Sheffield was not

The party was led by an engineer, Emilio Frey, who left ahead of the others.²³ Perez and colleagues add Santiago Andueza, a marksman, Alberto Merkle, a taxidermist of the Museo de La Plata, and the journalists Guillermo Estrella of La Nación and Augusto Vaccari of Caras y Caretas.²³ The zoo’s administrator, José M. Cinaghi, was the deputy chief; Caras y Caretas prints his name that way under the party’s photograph.¹⁰

Onelli told La Nación the party would go by sea to San Antonio and take the Patagonian railway to Punta de Rieles. That was a false route, and the others went straight to Neuquén.²⁴ Vaccari had suspected it: Lo hizo usted para despistar, he tells Onelli in his diary, “you did that to throw us off”.²⁴

The main party left on 23 March, drove from Neuquén to Bariloche, and reached Lake Nahuel Huapi on 30 March, per Perez and colleagues.⁶ On 17 April they set out for the Hoyo de Epuyén and came to Sheffield’s lagoon on 20 April.⁶ Sheffield was not there. He was convalescing in a town near Esquel, and they met his wife and children instead.¹¹ They searched the shallow lagoon beside the family’s hunting post, once on a raft, and left on 24 April.⁶ They were back in Bariloche on 28 April, tried Lake Gutiérrez, and set off down the Limay on 3 May.⁶

The commission found neither the plesiosaur nor the sloth Onelli expected, and a cable dated 28 April, printed in New Zealand in May, said the party had come back “empty-handed, unable to find the reported plesiosaurus, if such ever existed in Patagonia”.⁷

Cinaghi doubted the name too. In Vaccari’s diary he tells the journalist that the animal “no será plesiosaurio, será otra cosa”, but that it is not hard to believe it exists, because the hunter asked for the means to catch and keep it rather than for an expedition.²⁵

What the cables made of it

New Zealand newspapers show how the story shifted on its way abroad. The Southland Times of 22 March printed a London cable of 20 March, from the Daily Mail’s Buenos Aires correspondent, saying an expedition had left to search for the plesiosaurus and that scientists ridiculed the idea.¹² Perez and colleagues have only Frey leaving on 16 March and the main party on 23 March.⁶ By 5 May the Star had an Englishman who hunted in Chubut and found a trail of flattened vegetation.¹³ By 12 June it had a commander called Señor Frers.⁵ Sheffield was North American, and we take Frers to be Frey, though no source says so.⁹²³

A float at the Bariloche carnival

At the Bariloche carnival of 12 and 13 February 1923, per Perez and colleagues, a float in the “El Plesiosauro” troupe carried a mechanical plesiosaur with figures that included journalists and “Don Clemente” holding a syringe.²⁶ The troupe was run by Primo Capraro, a wealthy Italian resident of Bariloche who had offered the party his help.²⁶ The float was used in later carnivals until a sawmill fire destroyed it.²⁶

Onelli died on 20 October 1924, and Perez and colleagues say the search was nearly forgotten after it.²⁷ They say the name Nahuelito for the lake monster of Nahuel Huapi was given by the Bariloche journalist Carlos Bustos in the 1970s, and that Patagonian mentions of a plesiosaur in fresh water came before those for Loch Ness.²⁸