Case files — Latin America

1. Nahuel Huapi, Patagonia, Argentina — Nahuelito — reported from 1897

Rating: D (explained / folkloric) · Status: no official record retrieved; two photos, both weak

• Reported: a giant serpent or humped creature in Lake Nahuel Huapi, sometimes described as plesiosaur-like. The name derives from yaguareté/the lake's own name. Indigenous accounts predate colonisation; the modern record starts when Dr. Clemente Onelli, director of the Buenos Aires Zoo, began receiving reports about Patagonian lakes in 1897.
• The best early account: in 1910 George Garret, working for a company near the lake, reported a creature about 400 m away whose visible part was 5–7 m long and stood about 2 m above the water, and learned from locals that similar stories were known.
• Photographs: a hump photo (1988, sent anonymously to El Cordillerano with the note "El Nahuelito showed his face") and later video/photo material. None has held up.
• The folklore that outlived the animal: the retelling that the Argentine military spent days chasing a submerged object in the lake in the early 1920s, sometimes described as a small submarine. No contemporary document for this was retrieved for this pack, so it is recorded here as tradition, not fact.
• Leading explanation: boat wakes, floating vegetation, large fish and otters, plus a strong tourism layer — the Patagonian lake district sells the story directly.
• Sources: sources.md → Wikipedia index (C/D); Patagonian tourism-material descriptions (D).

2. Brazilian and Venezuelan Amazonia — the mapinguari — traditional; modern fieldwork 1990s–2000s

Rating: C (reported, one substantive field programme) · Status: reported only; a real fossil connection that is a separate question

• Reported: a foul-smelling, hairy, bipedal creature with a gaping mouth on its abdomen, hook-like nails, backwards-turned feet and a single eye — a compound of Amazonian tradition rather than a single zoological description. The name derives from Tupi-Guarani (mbaé-pi-guari, "the thing with the twisted foot"). The Karitiana know related beings as Kida harara ("laughing beast").
• The field programme: Brazilian palaeontologist David Oren argued the mapinguari could be a surviving ground sloth, and by 2001 had interviewed between fifty and eighty Indigenous Brazilians, rubber tappers and miners who claimed sightings, plus seven hunters who claimed to have shot one — concentrated around Eirunepé, Manicoré and Carauari. He noted the reported diet (twisting bacaba palms to eat the heart and fruit) as a break from the predatory classic.
• The ethnographic correction: ethnologist Glenn Shepard, working with the Matsigenka of Peru, identified their equivalent being (the Oshetoniro, "mother of spider monkeys") as connected to folk memory of a ground sloth rather than a living animal — i.e. the tradition preserves a memory of something extinct, which is a different claim from a surviving population.
• The real science nearby: the 1995 discovery of giant sloth osteoderms modified into pendants, analysed in a 2023 study suggesting human manufacture 25,000–27,000 years ago — humans and giant sloths coexisting in South America. That is why the folk memory has something to be a memory of.
• Leading explanation: the tradition encodes encounters with real megafauna (or their remains, including the distinctive claw marks and the smell of decomposing hides), and is maintained by a rainforest full of genuinely dangerous large animals.
• Sources: sources.md → Wikipedia index (Oren 2001; Shepard 2002; 2023 osteoderm study).

3. Tarra River, Colombia–Venezuela border — de Loys's ape — 1920

Rating: D (demonstrated hoax / misidentification) · Status: a spider monkey in a posed photograph

• The claim: Swiss oil geologist François de Loys, on a 1917–1920 petroleum expedition along the Colombia–Venezuela border, reported that two large creatures approached his camp in 1920; the party shot them, killing a female said to be 1.57 m tall with 32 teeth and no tail — much larger than any spider monkey. The body was posed on a crate with a stick propping the chin. All but one photograph was lost, and the story was not published until 1929.
• The promotion: de Loys's friend George Montandon found the photo, had de Loys publish in the Illustrated London News (15 June 1929), proposed the name Ameranthropoides loysi, and promoted the creature as an ancestor of Native Americans — in service of his "hologenesis" hypothesis, which held that human "racial groups" evolved independently from different ape ancestors. That hypothesis is now recognised as racist pseudo-anthropology, and it is the reason the photo had a career.
• The refutation: primatologist Philip Hershkovitz, anatomist Arthur Keith and others rejected it — the animal is a spider monkey, the size could not be read from the photo, and by not photographing the animal's rear de Loys left the tail question conveniently open. Later documentation, including a letter from the expedition's own surviving member Tejera, described the photographed animal as a pet spider monkey adopted by the party.
• Why it is on the site: it is the canonical example of a cryptid manufactured as a racial argument rather than a zoological one, and it shows how an image with no scale, framed by an interested party, can outlive every expert who appraises it.
• Sources: sources.md → Wikipedia index; Scientific American / Tetrapod Zoology (Naish); AAPG Explorer on the fraud's creation.

4. Puerto Rico, then Mexico and Texas — the chupacabra — from 1995

Rating: D (explained) · Status: DNA-tested repeatedly — known canids

• Reported: an animal blamed for livestock deaths with a distinctive pattern of puncture wounds and drained blood. In Puerto Rico and much of Hispanic America it is portrayed as reptilian or alien-looking; in Mexico and the southern US the "chupacabra" of reports became a hairless, blue-grey quadruped.
• Where the name and the wave came from: the first widely publicised sightings and descriptions were in Puerto Rico in 1995. The word is generally credited to San Juan radio comedian Silverio Pérez, coining "chupacabras" on air while discussing the attacks; the first attack later associated with the phenomenon occurred in March 1995, and the Canóvanas sighting — the one that made it international — was reported by Madelyne Tolentino in August 1995. An earlier local precedent, the 1975 "vampire of Moca", shows the story shape pre-dating the name.
• The testing record: the Elmendorf Beast (Texas) was identified by DNA at UC Davis as a coyote with sarcoptic mange; two further Texas carcasses were identified by biologists as coyotes with severe mange; Texas State University (Mike Forstner) reported a sequence "a virtually identical match to DNA from the coyote"; one specimen proved to be a wolf–dog hybrid. Surveys of northern Mexico and southern US reports have repeatedly resolved to canids with mange.
• The mundane driver on file: the 1995 Puerto Rican and 1996 Mexican outbreaks both followed severe droughts — which kills livestock and strips vegetation, making sick, hairless canids both more visible and more likely to scavenge near settlements.
• Leading explanation: mange (which causes hair loss and a cadaverous look) on coyotes and dogs, plus normal predation/exsanguination patterns exaggerated by press interpretation.
• Sources: sources.md → Wikipedia index; BBC 2007 (Forstner DNA); mongabay 2007.

5. Atacama Desert, Chile — "Ata" — found 2003; genome published 2018

Rating: A (tested, resolved) · Status: human — a fetus with a severe skeletal dysplasia

• The claim: a 15 cm mummified skeleton found in a leather pouch in the Atacama Desert in 2003, with an elongated skull, ten ribs instead of the usual twelve, and a look that made it a fixture of "alien" claims for a decade.
• The test: whole-genome sequencing (Bhattacharya et al., 2018, Genome Research; Stanford and UC San Francisco groups, led by Garry Nolan and Atul Butte) established that it is human, a fetus, carrying novel and rare mutations associated with severe skeletal dysplasia and bone disease — the work's value is in the genetics of rare bone disorders, not in the mystery.
• Why it is worth a site card: it is the cleanest "tested and closed" case in the pack — an unidentified-human-anomaly legend resolved by sequencing, with the resolution producing real science. It also belongs to the aerial file's Chile entries by geography and to this file by form.
• Sources: sources.md → Genome Research abstract via PubMed (29567674); UCSF/Stanford releases.