On August 7, WikiProject Palaeontology member Rextron discovered a suspicious taxon article, Mustelodon, which was created in November 2005. The article lacked references and the subsequent discussion on WikiProject Palaeontology found that the alleged type locality (where the fossil was first discovered) of Lago Nandarajo "near the northern border of Panama" was nonexistent. In fact, Panama does not even really have a northern border, as it is bounded along the north by the Caribbean Sea. No other publications or databases mentioned Mustelodon, save a fleeting mention in a 2019 book that presumably followed Wikipedia, Felines of the World.
The article also appeared in four other languages, Catalan, Spanish, Dutch, and Serbian. In Serbian Wikipedia, a note at the bottom of the page warned: "It is important to note here that there is no data on this genus in the official scientific literature, and all attached data on the genus Mustelodon on this page are taken from the English Wikipedia and are the only known data on this genus of mammals, so the validity of this genus is questionable."
Editors took action to alert our counterparts on other projects, and these versions were removed also. As the editor who reached out to Spanish and Catalan Wikipedia, it was somewhat challenging to navigate these mostly foreign languages (I have a limited grasp of Spanish). I doubted that the article had very many watchers, so I knew I had to find some WikiProjects where I could post a machine translation advising of the hoax, and asking that users follow local protocols to remove the article. I was surprised to find, however, that Catalan Wikipedia does not tag articles for WikiProjects on talk pages, meaning I had to fumble around to find what I needed (turns out that WikiProjects are Viquiprojectes in Catalan!) Mustelodon remains on Wikidata, where its "instance of" property was swapped from "taxon" to "fictional taxon".
How did this article have such a long lifespan? Early intervention is critical for removing hoaxes. A 2016 report found that a hoax article that survives its first day has an 18% chance of lasting a year.[1] Additionally, hoax articles tend to have longer lifespans if they are in inconspicuous parts of Wikipedia, where they do not receive many views. Mustelodon was only viewed a couple times a day, on average.
Mustelodon survived a brush with death three years into its lifespan. The article was proposed for deletion in September 2008, with a deletion rationale of "No references given; cannot find any evidence in peer-reviewed journals that this alleged genus actually exists". Unfortunately, the proposed deletion was contested and the template removed, though the declining editor did not give a rationale. Upon its rediscovery in August 2020, Mustelodon was tagged for speedy deletion under CSD G3 as a "blatant hoax". This was challenged, and an Articles for Deletion discussion followed. On 12 August, the AfD was closed as a SNOW delete. WikiProject Palaeontology members ensured that any trace of it was scrubbed from legitimate articles. The fictional mammal was finally, truly extinct.
At the ripe old age of 14 years, 9 months, this is the longest-lived documented hoax on Wikipedia, topping the previous documented record of 14 years, 5 months, set by The Gates of Saturn, a fictitious television show, which was incidentally also discovered in August 2020. Based on the edit history of List of hoaxes on Wikipedia, new hoaxes are identified regularly at English Wikipedia. Dealing with this hoax and its fallout left me ruminating over some questions: How can we better identify hoaxes to keep them from reaching their tenth (or even fifteenth) birthdays? How can Wikipedia co-ordinate more readily across its different language versions once a hoax is discovered in one language? Does English Wikipedia harbor hoaxes that have been deleted elsewhere? Happy to hear your ideas.