In 1922, Henry Fairfield Osborn, the director of the American Museum of Natural History, declared that he had found a fossil molar tooth belonging to the Pliocene period in western Nebraska near Snake Brook. This tooth allegedly bore common characteristics of both man and ape. An extensive scientific debate began surrounding this fossil, which came to be called "Nebraska man," in which some interpreted this tooth as belonging to Pithecanthropus erectus, while others claimed it was closer to human beings. Nebraska man was also immediately given a "scientific name," Hesperopithecus haroldcooki.

Many authorities gave Osborn their support. Based on this single tooth, reconstructions of Nebraska man's head and body were drawn. Moreover, Nebraska man was even pictured along with his wife and children, as a whole family in a natural setting.

All of these scenarios were developed from just one tooth. Evolutionist circles placed such faith in this "ghost man" that when a researcher named William Bryan opposed these biased conclusions relying on a single tooth, he was harshly criticized.

In 1927, other parts of the skeleton were also found. According to these newly discovered pieces, the tooth belonged neither to a man nor to an ape. It was realized that it belonged to an extinct species of wild American pig called Prosthennops. William Gregory entitled the article published in Science in which he announced the truth, "Hesperopithecus Apparently Not an Ape Nor a Man."235 Then all the drawings of Hesperopithecus haroldcooki and his "family" were hurriedly removed from evolutionary literature.

Nebraska man, and Henry Fairfield Osborn, who named it.

235 William K. Gregory, "Hesperopithecus Apparently Not An Ape Nor A Man," Science, vol. 66, issue 1720, 16 December 1927, p. 579.