Robert Pyle argues that "Certain artifacts suggest that some Amerindians were acquainted with something having the visage of an ape," specifically "several carved stone heads from the Columbia River basin," which Pyle believes depict "prognathous, chinless faces with heavy brow ridges and in at least one case a sagittal crest." These stone carvings date to pre-Columbian times, According to B. Robert Butler these stone carvings date to the Wakemap Middle Period, circa 1500 BCE to 200 CE. Pyle adds, "relics do not prove that Bigfoot exists or that [natives] had contact with apes, but they do raise some uncomfortable questions."
These artifacts are discussed at length by anthropologist Roderick Sprague in Carved Stone Heads of the Columbia and Sasquatch. Dozens of similar stone heads were recovered and most depict common animals. Sprague examines seven carved heads, which he argues have distinctively primate-like features. Like Pyle, Sprague notes that this does not necessarily support Bigfoot's existence, but Sprague sees the question of what inspired the carved stone heads as intriguing and unresolved.
In The Tsimshian Monkey Masks and Sasquatch, the anthropologist and ethnologist Marjorie Halpin describes two wood facemasks that were collected from the Tsimshian and Nisga'a tribes near Prince Rupert, British Columbia. One was obtained by Lieutenant G. T. Emmons in about 1914, and the other was obtained by Marius Barbeau in 1927. Emmons described the artifact as "a mythical being found in the woods, and called today as a monkey." Halpin also reports that the physical anthropologist R.D.E. MacPhee examined the Emmons mask and noted that it had both primate-like features.