I was reminded of the (in)famous Acambaro (Mexico) clay dinosaurs this weekend by a list of famous archaeological hoaxes / conundrums sent to me. In case you had not heard of these before (see pictures below), you can get a nice overview on Wikipedia. Unfortunately, these often appear on Christian websites in “support” of creationism (but others have wised up and admitted they are fakes).
How do we know that they are fakes?
You’ll notice if you read the overview that things like fresh manure and fingerprints were found in the sites from which these figures were removed, and the sheer number (over 32,000) indicates chicanery (native inhabitants were paid for each figure by the Waldemar Julsrud, the “discoverer,” ca. 1944).
All that aside, the article and various websites note that thermoluminiscence dating techniques yielded a date of ca. 2500 BC for the figurines. The methods used proved erroneous. Here is a two page overview of the subject and problem from the University of Pennsylvania Museum publication, Expedition. That short article alludes to a study of the figures published in 1953 in the scholarly journal American Antiquity (vol. 18:4 : 388-389) by Charles C. Di Peso. Here is that article.
Lastly, a more recent report and scientific dating analysis has been done on the figures, proving conclusively they are fakes. That article is entitled, “Thermoluminescent Dating and the Monsters of Acambaro” (American Antiquity 41:4 [Oct. 1976]: 497-500).