In 1849 Zapatera was visited by American diplomat and archaeologist Ephraim George Squier, who noted the presence of a considerable amount of statues and petroglyphs in an area known as Punta de las Figuras. More than 30 years later, in 1883, Squier's report encouraged Swedish naturalist Carl Bovallius to undertake a more extensive survey of the island. Bovallius discovered 25 statues in Sonzapote and a number of petroglyphs on the islet of La Ceiba. Mexican Felipe Pardines also published a series of articles on the El Muerto island petroglyphs in the 1930s. The most recent archaeological investigations were carried out in the 1980s and involved a number of small excavations, but an in depth study of the island is still lacking.