Olmec colossal heads by Matthew Stirling in 1938 spurred the first archaeological investigations of Olmec culture. Seventeen confirmed examples are known from four sites within the Olmec heartland on the Gulf Coast of Mexico. Most colossal heads were sculpted from spherical boulders but two from San Lorenzo Tenochtitlán were re-carved from massive stone thrones. An additional monument, at Takalik Abaj in Guatemala, is a throne that may have been carved from a colossal head. This is the only known example from outside the Olmec heartland. Dating the monuments remains difficult because of the movement of many from their original contexts prior to archaeological
Proto-Mayan language Wastek to modern Wastek it can be seen that they were originally clusters of and a rounded vowel followed by a glide. For example the word for "vulture" which in modern Wastek is pronounced was written <nowiki><cuyx></nowiki> in colonial Wastek and pronounced . The Yucatecan languages have all shifted Proto-Mayan into in wordfinal position. Several languages particularly Cholan and Yucatecan have changed short into . All Cholan languages have changed long proto-Mayan vowels and into and respectively. Vowel length distinction has been lost in Q'anjob'alan-Chujean (except for Mocho' and Akateko), Kaqchikel and Cholan. Some languages have reduced the vowel length