 The flat backs of many of the colossal heads represented the flat bases of the monumental thrones from which they were reworked . Only four of the seventeen heartland heads do not have flattened backs , indicating the possibility that the majority were reworked monuments . Alternatively , the backs of many of these massive monuments may have been flattened to ease their transport , providing a stable form for hauling the monuments with ropes . Two heads from San Lorenzo have traces of niches that are characteristic of monumental Olmec thrones and so were definitely reworked from earlier monuments . 
 The flat backs of many of the colossal heads represented the flat bases of the monumental thrones from which they <a href='uninflect' title='1'><mark>were</mark></a> reworked . Only four of the seventeen heartland heads do not <a href='been_done' title='2'><mark>have</mark></a> flattened <a href='negative_concord' title='3'><mark>backs</mark></a> , indicating the possibility that the majority <a href='uninflect' title='4'><mark>were</mark></a> reworked monuments . Alternatively , the backs of many of these massive monuments may <a href='been_done' title='5'><mark>have</mark></a> been flattened to ease their transport , providing a stable form for hauling the monuments with ropes . Two heads from San Lorenzo <a href='got' title='6'><mark>have</mark></a> traces of niches <a href='null_relcl' title='7'><mark>that</mark></a><a href='drop_aux' title='8'><mark>are</mark></a>characteristic of monumental Olmec thrones and so <a href='uninflect' title='9'><mark>were</mark></a> definitely reworked from earlier monuments . 
The flat backs of many of the colossal heads represented the flat bases of the monumental thrones from which they was reworked . Only four of the seventeen heartland heads do not done flattened no backs , indicating the possibility that the majority was reworked monuments . Alternatively , the backs of many of dem massive monuments may done been flattened to ease their transport , providing a stable form for hauling the monuments wid ropes . Two heads from San Lorenzo got traces of niches characteristic of monumental Olmec thrones and soo was def reworked from earlier monuments .