Benfer's conservation work on the sculpture was funded by the National Geographic Society's Committee for Research and Exploration. (National Geographic News is part of the National Geographic Society.)
Benfer announced his discovery at an April meeting of the Society for American Archaeology in Puerto Rico.
The sculptures were beautifully preserved thanks to the temple-builders' habit of using temples for only a short time before carefully covering them up and building new ones on top.
Even so, Benfer said, archaeologists were lucky that the site hadn't been looted.
Treasure hunters had dug a 20-foot (6-meter) wide hole 7 feet (2 meters) deep into the layers above the site, he said.
The would-be looters stopped only inches from the temple.
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