"The section of the plaza that Bird Jaguar created functioned as a sunken viewing ground for ritual gatherings. Several pedestal stones (altars) carved with glyphic inscriptions are located near the center of this space. The Altar 10 inscription seems to date 220.127.116.11.5, which would place it in Shield Jaguar's reign. Altar 11 records the date 18.104.22.168.5, shortly after Bird Jaguar's accession. Two stones approximately 2 meters long are carved to resemble caimans. These are located at either side of Stela I."
Carolyn E. Tate, Yaxchilan: The Design of a Maya Ceremonial City, p. 134