The large central pillars, Pillars 18 and 31, are the most elaborate anthropomorphic figures known from the site.

The Vulture Stone, the foxes, and other distinctive imagery of Enclosure D have been the primary focus of iconographic analysis.

The overall impression of Enclosure D is of a more ambitious and more elaborately conceived architectural program than the other enclosures.

Whether the differences between enclosures reflect different dates of construction, different social groups responsible for different enclosures, different ritual functions, or some combination of all three is not clearly established.

The comparative analysis of the enclosures — their spatial relationships to each other, their relative chronology, the specific character of their animal imagery and architectural details — is an ongoing research area that may eventually produce clearer answers.