Sculptural pieces may seem to be a relatively new phenomenon in the world of Native American pottery but there are many ancient artifacts that point to sculptures being incorporated into functional pieces. For instance, I've come across pieces from Laguna based on ancient shards that incorporate a bighorn ram's head sculpture into the handle. The bighorn ram was a major influence in their lives back then: bighorn rams made for excellent game and they lived nearby on the slopes of Mount Taylor.
The Tewa pueblos of Santa Clara and San Ildefonso have a thing for the black bear. The Santa Clarans tell a story of time during severe drought when someone from the village followed a bear into the forest and came to a good spring. They attribute that bear with saving the tribe. Ever since the black bear has had a special significance for them and they make black bear sculptures in its honor.
The potters of Mata Ortiz are constantly pushing the boundaries of what they can do with their clay. They also draw on a tradition reaching back more than 500 years to a time when figures and sculptural pieces were made for ceremonial purposes.