Tlaltecuhtli Plaque vs. The Stone of Tizoc
Many scholars refer to Tlaltecuhtli in two major depictions, one in her anthropomorphic representation as seen in the Tlaltecuhtli Plaque and the other "a spiny monster with an extended snout (cipactli), based essentially on the crocodile" . Although the Tlaltecuhtli plaque solely shows the goddess in her anthropomorphic form, the Stone of Tizoc depicts her in this earth monster representation, or cipactli that has previously been discussed. As the goddess of the earth, Tlaltecuhtli is shown to make up the base of this piece with her mouth open to collect blood offerings and the dead. Representing teeth rather than a tongue in the Stone of Tizoc, the flint knife imagery from the plaque carry over again connecting Tlaltecuhtli to her veneration as the recipient of the blood sacrifices and the dead.
Her depiction as the cipactli is seen as framing the scenes on the Stone of Tizoc, which is dedicated to something other than the goddess. The spiny back of a crocodile as it sticks out of the water conjures imagery of mountain ridges and islands in a great primordial sea, from which Tlaltecuhtli was extracted, bifurcated and the earth created.
 H.B. Nicholson and Eloise Quinones Keber from "The Art of Aztec Mexico: Treasures of Tenochtitlan"