Archeologists Sugiyama and Sarabia also recently discovered older structures and Patlachique ceramics in the Sun Pyramid’s fill. Studies from their radiocarbon assays demonstrated that the construction of the pyramid was later than what many had thought before. Many now think that the construction began at around 229-330 A.D. If the Patlachique and Tzacualli phases are now this late, the chronology of Teotihuacán will require some crucial changes. No one has applied these changes yet to Teotihuacán's chronology, but it it important that these findings be noted.