Lamanai Museum: Post-Classic Ceramics associated with burials
"The ceramics assoicated with the [Post-Classic] burials share certain traits with those of Mayapan, principally the use of carved decoration, often incorporating serpent motifs, and the presence of segmented basal flanges, usually with border lines and center notches or vertical-line embellishment [see diagram on previous page]. Based on these shared features, it initially appeared that the Lamanai ceramics might be approximately contemporaneous with those from far northern Yucatan, and therefore likely to date from 1250 A.C. or later.
Radiocarbon dates, however, from the structure in N10-2, which contained the largest number of burials, indicate that the Lamanai Post-Classic ceramic complex was fully developed by about 1140 A.C., and presumably had its origins in the 11th century if not earlier. Judging by the apparent date of the ceramic features of Mayapan, the argument is strong for Lamanai as the source from which the concepts were transmitted northward. This reconstruction of events reinforces the picture of Lamanai as an important Post-Classic center based on the wealth and variety of artifacts alone."
Pendergast, Journal of Field Archaeology 8:1 (1981) 48-49