Archaeologists say they have found evidence indicating that Guam's ancient Chamorros came from two waves of migration.

Archaeologist Judy Amesbury presented findings from the Naton Beach excavation on Tuesday to the Rotary Club of Tumon Bay. The excavation took place nearly a decade ago, but the report is just now being released, the Pacific Daily News reported.

At the Naton Beach site, archaeologists found more than 400 burials from the Pre-Latte Period and Latte Period of Guam. More than 150 burials were from the Pre-Latte Period, marking the largest number of burials from that time and ever recorded in the Marianas.

The Pre-Latte Period is from 1,500 B.C. until latte stones were introduced. The Latte Period started around 1,000 A.D. and ended with Spanish contact in the 16th century.

More than 20 years ago, Micronesian Archaeological Research Services did an excavation in Saipan and found more than 500 cone shell beads and fragments of bracelets that dated back 3,500 years or more. No human remains were found with the artifacts, leaving archaeologists unable to connect the ornaments with the people until excavating the Naton site.

Amesbury said about 1,700 ornaments consisting of shells and shark teeth were found on the human remains at the Naton site.

A majority of the ornaments were from the Pre-Latte Period. They mainly consisted of three types of cone shell beads and beads made from clam shells, bracelets, and tiger shark teeth necklaces. Others featured inlaid teeth and the use of an earthy pigment called ochre.

A small percentage of the ornaments were tied to Latte Period burials. Those ornaments were made from cone shell beads, including a type that was a different shape from the pre-latte cone shell beads. Inlaid teeth were not found in latte burials, but eight burials revealed teeth with incised patterns of horizontal, diagonal or cross-hatched lines.

The distinguishing features of the ornaments lead archaeologists to believe that two waves of migration occurred in Guam's history.

"(Archaeologists) never knew if the latte stones were just in situ cultural development that the people thought of making after a while or if it was a new group of people coming in," said Amesbury. "And now it looks like a new group of people. So that's very interesting to know that there was more than one wave of migration."

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