The ancient Maya civilization of Central America, long thought to have collapsed centuries before the Spanish conquistadors arrived in the 1500s, appears to have been flourishing right up to the Spanish invasion.

This is the conclusion reached by two Florida archeologists who in August excavated a Maya grave containing the richly adorned body of a man who appears to have been a powerful ruler.

The researchers say the remains, found near the coastal town of Corozal in Belize, are probably those of a leader who ruled a Maya province that may have extended over 9,000 square miles.

The grave is only about 500 years old, dating to the period just before the Spanish conquest. The discovery adds weight to an emerging view that the final centuries of the Maya civilization were not a period of decadence and decline, as has long been held, but one of transition to a different kind of society.

During the classic period, from about A.D. 250 to 900, the Mayas built elaborate religious centers dominated by the great pyramids that remain tourist attractions in Guatemala, Belize and Mexico's Yucatan Peninsula.

In the ensuing centuries, however, architecture on the grand scale declined. Archeologists have thought that the civilization was disintegrating during that period.

The new view is that, instead of building pyramids, the Mayas concentrated on extending their commercial and political ties over steadily larger areas, converting political entities that once had been small city-states into much larger and more politically complex nation-states.

"Our entire view of the Maya has been wrong," said Diane Z. Chase, who, with her husband, Arlen F. Chase, discovered and excavated the burial site. "Just because they stopped building pyramids doesn't mean there's been a decline in the culture."

The Chases, both of whom teach at the University of Central Florida in Orlando, have been working in Belize for seven years under sponsorship of the National Science Foundation.

The burial site was found beneath a modest stone shrine that had become covered with soil. When the Chases dug beneath the shrine, they found the man's skeleton along with copper clasps that indicated it had once been wrapped in a shroud. Significant quantities of stone and metal jewelry had once adorned the body.

The chief clue to the man's status was a pair of gold earplugs inlaid with jade and turquoise. The plugs, which once fit inside a large hole in the earlobe, flared out to cover the ear. Small metal bells dangled from the lower edge.

Such adornments, Diane Chase said, are unknown among the Maya but are identical to those worn by Aztec rulers as the "supreme symbol of power." The Chases think that the man would not have been buried with such important symbols if he were not a powerful ruler.

Archeologists know that just before the Spanish conquest the empire-building Aztecs, who lived some 750 miles to the west, near Mexico City, were poised to subjugate the Mayas. Diane Chase speculated that the man may have received the earplugs from Aztec rulers trying to sway his allegiance.

Before the Aztecs could dominate the Mayas, however, the Spaniards invaded, bringing infectious diseases that, within a century and a half, killed an estimated 70 percent to 80 percent of the Maya population.

The new view of the late Maya civilization is supported by some of the writings of the conquistadors, who told of Maya provinces extending over thousands of square miles.

"But they also wrote from a very ethnocentric perspective," Diane Chase said, describing the Mayas as idol worshipers. Eventually, she said, this denigrating view, combined with the later realization that pyramid-building had ceased long before, led to the notion of a decadent Maya culture.

Five days before finding the grave, the Chases discovered another important Maya burial site dating back another thousand years. This find, an elaborate tomb containing dozens of artifacts such as painted pottery vessels and masks, appears also to have been of an important ruler who held sway during the Early Classic period.

The later burial site also contained a mystery. Buried with the presumed ruler was another man, with none of the kingly adornments, who appears to have been sickly at death. His body was riddled with 13 stingray spines and a long copper needle, all instruments of ritual bloodletting among the Maya elite. The Chases said they could not speculate about whom he might have been.

Most of the artifacts from the tombs will be displayed at Orlando's Loch Haven Art Center for a year, starting Jan. 6. After that they will be returned to Belize.