Archaeologists discover a Maya city behind a wall of trees in Mexico

East of the town of Dos Lagunas, past the major highway cutting through Mexico’s south, the forest rises up in a dense wall of grasping roots, spindly branches and veils of brown and green.

Beyond it lies the ruins of an old Maya city, barely a 15-minute walk from the busy roadway but until now unknown to archaeologists, its secrets cloaked over the centuries by unchecked foliage.

“It’s humbling,” said Marcello Canuto, an archaeologist at Tulane University and one of the researchers who have documented the site. “It’s how easy it is not to know what’s just another 100 meters beyond what you can see when the forest is intact.”

The team found the site not from the ground, but by scouring aerial scans taken for the use of ecologists. Upon close examination, the researchers revealed ruins with all of the hallmarks of ancient Maya.

“If you could design for a video game all of the classic features of a Maya city, they would look like this,” marveled Luke Auld-Thomas, a doctoral student at Tulane who spotted the site in the scans. “It’s got temple pyramids, a palace complex, big public plazas, reservoirs, dams, a broad processional causeway linking different complexes across hilltops.”

Auld-Thomas said the archaeologists also found the remains of residential buildings, terraces, field walls, garden areas, stabilized hills and other signs of human industry.

At another site identified by the team, the researchers found a deep sinkhole connected to a partly collapsed cave system, and adjacent to that, an architectural complex surrounded by a ditch shaped like a cross.

“That is the canonical representation of a cave in Mesoamerican art, going back to the very beginning of Mesoamerican art,” Auld-Thomas said. “I don’t really know what else to make of it. I’ll describe it – and then I cannot venture an interpretation of what it means or when it dates to. It’s super strange.”

The ruins may have been unknown to researchers who spend their days in search of just such finds, but some farmers in Dos Lagunas were “perfectly aware of the site’s existence,” Auld-Thomas said. He described his own discovery of it as something other than a mere accident – a “mix of deliberation and serendipity.”

The search began after he heard about other researchers using NASA data collected with lidar, a technology that uses airborne lasers to pierce dense vegetation. Among other things, it allows scientists to scan for hidden structures and landscapes.

“So I just set about digging on the internet, wondering if I could find another airborne lidar set like the one they had found,” he said. “Lo and behold, one turned up.”

He found lidar surveys collected over a decade ago by a group of ecologists mapping Mexico’s forests, and soon saw “a pretty substantial ancient Mayan city, right there mapped in detail.” The ecologists, he said, “were looking at the trees that cover the city, and not the city itself.”

Auld-Thomas and his colleagues, who published their findings Monday in the journal Antiquity, call the city Valeriana, after a nearby lagoon. They estimate that it may have had a population of as many as 50,000 people at its peak, which was most likely around the end of the late Classic Maya era, probably between about A.D. 750 and 850.

Kathryn Reese-Taylor, an anthropologist at the University of Calgary who was not involved in the research, said she was “thrilled” by the findings. The work builds on growing evidence, like the discovery last year of another city hidden in the jungle, that the region – long understudied by archaeologists – had a dense and widespread population during the Maya period.

“It’s a sprawl,” Reese-Taylor said, comparing it to the spread of medium-size cities and their heavily populated exurbs and suburbs across North America. “Apparently, the Maya had the same kind of spread of dispersal.”

Archaeologists have yet to reach Valeriana on foot, as another team led by archaeologist Ivan Šprajc did last year with the city discovered last year, called Ocomtún.

The newly documented sites appear to be smaller than that city and the largest city of the region, Calakmul, but the findings bolster the idea that there was once widespread settlement across the region. As a map of the Maya Yucatán is slowly created, a dense mosaic of ancient cities, towns, villages, farms and earthworks is emerging.

“It is fascinating,” said Simon Martin, a political anthropologist at the University of Pennsylvania who was not involved in the work. “This demonstrates, to a high degree of confidence, that the landscape was heavily populated everywhere.”

Martin, an associate curator at the Penn Museum, said that the growing body of research in the region “has enormous implications for estimating the total population” of the Maya.

“It raises all sorts of questions, too,” he said. “I think it makes the collapse of Classic civilization even more mysterious: The more people there were, the more difficult it is to explain the massive depopulation later on.”

This article originally appeared in The New York Times.