A previously unrecorded Maya city has been identified in eastern Campeche, Mexico, not by an expedition cutting through jungle but by a graduate student reanalysing a laser survey flown in 2013 to monitor forests. The find, named Valeriana and reported in the journal Antiquity in October 2024, had been sitting in a dataset that had never been examined this way by archaeologists.

Luke Auld-Thomas, then a doctoral candidate at Tulane University, came across the survey far down a list of online search results. It had been collected for forest and carbon monitoring by a conservation organisation, with no archaeological purpose. He applied archaeological analysis to it and found a city.

What the data showed

Lidar works by firing hundreds of thousands of laser pulses a second from an aircraft. Enough of them slip through gaps in the canopy and reflect off the ground that the vegetation can be stripped away digitally, leaving a bare-earth model of the surface beneath. Mounds, platforms and plazas that are invisible from the air, and nearly so from the ground, stand out clearly.

The 2013 survey covered about 122 square kilometres. Across it, the team identified 6,764 structures, an aggregate density of about 55 per square kilometre. Valeriana itself has the features of a Classic Maya political centre: two monumental precincts, enclosed plazas joined by a broad causeway, temple pyramids, a ball court and a reservoir formed by damming a seasonal watercourse. Some reports have put its possible peak population at 30,000 to 50,000 people, around 750 to 850 CE, though that remains an inference from settlement density rather than a direct count.

What “lost” and “by chance” do and do not mean

The headline version of this story is tidier than the find itself. Campeche was a blank spot on the archaeological map, but it was not a genuine unknown. Researchers had suspected since at least the 1940s that the area held Maya ruins, and Auld-Thomas has said the result confirmed what he expected rather than overturning it. The city’s original name is gone. Valeriana is a modern label, taken from a nearby lagoon.

It is also worth being clear about what lidar establishes and what it does not. It reveals the shape of structures, not their age, their function or whether they were all occupied at the same time. The site has not been excavated, and the team plans fieldwork to check the survey against the ground. What exists now is a strong lead, not a closed case.

The point that actually matters

The interesting part is not that one more city turned up. It is where it turned up. Flying lidar is expensive, but once the data exists it can be reanalysed cheaply, and a great deal of it has been collected for reasons that have nothing to do with archaeology: forestry, carbon accounting, agriculture, mining, infrastructure planning. Most of it is never looked at by anyone asking what is under the trees.

That is the argument the researchers themselves make, and the paper’s title puts it plainly in terms of a landscape running out of empty space. The limiting factor on finding more sites like Valeriana may not be coverage. It may be attention. The data is already on disk somewhere.

This is a quieter version of a problem that keeps recurring across the sciences, where the volume of information collected outruns the capacity to examine it. This was not an AI discovery. It was a person noticing the archaeological value of a dataset collected for another purpose, then reprocessing and interpreting it with archaeological tools.

How it fits the wider record

Valeriana sits within a decade of lidar steadily revising how densely the Maya lowlands were built. The largest example remains the 2018 survey by Marcello Canuto and colleagues, published in Science, which mapped about 2,144 square kilometres of the Petén region in Guatemala and identified more than 61,000 structures, along with causeways, terraces and reservoirs that pointed to a far larger and more connected population than older estimates allowed. Canuto is also a co-author on the Valeriana paper.

The difference is the source. The Guatemala survey was commissioned for archaeology. The Campeche city came out of data flown for something else entirely, which is what makes it a marker rather than just another dot on the map.

What to watch

The near-term test is the fieldwork. Lidar can show that a place was built, but only excavation and survey on the ground can confirm when it was occupied, by how many people, and for how long. Until that happens, Valeriana’s scale remains a careful inference from topography.

The longer question is how many other environmental and commercial lidar archives contain settlements that no one has examined. The answer is not yet known, and finding out depends less on new flights than on someone going back through the data already collected.