Scientists Uncover a Trove of Ice Age Bones in Peruvian Tar Pit

Beneath the dusty hills along northwestern Peru’s Pacific coastline, petroleum pools into subterranean reservoirs. In a few places near the city of Talara, the oil seeps through fissures in the ground, creating mud-colored pits of gooey asphalt.

During the Late Pleistocene, around 15,000 years ago, these tar pits were death traps that ensnared giants like ground sloths and dire wolves. The first glimpse of this Ice Age graveyard came in the 1950s, when workers collecting asphalt to pave a highway unearthed several large bones stained an inky shade of black. The find attracted a team of Canadian paleontologists who excavated the pit and uncovered tens of thousands of bones from sabertooth cats to songbirds. The Canadian team transported four tons of these fossils to the Royal Ontario Museum (ROM) in Toronto but left even more material behind.

In 2025, paleontologist Emily Lindsey, a curator at the La Brea Tar Pits in Los Angeles, arrived in Talara to sift through the Canadian team’s leftovers, which were strewn about in heaps of bone. As her team dug into the sediment near the 1958 site, they uncovered the vestiges of another pit with even more bones lodged in globs of dried asphalt. They had literally struck oil—or tar.

This past summer, Lindsey returned to exhume more bones from the newly discovered pit as part of a joint expedition with the Institute of Paleontology at the National University of Piura in northern Peru. The trove of Pleistocene fossils the team recently uncovered is now poised to make Talara one of the best-known Ice Age ecosystems on the planet.

“Talara provides a rich record of how the end of the Ice Age played out in the tropics,” she says.

The team used small chisels and dental tools to remove some 300 fossils from the new tar pit, which may contain tens of thousands of bones. They encased larger specimens, like the pelvis and jaw of a giant ground sloth or the femur of a dire wolf, in foil and then layered them with wet strips of plaster medical bandages that hardened into protective casts. Meanwhile, they wrapped smaller specimens, like bird and reptile bones, in toilet paper for safe transport back to the lab. This new batch of fossils included several new rodent and bat specimens as well as the vertebrae of an arboreal snake that hints at the existence of forests at the site.

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The clues inside the pit reveal that this windswept coastal desert was once a marshy wetland fringed with forests before receding glaciers transformed South America’s climate. To Jean-Noël Martinez, the director of the Institute of Paleontology and co-leader of the summer expedition, these fossils show that scientists are just scratching the surface of this site.

“These fossils provide more than a single snapshot in time,” he says, “they show that there is a much larger story to be told at Talara.”

Tar pits form when lighter elements of oil deposits evaporate and leave behind a sticky, sludge-like deposit of asphalt. These asphalt deposits are found across the world from Azerbaijan to Venezuela and are crucial resources for understanding past life. Lindsey, who leads an international research initiative at the La Brea Tar Pits to study asphalt seeps around the world, compares these sites to flypaper traps—anything that gets too close gets stuck.

“At tar pits you find everything from elephant-size ground sloths to tiny insects,” she says. The ability to capture an entire cross-section of an ancient ecosystem makes them the ideal Ice Age time capsule.

But not all tar pits accumulate bones in the same way. Some covered the buried remains of animals that died well before the asphalt seeped out of the ground. Others, like La Brea, actively entrapped animals that got too close and added to their kill count as carnivores came to scavenge the carcasses. Talara’s tar pits worked the same way, capturing hungry predators that got stuck while pursuing an easy meal. Nearly 80 percent of the mammal fossils excavated here in 1958 belonged to just eight species of carnivores, including dire wolves, Smilodon cats, giant jaguars, and pumas.

These prehistoric predators drew paleontologist Gordon Edmund, a longtime curator at the ROM, here nearly 70 years ago. A Canadian geologist working at a Talara refinery sent Edmund the first batch of fossils the road crew unearthed. Intrigued by the quality of the blackened bones, Edmund petitioned to halt the highway construction and organized an expedition.

With help from local Peruvian excavators and bulldozers, Edmund’s team cleared several feet of tar-soaked sediment to reach the bones below. Over a single month, the team excavated more than 28,000 bones. The expedition drew international attention with the New York Times reporting that the paleontologists had unearthed everything from “the three-foot thigh bone of a mastodon to the tiny, purple sheened leg of an ancient beetle.”

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Many of these remains represented the major players in Ice Age Peru’s ancient ecosystem. Beyond the cadre of carnivores, Edmund’s team collected bones from several ground sloth species, including the elephant-sized Eremotherium, and armor from giant armadillo-like animals called pampatheres. Other herbivores from the site included llamas, horses, and an ancient elephant relative known as a gomphothere.

“As a researcher who worked in a museum, Edmund was aiming to collect the big stuff—he wanted the sloths and the elephants and the saber cats,” says paleontologist Kevin Seymour, who recently retired as an assistant curator at the ROM. Seymour worked under Edmund in the 1980s and analyzed the giant jaguar skull he found in the Talara pit. “What was mostly lacking from the collection was the small side of the story.”

While massive skeletons are good for filling museum halls, the ancient remains of much smaller species often tell a much larger story about an ancient environment. Tiny critters like amphibians, rodents, and insects are often more sensitive to changes in climate and precipitation. They also evolve much faster than their larger counterparts, making them useful barometers for tracking how species change across a bonebed.

The ROM team collected thousands of tiny microfossils, many still entombed in asphalt clumps and needed to be dissolved in kerosene. But after they were prepared, many of the small specimens sat in drawers in Toronto for decades, waiting for scientists to take a closer look. And the piles of fossils that Edmund’s team left behind in Talara were left to bake in the Peruvian sun.

Finding this stockpile of fossils took decades. Edmund briefly returned to Talara to collect more data during a 1961 expedition to southern Ecuador, according to Seymour. Unfortunately, his field notes, along with any new insights he gleaned during his return to Talara, were lost.

In the decades since, the Talara tar pit was largely forgotten, says Martinez, who learned about the site himself while doing postdoctoral research at the Institute of Paleontology in Piura. To locate the site, he tracked down a local man who had worked on Edmund’s expedition. 

“He told me about a site where the sediment smells like oil,” Martinez says. 

With the man’s help, Martinez and his team rediscovered the tar pit and in the early 2000s conducted a series of small expeditions to collect some of the blackened specimens littering the site. In the lab, they began piecing together these tantalizing tidbits of Talara’s larger story.

Around the same time, researchers at the museum took a closer look at the tiny Talara fossils kept in collections in Toronto. In 2015, researchers finally described the bounty of delicate bird bones that Edmund’s team had dissolved out of the clumps of tar. Talara’s ancient aviary included about 90 species, including a range of waterfowl and shorebirds like ducks, herons, grebes, and plovers. Lindsey says the Talara findings differ significantly from what researchers have found at La Brea, which is dominated by vultures and other birds of prey.

The rich record of waterfowl, as well as other aquatic species like diving beetles and amphibians, reveals that Talara was not always arid. In 2024, Lindsey and a colleague reconstructed Talara’s ancient climate and concluded that this region was cooler and much wetter during the Late Pleistocene. Martinez thinks this area was once a marshy expanse of wetlands reminiscent of Brazil’s Pantanal. Talara’s tar pits have even yielded traces of modern Pantanal inhabitants like jaguars, caimans, and rodents related to capybaras.

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Natalie Villavicencio Figueroa, a paleoecologist at O'Higgins University in Chile who was not involved in the recent excavation, says the rich fossil record of Talara provides a rare opportunity to track how animals fared during environmental upheaval.

“Because these are highly diverse sites with a rich variety of preserved organisms, they allow us to reconstruct the ecological community much more completely,” she says. “That helps us understand how the community responded to the major environmental changes that took place as the last Ice Age gave way to present-day conditions.”

Talara’s fossil record reveals that many species could no longer survive here when the local environment dried out. Some animals eventually went extinct while others moved elsewhere, causing the area’s overall biodiversity to plummet. Of the 21 songbird species identified among Talara’s fossils, only two still live in this area today.

While the relatives of Talara’s Ice Age inhabitants had to flee to other parts of the continent to find favorable climates, the area’s ancient bones are not traveling far. The fossils from the new tar pit are staying in Peru and are currently being prepared for closer study at the Institute of Paleontology in Piura.

“Instead of taking everything to North America, we now want to make these specimens accessible to local researchers and build scientific collections in the country of origin,” says Seymour, who participated in the recent expedition.

Martinez is excited to add to this growing fossil collection by uncovering the next batch of blackened bones entombed in Talara’s tar pits. Before this most recent field season, one of his colleagues thought that the site had already been picked clean of major discoveries.

“As a paleontologist, I know that is never true,” Martinez said. “We can think that all has been written or discovered at a site, but there are always many, many bones still waiting to be found.”