Does This Amazon Rock Art Depict Extinct Ice Age Mammals?

At the end of the last ice age, South America was home to strange animals that have since vanished into extinction: giant ground sloths, elephant-like herbivores and an ancient lineage of horses. A new study suggests that we can see these lost creatures in enchanting ocher paintings made by ice age humans on a rocky outcrop in the Colombian Amazon.

These dazzling rock art displays at Serranía de la Lindosa, a site on the remote banks of the Guayabero River, were long known to the area’s Indigenous people but were virtually off limits to researchers because of the Colombian Civil War. Recent expeditions led by José Iriarte, an archaeologist at the University of Exeter in England, have sparked renewed interest and heated debate over the interpretation of the animals in the paintings.

“The whole biodiversity of the Amazon is painted there,” Dr. Iriarte said, both aquatic and land creatures and plants, as well as “animals that are very intriguing and appear to be ice age large mammals.”

Dr. Iriarte and his colleagues, who are part of a project studying human arrival in South America, defend the case that the rock art depicts ice age megafauna in a study that was published on Monday in the journal Philosophical Transactions of the Royal Society B. But as the study itself acknowledges, the identification of extinct animals in rock art is extremely controversial — and the site at La Lindosa is no exception.

Ekkehart Malotki, a professor emeritus of languages at Northern Arizona University who has published research about petroglyphs that depict extinct megafauna, called the team’s claims “wishful thinking” in an email. In his view, the ice age interpretation is the result of an “eyeballing” approach that guesses at the nature of the paintings.

Fernando Urbina and Jorge Peña, archaeologists at the Universidad Nacional de Colombia, also pushed back against an ice age origin for the paintings. The team argued in 2016 that many scenes at La Lindosa might depict animals introduced by Europeans, making them only a few centuries old. Dr. Malotki also suggested that the exceptional preservation of the rock art, despite its exposure to the elements, hinted at a younger origin.

These disputes could be resolved later this year when age estimates of the paintings are refined, Dr. Urbina said in an email.

One of the most evocative images at La Lindosa portrays a stocky animal with a small offspring in tow. Dr. Iriarte’s team believe these figures represent an adult giant ground sloth and its pup, noting its idiosyncratic frame and claws.

“This animal is vastly different than the thousands of other paintings in regard to its prevalence and anatomical depiction,” said Michael Ziegler, a doctoral student at the Max Planck Institute for the Science of Human History and co-author of the new study, adding that this painting offered potential evidence of interactions between ice age megafauna and humans.

The researchers also identified other possible extinct species in the paintings, including relatives of elephants, camels, horses and bizarre hoofed mammals from the Litopterna family.

Where Dr. Iriarte’s team sees potential giant ground sloths and Pleistocene horses, Dr. Urbina and Dr. Peña see modern capybaras and horses. Dr. Malotki said the painting that Dr. Iriarte’s team believed to be possible elephant relatives, known as gomphotheres, bore “absolutely no resemblance” to the extinct animals.

Dr. Iriarte and his colleagues counter these critiques by pointing to archaeological and paleontological evidence that humans coexisted with some of these ice age megafauna before they went extinct. They also note that ocher has been found in sediments that were laid down at La Lindosa during the end of the ice age, suggesting that the rock art could be that old.

“We’re pretty sure they were painting very early on,” Dr. Iriarte said.

Extinct megafauna have previously been identified in rock art in other parts of the world, but the burden of proof is exceptionally high.

“The interpretation of rock art images is always subject to debate, especially when it is argued that extinct animals were depicted,” Paul Tacon, a professor of archaeology and anthropology at Griffith University in Australia, said in an email.

“In this case there is a strong argument using multiple lines of evidence to support the contention that some surviving paintings in the Colombian Amazon are of extinct megafauna from the late Pleistocene or early Holocene,” he added. “The next challenge is to scientifically date the paintings to support or refute this contention.”

If these efforts do end up supporting an ice age origin, the La Lindosa paintings may capture a rare and fleeting glimpse of animals doomed to oblivion, opening an eerie window into the lost ecosystems of the past and the people who inhabited them. Even if the art is much younger, it will help researchers understand cultures that thrived in this lush wilderness.

“At Serranìa de la Lindosa, the people who made the paintings were depicting things important to them that certainly would have been associated with stories, knowledge sharing and aspects of both domestic and spiritual life,” Dr. Tacon said.