The ancient Mayan city of Ceibal was once a world where dogs were served up as food and big cats kept as pets. Today, it's an archaeological goldmine. Buried beneath its surface are the bones and teeth of more ancient animals that researchers say offers some of the earliest evidence for trading and domesticating animals in the Americas.

They used a multi-isotopic approach to date the remains found at Guatemala's 3,000-year-old site. Based on an animal's diet, the isotopic levels – or chemical elements – found in their bones and teeth will vary. Researchers analyzed the ratio of isotopes in the bone collagen of two dogs and one large cat that date back to the Maya Middle Preclassic period (1000-350 BC). The remains were high in carbon and nitrogen isotopes, which indicate the animals were fed corn by humans and possibly beginning at an early age.

Strontium isotopes were also found in tooth enamel, meaning some of the dogs probably came from distant volcanic highlands. 

"The study shows that the ancient Maya likely managed wild animals and moved animals, such as dogs, long distances as far back as 2,400 years ago," said study author Ashley Sharpe in an email to IFLScience. "These 'exotic' and captive animals might have been used for food, but because some were found in special contexts (pyramids), it seems more likely that they were used for ceremonies and for the elites to show off as demonstrations of their power."

Because these remains were found in the city’s ceremonial core, researchers believe they were "significant" in some way. Whether the animals were raised as pets, eaten as food, or used as sacrifices remains a bit of a mystery. 

"We sometimes see wild cats with humans in ancient art, including jaguar cubs held by kings. I suspect the early big cat at Ceibal is evidence that people had been capturing and raising wild cats for centuries in Central America," said Sharpe. "Possibly they did it for ceremonial displays of power – a similar case that happened recently was the last Brazil Olympics, where they brought a live jaguar out on stage during the torch ceremony!"

Dogs, on the other hand, were probably used as food, says Sharpe. 

Only a small subset of the thousands of animal bones found at Ceibal were tested. Evidence of nonlocal deer, wild pigs, turkeys, opossums, and tapirs indicate that these animals were perhaps “part of the market economy that existed at that time,” according to the study published in Proceedings of the National Academy of Sciences. 

The Ceibal heritage site is threatened by a number of human influences, including drug gangs, illegal logging, and pollution from agricultural runoff. Sharpe says she hopes both the Guatemalan government and its people take "stronger action" to protect Ceibal and other parks like it, but the work doesn't stop there. 

"Archaeologists and other scientists working the parks should try to raise awareness of these problems too, and report illegal activity to the Guatemala government when they see it," she said. "I think a lot of people find it easier to not say anything, but I don't think that's a solution."