Approximately 13 million years ago, massive predators clashed in a sprawling South American wetland. Fossils of a giant flightless bird discovered in Colombia bear tooth marks from enormous caimans.

Andrés Link from the University of the Andes in Colombia and his team were examining crocodile fossils in the museum’s collection when they identified an unusual bone. This bone belonged to the Forsulhacid bird, commonly referred to as “terror birds.” These predators possessed hooked beaks and muscular legs equipped with sharp claws. The fossilized remains were from the lower limbs of a bird standing 2.5 meters tall, making it one of the largest terror birds ever found.

However, this predator likely faced a grim fate. Initially unearthed in Colombia’s Tatacoa desert by local paleontologist César Perdomo, the bones exhibited four distinct puncture marks.

Link and his research team sought to identify the predator that dared to bite such a formidable bird. They scanned the fossil’s surface to create a digital model of the tooth marks, finding striking similarities to the teeth of ancient predators in the region. The culprit was almost certainly not a mammal.

“There are no signs of gnawing, and the markings are rounded,” Link explains. “The lines closely resemble those attributed to alligators and caimans.”

Terror birds roamed the earth when northern South America was dominated by the Pebas System, a vast network of wetlands interspersed with tropical forests and grasslands. This flooded habitat supported a diverse range of crocodile species, leading the team to link the dental impression to the giant caiman Purussaurus neivensis, estimated to be around 4.5 meters in length.

“Terror birds were undoubtedly apex predators,” remarks Link. “However, this evidence indicates that when they ventured near large bodies of water, they could also fall prey to massive caimans, either in pursuit of prey or while navigating this complex ecosystem.”

The researchers speculate that the bird may have already been deceased when the caiman encountered it, with the tooth marks indicative of scavenging. There are no signs of bone regeneration surrounding the marks. Either way, the encounter proved fatal for the terror bird.

“These types of [tooth] impressions are more prevalent than one might assume,” states Carolina Acosta Hospitalce from La Plata National University in Argentina.

In a study published last year, she and her colleagues discussed tooth marks found on a smaller, older fossil terror bird—about 43 million years old—suggesting that ancient carnivorous marsupials also preyed upon these birds. These markings were also found on the lower limbs, leading Hospitalce to ponder whether this area of the bird’s anatomy is particularly vulnerable to predators.

“[Bite marks] offer fascinating glimpses into past life,” comments Stephanie Drumheller from the University of Tennessee.

When studying ancient environments, she notes there is a tendency to categorize extinct organisms into strict ecological roles. However, food webs can be quite intricate.

“This is an animal that thrived in aquatic environments, while another lived on land, entirely separate from one another. Yet, nature often defies our neat categorizations,” Drumheller observes.