Historic ‘terror birds’ might have been no match for hungry large caimans

About 13 million years in the past in an unlimited South American wetland, colossal predators clashed. The fossilised bone from an infinite flightless hen present in Colombia reveals tooth marks made by a large caiman.

Andrés Hyperlink on the College of the Andes in Colombia and his colleagues had been learning crocodile fossils in a museum assortment after they realised one of many bones didn’t match. It turned out to belong to a phorusrhacid hen – a bunch often known as the “terror birds”. These high predators had hatchet-shaped beaks and highly effective legs with sharp claws on their toes. The fossilised bone got here from the decrease leg of a 2.5-metre-tall species, presumably one of many largest forms of terror hen but found.

However this predator might have met a grisly finish. The bone, initially found in Colombia’s Tatacoa desert area by native palaeontologist César Perdomo, was scarred with 4 deep divots: enamel marks.

Hyperlink and his staff wished to know what beast dared wrap its jaws round such an intimidating predator. So that they scanned the floor of the fossil to generate a digital mannequin of the tooth marks and in contrast them with the enamel of historic predators from the area. The perpetrator possible wasn’t a mammal.

“There’s no proof of gnawing and the marks are rounded and in [a] line, extra just like these inflicted by crocodiles and caimans,” says Hyperlink.

The fear hen lived at a time when northern South America was dominated by the Pebas system, an enormous community of wetlands interspersed with tropical forests and grasslands. The flooded ecosystem hosted an incredible range of crocodilians, and the staff discovered a match for the enamel marks in one among them: a large caiman referred to as Purussaurus neivensis. Hyperlink estimates the reptile would have been about 4.5 metres lengthy.

“Terror birds had been undoubtedly on the high of the meals chain,” says Hyperlink. “However this proof reveals us that they might additionally fall as prey of huge caimans when approaching giant water our bodies. Possibly they went there to search for prey or [were] shifting throughout this advanced ecosystem.”

The staff notes they will’t rule out the chance the hen was already lifeless when the caiman discovered it, and the tooth marks are proof of scavenging. There are not any indicators of bone therapeutic across the tooth marks. So both means, the hen didn’t survive the encounter.

“These sorts of [tooth] traces are extra widespread than folks assume,” says Carolina Acosta Hospitaleche on the Nationwide College of La Plata in Argentina.

In a research revealed final yr, she and a colleague described tooth marks on a a lot smaller and older terror hen fossil – roughly 43 million years outdated – from Argentina. The markings recommend an historic carnivorous marsupial consumed that hen. Since these traces had been additionally on the decrease leg, Hospitaleche wonders if that a part of the phobia hen physique was a susceptible place for predators to chomp and grip their prey.

“[Bite marks] present us with these wonderful little snapshots into life prior to now,” says Stephanie Drumheller on the College of Tennessee.

When learning historic environments, there’s a tendency to try to exactly categorise extinct organisms inside explicit ecological roles, she says. Nonetheless, meals webs may be advanced.

“That is an animal that was residing within the water and doing issues within the water, that is an animal that was residing up on land and doing issues upon land, and by no means the 2 shall meet,” says Drumheller. “However after all, nature is all the time messier than our good, little, neat bins.”