Apex Predators of a Lost World: Terror Bird Fossils Unearthed in Seymour Island

Paleontologists unearthed two fossilized claws (phalanges) on Seymour Island, Antarctica, hinting at a giant, carnivorous bird that dominated the skies 50 million years ago.

Found in the La Meseta Formation, these ancient bird fossils belonged to a massive predator estimated to weigh around 100 kg. 

Dr. Carolina Acosta Hospitaleche (Universidad Nacional de La Plata) and Dr. Washington Jones (Uruguay's Museo Nacional de Historia Natural) believe it's a terror bird (phorusrhacid) - an extinct member of the Cariamiformes order.

"While Cariamiformes were diverse in the past," the paleontologists noted, "only two species survive today in South America. Despite a rich fossil record, our understanding of their evolutionary relationships remains limited."

Within Cariamiformes, phorusrhacids are the most recent group, alongside the living Cariamidae. Idiornithidae and Bathornthidae are identified as extinct fossil families within this order.

The fossilized phalanges of an ancient cariamiform bird from Seymour Island, Antarctica. Scale bar – 10 mm. Image credit: Carolina Acosta Hospitaleche & Washington Jones, doi: 10.26879/1340.

These Antarctic terror birds likely preyed on small marsupials and medium-sized ungulates. "They were active hunters, acting as the continent's top predators, a role seemingly not occupied by mammals in Paleogene Antarctica," the researchers said.

This discovery unveils a previously unknown group of Phorusrhacidae-like birds in Antarctica. "These findings significantly reshape our understanding of the Early Eocene Antarctic ecosystem," they concluded. The full details are published in Palaeontologia Electronica.


Published February 2024 in the journal Palaeontologia Electronica; Were terror birds the apex continental predators of Antarctica? New findings in the early Eocene of Seymour Island

doi: 10.26879/1340

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