Superpredator fossils discovered in Antarctica | Polarjournal
A reconstruction of the animals that lived on Seymour Island at the time of the terror bird (foreground), which fossilized claws were recently discovered. Illustration: Carolina Acosta Hospitaleche and Washington Jones.

Fossilized claws belonging to a terror bird have been discovered in Antarctica. The presence of this superpredator could well offer a new scenario for reconstructing Antarctic ecosystems during the Eocene.

Two meters high and weighing a hundred kilos. Although it couldn’t fly, it could run fast and attack its prey thanks to its long, curved-tipped beak. Nicknamed the terror bird, the phorusrhacid (Phorusrhacos longissimus) was probably the dominant superpredator in Antarctica. These are the conclusions of a study published last month in the scientific journal Palaeontologia Electronica.

Two 8-centimetre fossilized claws of what appears to be a phorusrhacid have been discovered on Seymour Island in the Antarctic by two paleontologists.

Image of the two phalanges found in the northeastern part of Seymour Island. The left claw (A), remarkably well preserved, is designated MLP-PV 13-XI-28-546. It corresponds to a complete right ungual phalanx. The specimen on the right (B), MLP-PV 14-I-10-199, is also an ungual phalanx found a little further south than the first. Photo and map: Carolina Acosta Hospitaleche and Washington Jones.

Both phalanges were collected from levels corresponding to the early Eocene. According to the authors, the bird was probably an active predator that hunted and fed on the small to medium-sized marsupials and ungulates that lived on the island and were thought to be the main predators: “These terror birds-like, constitute the first evidence of apex predators within the continental environments, a niche that was seemingly underoccupied by other terrestrial vertebrates, which were mainly represented by medium to large-sized ungulates and small marsupials during the Eocene.”, note Carolina Acosta Hospitaleche, paleontologist and professor at the National University of La Plata, and Washington Jones, Doctor of Biological Science at the National Museum of Natural History in Montevideo.

A discovery that could well lead to a reconsideration of the scenario for the reconstruction of past Antarctic ecosystems: “This finding fundamentally changes our understanding of the dynamic within the Antarctic continental ecosystems during the early Eocene.”, note the authors.

Two claws of an Antarctic superpredator that evolved on the continent 50 million years ago were discovered on Seymour Island, in the extreme north-east of the Antarctic Peninsula. Photo : Wikipedia

This is not the first time fossils have been discovered on Seymour Island. The island is part of the James Ross archipelago and lies off the Antarctic Peninsula, north of Snow Hill, from which it is separated by Picnic Passage.

Since 1969, it has been home to Argentina’s Marambio scientific base. The island is also an interesting spot for paleontologists, as it is home to numerous fossils from the Eocene period, which stretches from -56 to -34 million years ago and is marked by the appearance of the first modern mammals.

Fossils of large penguins, marsupials, ungulates, frogs and even Elasosauridae (the long-necked marine dinosaur) have been discovered on the island in recent decades.

Link to study: Acosta Hospitaleche, Carolina and Jones, Washington. 2024. Were terror birds the apex continental predators of Antarctica? New findings in the early Eocene of Seymour Island. Palaeontologia Electronica, 27(1):a13.
https://doi.org/10.26879/1340, palaeo-electronica.org/content/2024/5162-eocene-cariamiformes-from-antarctica

Mirjana Binggeli, PolarJournal

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