Fossils from Seymour Island show that Antarctica, 40–50 million years ago, was warmer and ecologically diverse, hosting enormous pelagornithid “bony‑toothed” birds. These pelagornithids had jaw projections (pseudoteeth) for catching fish and wingspans near 21 feet — almost double that of today’s wandering albatross. Antarctic specimens include a lower jaw with ~1‑inch pseudoteeth, an estimated 2‑foot skull, and the largest known tarsometatarsus for the group. The finds underscore the research value of museum collections and the role of post‑extinction opportunities in producing giant flyers.
Giant Bony‑Toothed Birds Soared Over Antarctica 40–50 Million Years Ago
Fossils from Seymour Island show that Antarctica, 40–50 million years ago, was warmer and ecologically diverse, hosting enormous pelagornithid “bony‑toothed” birds. These pelagornithids had jaw projections (pseudoteeth) for catching fish and wingspans near 21 feet — almost double that of today’s wandering albatross. Antarctic specimens include a lower jaw with ~1‑inch pseudoteeth, an estimated 2‑foot skull, and the largest known tarsometatarsus for the group. The finds underscore the research value of museum collections and the role of post‑extinction opportunities in producing giant flyers.
07:39 PM, 11/15/2025Science
Giant bony‑toothed birds once ruled Antarctic skies
Picture Antarctica today: vast ice sheets, drifting floes and isolated research stations. Now imagine a very different Antarctica — warmer, greener and teeming with life. Fossils recovered from Seymour Island, off the Antarctic Peninsula, show that 40–50 million years ago the region hosted frogs, ferns, conifers, marsupials and even distant relatives of armadillos and anteaters, reflecting earlier land connections across the Southern Hemisphere.
Pelagornithids: the “bony‑toothed” giants
Among that diverse fauna were remarkable birds called pelagornithids, commonly known as bony‑toothed birds. My colleagues and I published a 2020 study describing Antarctic pelagornithid fossils that rank among the largest flying birds ever. These birds had blade‑like jaw margins studded with sharp bony projections — pseudoteeth — that helped them grasp slippery prey such as fish and squid.
For scale, the wandering albatross, today’s largest flying bird, reaches roughly 11½ feet across the wings. The Antarctic pelagornithid fossils we examined indicate wingspans near 21 feet — almost twice that of the albatross and comparable to the length of a two‑story building laid on its side.
Deep time and context
Only a few vertebrate groups have achieved powered flight, and only birds and Mesozoic pterosaurs grew to truly colossal sizes. Pterosaurs dominated the skies until their extinction about 66 million years ago; for example, Quetzalcoatlus may have had a wingspan near 33 feet. After the asteroid impact 66 million years ago wiped out most pterosaurs and non‑avian dinosaurs, surviving bird lineages diversified. Pelagornithids evolved in that recovery interval when aerial ecological niches were less crowded.
The oldest pelagornithid bones currently known come from about 62‑million‑year‑old sediments in New Zealand and belonged to gull‑sized birds. The giant pelagornithids discussed here appeared about 10 million years later during the Eocene Epoch (56–33.9 Ma) and are now known from fossils on every continent. The group persisted for roughly 60 million years before disappearing shortly before the Pleistocene; their exact extinction cause remains uncertain, though climate change is a plausible factor.
The Antarctic fossils and what they reveal
The Antarctic specimens we studied consist of fragmentary bones collected by University of California, Riverside paleontologists during fieldwork in the 1980s. In 2003 those specimens were transferred to Berkeley and are now curated in the University of California Museum of Paleontology.
Although the remains are incomplete, careful comparison with more complete pelagornithid skeletons allowed us to estimate size. We infer a skull length of roughly 2 feet for one individual. A lower‑jaw fragment preserves pseudoteeth up to about 1 inch tall; their spacing and jaw proportions indicate an individual as large as, or larger than, the biggest pelagornithids known. A second Seymour Island specimen — a portion of the tarsometatarsus (a fused foot bone) — is the largest recorded for the entire group, reinforcing the evidence for exceptional body size.
Why museum collections matter
These discoveries highlight the scientific value of natural history collections. Fieldwork provides new material, but many important specimens sit in museum storage awaiting preparation and study. Processing those backlogs can produce major findings without new expeditions.
Acknowledgement: This article summarizes research by Peter A. Kloess and colleagues and is based on fossils curated at the University of California Museum of Paleontology.