Brian Choo, CC BY-NC-SA
Image Antarctica at this time and what involves thoughts? Massive ice floes bobbing within the Southern Ocean? Perhaps a distant outpost populated with scientists from all over the world? Or maybe colonies of penguins puttering amid huge open tracts of snow?
Fossils from Seymour Island, simply off the Antarctic Peninsula, are portray a really completely different image of what Antarctica regarded like 40 to 50 million years in the past – a time when the ecosystem was lusher and extra numerous. Fossils of frogs and vegetation equivalent to ferns and conifers point out Seymour Island was a lot hotter and fewer icy, whereas fossil stays from marsupials and distant family members of armadillos and anteaters trace on the earlier connections between Antarctica and different continents within the Southern Hemisphere.
There have been additionally birds. Penguins have been current then, as they’re now, however fossil family members of geese, falcons and albatrosses have additionally been present in Antarctica. My colleagues and I’ve lately revealed an article revealing new details about the fossil group that may have dwarfed all the opposite birds on Seymour Island: the pelagornithids, or “bony-toothed” birds.
Giants of the sky
As their identify suggests, these historical birds had sharp, bony spikes protruding from sawlike jaws. Resembling tooth, these spikes would have helped them catch squid or fish. We additionally studied one other outstanding characteristic of the pelagornithids – their imposing dimension.
The biggest flying hen alive at this time is the wandering albatross, which has a wingspan that reaches 11 ½ ft. The Antarctic pelagornithids fossils we studied have a wingspan almost double that – about 21 ft throughout. In the event you tipped a two-story constructing on its facet, that’s about 20 ft.
Throughout Earth’s historical past, only a few teams of vertebrates have achieved powered flight – and solely two reached really large sizes: birds and a bunch of reptiles known as pterosaurs.
Pterosaurs dominated the skies throughout the Mesozoic Period (252 million to 66 million years in the past), the identical interval that dinosaurs roamed the planet, and so they reached hard-to-believe dimensions. Quetzalcoatlus stood 16 ft tall and had a colossal 33-foot wingspan.
Birds get their alternative
Birds originated whereas dinosaurs and pterosaurs have been nonetheless roaming the planet. However when an asteroid struck the Yucatan Peninsula 66 million years in the past, dinosaurs and pterosaurs each perished. Some choose birds survived, although. These survivors diversified into the hundreds of hen species alive at this time. Pelagornithids advanced within the interval proper after dinosaur and pterosaur extinction, when competitors for meals was lessened.
The earliest pelagornithid stays, recovered from 62-million-year-old sediments in New Zealand, have been concerning the dimension of contemporary gulls. The primary large pelagornithids, those in our research, took flight over Antarctica about 10 million years later, in a interval known as the Eocene Epoch (56 million to 33.9 million years in the past). Along with these specimens, fossilized stays from different pelagornithids have been discovered on each continent.
Pelagornithids lasted for about 60 million years earlier than going extinct simply earlier than the Pleistocene Epoch (2.5 million to 11,700 years in the past). Nobody is aware of precisely why, although, as a result of few fossil information have been recovered from the interval on the finish of their reign. Some paleontologists cite local weather change as a potential issue.
Piecing it collectively
The fossils we studied are fragments of entire bones collected by paleontologists from the College of California at Riverside within the Nineteen Eighties. In 2003, the specimens have been transferred to Berkeley, the place they now reside within the College of California Museum of Paleontology.
There isn’t sufficient materials from Antarctica to rebuild a whole skeleton, however by evaluating the fossil fragments with related components from extra full people, we have been capable of assess their dimension.
Peter Kloess, CC BY-NC-SA
We estimate the pelagornithid’s cranium would have been about 2 ft lengthy. A fraction of 1 hen’s decrease jaw preserves among the “pseudoteeth” that may have every measured as much as an inch tall. The spacing of these “tooth” and different measurements of the jaw present this fragment got here from a person as huge as, if not larger than, the biggest identified pelagornithids.
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Additional proof of the dimensions of those Antarctic birds comes from a second pelagornithid fossil, from a special location on Seymour Island. A piece of a foot bone, known as a tarsometatarsus, is the biggest specimen identified for all the extinct group.
These pelagornithid fossil findings emphasize the significance of pure historical past collections. Profitable subject expeditions lead to a wealth of fabric introduced again to a museum or repository – however the time required to organize, research and publish on fossils means these establishments sometimes maintain many extra specimens than they’ll show. Essential discoveries may be made by accumulating specimens on expeditions in distant areas, little question. However equally vital discoveries may be made by merely processing the backlog of specimens already readily available.
Peter A. Kloess doesn’t work for, seek the advice of, personal shares in or obtain funding from any firm or group that may profit from this text, and has disclosed no related affiliations past their educational appointment.