Picture Antarctica today and what comes to mind? Bobbing big ice beds in the South Ocean? Maybe a remote outpost populated by scientists from around the world? Or perhaps the colonies of burning penguins among the vast open passages of ice?
The remnants of Seymour Island, not far from the Antarctic Peninsula, are painting a very different picture of what Antarctica looked like 400 to 400 million years ago – at a time when the ecosystem was lucerne and more diverse. Fossil and plant fossils such as ferns and conifers indicate that Semer Island was much warmer and less icy, while fossils indicate distant relatives of marsupials and armadillos and anteaters in previous connections between Antarctica and other continents in the southern hemisphere.
There were also birds. Penguins were present as they were at the time, but fossilized relatives of ducks, falcons, and albatrosses have also been found in Antarctica. My colleagues and I have recently published a fossil that will publish new information about the fossil group that may have created all the other birds on Seymour Island: pelagornithids or “bone-toothed” birds.
Giants of the sky
As their name suggests, these ancient birds had sharp, bony spikes protruding from the wood-like jaws. To gather teeth, these spikes would have helped them catch squid or fish. We also studied another notable feature of pelagornithids – their impressive size.
The largest flying bird alive today is the wandering albatross, whose wingspan reaches 11 feet. The Antarctic Pelagornithids fossils we have studied have nearly doubled wings – about 21 feet. If you suggest a two-story building next to it, it’s about 20 feet.
Throughout Earth’s history, very few groups of vertebrates have received managed flight – and only reached two large sizes: a group of birds and reptiles, called pterosaurs.
During the Metozoic Era (252 million to 66 million years ago), pterosaurs ruled the skies, the same period dinosaurs orbited the planet, and they reached the supposed dimensions. The quetzalcoatlus was 16 feet tall and had a huge wing of 33 feet.
The birds get their chance
Birds originated while dinosaurs and pterosaurs were still roaming the planet. But when asteroids struck the Yucatan Peninsula a million 66 million years ago, both dinosaurs and pterosaurs became extinct. However some selected birds survived. These survivors today diversify into thousands of species of live birds. Pelagornithids developed during the post-dinosaur and pterosaur extinction periods, when competition for food diminished.
The oldest Pelagornithid fossils found in New Zealand from a 62 million year old silt were the size of a modern gull. The first giant pelagornithids, in our study, took flight over Antarctica about 10 million years later, during the Eocene epoch (56 million to 33.9 million years ago). In addition to these specimens, fossils of other pelagornithids have been found on each continent.
The peligornithids lasted about 60 million years before the Pleistocene era (2.5 million to 11,700 years ago) was destroyed. No one knows exactly why, as few relics have been recovered from the last period of his reign. Some paleontologists cite climate change as a possible factor.
Picking together
The fossils we studied are whole bone fragments collected by paleontologists at the University of California at Riverside in the 1980s. In 2003, the specimens were transferred to Berkeley, where they now reside in the University of California Museum Pale f Paleontology.
Not enough material from Antarctica to recreate the whole skeleton, but by comparing fossil fragments with similar elements of more complete individuals, we were able to evaluate their size.
We estimate that the skull of Pelagornithid will be about 2 feet long. Fragments of a bird’s lower jaw preserve some “pseudoteth” that would have measured an inch each. The distance of those “teeth” and other measurements of the jaw show that this piece is as large as a person, if not larger than it, the largest pelagornithid.
[Deep knowledge, daily. Sign up for The Conversation’s newsletter.]Further evidence of the size of these Antarctic birds has come from another location on Seymour Island from another pelagornithid fossil. One part of the leg bone, called the tarsometarus, is the largest specimen known to the entire extinct group.
These Pelagornithid fossil findings emphasize the importance of natural history collection. Successful field campaigns result in a wealth of material being returned to museums or repositories – but the time required to prepare, study, and publish on relics means that these organizations have far more specimens than they normally display. Important discoveries can be made by collecting samples on expeditions to remote locations, no doubt. But equally important discoveries can only be made by processing the backlog of samples already on hand.
This article is republished from The Conversion, a for-profit news site dedicated to sharing the views of academic experts. It was written by: Peter A. Klose, University of California, Berkeley.
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Peter A. Klose does not receive, seek advice, share or receive money from any company or organization that would benefit from this article, and has not disclosed any relevant affiliation other than his academic appointment.
