Fossil that most likely belonged to oldest-known swan species found at St. Bathans
Paleontologists digging near St. Bathans in Central Otago have discovered a fossil that likely belonged to the Southern Hemisphere’s oldest known swan species.
The Bannockburn swan, Notochen bannockburnensis, lived between 16 and 19 million years ago on Lake Manuherikia, a vast lake that covers most of modern Central Otago. Scientists from New Zealand and Australia have described the bird from a fossilized wing bone preserved near St. Bathans in a layer of prehistoric mud called the Bannockburn Formation. Although damage to the wing bone makes determining the exact size of this animal difficult, it was likely slightly larger than the black swans common in Aotearoa, New Zealand today.
Scientists have now discovered nine ancient species of waterfowl in St. Bathans, and the Bannockburn swan is the largest. Like today’s swans, it would have foraged for food in the water, but probably also spent some of its time grazing on land. Notochen bannockburnensis was described in an article published this week in the journal zoo taxa.
The lead author of the article, Dr. Trevor Worthy of Flinders University, Adelaide, says the shape and large size of the wing bone suggest it belonged to a prehistoric swan.
“This bone is quite damaged, but it clearly belonged to a member of the waterfowl geese and swan group. We can’t say with complete certainty what kind of giant waterfowl this bird was, but we think a swan is most likely and that’s why we’ve called it the Bannockburn Swan.”
Today, the only native swans of the Southern Hemisphere are the black swan of Australasia and the Coscoroba swan of South America – the closest living relative of the Bannock swan. These birds are a distinct group of swans in the Northern Hemisphere.
dr. Paul Scofield, chief curator of natural history at the Canterbury Museum, says the discovery of the Bannockburn swan provides a clearer picture of how swans, geese and their closest relatives evolved.
“This swan and another goose-like bird we found in St. Bathans are the oldest members of the Anserinae family, which includes swans and geese, found in the Southern Hemisphere. They show a long history of the group in the Southern Hemisphere. half of the world. This is another example of finds from St. Bathans that help us understand the evolution of birds.”
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Trevor H. Worthy et al, A swan-sized fossil anatid (Aves: Anatidae) from the Early Miocene St Bathans Fauna of New Zealand, zoo taxa (2022). DOI: 10.11646/zootaxa.5168.1.3
Quote: Fossil most likely of oldest known swan species found in St. Bathans (2022, July 22) recovered July 22, 2022 from https://phys.org/news/2022-07-fossil-oldest-known-swan-species -st.html
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