Fossil Discovery Adds New Chapter In History Of Venomous Snakes
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Lee Rannals for redOrbit.com – Your Universe Online
Scientists from Ohio University reported in the journal PLOS ONE that they discovered the oldest fossil of a modern venomous snake in Africa.
The discovery provides evidence that snakes such as cobras, kraits and sea snakes were present in Africa as early as 25 million years ago. These elapid snakes belong to a larger group of snakes known as colubroids that have been documented as far back as 50 million years, but scientists weren’t expecting the group to take up such a large part of the African snake fauna 25 million years ago.
“In the Oligocene epoch, from about 34 to 23 million years ago, we would have expected to see a fauna dominated by booid snakes, such as boas and pythons. These are generally ‘sit and wait’ constricting predators that hide and ambush passing prey,” Jacob McCartney, a postdoctoral researcher in the Ohio University Heritage College of Osteopathic Medicine and lead author of the paper, said in a statement.
The latest study also includes the description of the oldest evidence of African booid snakes. However, the scientists were surprised to discover that the fauna revealed more colubroids than booids. This ratio suggests that the local environment became more open and seasonally dry, making it more hospitable for the more active foraging colubroids.
“This finding gives further strength to the idea that tectonic activity in the East African Rift has helped to shape animal habitats in fascinating ways,” Nancy Stevens, an associate professor of biomedical sciences at Ohio University and co-author of the study, said in a statement. “The fossils suggest a fundamental shift toward more active and potentially venomous snakes that could exert very different pressures on the local fauna.”
McCartney said more fossils from additional locations excavated should indicate whether colubroid snakes dominated all of Africa during the Oligocene or whether it was just a local region.
“Whether this reflects general patterns across Africa or is simply a local phenomenon can only be clarified by further work at contemporaneous localities. Rukwa Rift Basin localities are beginning to provide new data on the evolutionary diversification of Cenozoic African snakes, providing insights into paleoenvironmental shifts and how animals respond to environmental change through time,” the authors concluded in the journal.
Image Below: A vertebrae from a fossil snake discovered in the Rukwa Rift in Tanzania. Credit: Ohio University