New Fossil Discoveries By American Museum Of Natural History Scientists Challenge Role Of Climate In Early Penguin Distribution And Evolution
Icadyptes salasi (right) and Perudyptes devriesi (left) are shown to scale with the only extant penguin inhabiting Peru, Spheniscus humbolti (center).
Art by Kristin Lamm.
The fossilized remains of two previously unknown, extinct penguin species found in Peru are challenging the idea that penguins originated in the Earth's far southern latitudes and migrated north during a period of global cooling millions of years ago. The findings are being reported by a team that includes scientists from the American Museum of Natural History and will be published online by the journal Proceedings of the National Academy of Sciences (PNAS) on June 25.
The two new penguin species, which also represent separate, previously unknown genera, were unearthed in 2005 by Peruvian paleontologists in the Ica region of Peru's southern coast. Previous hypotheses suggested that a few penguin lineages migrated north 4 to 8 million years ago after a period of global cooling that caused an increase in polar ice cover. However, the new discoveries reveal that penguins migrated north and lived near the equator more than 30 million years earlier than previously suggested, during one of the warmest times in the past 65 million years of Earth's history.
The study was led by Julia Clarke, a Research Associate in the Museum's Division of Paleontology and an associate professor at North Carolina State University, and also included Daniel Ksepka of the Division of Paleontology and Norberto Giannini and Sara Bertelli of the Division of Vertebrate Zoology. They and their colleagues report that one of the new species, Icadyptes salasi, at more than 1.5 meters (nearly 5 feet), is the most complete giant penguin specimen yet described and lived approximately 36 million years ago. The other, Perudyptes devriesi, stood approximately 3 feet tallabout as tall as modern king penguinsand represents one of the earliest evolutionary divides within the animal family that includes modern penguins, having lived nearly 42 million years ago. Both species also display a powerful, pointed beak construction that was previously found only in one other extinct species, but is now believed to be an ancestral form for all penguins.
The new fossils are the first to indicate a significant and diverse presence of penguins in the tropics during a period that predates one of the most important climatic shifts in Earth's history, the transition from extremely warm temperatures in the Paleocene and Eocene Epochs to the development of permanent polar icecaps.
By comparing the pattern of evolutionary relationships with the geographic distribution of other fossil penguins, the researchers estimate that the two Peruvian species are the product of two separate dispersal events. The ancestors of Perudyptes appear to have inhabited Antarctica, while those of Icadyptes may have originated near New Zealand.
"The new Peruvian species indicate that early in penguin evolution there was a much more complex relationship between global temperature and diversity than previously recognized," the researchers write. However, they also point out that these early lineages have gone extinct and all living penguins evolved in concert with present-day conditions. As a result, their findings do not indicate that penguins currently inhabiting the Antarctic will not be adversely affected by global warming and climate change.
Support for the study was provided by the National Science Foundation (Office of International Science and Engineering and the Assembling the Tree of Life project), the American Museum of Natural History, North Carolina State University, North Carolina Museum of Natural Sciences, the Frank M. Chapman Memorial Fund, and the Dorris and Samuel P. Welles Fund.
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