Two fossils recently discovered in Peru reveal that early penguins responded differently to natural climate change than scientists would have predicted. The larger skull, Icadyptes salasi (top), would have been fearsome to encounter because this penguin stood over five feet tall, and had a seven-inch beak, and is one of the largest penguins ever described. Compare this new penguin species to the smaller skull (below), which is from the modern-day Peruvian (Humboldt) penguin, Spheniscus humboldti.
Image: PNAS / Daniel Ksepka. [larger]
Two newly discovered fossils have revealed the hidden past of penguins: they were much larger and possibly more dangerous than originally thought. This fossil, which was discovered in Peru and was given the scientific name, Icadyptes salasi, was 1.5 meters tall and weighed as much as a man. The 36 million-year-old tropical bird’s intimidating appearance was topped off with powerful arms, a thick neck and a potentially dangerous 18-centimeter beak.
“It’s a monster,” said Julia Clarke, of North Carolina State University, who described the fossils with her colleagues from Peru and Argentina in Proceedings of the National Academy of Sciences. The bird is larger than any penguin known today and the third largest known to have ever lived, she added. (The largest is Anthropornis nordenskjoeldi, Nordenskjoeld’s giant penguin, which lived up to six million years ago and whose fossils were found in New Zealand, and was probably 2 meters tall and weighed 100 kilograms).
The team discovered a second penguin fossil nearby. This was from another species that was new to science, and it was given the scientific name, Perudyptes devriesi. This fossil was from an even older penguin, which lived approximately 42 million years ago. Despite its age, Perudyptes devriesi was actually quite similar to the modern king penguin, which is one of the largest living penguin species, standing approximately three feet tall. Interestingly, this particular fossil also revealed that ancient penguins’ wings were different from the very specialized “flippers” that they currently have.
The two fossil finds are remarkably complete and well preserved. In fact, the researchers were able to distinguish the fine patterning on the beak of the giant penguin that was from an outer layer of keratin — keratin makes up toenails and feathers and also covers bird beaks. Further, based on the structure of these new penguins’ beaks, both were likely fish eaters.
These discoveries challenge scientists’ understanding of the relationship between penguin evolution and cold weather as well as how species adapt to warmer temperatures, suggesting this connection more complex than originally thought. For example, scientists originally thought that ancient penguins first appeared more than 60 million years ago in cold habitats and didn’t move close to the equator until 8 million years ago. Large penguins, in particular, were thought to live only in colder climates.
“We have this ingrained notion of a penguin on an iceberg in a cool sea. But for most of their long history, penguins were in situations of no ice, with maybe crocodiles near them,” explained Clarke.
After reworking the penguin family tree to include these new fossils, scientists learned that modern penguins appeared only 8 million years ago — contrary to earlier estimates based on molecular studies that analyzed DNA from living penguins. The molecular studies suggested that the origin of modern penguins was approximately 40 million years ago.
These newly described ancient penguins lived between 30 and 40 million years ago during one of earth’s warm “greenhouse” phases, just before the planet began cooling. However, even as the planet cooled, the equator remained warm longer than any other region, with average temperatures in Peru hovering around 79 degrees.
“The global average temperature was much higher than at present,” Clarke pointed out. “And there was relatively little difference between the temperatures at the poles and the equator,” she said.
It is possible that the normally temperature-sensitive penguins migrated into warmer climates when new ocean currents first appeared, which moved cold nutrient-rich water northward. In fact, modern warm-weather penguins, such as the Galapagos penguin, still rely on these cold currents for their survival.
These two newly described penguin species became extinct before the earth formed its first polar ice caps about 34 million years ago. However, although these species were adapted to the tropics, it does not mean that modern penguin species will be able to adapt to rapid climate change, such as what is predicted in the near future.
“What happened over millions and millions of years cannot usefully inform us about what may happen over just the next 1,000 years,” emphasized Clarke. “The data from these new fossil species cannot be used to argue that warming wouldn’t negatively impact living penguins.”
Artist’s rendering of two penguin fossils recently discovered in Peru, compared to an extant species. The medium-sized of the two penguins (left), Perudyptes devriesi, was comparable in size to the living king penguin (not pictured). The larger, Icadyptes salasi (right), would have been fearsome to encounter at over five feet tall, with a seven-inch beak, because it is one of the largest penguins ever described. The smallest penguin in the picture (middle), appears to be a Humboldt penguin (although some of the field marks look a little “off” to me).
Image: PNAS / Daniel Ksepka. [larger]
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