Cape Town - The African Penguin is a loner on the continent these days, with its nearest relatives like Rockhoppers, Macaronis and King Penguins living well over 2 000km away on islands such as Marion, Gough and Tristan da Cunha.
But recently described fossils found in the Western Cape confirm that, millions of years ago, there may have been as many as four penguin species living together on the southern African coastline.
And the fossils, dating from between 10 and 12 million years ago, push back evidence of these iconic seabirds with their distinctive black-and-white livery living in Africa by about five to seven million years.
The new fossil research, by Daniel Thomas of the National Museum of Natural History in Washington and Dan Ksepka of the National Evolutionary Synthesis Center in North Carolina, is reported in this week’s Zoological Journal of the Linnean Society.
Just why the other fossil penguin species went extinct is still a mystery, but the researchers speculate it may be because of the sea levels that have changed significantly around the southern African coastline.
Thomas and Ksepka studied fossil penguin bones in museums and at field sites in the Western Cape in late 2010.
While sifting through rock and sediment excavated when the Saldanha Steel plant was established in 1997, they found 17 bone fragments that they identified as pieces of backbones, breastbones, wings and legs from several extinct species of penguins, among shark teeth and other fossils.
The pair estimated from the bones that these extinct species spanned nearly the full size spectrum for penguins living today, ranging from a “runty pint-sized” penguin that stood only about 30cm, to a giant just under a metre.
The tallest penguin still in existence is the Emperor, which reaches 122cm, followed by the King Penguin at about 95cm.
“The individual penguins and the populations they represent are certainly new to science, but the bones are not well enough preserved for us to be certain if we have new species,” Thomas told the Cape Argus.
“There are four species of fossil penguin already known the Western Cape, and there are other ancient penguins in South America that could have emigrated to South Africa. We can’t be certain if we are dealing with an already named species or a new species.”
The researchers are also not able to say exactly when penguin diversity in Africa started to decline, or why, and the gaps in the fossil record make it difficult to determine whether the extinctions were sudden or gradual.
“(Because we have fossils from only two time periods) it’s like seeing two frames of a movie,” explained Ksepka. “We have a frame at five million years ago, and a frame at 10-12 million years ago, but there’s missing footage in between.”
At least as far as these extinctions go, humans are not to blame, because all the penguins, apart from the African Penguin, had already disappeared by the time modern humans appeared on the scene about 200 000 years ago.
The researchers speculate that changing sea levels were responsible, since previously safe island nesting habitats became accessible to predators as the seas dropped as much as 90m at times. - Cape Argus