Extinct mega penguin was tallest and heaviest ever

• 16:16 01 August 2014 by Jeff Hecht

Forget emperor penguins, say hello to the colossus penguin. Newly unearthed fossils have revealed that Antarctica was once home to the biggest species of penguin ever discovered. It was 2 metres long and weighed a hefty 115 kilograms.

Palaeeudyptes klekowskii lived 37 to 40 million years ago. This was "a wonderful time for penguins, when 10 to 14 species lived together along the Antarctic coast", says Carolina Acosta Hospitaleche of the La Plata Museum in Argentina.

She has been excavating fossil deposits on Seymour Island, off the Antarctic peninsula. This was a warmer region 40 million years ago, with a climate like that of present-day Tierra del Fuego, the islands at the southern tip of South America.

The site has yielded thousands of penguin bones. Earlier this year, Acosta Hospitaleche reported the most complete P. klekowskii skeleton yet, although it contained only about a dozen bones, mostly from the wings and feet (Geobios, DOI: 10.1016/j.geobios.2014.03.003).

Now she has uncovered two bigger bones. One is part of a wing, and the other is a tarsometatarsus, formed by the fusion of ankle and foot bones. The tarsometatarsus measures a record 9.1 centimetres. Based on the relative sizes of bones in penguin skeletons, Acosta Hospitaleche estimates P. klekowskii was 2.01 meters long from beak tip to toes.

Its height will have been somewhat less than its length owing to the way penguins stand. But it was nevertheless larger than any known penguin.

Emperor penguins can weigh 46 kilograms and reach lengths of 1.36 metres, 0.2 metres above their standing height. Another extinct penguin used to hold the height record, at around 1.5 metres tall.

P. klekowskii's tarsometatarsus "is the longest foot bone I've ever seen. This is definitely a big penguin," says Dan Ksepka at the Bruce Museum in Greenwich, Connecticut. However, he cautions that the estimate of its length is uncertain because giant penguins had skeletons "very differently proportioned than living penguins."

Larger penguins can dive deeper and stay underwater longer than smaller ones. A giant like P. klekowski could have stayed down for 40 minutes, giving it more time to hunt fish, says Acosta Hospitaleche.

Journal reference: Comptes Rendus Palevol, DOI: 10.1016/j.crpv.2014.03.008

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