March of the Fossil Penguins

Fossil penguin discoveries and research

Archive for October 2011

Tour of the Penguin Skeleton III: The Pygostyle

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It’s time to continue our tour of the penguin skeleton.  Today, we will look at the pygostyle.  This is a special element that is formed by multiple caudal (tail) vertebrae that fuse together as birds reach adulthood.  Whereas the dinosaurian ancestors of modern birds had long bony tails with dozens of individual vertebrae, living birds only have a few individual “normal” caudal vertebrae with a pygostyle at the end.  This structure is usually somewhat plate shaped – that is,  flattened in the vertical plane. The pygostyle is very important in flight because it serves as the attachment site for muscles the raise and lower the tail, and those that move the tail from side to side.  This allows volant birds to change the angle of the tail feather fan, which is critical in landing and turning.

A typical avian pygostyle (left) compared to a penguin pygostyle (right). The grey shapes show the cross-section of the bone at the plane of the red line.

Penguins have a pygostyle, but it is quite different in shape from the standard avian pygostyle.  In penguins, the element is more elongated and less flattened. Rather than being plate-like, it is almost triangular in cross-section with a flattened base.  Penguins also have a very different set of tail feathers.  Rather than forming a fan, penguin tail feathers are very stiff and quill-like, and stick out somewhat like the bristles of a broom.  This is especially true of penguins from the genus Pygoscelis – the Linnean name Pygoscelis actually translates to “stiff tail”.  These penguins are prone to be caught slouching around, partially propped up on their tail feathers.  It seems that without the necessity of maintaining a  “fan” of tail feathers, penguins have gone ahead and modified their pygostyle to a shape more suited to supporting themselves on land than steering in flight.

A gentoo penguin (Pygoscelis papua) propping itself on its tail feathers.

Written by Dan Ksepka

October 28, 2011 at 7:46 pm

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Knit a sweater for a penguin

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Following up on rescue efforts in New Zealand, perhaps you’d like to contribute by knitting a penguin a sweater.

Written by Dan Ksepka

October 19, 2011 at 1:08 pm

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Update on the New Zealand Oil Spill

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Salvage workers and wildlife rehabilitators are working hard to minimize damage from the container ship wreck on Astrolabe Reef.  The ship Rena has been aground since October 5th, and oil spilled has killed hundreds of birds, including some penguins.  It seems like penguins cannot catch a break from wrecks, after a wreck off the Tristan Da Cunha islands earlier this year.

An oiled Little Blue is pictured below -if you’d like some good news, click the photo to link to an article on the rescue and see this fellow fully cleaned.

Click to see the rescue efforts for oiled Little Blue penguins at BBC News

You can read more about the oil spill and rescue efforts at Radio New Zealand.

Written by Dan Ksepka

October 16, 2011 at 5:18 pm

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A Map for Our Tour of the Penguin Skeleton

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One of the new themes that has appeared on March of the Fossil Penguins is a tour of the penguin skeleton – looking at each bone and discussing how it is different from flying birds.  A map might be handy, so here is a King Penguin (Aptenodytes patagonicus) skeleton with the bones we’ll visit labeled.  Check the list below the image, and I will link in each bone as new posts occur.

Learn more about the:


Cervical Vertebrae

Thoracic Vertebrae







Manual Phalanges



Pedal Phalanges

Written by Dan Ksepka

October 4, 2011 at 12:04 pm

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