# Birds: spinal column and sacrum

**URL:** <https://boards.straightdope.com/t/birds-spinal-column-and-sacrum/682048>\
**Category:** Factual Questions\
**Created:** [February 23, 2014, 11:54pm UTC](https://boards.straightdope.com/t/birds-spinal-column-and-sacrum/682048 "2014-02-23T23:54:37Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![dougie\_monty](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@dougie\_monty](https://boards.straightdope.com/u/dougie_monty)\
**Post date:** [February 23, 2014, 11:54pm UTC](https://boards.straightdope.com/t/birds-spinal-column-and-sacrum/682048/1 "2014-02-23T23:54:37Z")

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I recently mentioned, in another thread, a drawing of several modern-day animal skeletons (specifically referring to a giraffe’s pelvis). What I’d like to know has to do with another critter.  
In the same drawing, which shows 14 animals’ skeletons postioned in natural standing poses, is a penguin’s skeleton. Unlike the mammal skeletons, the penguin’s spinal column, halfway down from the shoulders, becomes a solid bone which takes on a swallowtail shape at the bottom and a jagged coccyx-like shape in the tail, also apparently solid. Is this common to all birds?  
Also, the sternum is not continuous, but at the top of the rib cage there is a gap in it, between the top of the rib cage and a crescent-shaped descending bone apparently attached to the clavicle. Is this, too, a feature common to birds?