14 September 2009

Another optical illusion: the skull

This is the ilium of the great albatross (Diomedea) I told you about three years ago when it was washed up on a nearby beach. Although it was dead, its chest ravaged, it smelled of the sea —fresher than any supermarket chicken.

Mistakes are frequently made in albatross identification, but I'll stick my neck out and say that this is a wandering albatross, although since that time, I've come across two more washed-up albatrosses with no damage evident, including, like this one, no damage from long-line or ingestion that I could see. One was a Buller's that was banded, so I could communicate to the New Zealand scientists who told me that it bred on an island colony near Auckland, and that it was about, they thought, 4 years old. The third albatross was too mangled in the head to make any guess as to species. The cause of death is unknown for each of these three, as it often is — for a dead albatross or a sick, dying, or ex-member of any other species (as doctors and coroners know more than they are free to tell).

The ilium is a fancy name for the pelvic bone of a bird, though the ilium also refers to the upper pelvic bone in other species such as our own. If you have ever experienced sacroiliac joint pain you'll be able to locate your ilium. Those "eye sockets" on this albatross ilium are actually for the leg bones.

The albatross was brought home to decompose at its own rate, and has only reached this state. The picture below is the inside of this structure built for lightness.

This is the skull and top mandible:

Here is a whole skeleton put together at the University of Iowa Museum of Natural History, and here is a generic diagram of a bird skeleton.

I highly recommend Albatrosses by Terence Lindsey, Principle Photographer Rod Morris, Australian Natural History Series, CSIRO Publishing, Australia, 2008.

That refers to this previous post on Medlar Comfits:
Optical Illusions, Spiders and Waspishness

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