In praise of humble bones
The Land Vertebrate collection at Auckland Museum has more than three thousand bones from mammals, reptiles and birds. But why are bones important?
Bones tell stories
The primary reasons for this valuable collection are for identification and for research.
Customs, the Ministry of Primary industries, police and other health organisations are all agencies that use this collection to identify bones relating to smuggling, poaching, forensics and food contamination issues.
From a research perspective bone collections are a major source of material for zoological and archaeological research, particularly with the advent of modern molecular techniques from extracting DNA and other chemical markers from bones, that tells much about the former lives of their owners.
Finally bones, and particularly birds bones, are amazing. Laid out on the imaging table in the land vertebrate department lab, the full assortment of bones from a black-backed gull skeleton (Larus dominicanus) numbers around 130 individual bones, but doesn't really convey the wonder how those bones work together.
Have you ever stopped to consider what keeps those seagulls, waiting for your left over fish and chips, in the air? Sure it's muscle power but underlying all that tissue is an amazing skeleton adapted for life in the air. Bird skeletons are lightweight, for example a black-backed gull skeleton weighs around 100 grams or only 10% of the total weight of a live bird.
This reduction in mass is achieved through unique bones. Snap a roast chicken thigh bone in half and you will find it is filled with air spaces - a trait scientists call pneumatic. These pneumatic bones are connected to the animals respiratory system giving it greater oxygen storage capacity – like how fuel is stored in the wings of a passenger jet plane. As a young bird grows its lungs develop a series of tubes and growths that enter the pneumatised bones making them both light and strong.
Adapted for flight
Modern birds have also done away with heavy teeth and instead rely on a strong gizzard to "chew" food into small bits for digestion and have fused together bones of the pelvis into a rigid and lightweight platform for the attachment of the legs and tail.
The skeleton of our gull is also dominated by the large breast bone called the sternum. The sternum provides a strong anchor point for the powerful muscles that draw the wings up and down during flight. The size and shape of the sternum reflects the lifestyle of a given bird. Flying birds, such as the gulls, have large sternums whereas birds that have lost the power of flight altogether, such as New Zealand's critically endangered night parrot, the kakapo (Strigops habroptilus), barely have a sternum at all and have all their muscle mass in their large legs suited for running through the night.
So remember bones are awesome and next time you are throwing the remains of that Sunday chicken roast into the rubbish bin, spare a thought for the millions of years of evolution in your hands.
Cite this article
In praise of humble bones. Auckland War Memorial Museum - Tāmaki Paenga Hira. First published: 13 June 2016. Updated: 27 June 2016.