More on varying colours of bones

Last time, I noted that photographs of the exact same object, even under the same lighting conditions, can come out different colours. That is one of the two reasons why I am not persuaded that the very different colours of my photos of the two Supersaurus scapulae is strong evidence that they are from different individuals.

The other reason is that, as BJ Nicholls pointed out in a comment on that post, “Color in fossils can be misleading even in real life. As bones erode out, surface float pieces can be bleached on exposed surfaces. Bones within a bed can vary a lot in color too.”

Here’s an example:

What we have here are some of bones from the skeleton of Charlie the monitor lizard. After I extracted these bones from Charlie’s decomposing carcass ten years ago (can it really have been that long?!) I have left them sitting on a tray, awaiting articulation.

At the top of this photo is a scapulocoracoid; at the bottom, some dorsal vertebrae. As you can see, the former has bleached white, while the latter have remained ivory coloured. Remember, these are bones from the same individual that were extracted at the same time (give or take maybe a day or two), and that have been in exactly the same situation (on a tray, on a window sill, in my office) ever since.

The moral: bone colour doesn’t really tell you much at all.