Here’s what I mean about bone colour in photos being misleading

June 26, 2019

In part 5 of the Supersaurus series, I made the point that my photos of Scap A and Scap B seem to show them as being very different colours, suggesting different preservation. However …

I don’t trust that line of evidence as much as I might for two reasons. First, different photography conditions can give strikingly different coloured casts to photos, making similar bones appear different. And second, I know from experience that bones from a single specimen can vary in colour and preservation much more than you’d expect.

The first of these points has just been brought home to me by an unrelated experience. The rendering on an outside wall of our house had come loose, and needed to be removed and replaced. I am soliciting a quote for doing the re-rendering, and took some photos to send to the builder who might be doing the work. First, the whole of the relevant wall:

And now a close-up of the leftmost part, around shoulder level:

Now these photos were taken with the same pretty good camera (Google Pixel 4a), in the same place, under the same lighting conditions, eleven seconds apart. Yet in the first photo, the underlying brickwork is brown, and in the second it’s grey — presumably because the camera made a judgement about white balance based on what was in its viewfinder at the moment each photo was taken.

Here is the same part of the wall, juxtaposed, from both photos:

Let this be a cautionary tale: don’t over-interpret colour from photos. When comparing the colour of two fossils, the best thing to do is put them physically next to each other so you can see both at once under identical conditions. (Sadly, that wasn’t an option with the two Supersaurus scapulocoracoids.)

7 Responses to “Here’s what I mean about bone colour in photos being misleading”

  1. Andrea Cau Says:

    “don’t over-interpret colour from photos”

    If you link today post to one famous pterosaur blog, the latter could annihilate itself.

  2. BJ Nicholls Says:

    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. And in most cases, color isn’t meaningful in any way for interpretation. I’d suggest that deriving any meaning from random photos of specimens is a Petersian fool’s errand. Even under controlled lighting, inconsistent image processing can cause big color and tonal shifts.

  3. […] time, I noted that photographs of the exact same object, even under the same lighting conditions, can come out differen…. That is one of the two reasons why I am not persuaded that the very different colours of my photos […]

  4. Mike Taylor Says:

    You make an excellent point, BJ — one that I have followed up in a new post.

  5. Mike Taylor Says:

    Excellent point, Andrea. Link added!

  6. […] bones in our photographs when trying to determine whether they’re from the same individual: cameras do lie, and in any case different bones of the same individual can age differently. Since then — […]

  7. […] that post), there are probably no more than the couple in that old blog-post. (By the way, notice how very different the colour of the bone appears in Matt’s old photos from how it appears in my more recent one […]

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