On Friday I did a bit of prep work on “Picasso”, the whale we collected from Carmel Church in 2005 and began preparing last year. Picasso’s skull, to use a technical term, is “a big ‘ole mess”; it’s badly crushed and pieces are all out of position. On Friday I removed the right zygomatic process of the squamosal (essentially, the cheekbone) from the jacket. The image at the top is a lateral (side) view of the bone; this is “5” in the image below (before removal):
Once I removed the bone, I recognized a few things. First, the broken surface of the bone fits well to the rest of the squamosal (bone 4 above), so I should be able to put it back together pretty well. Second is the big hole in the middle of the bone visible in the image at the top; that hole shouldn’t be there. The hole can be explained by turning the bone over and looking at the medial side:
This erosion is a little unusual for Carmel Church, and there are two possible explanations for it. One is that this part of the bone was sticking up out of the sediment after the rest of the skull was buried, and it was worn away by currents. This type of erosion is actually quite common in many deposits (there are lots of examples from Sharktooth Hill, for example), but it doesn’t seem to be common at Carmel Church (there is a possible example in “Sinistra”, but that may be due to its injury). Supporting this cause is the fact that, the way the bone was turned, this would have been the top surface. However, there were other parts of this skull that would have been sticking up higher, and that don’t appear to be eroded.
Carmel Church offers a second possibility for this damage. It seems that there was some as-yet unidentified creature that ate away at the spongy cancellous bone in the inside of the whale bones. We usually see this in vertebrae, where a small hole is punched through the dense cortical bone and the bone is hollowed out on the inside, such as happened with this Eobalaenoptera vertebra:
There are some indications that the same thing happened to some of the zygomatic processes in other whales from Carmel Church, and it’s possible that this could be the cause of the erosion in “Picasso”.
I have no idea what kind of organism did this to the whale bones, and I haven’t yet studied it closely. I’ll probably post some more on these features when I have a better idea what’s causing them.
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