“Picasso” progress

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:

It turns out this bone has been heavily eroded. The entire tip of the bone is almost completely worn away. The eroded area is outlined in red below:

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.

***

For those of you on Facebook, I’ve now registered this site with NetworkedBlogs. There is a link on the lower right of the blog home page if you’d like to follow the blog on Facebook.

Advertisements
This entry was posted in "Picasso", Carmel Church mysticetes, Carmel Church Quarry, Chesapeake Group and tagged . Bookmark the permalink.

6 Responses to “Picasso” progress

  1. Doug says:

    Another possibility (and i know it’s is practically useless/pointless but i’m throwing it out there cause i saw it recently on tv) pertains to what people think are artifacts of atlantis. Stones found in the Bahamas with a hole in the top are thought by some to be anchor stones. However, these holes can be explained easily. A hole was somehow made in the rock and then a small stone got into it. Water action swished the rock around in the hole, and since it’s soft limestone, slowly carved a hole through the rock. Could that have happened to the whale?

    But the critter hypothesis sounds far more plausible. Did you know there’s a type of deep sea worm that lives solely off whale bones? It’s actually the most sexually dimorphic animal know to science. Being an invertebrate it wouldn’t fossilize, however a fossil whale fall has been found at Ano Nuevo. I wonder if it had any such holes.

  2. Alton Dooley says:

    I don’t think this is mechanical erosion from a pebble, mostly because it’s fairly rare. There were a lot of rocks and a lot of bones at Carmel Church, yet probably no more than a dozen or so show indications of this type of wear. I’m also not convinced that the damage pattern would look like this (small entry hole widening on the inside of the bone.

    I’m leaning toward a biological cause. Some type of soft-bodied critter that lives on deadfalls like the worm you mentioned is a strong possibility. Another is a callianassid shrimp, burrowing down from the Choptank formation and stopping when it hits the bones. There are certainly burrows like that at Carmel Church, but I’ve never noticed Choptank Formation filling the holes in the bone. I think another good candidate is a clionid sponge. Clionids use acids to bore into shells and coral reefs. However, I’ve never heard of them boring into bone, and I’m not sure their acids would dissolve bone.

  3. Nick Gardner says:

    Have you thought about CAT scanning the material? Maybe being able to see the deeper internal structure would shed new light on what was going on there.

    I don’t know what kind of diagenetic factors are present for Carmel Church fossils, but it should be useful to scan as long as there isn’t a heavy presence of metallic precipitates.

    You could probably arrange to do it with a local hospital or medical school for free (at least around here in WV, there are some places that do it that way).

  4. Alton Dooley says:

    I hadn’t considered it for these particular features, but it might be a possibility. The sediment has a large amount of sand-sized garnets in it; do you think that would have an adverse effect on the CT scan?

  5. Nick Gardner says:

    I’m not a chemist or a geologist, so if I say something wrong here, please please please by all means correct me.

    My guess is that since garnet is a silicate, it shouldn’t be an issue. I’ve worked with specimens which were actually chambered with sand to hold the specimen in the middle of the chamber. I can’t be sure, it’d be good to get the opinion of a chemist or geologist on this matter who might know better how garnet responds to xray.

  6. Alton Dooley says:

    Could be an interesting thing to find out, at any rate. The Carmel Church sediments have not been described, so I don’t know fully what’s in them. A lot of garnet and (apparently) epidote, clay minerals, lots of quartz. Certainly the quartz shouldn’t be an issue; I think it’s transparent to X-rays (could be wrong on this; I’m not a mineralogist). I’m not sure about the others, though (although they’re certainly more dense than quartz). I’ll have to look into that…

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s