A few hours of cleaning…

One of the obstacles we face at Carmel Church is weathering. In Virginia’s wet and variable climate weathering rates are very high. Moreover, at Carmel Church the sediment chemistry is such that the sediment becomes very acidic when exposed to air and rain. The end result is that bones left on or near the surface rapidly develop a very hard crust that then eats into the bone. If the bone isn’t too thin and delicate and is collected quickly it’s sometimes possible to remove the crust, but if the bone has been exposed too long we usually can’t save it. That’s why we try to only expose bone as we remove it, and we don’t spent a lot of time on material that has already weathered.

Even so, we do collect the weathered bone, because occasionally we are able to recover fairly good material. That’s why we saved the lump shown above, which Tim collected from the weathered zone during our last excavation. In the field I suspected that this was a odontocete (toothed whale) atlas vertebra, the first bone in the neck. But I wasn’t sure how much was actually preserved, or what condition it would be in. What a difference six hours in the lab with a MicroJack makes:

As it turned out, nearly the entire vertebra was preserved, with only moderate weathering damage to the surface of the bone.

As I had thought in the field, this is a fairly small odontocete atlas vertebra. In fact, it’s a type of atlas we see fairly frequently at Carmel Church; compare it to the two examples below (the scales are slightly different):

We now have at least five of these vertebrae in our collection, easily making it the most common odontocete atlas at Carmel Church (we have atlases from at least three other species). While I haven’t done the detailed comparisons yet, in size and shape this seems to be close to Xiphiacetus. This makes sense, as Xiphiacetus is the most common odontocete at the quarry, with parts of at least four skulls collected so far.

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This entry was posted in Carmel Church odontocetes, Carmel Church Quarry, Chesapeake Group and tagged . Bookmark the permalink.

4 Responses to A few hours of cleaning…

  1. Brooke Haiar says:

    Wow, excellent prep work Butchie!

  2. Bobby says:

    That’s a pretty impressive result from the first photo to the second.

  3. George F says:

    Butch

    When I interned at the USGS one summer preping whale fossils for Dr. Whitmore, I prepared a large cetothere that had severe crushing of the neural arches and chevrons. Lots of ambroid use back then. Weathered material is weird back in 1980 I collected a Leptophoca skull from Zone 12 Calvert Formation and when I first walked by it it looked like that weird shell that reminds me of asbestos fibers. On the way back I decided to check it out and part of the basicrania had erroded away and there was this off yellow crust growing on the bone. It surely had a sulfurous smell to it

    All the best

    George F

  4. altondooley says:

    George,

    The fibers were probably calcium sulfate (gypsum) crystals. Generally the sulfur is thought to be derived from the decaying organism (certainly modern whale deadfalls are associated with a lot of sulfur compounds), and we see it frequently around large bones; our dinosaur bones are riddled with it. It’s usually not too severe a problem in the Calvert, probably because the skeletons are mostly scattered. But at Carmel Church I think the bonebed is so dense that all the sediment is loaded with sulfur, so we get the gypsum growing everywhere (although it’s most common close to the bones).

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