Carmel Church Day 8 (updated)

Once again the weather is about to truncate our excavation; rain is forecast for the next four days. Tim and I were joined this afternoon by Keith and Carter, and we managed to get a lot of sediment removed, and we also completed yesterday’s jacket containing a large part of a flipper.

What did we find behind that jacket? Another flipper! The bone shown above is a baleen whale humerus; this is not the same humerus that we jacketed yesterday. The two humeri are about the same size, and so it’s possible (but not yet definite) that they come from the same whale. Another phalange is visible just below the humerus, as well.

We removed the second humerus, and found a possible radius and scapula right beside it, as shown below. We also found the 19th vertebra in the series we’ve been excavating (it’s at the center of this photo, but is hard to see):

And one more goodie, a nearly complete posterior rib that had to be removed from a trench (photographed in the hotel bathtub to get a white background):

It’s supposed to start raining tonight. Tim and I are going to return to the quarry tomorrow to try to recover the rest of the exposed bones.

***

On Thursday, Tim and I removed and loaded exposed bones and shut down the site just in time; a driving rain started just as we were taking the tarps down. We should have this load of bones (about 500 lbs worth) back at the museum this weekend.

Tim also has some additional modern Carmel Church critters on his blog.

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4 Responses to Carmel Church Day 8 (updated)

  1. Doug says:

    And the great fossil headache throws you another curve ball. I wonder (and I feel a little stupid for asking): Why go through so much to collect mainly vertebrae and ribs? I know that all fossils should be saved, and there is probably at least some taphonomic reasons, but.. I dunno, I’m having a little trouble putting this together. I have heard some paleontologists will leave vertebrae and rib material in the ground because only the skulls are diagnostic and they have no space or time to collect them. Like I said, just a stupid little question.

  2. Alton Dooley says:

    (Climbing up on a soapbox…)

    Many people, especially in the past, have collected only skulls. It’s a process I personally disapprove of, for reasons I’ll explain in a second. But I will say that, on occasion, there is no choice but to collect only the skull. Time might be short (maybe the skeleton is in an intertidal area and the tide is coming in), maybe there is a big risk of poaching or vandalism, or maybe excavating the entire skeleton is logistically difficult or impossible. So, sometimes there’s no choice.

    (In fact, I’ve made that call myself on some excavations. In excavating a baleen whale in Westmoreland County, I recovered the skull and front half of the skeleton, but left at least some of the posterior vertebrae in the ground because we would have needed many days and would have had to remove many tons of sediment to recover them.)

    However, at a place like Carmel Church these risks are minimized. The site is on private land, behind a locked gate, so it is reasonable secure (thanks, Martin Marietta!). There isn’t a huge amount of overburden to remove, and there are no tides to wash the bones away, so we have the luxury of taking our time. So, given that we CAN collect the postcranial skeleton, why bother?

    Well, for starters, when we collect these big Carmel Church jackets, we aren’t just getting the visible skeleton. When we open these jackets possibly half the remains inside will be from other animals that we weren’t even aware of in the field. There will be a plethora of sharks’ teeth, fish bones, and other whale remains. We also have to remove those remains to get at additional skeletons buried further into the hillside. This is an unusual feature of Carmel Church; pretty much, we take everything because you never know what you might be getting.

    Second, there’s a lot of additional information in the postcranial skeleton, especially taphonomic data. How is the skeleton preserved–is it articulated, semi-articulated, or disarticulated? Are the flippers and tail present? Is there any evidence of scavenging? Are there any injuries, like broken ribs?

    Third, I think postcranial remains have gotten a bum rap over the years. The “conventional wisdom” is that there is little useful information in the postcrania. But over the last 10 years I’ve come to doubt this.

    Some remains are considered potentially significant, especially the scapula and the humerus in whales, but others might be important as well. The first paper I ever published was about an unusual birth defect in the ribs of a fossil baleen whale, that turns out to have implications for the genetic basis for the development of the vertebral column. One of the characters we used in the description of Eobalaenoptera was the shape of the first rib.

    When the Eobalaenoptera skeleton was being molded to produce an exhibit cast, the neural spines on the vertebrae were missing, so the casting company (RCI) asked me for a reference image so they could model them. It turned out to be difficult to find an image, because no one ever publishes postcranial remains, but I eventually came up with some images of modern baleen whale skeletons, plus some detailed descriptions of fossil baleen whales written by Remington Kellogg in the 1960’s. To my amazement, the vertebrae in these different whales were completely different from each other. I believe there’s a lot more information in these bones than many people suspected.

    (Getting off soapbox…)

  3. Doug says:

    Haha, great bit with the soapbox. Anyway, sounds like i was partly right in that there is taphonomic reasons. And about finding other stuff in the jacket, when they began working on Dakota, the “Dinosaur Mummy”, they found the leg of a crocodile in there (they think it was scavenging the carcass and dug in a little too deep).

    And I actually found some o that info useful. I know of a site where there could be a whale skeleton, but I haven’t reported it to any experts yet because it’s in the side of a bluff and it would take a lot of work to get it out (and the position would make it difficult to determine how much is there).

  4. Alton Dooley says:

    An email question from BPH:

    With more than 15 years of excavation work behind you at Carmel Church, have you (or anyone) figured out the reason why there is such a high concentration of fossils in such a small area?

    In a word, no. We have ruled out some ideas. Without going into all the details right now, it does not appear to be a mass stranding, or a calving lagoon. It also does not appear to be an attritional deposit that was formed over a long period of time, nor was it an instantaneous mass kill.

    There is an attritional component, comparable to what we find at the base of various units all over the coastal plain. At Carmel Church, this attritional material is overlain by the associated remains (like the articulated skeletons). We can be pretty sure that they weren’t deposited instantaneously because the different skeletons show different levels of scavenging. But they were deposited fairly close together in time because of the completeness of the material, and the similar levels of decay. We’ve also ruled out most unique preservational environments, like anoxic conditions.

    So we need something that kills a lot of animals fast, but not too fast. I’m not sure yet what that might be.

    The other factor that I think will be key is the conglomerate. The two unique signature features at Carmel Church are the conglomerate and the bonebed, and they occur in the same bed. The conglomerate itself is strange, because it has some characteristincs that indicate that is was formed rapidly, in a single event, and other features that indicate that it took some time to form (like the bonebed).

    I think the origins of the bonebed and the conglomerate are linked, and if we can explain one then we’ll understand the other.

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