Introducing Buttercup

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During last summer’s Carmel Church excavation we collected a left squamosal fragment from a small baleen whale, which included most of the petrosal (part of the ear); it was the only significant skull material we found on that excavation. Upon retuning to VMNH I cleaned up the specimen a bit and compared the petrosal to others in our collection, and found it to be an almost perfect match to the same bone in “Sinistra“, a specimen of Diorocetus hiatus which was also found at Carmel Church (“Sinistra” is on the left, below, while the new specimen is on the right):

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I had hoped that we might find more pieces of this skull when we went back into the same pit last March. While we found quite a few bones, at the time it appeared that we hadn’t recovered any more of the skull. But at Carmel Church we bring everything back, even if it doesn’t look like much at the time. While going through the March 2012 material last week, Kathy and Ray found another squamosal, a right one this time, which was found only a few inches from where the first one was collected. Once they had cleaned it up, it was clear that the two bones were almost certainly from the same whale:

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We may also have a third piece, the basioccipital (the bone that makes up the floor of the braincase), but we haven’t finished cleaning that one yet so we’re not sure about its identification.

One of the interesting things about these fragments is that, other than the missing zygomatic processes (which often break off), these bones are broken along sutures. That suggests that the skull wasn’t crushed post-burial, but rather that it fell apart because the bones weren’t fused yet, and that suggests that the whale was a baby. Even the exoccipital-squamosal suture is open; I think this suture closes very early in whale ontogeny, so this may have been a really young whale. This is also borne out by showing the fragments next to “Sinistra” at the same scale (the red-outlined areas on “Sinistra” are approximately the portions preserved in the new whale):

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This is a tiny whale! And keep in mind that the petrosal is just as large as in “Sinistra”; the petrosal in whales doesn’t show a lot of ontogenetic variation.

We’ve named this tiny whale “Buttercup”, in honor both of one of the Powerpuff Girls, and volunteer Laura Kellam (to whom we gave the same nickname), who predicted that we would find a whale skull in this particular pit.

We are hoping to reopen “Buttercup’s” Pit this summer, if our Petridish fundraising campaign is successful. We only have 11 days left and are still short of our goal, so if you have not yet pledged please do so!

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

3 Responses to Introducing Buttercup

  1. George says:

    Butch

    That is so neat, I found a squmosal from one of the rarest Cetotheres years ago in Zone 12 Calvert Formation and Dr, Whitmore was so pleased Unfortunately at my age I forgot get genus it may be Herpetocetus, Your finds make me proud

  2. Boesse says:

    Hey Butch,

    Nice find – What precisely do you think is going on with juvenile mysticete zygomatics? I’ve collected several juvenile crania of Herpetocetus where the zygomatic is gone, and there is a hollowed out cavity instead – and no other obvious signs of abrasion/fragmentation or other taphonomic damage. However, it’s not like that part isn’t ossified yet, as I’ve seen juvenile minke whale skulls with fully ossified zygomatics. In this case, given what you know about Carmel Church taphonomy… it likely is related to breakage, though.

  3. altondooley says:

    I don’t know what’s going on, but it’s not just juveniles. Several of the Carmel Church whales are like that, including at least one from a near-articulated adult skeleton (“Caroline”, the type Eobalaenoptera). I think part of it has to do with the fact that the cortical bone is really thin along the zygomatic processes, and they’re really spongy inside (at least in mysticetes), so one the process starts it goes quickly. But that’s clearly not a complete answer, otherwise zygomatic would be quite rare, and we should almost never find them isolated. Although, now that I think about it, I’m not sure we’ve ever found an isolated mysticete zygomatic process at Carmel Church, but I’ve definitely seen them from elsewhere in the Calvert.

    Maybe related, maybe not, but we also occasionally find vertebrae at Carmel Church that are hollowed out in a similar fashion; 3 of “Caroline’s” vertebrae are like that. I’ve always guessed that it’s from some sort of bone-working organism, but I don’t know that for sure.

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