Whale update-almost finished!

We’ve reached a milestone in the preparation of our Carmel Church whale skull. This was the very first jacket we opened at the new museum, on March 31, 2007. It was featured in my first blog entry last September, and we’ve had numerous updates about this specimen. Today, we took the last pieces of bone out of the jacket.

The skull has rapidly come together in the last week, and is now almost finished. This is a dorsal view, with the front to the left. The braincase has now been attached, and there are only a few bits and pieces remaining (a few of these pieces are visible at the top of the photo). The paper in the photo is Remington Kellogg’s description of Diorocetus hiatus, which is the closest match we’ve found so far (I’m still not 100% sure our whale is Diorocetus).

As I had suspected, this is one of the most complete baleen whale skulls ever collected in the Calvert Formation. I estimate that it is more than 90% complete; the only major missing pieces are parts of the parietals that make up the sides of the braincase. (The yellow strips near the back of the skull is wax that I’m using to temporarily replace the missing parietals.)

After the last few pieces are attached, we’ll make a storage jacket so that we can more easily flip the skull over to see the other side of it.

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

10 Responses to Whale update-almost finished!

  1. Alton Dooley says:

    Just checking to make sure comments are working.

  2. Alton Dooley says:

    Posted for Grenda:
    “I have the same bulletin with Diorocetus hiatus. There are two specimens. I have reviewed. My inexpert opinion—the suprorbital process of the frontal seems to be deeper along the exterior edges in the Carmel Church fossil. Do you have the nasals? I’m trying to figure out what the vomer area would look like with nasals. Do the palatines on the ventral surface ring true with Diorocetus? Is the overall ratio of rostrum to posterior skull within variation limits?”

  3. Alton Dooley says:

    One issue with identification is that, while Kellogg’s specimens were juveniles, the Carmel Church specimen is an adult.

    We do have the nasals, but I haven’t attached them yet. They are the two small bones sitting side by side in the sand, directly across from the scale bar. Kellogg reconstructed the nasals to be much larger, but in fact most of the nasals were not preserved in his specimens.

    We do have the palatines, but they are not well preserved (I haven’t attached them yet, but you can’t see them in dorsal view anyway). The pterygoids seem to be missing.

  4. Grenda says:

    No wonder the palatines didn’t ring true, they’re not attached. Need to hit the books again. Yes I see the nasals. Thanks for the explanation.

    How many specimens are there of Diorocetus? What type of calculations do you make to account for variability in a species? When comparing juvenile specimens to an adult or vice versa what aspects do you take into consideration? Do you predict growth rates? If you have a small sample of fossils can you make predictions?

  5. Alton Dooley says:

    You can always make predictions; they just might be based on pure speculation 😉

    There are maybe 3 or 4 pretty good Diorocetus skulls; I haven’t looked at all of them. Most vertebrates species are so rare that pinning down variation is difficult. In fact, I would suggest that the majority of work done by “alpha-level” taxonomists is based on differing interpretations of limited data.

    Getting a handle on variation is difficult, in part because there are lots of overlapping sources of variation. The most obvious is individual variation; not everyone looks the same (my wife and I are adults of the same species, but she’s only 85% of my height). There is sexual dimorphism––the differences between sexes. Then there is ontogenetic variation. This is the change in shape that most organisms undergo as they grow (anisometric growth, as opposed to isometric growth in which babies look like miniature adults). On top of all these there is variation across different population of the same species.

    With all of these sources of variation, it can be difficult to rigidly define a species even in a living population. Fossil organisms introduce an additional difficulty, temporal variation. Even with all of these Diorocetus specimens coming from the same sedimentary bed, there is only so much time resolution. The animals could have lived as much as 500,000 years apart. How much does a species change over that much time?

    Yet all is not hopeless. We have modern animals in which we can look at large samples, that include a range of individual, sexual, ontogenetic, and population differences to establish a baseline for that type of organism. In a given group, some characters tend to vary more than others. In modern whales, for instance, earbones tend not to vary a great deal, while things like the total number of vertebrae can vary a fair amount. The amount of telescoping of the bones of the skull tends to vary between age groups, but not as much within an age group.

    So what is typically done in a fossil species description is to list a bunch of features that all the members of the species should have. Ideally, these will be features that are unique to the species (apomorphies), but they can also be a unique combination of features that are individually found in other species.

    On this particular skeleton, the problem is that it has the single most important defining character of Diorocetus, but not some of the others. There are other features, like the shapes of the premaxillae and dentaries, that seem to be unique to the Carmel Church specimen. These are things that don’t tend to show a lot of individual variation, but they might vary ontogenetically.

  6. BPH@CMMFC says:

    Speaking of Carmel Church, is there any truth to the rumor that the owner of the quarry has removed the VMNH padlock and replaced it with his own, effectively closing the site after nearly 20 years of bountiful digging?

  7. Grenda says:

    Great discussion regarding variation. I should have said,”If you have a small sample of fossils should you make predictions?” Because as someone very wise said, “…they just might be based on pure speculation”. OY VEY! Even if the animals lived 500,000 years apart they might not exhibit any change. I have read that there is less than one-half of a percent variation across homo sapiens. There is more variation among the so-called “racial” populations. Very interesting.

    Is the single most defining characteristic of the Carmel Church fossil the wide incisure, the maxillary foramen?

  8. Alton Dooley says:

    I should be making a post about the status of Carmel Church next week.

  9. Alton Dooley says:

    Nothing wrong with speculation, as long as everyone (including the speculator) acknowledges that it’s speculation!

    Those statements of “0.5% variation across the species” are based on genetic variation; essentially they count up the percentage of DNA base pairs that vary.

    That’s only peripherally applicable in paleontology (“Jurassic Park” notwithstanding). We’re looking at morphologic variation, with is caused by genetic variation but does not quantitatively correlate to it. A very minor genetic difference can cause a huge morphologic difference if it occurs in a gene that controls embryonic development. Chimpanzees are probably genetically closer to use than they are to gorillas, but the look more like gorillas because the small genetic differences between humans and chimpanzees result in larger morphologic differences.

    Back to the Carmel Church whale, the enlarged maxillary foramina is not the only feature that links this whale to Diorocetus, but it’s a big one. That feature is rare, and as far as I know only occurs in two other baleen whales (all three seem to have evolved the feature independently). But the other differences (in the dentary and premaxilla) may turn out to be more important.

  10. Don D says:

    The scientific stuff aside, that is an absolutely beautiful specimen. I sincerely hope that rumor is just that and we can continue to find important fossils like that.

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