Whale update-more vertebrae

Just before I left for SVP, I found the last two jackets from the Carmel Church whale and moved them into the lab so Ward could work on them while I was gone. The larger of the two jackets (above) is from fairly far back in the skeleton, near the end of the ribcage. It includes parts of at least 6 ribs, and two vertebrae. The smaller of the two jackets (below) came from just behind the skull.

My field notes indicated that there were ribs and vertebrae in this jacket, but it had some surprises. The vertebra indicated by the arrow is the second cervical (neck) vertebra, called the axis. Since we prepared the other jackets I had been wondering where the axis was, since I didn’t identify it in the field.

The other vertebra in this jacket is also a surprise to me, because it is also a cervical vertebra. I thought the only one we were missing was the axis, but this extra vertebra is either the 3rd, 4th, or 5th cervical (most likely the 3rd).

There is also a lot of sea turtle material in these jackets (that’s mentioned in my field notes as well). For example, the flat rectangular bone under the rib at the bottom of the second photo is part of a turtle shell.

These are both fairly small jackets, and they should go pretty quickly.

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6 Responses to Whale update-more vertebrae

  1. Doug says:

    So, just how much of this whale do you think you’ve got?

  2. Haha… Thats great, I find it extremely amusing that the RCI ruler appears so soon after SVP. I nabbed two of those – I didn’t realize that they were brown until I took them out of my bag.

    Funny story about my SVP scalebar – I guess I used it as a bookmark in an interlibrary loan two years ago. Then, I got the same book on ILL again, and out popped my old scale bar, two years later.

    Sorry…. slight tangent.

  3. Alton Dooley says:

    RCI gave me a whole stack of scale bars. See, my ability to lose scale bars is legendary. They’ve been found inside storage storage jackets at the Smithsonian. One is apparently somewhere in the lab at the Calvert Marine Museum, and has been there for years. Several are at the bottom of the Potomac River, I think. At least two are in the Atacama desert. I usually pick up at least three scale bars at SVP. If I’m really careful, those last me until the next SVP meeting.

    On this whale (which I still suspect is Diorocetus), I think we have the more-or-less complete skull (including lower jaws), 24 vertebrae, and the majority of the ribcage. It is possible that we could have left part of it in the ground, but there was no more obvious at the time.

  4. Doug says:

    Hey Butch, I have a question I have been meaning to ask. In a much, much earlier post you had an illustration that depicted Squalodon attacking a dolphin. My question is: What did squalodont whales eat? What do we think they were feeding on and why?

  5. Alton Dooley says:

    Good question.

    Squalodont feeding habits have been much debated among the tiny group of people that work on them. Back in 1923, Remington Kellogg suggested that squalodonts filled a niche similar to modern killer whales, based largely on their size (although the squalodonts known at that time were quite a bit smaller than killer whales). This suggested that they were often taking marine mammals and large fish, but that most marine animals were possibilities.

    When I was working on my dissertation I started have doubts about the killer whale analog, for two main reasons. One, killer whales have a broad, massive snout, while it is very long and narrow in squalodonts. Two, killer whales show a unique wear pattern on their teeth, with lots of broken and polished facets on their teeth that squalodonts lack. These breaks apparently occur when the conical teeth hit against bones in marine mammal prey. I believed at the time that squalodont jaws were too weak to attack large, strong prey, and their teeth didn’t show the right wear pattern anyway. I wondered if squalodonts were maybe doing something completely different from what’s seen in the modern world, since no modern whale has a comparable combination of tooth and skull morphology.

    After several years, though, my opinion changed. The first doubts I had concerned the teeth. A problem with squalodonts is that there are no modern whales with a similar dentition, so I didn’t have a good modern analog. But there was reason to believe that the unique breakage seen in killer whales was due to their particular tooth morphology. A whale with different teeth could be eating the same thing, but show different tooth wear. In fact, that seems to be the case. Some mosasaurs have known stomach contents, so we know the diet, and it’s a lot like killer whales (that is, they eat everything). But these mosasaurs have a tooth shape and wear pattern similar to squalodonts.

    The second issue was the shape of the rostrum. Even with their massive, wide upper jaw, killer whales occasionally break their rostrum at its base, just in front of the eye sockets (which is a fatal injury). I originally didn’t think that the squalodont rostrum was strong enough to withstand strong, struggling prey. But on closer examination, the squalodont skull is stronger than it seems. While the rostrum is very narrow in dorsal view, it is very deep in lateral view, especially at the base of the rostrum where it is usually at its weakest. In fact, in cross-section the base of the squalodont rostrum is almost square.

    I now think that Kellogg may have been right (although not necessarily for the right reasons). Squalodonts seem to be specialized for the role of feeding on other marine mammals, marine reptiles, and large fish (in fact, in many ways they seems to be more specialized for this than are killer whales).

    I wouldn’t necessarily extend that to hunting large baleen whales. Killer whales hunt large baleen whales successfully only because they hunt in packs; there’s no evidence for or against that behavior in Squalodon. But while killer whales are the only modern predator of baleen whales (excluding humans), there is another animal in the Miocene known to fill that role: the giant shark Carcharocles megalodon.

    So, to make a long explanation even longer, I _think_ squalodonts were feeding on large fish, seals, sea turtles, and small dolphins. These are all animals that were smaller than Squalodon, but still large enough to need some level of mastication (Squalodon couldn’t swallow them whole), and they’re all known from the same deposits.

  6. Brian L. Beatty says:

    I’m glad to see the axis for this individual was there, and it looks like a number of ribs too.
    Regarding losing scale bars, I guess I can come out about my personal shame now…. I, too, lose scale bars regularly. I know one of them is in the Smithsonian (maybe 2), and at least one is somewhere in the AMNH Mammals colln, one on the coast of Oregon near the Yaquina Fm, and probably several in the Florida Museum of Natural History… ugh!

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