One of my colleagues is trying to crowdfund (through scientific crowdfunding site Experiment.com) part of her extinct whale research. Please take a chair while I interview her about her proposed research, and she should be in the comments if you have any questions for her.

Earlier this year, Rachel Racicot and her colleagues described material for a new species of fossil porpoise (small toothed whales). The relevant scientific paper is here and the popular science media discussed it as well, including here, here, and here. The fossil porpoise had a lower jaw that extended well beyond its upper jaw, giving it a quite bizarre look. Its scientific name, Semirostrum ceruttii, which means Cerutti's half-snout, refers to this. Dr. Racicot and her co-authors have some interesting ideas about what this extinct porpoise did with its half-snout.

Assume we're unfamiliar with your work. What have you done so far?

My group and I have done a detailed description of the whole skeleton of Semirostrum ceruttii, the first mammal to have a long, narrow jaw extending well beyond the length of the upper jaw. The description we did used CT scans of the skull and jaw, and in a different paper I also described endocranial cavities that tell you a bit more about which sensory structures were important. These two publications are really just first steps in the process of being able to figure out other questions like: Why does it have a weird jaw shape? How did it get such a jaw shape? What was it eating? We could answer some of these questions based on medical CT scans I acquired in the original description (there seems to have been extended and numerous nerves and arteries along the length of the elongate jaw), but we need higher-resolution scans of a more complete jaw (which we have access to) to really nail this down, and to test more complex hypotheses about stresses that the jaw could have withstood using high-end engineering based analyses (like finite element analysis). This would also allow us to reconstruct a model of the head to then test whether and how it was able to swim and probe around for food.

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(Semirostrum ceruttii life reconstruction by Nobu Tamura)

Is there a common name we can use for this animal?

Skimmer porpoise is what we've been calling it because its jaws are similar in shape to those of the Black Skimmer, a bird that "skims" the surface of the water.

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How long does the jaw extend beyond the length of the snout of the skimmer porpoise?

On one of the specimens, about 18.6 centimeters (7.3 inches). In the few complete lower jaws we have, this lower jaw extension accounted for about 40% of the porpoises entire jaw length, so it looked like it had a really big chin or underbite.

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(Semirostrum ceruttii life reconstruction by Nobu Tamura)

What's the most out-there hypothesis you want to test about the skimmer porpoise?

There's the idea that the skimmer porpoise used its extended lower jaw for combat or for damaging or stunning prey. Males may have used it in combat with other males to establish dominance during mating season. It may have also been able to use its jaw like a large club that it would smash down on prey animals to stun them, making them much easier to catch and devour.

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How would you go about testing that?

Two-fold. One of my co-authors looks at tooth wear, and this could determine what the teeth in the jaw were being used for, which would help us determine what the half-snout was being used for. Another avenue is using an engineering approach by using finite element analysis (FEA). This would take a CT scan of the skull to model stresses on the jaw and skull and check what parts of the skull can withstand stress, and see how parts of the skull respond to bending stress, such as those the animal might experience if using the lower jaw to strike rivals or prey. Also the lower jaw would be scanned and the strengths of this would be compared to modern analogues with odd lower jaws like Black Skimmers and half-beak fish. Those groups use their lower jaws for probing and prey capture.

(A video featuring uncredited images from Racicot et al. 2014, Nobu Tamura, Robert Boessenecker, Brian Switek, and Yale's Office of Public Affairs & Communications)

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Where was the skimmer porpoise living, when it was alive?

It's been found along the Pacific coast of California, near San Diego, Los Angeles, and San Francisco. A colleague of mine has also seen a skeletal element in collections in Australia that might have been skimmer porpoise too, but that needs to be checked out.

So how will this funding help you get some of these hypotheses tested?

In order to properly examine the lower jaws, I need to acquire high-quality CT scans from the University of Texas at Austin, and those cost quite a bit of money. This funding would basically pay for that. Thankfully, we already have scans of one of the modern analogues I mentioned earlier, keeping the overall cost of the project as low as possible. It would be great to have a high-quality scan of a more complete fossil jaw for a lot of reasons, not only to help answer multiple questions for this project, but they could also be used to make 3D printouts and other useful items for other researchers and the education of the general public.

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Lead video produced by Yale's Office of Public Affairs & Communications featuring images and video from Racicot et al. 2014 and from two of the authors (Rachel A. Racicot, Robert W. Boessenecker) of that study.