Tetrapod Zoology

Killer sperm whales

You would be forgiven that doubting that this awesome object – displayed in the Santa Barbara Museum of Natural History – is a fossil odontocete skull, but it is. Discovered in Lompoc, California, and as yet unreported in the scientific literature (so far as I can tell), it is the skull of a large predatory sperm whale purportedly closely related to the Japanese Miocene physeterid Brygmophyseter shigensis (but read on).

i-206800ec1f478b824e2d393e434f0e63-gigantic killer odontocete skull.jpg

The extant sperm whale Physeter lacks functional teeth in the upper jaw and in fact even possesses special sockets in the maxillae that house the lower jaw teeth when the mouth is closed (it may actually have as many as eight teeth in each maxilla, but when it does they are unerupted and remain buried in their alveoli). However, this was not true of all extinct physeteroids, many of which possessed fully erupted premaxillary and maxillary teeth (Kellogg 1928, Kazár 2002). In some of these sperm whales, large upper and lower jaw teeth, combined with a robust skull morphology and large body size (6-7 m long), indicate that the animals were macropredators, probably attacking other cetaceans (Bianucci & Landini 2006, Hampe 2006)…

The best known of these ‘killer sperm whales’, Zygophyseter varaloi from the Late Miocene of Italy, had an extremely long zygomatic process on the squamosal that provided an attachment surface for hypertrophied jaw musculature, and helped stabilise the lower jaw when it was opened wide. This character is clearly present in the Lompoc sperm whale, suggested that it might be a close relative of Zygophyseter. If this is correct, the Lompoc animal might have been outside of the kogiid-physeterid clade within Physeteroidea, as Bianucci & Landini (2006) found Zygophyseter to be a stem-group physeteroid. Other macropredatory sperm whales, the hoplocetines (the monophyly of this group is controversial), were crown-group physeteroids and are probably members of Physeteridae (Muizon 1991, Hampe 2006). If the Lompoc animal is close to Zygophyseter it can’t also be close to Brygmophyseter, for Brygmophyseter is a crown-group physeteroid and probably a hoplocetine [image below shows Zygophyseter, from Bianucci & Landini (2006)].

i-61991cbce7b1bf00b2c60bcf0e82ca16-Zygophyseter Bianucci & Landini.jpg

What makes the Lompoc skull look particularly incredible is its deep, massive rostrum. It almost looks like the skull of Andrewsarchus. In fact this makes it look decidedly different from all other sperm whales, as even the macropredatory ones have a low, dorsally flattened rostrum that, in the nasal region, exhibits scaphidiomorphy due to the possession of the spermaceti organ. Alas, this massive rostrum seems to have been reconstructed without reference to sperm whale anatomy. Dammit! The photo is from Doug Shore’s flickr site (here) and is used with permission.

Another one tomorrow!

Refs – –

Bianucci, G. & Landini, W. 2006. Killer sperm whale: a new basal physeteroid (Mammalia, Cetacea) from the Late Miocene of Italy. Zoological Journal of the Linnean Society 148, 103-131.

Hampe, O. 2006. Middle/late Miocene hoplocetine sperm whale remains (Odontoceti: Physeteridae) of North Germany with an emended classification of the Hoplocetinae. Fossil Record – Mitteilungen aus dem Museum für Naturkunde in Berlin 9, 61-86.

Kazár, E. 2002. Revised phylogeny of the Physteridae (Mammalia: Cetacea) in the light of Placoziphius Van Beneden, 1869 and Aulophyseter Kellogg, 1927. Bulletin de l’Institut Royal des Sciences Naturelles de Belgique. Sciences de la Terre 72, 151-170.

Kellogg, R. 1928. The history of whales – their adaptation to life in the water (concluded). Quarterly Review of Biology 3, 174-208.

Kimura, T., Hasegawa, Y. & Barnes, L. G. 2006. Fossil sperm whales (Cetacea, Physeteridae) from Gunma and Ibaraki prefectures, Japan; with observations on the Miocene fossil sperm whale Scaldicetus shigensis Hirota and Barnes, 1995. Bulletin of the Gunma Museum of Natural History 10, 1-23.

Muizon, C. de 1991. A new Ziphiidae (Cetacea) from the Early Miocene of Washington State (USA) and phylogenetic analysis of the major groups of odontocetes. Bulletin du Muséum national d’Histoire naturelle (4e sér.) 12, 279-326.

Comments

  1. #1 JW Tan
    August 1, 2008

    In the image of Zygophyseter, underneath the spermaceti organ there’s a space labelled “junk”. What kind of junk is this? Presumably the term means the same thing as it does to laymen?

  2. #2 Sordes
    August 1, 2008

    Great to see now a killer sperm whale at TetZoo! When I saw a photo of this skull for the first time (one or two years ago) I had really no idea what it was, although I saw already some associations with a sperm whale skull, but similar to none I have ever seen. Therefore I wrote to the Santa Barbara Museum, but they had not further information too, but I was adviced to ask Dr. Barnes who kindly told me some further information about it. He sad that its rostrum most probably did not look this way in life, cause of a false restauration. That?s really a shame, this guy would have looked even more fierce with such a massive upper jaw. But as the jaws of the japanese specimen of Brygmophyseter shigensis show, they were anyway quite strong.
    I just discovered two days ago that Carl Buel made a wonderful picture of Zygophyseter which can be seen at cetacea-evolution.org
    In real life Zygophyseter looked probably a little bit different from the image above, as its lips covered its upper teeth.
    I once blogged about Zygophyseter and made a little sketch to illustrate it: http://bestiarium.kryptozoologie.net/artikel/der-killerpottwal-zygophyseter-varolai/
    I made the body more rounded and compact, similar to orcas or Kogia, as the nearly complete skeleton of Brygmophyseter seems to have similar proportions.
    BTW, Dr. Alton Dooley from the Virginia NHM discovered just few months ago relics of another killer sperm whale, possibly Zygophyseter. The teeth show very well the abrasion facettes similar to modern orcas (or at least most orcas, I found a flickr an orca skeleton of a supposed shark-hunting population whose teeth were only plain stumps).
    I already wait eagerly for the other skulls of this week.

  3. #3 Sordes
    August 1, 2008

    Just an additional note, it was not discovered at Bakersfield but Lompoc.

    Here is a part of the message Dr. Barnes sent me with some additional information:

    ————————————————————

    The specimen is not yet scientifically described, but
    has been published, and it is the subject of research
    by Dr. Edward Mitchell, myself, and others.

    The specimen is not yet scientifically described, but
    has been published, and it is the subject of research
    by Dr. Edward Mitchell, myself, and others.

    It was collected not at Bakersfield, Kern County,
    California, but near Lompoc, Ssnta Barbara County,
    California.

    It is related to Brygmophyseter shigensis (Hirota and
    Barnes, 1995) (the genus Brygmophyseter Barnes, 2006,
    has date priority over Naganocetus Bianucci et al.,
    2006).

    Like most fossil sperm whales, the Santa Barbara
    specimen has functional upper teeth in addition to the
    mandibular teeth.

    The rostrum and top of the cranium of the specimen at
    the Santa Barbara Museum have been restored, with no
    basis on sperm whale anatomy, so those parts of the
    specimen provide no information for its relationships.

    ————————————————————

    I really hope there will be soon further information about this amazing animal.

  4. #4 Andreas Johansson
    August 1, 2008

    The head of Zygophyseter looks crazy beyond belief. Wouldn’t one expect there to be soft tissue giving it a more hydrodynamic profile?

  5. #5 Sordes
    August 1, 2008

    The supracranial basin of the skull showed that the spermaceti organ did not cover the rostrum as in living sperm whales. How it actually looked is just speculation, but keep in mind that the heads of northern bottlenose whales, especially those of old males, have nearly the same shape.

  6. #6 neil
    August 1, 2008

    JW: “Junk” refers to a fatty structure found in sperm whale heads that is homologous with the melon of other odontocetes. I’m guessing that the name reflects a quality contrast with the valuable oil found in the spermaceti organ, perhaps someone else can back me up on that?

  7. #7 Ned
    August 6, 2008

    Dangit.

    When I grow up I want to be Darren Naish.

  8. #8 Alton Dooley
    September 16, 2008

    We’ve been discussing the Lompoc sperm whale and other sperm whales over on my blog for a few months now; for example, the post on May 12:

    http://web.me.com/dooleyclan/Site_2/Blog/Entries/2008/5/12_More_sperm_whale.html

    and others from the archives. It seems that most of the dorsal surface of the Lompoc whale, including the rostrum, is modeled (probably incorrectly). The zygomatic process of the Lompoc whale appears to be real, which sugests affinities with Zygophyseter rather than with Brygmophyseter.

  9. #9 kat
    November 16, 2008

    help!! this is for a school project, does anyone know where in lompoc and by whom this was discovered? thanx

  10. #10 Jorge Velez-Juarbe
    July 11, 2010

    I wonder if the Lompoc sperm whale is just a better more complete specimen of “Ontocetus” oxymycterus” Kellogg, 1925. It seems to be about the right size, age and provenance.

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