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Odobenocetops: ridiculous ‘walrus whales’

The views expressed are those of the author and are not necessarily those of Scientific American.

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I always hoped that, one day, I’d have time to talk at length about Odobenocetops, one of the strangest and most exciting of fossil cetaceans. Alas, I haven’t yet found that time, so here are a few slides on the beast from one of my fossil marine mammal lectures.

Odobenocetops was originally described by Muizon (1993a, b). The second species was described in Muizon et al. (1999) and substantial additional data was provided by Muizon & Domning (2002). The illustrations used above are taken from these publications.

For (hopefully functional) links to all of the many Tet Zoo cetacean articles, see…

Refs – -

Muizon, C. de 1993a. Walrus-like feeding adaptation in a new cetacean from the Pliocene of Peru. Nature 365, 745-748.

- . 1993b. Odobenocetops peruvianus: una remarcable convergencia de adaptación alimentaria entre morsa y delfín. Bull. Inst. Fr. Études Andines 22, 671-683.

- . & Domning, D. P. 2002. The anatomy of Odobenocetops (Delphinoidea, Mammalia), the walrus-like dolphin from the Pliocene of Peru and its palaeobiological implications. Zoological Journal of the Linnean Society 134, 423-452.

- ., Domning, D. P. & Parrish, M. 1999. Dimorphic tusks and adaptive strategies in a new species of walrus-like dolphin (Odobenocetopsidae) from the Pliocene of Peru. Comptes Rendu de l’Academie des Sciences, Paris, Serie II 329, 449-455.

Darren Naish About the Author: Darren Naish is a science writer, technical editor and palaeozoologist (affiliated with the University of Southampton, UK). He mostly works on Cretaceous dinosaurs and pterosaurs but has an avid interest in all things tetrapod. His publications can be downloaded at He has been blogging at Tetrapod Zoology since 2006. Check out the Tet Zoo podcast at! Follow on Twitter @TetZoo.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. naishd 7:32 am 11/14/2013

    A discussion on facebook (kudos to Jaime Headden) reminds me that new data on Odobenocetops was due to be presented at the 2013 SVP meeting: alas, the talk didn’t happen. I just want to note that I’m aware of this new stuff but don’t want to discuss it here until the paper sees print.


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  2. 2. llewelly 8:00 am 11/14/2013

    Sadly the links to various whale articles need some work.

    From the first article ( All the whales of the world, ever (part I) ):

    Did I mention that Caperea is really, really weird?
    Once more on little Caperea
    Caperea alive!

    Link to this
  3. 3. llewelly 8:31 am 11/14/2013

    And from the second article ( All the whales of the world, ever (part II) ) :

    Santa Cruz’s duck-billed elephant monster (a Berardius carcass)
    Skull of the Moore’s Beach monster revealed! (Berardius)
    The newest whales (mentions recently described ziphiids)

    Link to this
  4. 4. llewelly 8:32 am 11/14/2013

    More from the second article :

    Sea floors worldwide are littered with the remains of diverse extinct beaked whales

    Inia: gnarly, heterodont, carries rocks for fun
    The dolphins with the massive jagged bony crests (Platanista)

    Link to this
  5. 5. llewelly 8:32 am 11/14/2013

    Still more from the second article :

    A 3-m tooth that can bend 30 cm in any direction and is hypersentitive to salinity, temperature and pressure… and the sonic lance hypothesis (narwhals)
    Blunt-nosed paedomorphic cutie (on Orcaella)
    Weird whales grand finale (walrus whales and half-beak porpoise)

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  6. 6. llewelly 8:34 am 11/14/2013

    Still more from the second article :

    On identifying a dolphin skull (mostly on bottlenose dolphins)
    The first over-land migration of Canadian beluga

    Link to this
  7. 7. llewelly 8:34 am 11/14/2013

    And, finally, Still more from the second article :

    A weird whale to identify, with musings on the subject of how avian deaths might be caused by offshore oil platforms (brief musings on wolphins)
    Cristina Eisenberg’s The Wolf’s Tooth: Keystone Predators, Trophic Cascades and Biodiversity (mentions trophic cascades involving Killer whales and other marine mammals)

    Link to this
  8. 8. llewelly 8:37 am 11/14/2013

    With a few exceptions (involving apostrophes and such), you can paste the title of the intended article into goggle, surround it with quotes, and the actual article will be found as the first link. If that doesn’t work, remove the quotes, and add to the end of your search line, telling google to restrict the search to the site.

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  9. 9. naishd 9:01 am 11/14/2013

    Ah, thanks. I don’t know why the ScienceBlogs links don’t work any more – I’ll fix them myself when I find the time…


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  10. 10. llewelly 9:42 am 11/14/2013

    They don’t work because national geographic changed its blog system after the articles were written, and the pages they linked to moved; the new urls have the day of the month in them, in addition to the year and the month, and they end with a slash, rather than with .php .

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  11. 11. Halbred 1:33 pm 11/14/2013

    How does one infer the presence of a melon? It’s curious that one species would have one, but not another, and it’s curious that a durophageous whale would have any USE for a melon (which implies echolocation, right?). Is there postcranial material known for this weird whale?

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  12. 12. Boesse 2:03 pm 11/14/2013

    The presence of a melon can be inferred from certain aspects of the facial morphology of the skull, including the facial plane and structure/size of the premaxillary sac fossae. Carolina Gutstein had a very interesting talk about this and inferring the size of the melon in extinct odontocetes, but I’ll refrain from mentioning any of the specifics since it is an unpublished study. In the case of O. leptodon, Muizon and Domning inferred the presence of a small melon based on the retention of a slightly concave facial region.

    Regarding postcrania, there is at least an atlas and part of a forelimb.

    WRT the phylogenetic affinities of Odobenocetops – I’ve spoken with a number of researchers skeptical of Odobenocetops’ inclusion within the Delphinoidea by Muizon et al., and several out there suspect it’s not a delphinoid at all. Looking again at the earbones associated with skulls – they are really, really strange looking, and somewhat resemble ‘platanistoid’ (sensu lato) periotics in some regards. The tympanic bulla is equally strange, and lacks a couple of classic Delphinidan characteristics (reversals? who knows). That all being said, only two studies have ever really included Odobenocetops within a cladistic analysis – Murakami et al. 2012a (and 2012b) in JVP (effectively the same character matrix), and that study found Odobenocetops to be sister to the Monodontidae. We need to dig deeper in the Sacaco basin and get some middle Miocene proto-Odobenocetops critters who aren’t so damn derived, I think.

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  13. 13. Yodelling Cyclist 2:03 pm 11/14/2013

    Any news on the next podcast?

    Enjoyed the article as always – thank you.

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  14. 14. Christopher Taylor 5:35 pm 11/14/2013

    ‘Scuse self-promotion: I wrote a post on Odobenocetops at The whale that looked like a walrus.

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  15. 15. Heteromeles 7:37 pm 11/14/2013

    Hmmm. Obviously Odobenocetops had those teeth to defend itself against attacks on its neck and chest from predatory Thalassocnus…

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  16. 16. Karskadon 9:33 am 11/15/2013

    The type specimen of _Odobenocetops_ (USNM 488252) is also one of the many awesome new 3D models available on Smithsonian X 3D.

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  17. 17. BrianL 5:22 am 11/16/2013

    What’s the likely reason that the ‘*Odobenocetops* fauna’ is so restricted geographically? Also, what is thought to have caused its extinction? Quaternary cooling, perhaps?

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  18. 18. BrianL 5:22 am 11/16/2013

    Quarternary of course.

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  19. 19. Heteromeles 4:17 pm 11/16/2013

    Brian, I think you were right the first time. Still, it’s a good question, one of many. It seems that South America had a unique marine fauna, as well as a unique land fauna, and it makes one wonder whether they were a victim of changing currents, or whether the north Pacific marine fauna swam south and killed them off, as happened to the land-bound oddities.

    Some other questions: how’d a dolphin shed its melon so fast anyway? Was that tusk an environmental sensor equivalent to a narwhal tusk, or just a sexual ornament?

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  20. 20. Gigantala 7:39 pm 11/16/2013

    Do molluscivores have particularly wide ranges anyways? Walruses and sea otters are rather retricted as well.

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  21. 21. Christopher Taylor 3:23 am 11/17/2013

    In the case of sea otters at least, their current restricted range is at least partially human-influenced. They were historically present over the greater part of the temperate North Pacific.

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  22. 22. BrianL 4:44 am 11/17/2013

    @Christopher Taylor:
    Were sea otters present in eastern Asia as well, then? I know this was the case for Steller’s Sea Cow but had no idea that the otters were that widely distributed as well. Did humans drive them extinct in Asia by overhunting?

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  23. 23. naishd 5:44 am 11/17/2013

    Interesting comments everyone, thanks. Regarding the apparent restriction of Odobenocetops to the south-eastern Pacific, I wonder if it’s anything to do with the hypothesis proposed in Vermeij’s Evolution and Escalation: An Ecological History of Life? Therein, he proposes that the geological and ecological history of this region was especially complex and tumultuous, and that this drove escalation, complexity and diversity exceeding that of some/most other marine regions. I don’t have the book to hand – will have to dig it out to see exactly what he says.

    Sea otters were indeed more widespread in the past, with members of Enhydra reported from the Pleistocene of England. See…

    Willemsen, G. F. 1992. A revision of the Pliocene and Quaternary Lutrinae from Europe. Scripta Geologica 101, 1-115.

    And… hello, comment 23. We move on…


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  24. 24. Christopher Taylor 5:17 pm 11/17/2013

    As it turns out, a check of Wikipedia indicates that sea otters are not extinct in Asia, so I was wrong on that point. They were hunted to very low numbers, but the population around the Kuril Islands is currently not doing too badly.

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  25. 25. David Marjanović 6:41 pm 11/17/2013

    Brian, I think you were right the first time.

    …So I got curious and turned to Wikipedia. Turns out that the first r is there in German and Dutch, but not in English or French or Spanish or the original Italian. I suppose the latter group derives the word from Latin quater “four times”, while the former derives it from Latin quartus/-a/-um “fourth”, in analogy to the Primary, Secondary and Tertiary clearly being derived from primus/-a/-um, secundus/-a/-um, tertius/-a/-um “first, second, third” and not from semel, bis, ter “once, twice, thrice”.

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  26. 26. BrianL 10:40 am 11/18/2013

    Well, I happen to be Dutch and used to spelling it ‘Kwartair’. That is, on those very rare occasions where I get to say it, which is limited to a limited number of geography or history lessons to high school students and the rare but precious moments when I get to talk about prehistoric mammals to other people. That being said, I tend to use Pleistocene, Holocene and Late Neogene in the last case and avoid saying Kwartair.

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