‘Weekly’ Wonders (Mini Version): Gomphotaria

18 01 2010

Good tidings and well-wishes!

(NOTE: In light of my recent preparation for the onset of my fourth semester later this week, this post will be on the small side comparatively. My apologies go to any and all pinniped enthusiasts who might be reading this.)

While popular culture maintains that cetaceans and sirenians are fascinating, majestic, and wonderfully mysterious animals, considerably less reverence is maintained for another group of modern marine mammals: the pinnipeds. Perhaps this unfortunate tendency is the result of the fact that, while whales, dolphins, manatees, and dugongs roam the seas without ever having to return to the recesses of ‘our world’ and are thus perceived to be ‘earth-bound aliens’ of sorts, their oceanic grace and manuverability, seals, sea lions, and walruses are still very much tied to the terrestrial habitats of their ancestors. Thus, they’re invariably denied the admiration reaped by their distant relatives simply because of the fact that they seem too similar to ourselves by comparison.

However, though you wouldn’t know it by following the mainstream media, pinnipeds are actually a surprisingly diverse group with a rich history of their own, which has been studded by a menagerie of intriguing genera including this week’s beast: Gomphotaria pugnax, a unique Miocene mollusk-eater from the coast of modern California.

Gompotaria skull. (Courtesy of http://www.coastalpaleo.blogspot.com)

Before moving on to coverage of this bizarre and somewhat ferocious-looking beastie, a review of it’s phylogeny is in order. Gomphotaria  is a member of the Dusignathinae, a group whose exact affinites are rather controversial. According to the paleobiology database, it’s been alligned with the Otariidae, the Odobenini, and the Odobenidae with the majority of recent authors asserting that it was a superfamily belonging to the latter. In the masterful second edition of the textbook “Marine Mammals: Evolutionary Biology”, authors Annalisa Berta, James L. Sumich, and Kit M. Kovacs write “The Dusignathinae includes the extinct genera Dusignathus, Gomphotaria, [and] Pontolis…Dusignathine walruses  developed enlarged upper and lower canines, whereas odobenines evolved only the enlarged upper canines seen in the modern walrus.”

Right, then. On to the featured critter itself!

Lawrence Barnes and R.E. Raschke formally described Gomphotaria in a 1991 paper, a key excerpt of which reads as follows:

“Both upper and lower canines are enlarged and procumbent and worn anteriorly, indicating that the animal may have probed the substrate in search of benthic invertebrates for food. Extreme breakadge and subsequent wear of large, single-rooted cheek teeth indicate that at least some, if not all, the food species (e.g. mollusks) probably had hard shells. Absence of a highly vaulted palate, present in walruses, indicates that G. pugnax did not suck bivalve tissues using the tongue-piston method employed by walruses [(the modern walrus, Odobenus rosmarus, feeds by attatching its strong lips to the prey item in question before rapidly withdrawing its tongue which creates a vacuum. The pinniped's vaulted palate eases the process)] .”

Gomphotaria reconstruction, courtesy of Wikipedia.

May the fossil record continue to enchant us all!

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7 responses

19 01 2010
Bruce Keegan

We love our sea lions here in San Francisco.
When they disappeared from Pier 39, a favorite hangout, it became headlines.
Where did they go, what happened?
Then, our California Sea lions were found mixing with the much bigger Stellar Sea Lions at Sea Lion Cave in far to the north, Oregon.
Great relief and we want them back. Apparently, they were chasing the herring.

19 01 2010
tanystropheus

It’s wonderful to hear stories of local residents showing concern for their resident wildlife…in my humble opinion, it’s the greatest ally the environmentalist cause has.

22 01 2010
Doug

When it comes to marine mammals, whales and dolphins don’t interest me as much as pinipeds, sirenians, and desmostylians. Gomphotaria has what has to be the weirdest skull i have seen on a pinniped. A most wondrous animal. Which is why I’m annoyed LA isn’t showing it in their new Cenozoic hall (though the skull may be put on display. beggers can’t be choosers).

27 01 2010
Robert Boessenecker

Hey, nice post – another interesting thing about Gomphotaria is that it is gigantic – it has the second largest skull of any pinniped (40cm+ long), the longest being another Dusignathine, Pontolis magnus (60cm+) – although I can’t seem to remember how large the southern elephant seal skull is (Mirounga).

27 01 2010
tanystropheus

Interesting…I’d never read anything to that effect.

29 01 2010
johannes

Fossil walruses are utterly fascinating. Wasn’t *Pontolis* a killer walrus, hunting large marine vertebrates?

29 01 2010
tanystropheus

I think you’re referring to Pelagiarctos, though Robert probably knows for sure…

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