Desmostylians

Let’s look back through the mists of time to peak at one of the most mysterious and perplexing of mammals, the desmostylians, the only extinct order of marine mammals (although in dark moments I worry that more are soon to follow). Desmostylians were large quadrupeds adapted to life in the water. They had short tails and mighty limbs. Because of this morphology, taxonomists initially thought that they were cousins of proboscideans and sirenians (elephants and manatees), but the fact that their remains have only been found far from Africa (the origin point of elephants, mammoths, mastodons, and manatees & sea cows) along with perplexingly alien traits has caused a rethink of that hypothesis.

(Art by Ray Troll fror SMU)

Extant between the late Oligocene and late Miocene, the desmostylians had powerful tusklike cylindrical teeth and dense heavy bones. The smallest (and oldest) were peccary sized creatures whereas the largest grew to the size of medium whales. It seems like desmostylians lived in littoral parts of the ocean—near coasts and shores where they used their pillar like teeth to graze great kelp forests. They scraped or rasped up the kelp and sucked it down their voracious vacuum maws like spaghetti! It must have been an astonishing sight! My favorite marine paleoartist, Ray Troll has made exquisite pictures of these majestic creatures which help us to visualize them. I really hope they looked this funny and friendly (if they were anything like herbivorous manatees, they probably did!).

(Art by Ray Troll, courtesy SMU)

Speaking of manatees, the gentle sirenians had a hand (or flipper?) in the demise of the poor desmostylians. The dugongs and manatees would never fight anyone or even protect themselves with force—they simply outcompeted the less nimble desmostylians for resources, although one wonders if climate-change and the continuing evolution of different coastal sea plants might also have helped do in the great desmostylians.

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