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| Enaliarctos | |
|---|---|
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| Enaliarctos mealsi cast of a specimen fromCalifornia. At theAMNH. | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Clade: | Pinnipedimorpha |
| Family: | †Enaliarctidae Mitchell & Tedford, 1973 |
| Genus: | †Enaliarctos Mitchell & Tedford, 1973 |
| Species | |
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Enaliarctos[2] is an extinctgenus ofpinnipedimorph, and may represent the ancestor to all pinnipeds. The five species in the genusEnaliarctos have been recovered from lateOligocene and earlyMiocene (ca. 28-17 million years ago) strata ofCalifornia andOregon.[1]
It had a shorttail and developed limbs with webbed feet. Unlike modernsea lions, it had a set of slicingcarnassials; the presence of slicing teeth (rather than purely piercing teeth as in modern fish-eating pinnipeds) suggests thatEnaliarctos needed to return to shore with prey items in order to masticate and ingest them. Still,Enaliarctos had some sea lion-like characteristics, such as large eyes, sensitivewhiskers, and a specializedinner ear for hearing underwater.
Enaliarctos has been heralded as the ancestor of all known pinnipeds, including the familiesOtariidae (fur seals and sea lions),Desmatophocidae (extinct seal convergent pinnipeds),Phocidae (true seals), andOdobenidae (walruses). Investigations of the biomechanics ofEnaliarctos indicate that it used both its forelimbs and hindlimbs during swimming. Modern fur seals and sea lions only use their forelimbs, while true seals primarily use their hindlimbs for aquatic propulsion; lastly, the extant walrus uses both fore- and hindlimbs for swimming. It has been postulated that the condition inEnaliarctos is ancestral for all pinnipeds, and that forelimb swimming was lost in true seals, while hindlimb swimming was lost in fur seals and sea lions. This is significant because there has been considerable debate as to whether pinnipeds share common ancestry. Interpretation ofEnaliarctos indicates that all pinnipeds share a common ancestor (which, if it was notEnaliarctos, must have been something very similar, such as the more recently discoveredPuijila, of controversial affinities, though).
Enaliarctos emlongi is represented byfossils from coastalOregon. It existed between 13 and 20 million years ago, during theHemingfordian age of theMiocene epoch. It was named for renowned fossil collectorDouglas Emlong in 1991 by paleontologistAnnalisa Berta.
