Blog post: The terrible fossil record of sea otters

[Boesse]

Hi all - in the hopes of attempting to reach a wider audience, and anyone who has collected possible sea otter fossils, I'm sharing the first two posts from my blog "The Coastal Paleontologist" in a short series on sea otter paleontology and evolution. The first one is mostly a bit on sea otter biology, and the second is the first one that really deals with the paleontology aspect. The third (and fourth?) posts will deal with what the limited fossil record can tell us about sea otter evolution. The sea otter fossil record is quite poor, and I'm hoping that some of you may have found some fossil specimens and might consider making them available for scientific study.

 

Anyway, here's part 1: https://coastalpaleo.blogspot.com/2020/05/the-terrible-fossil-record-of-sea.html

 

And part 2: http://coastalpaleo.blogspot.com/2020/06/the-terrible-fossil-record-of-sea.html

 

Part 3: will update as soon as I get it finished!

 

And a teaser - the left mandible of the holotype specimen of Enhydra macrodonta from the Crannell Junction locality right off of Highway 101 near Arcata, California. I spent about 3 years emailing various curators about this fossil, if they had it on loan, and I finally got a response from Dr. William Miller III at Humboldt State University in Arcata that he didn't remember such a specimen existing there. The paleontologist who named it, Dr. Frank Kilmer, who was retired, mailed me a letter indicating that the mandibles had been given back to the private collector (!!!) after the species was published  - but nobody at HSU knew their name! One former student did, but would not return my phone calls. I visited HSU in 2008 when I was an undergraduate student and rifled through their teaching collection and found A mandible, but I didn't think it was THE mandible, because of Kilmer's letter, and a misplaced label suggesting it was from a different locality (and therefore a duplicate specimen rather than the original). Dr. Miller indicated I should arrange for the fossils to be transferred to a larger museum, as he was certain that the collection would be thrown in the garbage after he retired! I visited again two years later and set aside all the specimens that should be transferred and secured an agreement from HSU for the material to be transferred to UC Berkeley, which finally happened about five years later. I did not realize that this mandible was in fact THE mandible, or at least half of the holotype (the right mandible is still missing, presumably in that private collection) until I was able to download a much, much higher quality scan of the photographic plates in Kilmer's 1972 paper, and I was able to match barnacle scars between the published image and the fossil. So, we may not have the more complete of the two mandibles, but at least we have one of them, and it is my hope that there is more material in private collections and that more can be discovered in the future.

 

 

[siteseer]

Hi Bobby,

 

I can tell you that fossil sea otter specimens have been almost unheard of among collectors in the time I've been collecting fossils (since 1987).  I think it's possible that there are specimens in smaller museums and private collections that have not been identified or are misidentified as bear especially if the teeth are worn or incomplete but I doubt that it would be more than a couple.  Maybe 30 years ago, I did hear of a specimen from the San Mateo Formation, Oceanside locality which may be the same one noted in Barnes et al., (1981) although I recall it as LACM having the actual fossil with the private collector having the cast. 

 

There are collectors who would know if they had a sea otter or at least something weird but I haven't seen or heard of anyone finding something like that.  Maybe there's an offshore Pliocene bed full of otter stuff.  Maybe the Drake's Bay Formation needs more of a look.

 

Jess

[Boesse]

On 6/16/2020 at 5:26 AM, siteseer said:

Hi Bobby,

 

I can tell you that fossil sea otter specimens have been almost unheard of among collectors in the time I've been collecting fossils (since 1987).  I think it's possible that there are specimens in smaller museums and private collections that have not been identified or are misidentified as bear especially if the teeth are worn or incomplete but I doubt that it would be more than a couple.  Maybe 30 years ago, I did hear of a specimen from the San Mateo Formation, Oceanside locality which may be the same one noted in Barnes et al., (1981) although I recall it as LACM having the actual fossil with the private collector having the cast. 

 

There are collectors who would know if they had a sea otter or at least something weird but I haven't seen or heard of anyone finding something like that.  Maybe there's an offshore Pliocene bed full of otter stuff.  Maybe the Drake's Bay Formation needs more of a look.

 

Jess

Hey Jess, I didn't see this for some reason. Agreed 100%, and I had never even thought of looking through bear teeth. I have, however, scoured every vertebrate paleontological collection (by stratum) in Northern California - Cal Academy, UCMP, Santa Cruz Museum, Sierra College, HSU Natural history Museum, former HSU geology dept. collection, etc. - and at least I can say there are no bear specimens in marine deposits. I've not bothered looking through terrestrial/fluvial deposits.

 

As far as the Oceanside specimen goes - I've seen a cast of it at the San Diego NHM, but not the original; there is at least one Oceanside specimen referred to by Repenning (1976) where the private collector kept the specimen and a cast was kept at LACM. Maybe one of us has it backwards. OK, just interrupted my typing to double check Barnes et al. 1981: the tooth from Oceanside was kept by the collector and the cast is at LACM as LACM 121591.

[Boesse]

OK, for some reason, I cannot edit the original post - which is fine. I've now written part 3, which covers what we can say from the scrappy sea otter fossil record, including the revelation that sea otters invaded the Pacific ocean quite recently. Read it here: https://coastalpaleo.blogspot.com/2020/06/the-terrible-fossil-record-of-sea_28.html

[siteseer]

4 hours ago, Boesse said:

Hey Jess, I didn't see this for some reason. Agreed 100%, and I had never even thought of looking through bear teeth. I have, however, scoured every vertebrate paleontological collection (by stratum) in Northern California - Cal Academy, UCMP, Santa Cruz Museum, Sierra College, HSU Natural history Museum, former HSU geology dept. collection, etc. - and at least I can say there are no bear specimens in marine deposits. I've not bothered looking through terrestrial/fluvial deposits.

 

As far as the Oceanside specimen goes - I've seen a cast of it at the San Diego NHM, but not the original; there is at least one Oceanside specimen referred to by Repenning (1976) where the private collector kept the specimen and a cast was kept at LACM. Maybe one of us has it backwards. OK, just interrupted my typing to double check Barnes et al. 1981: the tooth from Oceanside was kept by the collector and the cast is at LACM as LACM 121591.

 

Hi Bobby,

 

I must be mistaken then if LACM has the cast.

 

You should be able to edit the post for at least two days.

 

Jess