Alaskan Polar Bear & Walrus Fossils - Date Ranges

[BellamyBlake]

Hi everyone,

 

I recently came across online Alaskan fossils. Specifically they are a Polar Bear and Walrus tooth from St. Lawrence Island, Alaska. There doesn't seem to be much of a consensus on the age ranges for those teeth, and having those would be useful to me.

 

According to a geological map, St. Lawrence Island, Alaska, is Quaternary at its earliest: https://alaska.usgs.gov/science/geology/state_map/interactive_map/AKgeologic_map.html. That already puts me at a range of 2.6 million - 11,000 years, pretty wide. Initial research suggests polar bears evolved maybe 150,000 years ago, and their oldest fossils are around 120,000. I have no idea on the walrus yet. Does this mean, though, that my polar bear tooth is between 11,000 and 120,000 years old, or could it be narrowed down further?

 

I'd love some insight from those who have knowledge of these aspects of paleontology. I would appreciate age ranged on the polar bear and walrus fossils found on St. Lawrence Island, Alaska.

 

Thank you,

Bellamy

[Top Trilo]

i'm not sure how you would narrow it down any further unless you had a more exact location of where it was found. However a range of 109,000 years is pretty good for most fossils.

[BellamyBlake]

24 minutes ago, Top Trilo said:

i'm not sure how you would narrow it down any further unless you had a more exact location of where it was found. However a range of 109,000 years is pretty good for most fossils.

For sure, I'm a little more curious about the walrus. The seller noted it's Pleistocene and from St. Lawrence Island in Alaska, but nothing more is known. 

[siteseer]

On 9/16/2020 at 6:03 PM, BellamyBlake said:

Hi everyone,

 

I recently came across online Alaskan fossils. Specifically they are a Polar Bear and Walrus tooth from St. Lawrence Island, Alaska. There doesn't seem to be much of a consensus on the age ranges for those teeth, and having those would be useful to me.

 

According to a geological map, St. Lawrence Island, Alaska, is Quaternary at its earliest: https://alaska.usgs.gov/science/geology/state_map/interactive_map/AKgeologic_map.html. That already puts me at a range of 2.6 million - 11,000 years, pretty wide. Initial research suggests polar bears evolved maybe 150,000 years ago, and their oldest fossils are around 120,000. I have no idea on the walrus yet. Does this mean, though, that my polar bear tooth is between 11,000 and 120,000 years old, or could it be narrowed down further?

 

I'd love some insight from those who have knowledge of these aspects of paleontology. I would appreciate age ranged on the polar bear and walrus fossils found on St. Lawrence Island, Alaska.

 

Thank you,

Bellamy

 

Unless the walrus and polar bear teeth were collected in a layer with some kind of remains of a Pleistocene animal that didn't survive well into the Holocene (mammoth, sabercat) you're not going to know if the teeth are Pleistocene or maybe just several thousand or even just hundreds of years old.  Since at least the early 90's, I've seen walrus teeth/bones, canid teeth, and smaller teeth for sale from St. Lawrence Island.  One collector took a look at a couple of the canid teeth and leaned toward a decent-sized domesticated dog ID rather than a wolf which indicates that the other remains may be most likely Holocene age too.  The walrus teeth are usually offered polished for the jewelry business.  

 

I have tended to avoid the St. Lawrence Island and other possibly Pleistocene fossils just because there is a question of the age.  I have seen mammoth teeth from Alaska so there are other Pleistocene fossils there but it's not really possible to know whether a particular walrus tooth is Pleistocene unless you go to the point of having a piece of it carbon-dated, specimens of that age being young enough to have their age determined that way.  It comes down to a specimen-by-specimen decision and knowing the dealer.  I have known a couple of them that were very knowledgeable about what they have but I'm more of a shark tooth collector and haven't really made it a priority to pick up stuff from there.

 

I would also look for scientific journal articles on the Pleistocene of St. Lawrence Island.

 

Jess

 

[BellamyBlake]

4 minutes ago, siteseer said:

 

Unless the walrus and polar bear teeth were collected in a layer with some kind of remains of a Pleistocene animal that didn't survive well into the Holocene (mammoth, sabercat) you're not going to know if the teeth are Pleistocene or maybe just several thousand or even just hundreds of years old.  Since at least the early 90's, I've seen walrus teeth/bones, canid teeth, and smaller teeth for sale from St. Lawrence Island.  One collector took a look at a couple of the canid teeth and leaned toward a decent-sized domesticated dog ID rather than a wolf which indicates that the other remains may be most likely Holocene age too.  The walrus teeth are usually offered polished for the jewelry business.  

 

I have tended to avoid the St. Lawrence Island and other possibly Pleistocene fossils just because there is a question of the age.  I have seen mammoth teeth from Alaska so there are other Pleistocene fossils there but it's not really possible to know whether a particular walrus tooth is Pleistocene unless you go to the point of having a piece of it carbon-dated, specimens of that age being young enough to have their age determined that way.  It comes down to a specimen-by-specimen decision and knowing the dealer.  I have known a couple of them that were very knowledgeable about what they have but I'm more of a shark tooth collector and haven't really made it a priority to pick up stuff from there.

 

I would also look for scientific journal articles on the Pleistocene of St. Lawrence Island.

 

Jess

 

Hi Jess,

 

Thank you for sharing your experiences. I understand your point. I, like you, am a shark tooth collector. I'm pretty new to the mammal world which is why I became curious when it was noted that these were Pleistocene but they didn't look it. I know that color alone doesn't accurately speak to age and it can be misleading. So I asked how one might know the difference. I think a part of this comes from being a historian - we're obsessed with dates and narrowing those down as accurately as possible haha. Ultimately, I understand that it can't be narrowed down further than "this is from the Pleistocene to Holocene" and I'm fine with it, though I will continue to look for relevant journal articles simply because it's interesting, and who knows I may even find answers.