Encrustation

[Rockwood]

Found in glacial drift in north western Maine. The rock type is a good match for Tarratine sandstone. Lower Devonian marine delta deposits.

I've walked by this fossil so many times it's like an old friend. I had always assumed it to be a bivalve with weathered out pyrite crystals. It was exposed on a small gravel beach as I skied by this morning so I decided to give it a look.

I think I have been wrong. What do you think ?

[Peat Burns]

Bivalve steinkern would have been my guess, too. 

[Tidgy's Dad]

And mine. 

[Rockwood]

10 minutes ago, Peat Burns said:

steinkern

Wouldn't it be an internal mold of a single valve, and hadn't there been something that settled in and colonized it ?

[Peat Burns]

7 minutes ago, Rockwood said:

Wouldn't it be an internal mold of a single valve, and hadn't there been something that settled in and colonized it ?

I wanted to say that, but I didn't want to start the whole debate on internal / external mold / cast controversy.  Is "steinkern" as it might be used for bivalves restricted to only those that were created between both valves?

[Rockwood]

15 minutes ago, Peat Burns said:

I wanted to say that, but I didn't want to start the whole debate on internal / external mold / cast controversy.  Is "steinkern" as it might be used for bivalves restricted to only those that were created between both valves?

Ah !

The old 'can of worms' defense. 

[Rockwood]

18 minutes ago, Peat Burns said:

Is "steinkern" as it might be used for bivalves restricted to only those that were created between both valves?

My understanding.

[Peat Burns]

1 hour ago, Rockwood said:

My understanding.

One can't win no matter what term they use, I guess 

[abyssunder]

I'm not familiar with that area, but I wonder if can't be a lingulid brachiopod valve.

[Rockwood]

I  sort of anticipated it to be called a phyllocarid.

[Fossildude19]

1 hour ago, Rockwood said:

I  sort of anticipated it to be called a phyllocarid.

I had considered, that, Dale, but the shape is off for me. 

Looks more like a pelecypod to me. 

 

 

If there are arthopodish texture (pustules or divots) on the right side, I would say it could be a phyllocarid.

One of mine:  Rhinocaris columbia

 

 

 

 

Lingula brachiopods are much more unilaterally oval, ... where as this has a taper, and faint growth lines on one end, that are not concentric. 

Here's one of mine: Lingula delia

 

 

 

[abyssunder]

What made me think that might be a lingulid is not just the entire shape of it, but the flagellated margin (chaetae) which I think I see in the pictures. I can't see encrustation, but dissolution.

 

[Rockwood]

4 hours ago, abyssunder said:

I can't see encrustation, but dissolution.

Like the under side of an overturned boat. There would tend to be a void that would fill with solubles.

So much for my rare preservation of a phyllocarid body.

I'll be traveling that shoreline until the road thaws and hardens. I prefer rocks over snow and mud. So maybe next time.

Thanks all.