Number 2 invert fossil

[Mainefossils]

This is another fossil that has me stumped. I think that there is a possibility of bryozoan, because of the pits, but I remain unconvinced. It is from the Leighton Formation, which is Pridoli. The pictures below are of the fossil under raking lighting, to show the pits, then of it under lighting from directly above, and finally with scale (mm). Thanks everyone!

 

 

 

[EMP]

On 5/31/2021 at 7:18 PM, Mainefossils said:

This is another fossil that has me stumped. I think that there is a possibility of bryozoan, because of the pits, but I remain unconvinced. It is from the Leighton Formation, which is Pridoli. The pictures below are of the fossil under raking lighting, to show the pits, then of it under lighting from directly above, and finally with scale (mm). Thanks everyone!

 

 

 

 

Pretty hard to tell given the photos. Best I can do is offer some options:

 

- bryozoan, like you said, or maybe tabulate coral

 

- mineralization, like calcite 

 

- trilobite genal spine, but I don't know if your unit has trilobite species with such spines?

 

- Some kind of brachiopod hinge

 

Really depends on the fauna of your formation. 

 

 

Ok, I quickly read up on the Leighton:

 

"On Leighton Neck, most of the Leighton Formation consists of gray and glue-gray, somewhat limey, siltstone and shale (Sls). Lenses and elongate nodules of limestone within bedding, thin lensing beds, and irregular wavey contacts between beds are typical. Near the base of the Leighton Formation, the typical siltstones and shales interstratify with siliceous well-bedded tuffs and tuffaceous siltstones containing pumice lapilli and feldspar crystals, indicative of ash falls. Outpourings, apparently through vents in the sea floor, of coarse basaltic tuff-breccia. and lapilli tuff (Slbt) produced thick lenses whose upper surfaces and margins were reworked by waves and currents. Thin basalt flows, (Slb), also apparently erupted through the sea floor, overlie some of the basaltic tuffs, Several thin submarine pyroclastic flows (Slt) moved across the muddy sea floor churning up and incorporating the underlying muds. These pyroclastic debris flows consist of broken quartz and albitized plagioclase crystals, shards, pumice lapilli and abundant fragments of silicified shale and argillite."

 

Your piece definitely appears as siliceous, but that could be the lighting, I don't know. If it is siliceous I'd say mineralization sounds like a decent option? The pitting could be due to chemical weathering or some other mechanism. It could also be possible this was such a mineral crystal re-worked into another layer, if this doesn't come from the more volcanic layers. 

 

Geologic map and cross sections of the Eastport quadrangle, Maine (core.ac.uk)

[Mainefossils]

Thank you so much for the information! I have prepped it out, and it looks like a badly weathered piece of brachiopod, like your 4th suggestion. I appreciate all the detail you provided. Do you have any suggestions for how I could have presented the photos to make identification easier?

 

[EMP]

2 hours ago, Mainefossils said:

Thank you so much for the information! I have prepped it out, and it looks like a badly weathered piece of brachiopod, like your 4th suggestion. I appreciate all the detail you provided. Do you have any suggestions for how I could have presented the photos to make identification easier?

 

 

Of course, no problem!
 

Honestly your photos are usually pretty good, it's just with any kind of photo on the internet it's going to be harder to tell what something is. It might help adding different angles/shading to see if there's maybe some detail or color/texture not present in the other photos. Shading can be helpful with small details on the surface especially. 

[minnbuckeye]

12 hours ago, Mainefossils said:

 Do you have any suggestions for how I could have presented the photos to make identification easier?

Waiting until post prep!!! Actually from my vantage point, your pictures are fine! In focus, cropped down properly, and includes a scale for viewers to understand size. Great job. 

 

Mike

[Mainefossils]

51 minutes ago, minnbuckeye said:

Waiting until post prep!!! Actually from my vantage point, your pictures are fine! In focus, cropped down properly, and includes a scale for viewers to understand size. Great job. 

 

Mike

Thanks!  Below is the a post-prep picture, a rather unimpressive piece of a Camarotoechia leightoni. 

 

 

 

[Coco]

Hi,

 

19 hours ago, minnbuckeye said:

and includes a scale for viewers to understand size.

 

Just a small remark: when we do not see the measuring marks in full, we cannot know if it is cm/mm or inch! You have to show all the features (all the way up)

 

Coco