Coprolite?

[Mainefossils]

I have just found this little coprolite? yesterday. This is the second time a coprolite-like fossil has turned up in the shale from the Leighton Fm. I am not really sure on this one, though, due to the presence of crinoid stems. The fossil(s) are from the Leighton Formation, Maine; which is Pridoli, Silurian. 

 

The main reason I think it is a coprolite is because of its situation in the shale. The rest of the shale around it is relatively uniform, with no fossils whatsoever. The fossils present in it are one crinoid stem, quite a few ostracods, a very small Orbiculoidea brachiopod, and an unidentified piece of rather bluish-black material in the center, possibly some sort of shell. 

 

My main concern for its identification as a coprolite is the wide range of rather large fossils in it. I don't know what animal would have had such a diet, except possibly a very large detritivore - but I don't know of any super large ones here. The only animals that I can think of producing coprolites in this formation would be eurypterids, phyllocarids, agnathan fish, and possibly trilobites. A coprolite of this size I would identify as an agnathan fish, but I would defer to some of our fish and coprolite experts for this. @jdp @GeschWhat

 

Below are two photos of the two different sides of the coprolite. If you would like closeup photos of some of the fossils inside the coprolite, I have some available. Just did not want to overload this post with too many photos. 

 

Thanks in advance for your help everyone! 

 

 

Edited September 2, 2021 by Mainefossils

[Fossildude19]

Could be a coprolite, or regurgitant.

 

[fifbrindacier]

You can follow Lori's thread about coprolites.

On 7/17/2018 at 3:01 AM, GeschWhat said:

Rather than writing information about coprolite identification on multiple threads, I thought I would post information about coprolite identification here so it can be referenced in ID threads (I'm getting lazy, I know). I was also thinking it might be fun for others to post coprolites in their own collections so others can use them for comparison. So here we go:

 

IDENTIFYING COPROLITES:  Not all rocks that look like poop have a fecal origin. Here are a few things to consider when trying to make this determination:

 

1. Location, Location, Location – If you haven’t guessed, the first and most important thing to consider is the location your rock was found. Don’t expect to find a coprolite unless you find it in geologic area/layer where other fossils are found. If you find things like bones, teeth and fish scales, or prehistoric tracks, you may just be in in luck.

 

2. Shape – While fecal matter can be rather freeform when exposed to the elements or when digestion issues arise, most coprolites are shaped like poo. As with modern extrusions, fossilized feces can be shaped like pellets, spirals, scrolls, logs, piles, etc.  Their shape is dependent on shape of their producers intestinal and anal structure. Look for things like compaction folds and pinch marks.

 

3. Texture - Most coprolites are fine grained. If your specimen appears granular under magnification, it is most likely not a coprolite.  There are some exceptions, such as marine creatures that feed on bottom sediments or coral. That is why knowing the location and geology of the area where it was discovered is so important.

 

4. Inclusions – Many times, coprolites will have visible inclusions. Things like fish scales, bone fragments, and teeth may not get fully digested, and can be visible on the surface. Some animals ingest stones for ballast or digestive purposes. These are known as gastroliths, and if present, are generally smooth.

 

5. Composition –  Because herbivore scat tends to break a part and decompose rapidly, it rarely survives the fossilization process. So most fossil poo that is found is from carnivores. The reason for this is that their poo is usually high in calcium phosphate, the same mineral found in our bones.  This mineral can appear in many forms. It can be hard and dense or soft and porous. If the potential coprolite appears soft and porous, there is a quick test that is often used in the field. If you touch to stone to the tip of your tongue and it sticks, chances are, it is high in calcium phosphate and could be a coprolite.  If you are not that brave, you can also touch it with wet fingers to see if it feels sticky, but this is not nearly as fun. If the calcium phosphate takes a harder, denser form the “lick test” won’t work. In some instances, chemical analysis is required to definitively identify the mineral composition.

 

@Carl do you have anything you want to add?

 

 

 

[Rockwood]

'spose it could be the equivalent of a capped landfill ? A burrow fossil with the discarded bits from a predators meals. 

[Mainefossils]

Thanks everyone for your opinions! 

 

@fifbrindacier , I have really enjoyed reading @GeschWhat's thread, it is very comprehensive. 

 

@Rockwood, I did not think of a burrow fossil. I was pretty certain that whatever critters are in it had fallen to the sediment, but a burrow opens up a whole different train of thought. I will have to look into this more. 

 

Thank you all for your time!  

 

 

 

[Rockwood]

Tiny lingulids in a loosely consolidated phosphate nodule ? Begging the question why the congregation, but perhaps suggesting a taphonomic  route to existence ?