Prehistoric thumbprint? Monterey seaweed? Trilo trickster?

[MrR]

Greetings experts, enthusiasts, and fellow pareidolia sufferers.

I just got back from spending a couple of nights at Jalama Beach Park. I did manage to get in a little bit of rock splitting while there. I didn't see anything fish-like. After searching for a bit before my back said "no more", I reached the pick end of my hammer over towards a larger chunk of material and gave it a whack on the side where I thought it would split. It split nicely. At first I didn't see anything, and maybe I still didn't see anything, but something did stand out as unusual no matter what it actually is. At the bottom of that balloon shaped staining there is iron-colored staining(?) that is reminiscent of a human fingerprint. And while I know it's impossible for it to be a trilobite in such a formation, the imprint looks like a trilobite stain. The overall shape of the staining also looks like a horseshoe crab. All of that said, I'm thinking that it's most likely a seaweed fossil print something of that nature. Any thoughts are appreciated.

If anybody would like another image of another area on the split, let me know. Cheers all.

MrR.

[Rockwood]

It's an odd place for it, but it looks for all the world like cone in cone.

[MrR]

6 minutes ago, Rockwood said:

It's an odd place for it, but it looks for all the world like cone in cone.

Interesting. I'm not familiar with that. Thanks, Rockwood, I'll search on it. Cheers.

 

[MrR]

Ah, so geologic in origin, and a faux fossil. Oh well, interesting anyway. That's the first I've heard of such a thing. Thanks.

 

[Fossildude19]

Isn't cone-in-cone  perpendicular to bedding planes? 

[Rockwood]

2 hours ago, Fossildude19 said:

Isn't cone-in-cone  perpendicular to bedding planes? 

It would represent a pressure gradient that could have been replicated under the shell. 

[westcoast]

Have you considered limpet or other molluscan grazing traces? Kimberichnus.

[Rockwood]

2 hours ago, westcoast said:

Have you considered limpet or other molluscan grazing traces? Kimberichnus.

No.

You think they might be found under a limpet shell, huh ? 

Could be. 

[MrR]

A relative newbie asks, "So what's a nice trace fossil from the time of the Ediacarans doing in a place like this?"  My readings regarding Kimberinchnus seem to take me back many more millions of years than I believe this formation to be? So, Rockwood, when you mention a limpet, are you referring to a possible descendant of a life form like Kimberinchnus?

[MrR]

I should add that the matrix didn't split in a clean plane. Maybe that will help narrow down what it might or might not be.

[Rockwood]

30 minutes ago, MrR said:

A relative newbie asks, "So what's a nice trace fossil from the time of the Ediacarans doing in a place like this?"  My readings regarding Kimberinchnus seem to take me back many more millions of years than I believe this formation to be? So, Rockwood, when you mention a limpet, are you referring to a possible descendant of a life form like Kimberinchnus?

The ichnospecies names are based purely on morphology. That means that there is no exclusive  time or creature strictly tied to it.

[MrR]

As I searched the web for information related to limpets, I came across Monoplacophora. According to the attached Wikipedia information, a living example of this creature was found in a 1952 dredging operation off of Baja, CA. That discovery reportedly moved up the existence of this creature some 400 million years. I'll bet that doesn't happen every day.

 

The shape and location of those strange "fingerprint-ish" markings on the matrix are consistent with where I believe a limpet-like creature's teeth would be doing their scraping. The larger outline of whatever I found (Interesting stain?) also seems to match the outline of some types of limpets.

 

If I'm not mistaken, so far the two suggestions have been a geologic phenomenon called "cone in cone", and possible traces from a kimberinchus-like creature.

 

I'd be curious to know how many think this find is more likely related to an animal, or animal's activity, or something geologic. Or perhaps nothing but an interesting stain on diatomaceous shale(?).  Comments are much appreciated. Many thanks.

 

Monoplacophora

[Rockwood]

It might be fun to throw the idea of them being gill structures in an arthropod in there.

[LabRatKing]

I present this extant example pulled from the web....looks like trace fossils from a radula to me.

 

 

If I remember it is something like inchnogenus Radulichnus, but that may be outdated terminology/taxonomy.

 

EDIT: Take a look at Figure 3 #B...I see lots of similarities.

https://www.researchgate.net/publication/261926351_Early_molluscan_evolution_Evidence_from_the_trace_fossil_record/figures?lo=1

[LabRatKing]

Of course, being a bit familiar with the site, were these found above or below the tide line? I ask as there are some spots where the trace goes over/around fracture lines and plates, which might indicate passes by an extant species that then resulted in exposure and oxidation of the next layer with a higher FeO⁺ content. Just my two cents. I'm not clear if it was found fractured or not.

 

howevey, given the fossil in the rock, the most likely is as others have stated, marks like these and fossil limpets make a pretty strong body of evidence!

 

 

[jpc]

In these pix, I see the impression of a fish scale that is n o longer there.  

[MrR]

Thanks, LabRatKing. The fossil(?) was found above the high tide line. It was in the pile of broken shale at the first land point south of the campground. I saw a large rock and hit it on the side with the pick side of my hammer and it split to expose whatever this is. I'll attach an image of both halves of the matrix as it broke.

 

At higher magnification I still don't see those vertical scratches that show throughout those radula traces, FWIW. Cheers.

 

 

[LabRatKing]

35 minutes ago, MrR said:

Thanks, LabRatKing. The fossil(?) was found above the high tide line. It was in the pile of broken shale at the first land point south of the campground. I saw a large rock and hit it on the side with the pick side of my hammer and it split to expose whatever this is. I'll attach an image of both halves of the matrix as it broke.

 

At higher magnification I still don't see those vertical scratches that show throughout those radula traces, FWIW. Cheers.

 

 

Nice, well, that clears any extant species playing tricks on us! I admit, this one has me stumped. Radual ichnos was my knee-jerk. I'm curious to see what others come up with.

[MrR]

Well, according to an expert from the Natural History Museum of Los Angeles, this puzzling example appears to be of inorganic origin. It is likely something called Liesegang staining/banding, which is something found in the Monterey Shales. This expert provided a link to information on Liesegang staining on Wikipedia. Special thanks to the NHMLA for indulging me and my question and providing the specific link.

 

These rings seem to be described as concentric, and following coincoidal fracture lines. Apparently, the exact mechanics of the formation of such hasn't been well established. I'm wondering now if the "fingerprint" mark, not overly, or perfectly concoidal, might help solve part of the puzzle of formation. At the invite of the expert, I will be bringing the shale with me to the museum when it finally reopens so he can get a better look. Cheers.

 

https://en.wikipedia.org/wiki/Liesegang_rings_(geology)

 

 

[LabRatKing]

5 minutes ago, MrR said:

Well, according to an expert from the Natural History Museum of Los Angeles, this puzzling example appears to be of inorganic origin. It is likely something called Liesegang staining/banding, which is something found in the Monterey Shales. This expert provided a link to information on Liesegang staining on Wikipedia. Special thanks to the NHMLA for indulging me and my question and providing the specific link.

 

https://en.wikipedia.org/wiki/Liesegang_rings_(geology)

 

 

Wow. That is cool! I would have never guessed Liesgang from that site. Still a worthy specimen and interesting example of what must be an uncommon form of a fairly common geologic