Miocene Sea Snail And ?

[AncientEarth]

Went out last Tuesday to one of my favorite local fossil spots and found something I'd not seen yet. Curious what the group might make of it.

I was collecting a layer of Forreria carisaensis from an outcropping of the Santa Margarita Formation I'd not previously hunted before and this popped off the wall when I was extracting the Forreria. The other half did not show any remains of these circular ... things.

My thoughts are something fishy, sometimes you see the random scale or vert, but they tend to be a lighter red/orange color and different texture.

I'll try and prep the piece later this week and see if other clues show.

If anyone knows of, or has, research documents for this formation layer that are more recent than 1978, it'd be greatly appreciated if you shared them or sent me a PM, I will buy hard copies.

[siteseer]

AncientEarth,

I have collected the Santa Margarita. I used to go to the Lockhart Gulch site to dig/sift for teeth and I have looked for Astrodapsis sites higher in the formation as well. With Astrodapsis I found a couple of barnacles, some sea urchin spines, and a couple of gastropods. I don't know what your photo shows.

You can look for this publication:

Clark, J.C. 1981

Stratigraphy, paleontology, and geology of the central Santa Cruz Mountains, California Coast ranges. U.S. Geological Survey Prof. Paper 1168.

When the USGS is open again, you should be able to order it.

Went out last Tuesday to one of my favorite local fossil spots and found something I'd not seen yet. Curious what the group might make of it.

I was collecting a layer of Forreria carisaensis from an outcropping of the Santa Margarita Formation I'd not previously hunted before and this popped off the wall when I was extracting the Forreria. The other half did not show any remains of these circular ... things.

My thoughts are something fishy, sometimes you see the random scale or vert, but they tend to be a lighter red/orange color and different texture.

I'll try and prep the piece later this week and see if other clues show.

If anyone knows of, or has, research documents for this formation layer that are more recent than 1978, it'd be greatly appreciated if you shared them or sent me a PM, I will buy hard copies.

Edited October 14, 2013 by siteseer

[mako-mama]

Made by boring clams?

[Plax]

sounds right to me mako mama a bit too big for boring sponges, thats probably a ghost of a mollusk they're in

[AncientEarth]

The impressions come to a flat surface with wrinkled texture across it rather than a concave bore. That's why I was leaning towards fish scale, but the scales I generally find are broken along suture/growth lines and different texture entirely. Do different clams bore different shapes? It may be possible this is the inside of something, you can see the yellow material filled the circular areas to a point but still are fairly flat in shape. It was my impression boring clams likes rockier and denser materials.

Hopefully this photo is slightly clearer. I might have to take another stab at it today for something with more light.



Siteseer,

Thanks again for the informative response. Any experience with the SM Frm along 58 in Santa Margarita, CA? From what I can tell, there is some variation in the fossils found, particularly the Astrodapsis sp. here are more varied it seems (3-4 types). I also find tons of barnacles, clams, oysters, scallops, occasional coral and teeth as well. I've pulled a few Astrodapsis with the spines still intact, but those are rare from here. To me this area seems like it was a reef environment, I am unsure how that compares to the site in the Santa Cruz Mtns, when I was younger (grew up in San Jose), I just recall hearing about the sand dollars and teeth.

The outcropping further East of here in Kern County exposes some of this same, more siliceous sandstone, but the site is primarily pecten and muscles.


How is this for another loop, fossil fish eggs? Maybe this is more plausible, a pharyngeal tooth plate from a Labrid fish?

AncientEarth,

I have collected the Santa Margarita. I used to go to the Lockhart Gulch site to dig/sift for teeth and I have looked for Astrodapsis sites higher in the formation as well. With Astrodapsis I found a couple of barnacles, some sea urchin spines, and a couple of gastropods. I don't know what your photo shows.

You can look for this publication:

Clark, J.C. 1981

Stratigraphy, paleontology, and geology of the central Santa Cruz Mountains, California Coast ranges. U.S. Geological Survey Prof. Paper 1168.

When the USGS is open again, you should be able to order it.