Sand Dollar and Oyster Fossils - "Fossil Creek" - Los Padres Mountains - Southern California

[ezeemonee]

Sand Dollar and Oyster Fossils found at un-named tributary of the Sespe Creek drainage sometimes called "Fossil Creek" by the locals.  In the Los Padres Mountains of Southern California.  Many fossils from the Miocene and maybe Eocene era wash down this creek from the cliffs above.  Someone I met on the hike found a large gastropod fossil and I should have asked to take a picture but forgot to. The thick Shelled Oyster could be any one of the known species from these mountains:  Ostrea titan, Ostrea wiedei, Ostrea howelli, Ostrea verpertina or a Pycnodonte species.  Found what appeared to be concentrated sea urchin spines too but might be something else.  At home, I tried carefully extracting the sand dollars from the hard sandstone matrix using soaking, freezing, and heating and had some luck but they all ended up shattering to some degree.  Not sure if a Dremel tool would be any better even if its faster.  

 

[DPS Ammonite]

Show us some urchin spines. 

 

If they are hollow and have cross pieces then they are cross sections of sand dollars.

[ezeemonee]

On 6/3/2024 at 10:55 PM, DPS Ammonite said:

Show us some urchin spines. 

 

If they are hollow and have cross pieces then they are cross sections of sand dollars.

Check the last pic.  Sea Urchin spines was my best guess but let me know if you think they may be something else.  Thanks!

[Coco]

Hi,

 

Obvious example where the size in cm or inches is very important for a good identification !

 

In your last photo I don’t see sea urchin spines. In addition, the pieces of sea urchins correspond to burrowing sea urchins (many different species), which they do not have thorns strictly speaking, they have "silks", that is to say, hairs a little like those of domestic pigs, so less than 1 mm in diameter !

 

Here is the example of a sea urchin with silks

 

 

Coco