Micros from an unknown Cretaceous (?) Colorado formation.

[Brett Breakin' Rocks]

Hello Everyone, 

 

I picked up some Cretaceous fossil matrix (fossiliferous rocks) from an auction that our WIPS (Western Interior Paleontological Society) group held last year. I picked them up knowing I wanted to give them a nice Vinegar bath and pull out the teeth/fossils trapped in the matrix. So far it looks like it was a very vigorus marine environment. The teeth and fossils are fairly worn and broken. Lots of fishy bits and pieces. A few shark teeth, fish teeth etc...

I'm going to share the finds as they drop out of the matrix. I pull the fossils out of the solution every day or so, and refresh the vinegar once or twice a week. I manipulate and move the fossils using a small paintbrush. With what I have so far being able to sit quite comfortably in a pencil eraser's footprint.

1) My question is, what are these round things ? They have bands of light/dark and they are water polished. They don't 'look' geological. But I'm not familiar with fossils/structures such as these. Average size is less than a mm. Maybe 0.5mm if I had to guess. I'm not familar with Ostracods .. but I thought they were more assymetrical in shape. See image below. These survived the Vinegar bath and I've probably noted 2 dozen of about the same size and shape. 

 

2) The formation I am assuming is from Colorado?  The member these fossil rocks belonged to was a long-time member here in Colorado. The fossils feel like they are lying in that Cretaceous timeframe and look familar to what I have seen before. Does anyone recognize this rock type/formation ?

 

A selection of the finds so far:

 

 

The Ptychodus is about 2mm

Thanks,
Brett  

Edited May 7, 2023 by Brett Breakin' Rocks

[GeschWhat]

Lincoln Limestone (basal) maybe? I have some from Kansas. The little white bits are coprolites me thinks. The will likely dissolve in the vinegar.

 

Just did a quick check. There are exposures of this formation in southeastern Colorado as well.

 

https://via.library.depaul.edu/cgi/viewcontent.cgi?article=1038&context=depaul-disc

Edited May 7, 2023 by GeschWhat

[Brett Breakin' Rocks]

1 hour ago, GeschWhat said:

Just did a quick check. There are exposures of this formation in southeastern Colorado as well.

Ahh ... Indeed, I am familiar with these exposures and some of the various layers in SW Colorado.  This new material has a different look and feel. The material in the grasslands is more traditional sandstone-like. Yellow and reds. And there are many shell hash plates and various invertebrates to be found. Ammanoids etc.. This stuff feels different. 

 

I appreciate the paper. I have poured over these images quite alot. Though the shark teeth are off-limits for collecting in the Grasslands, they are easy to spot in the rocks. The Ptychodus is the most abundant. 

 

Thanks for the help all the same. I'll keep a few bits of the coprolite portion as a specimen. Very cool. 

 

PS. If anyone wants a chunk of this rock to explore just let me know. 

[Al Dente]

Nice finds. These two are fish pharyngeal teeth.

 

 

[GeschWhat]

12 hours ago, Brett Breakin' Rocks said:

Ahh ... Indeed, I am familiar with these exposures and some of the various layers in SW Colorado.  This new material has a different look and feel. The material in the grasslands is more traditional sandstone-like. Yellow and reds. And there are many shell hash plates and various invertebrates to be found. Ammanoids etc.. This stuff feels different. 

 

I appreciate the paper. I have poured over these images quite alot. Though the shark teeth are off-limits for collecting in the Grasslands, they are easy to spot in the rocks. The Ptychodus is the most abundant. 

 

Thanks for the help all the same. I'll keep a few bits of the coprolite portion as a specimen. Very cool. 

 

PS. If anyone wants a chunk of this rock to explore just let me know. 

I only have one small piece of basal Lincoln Limestone that I received from @Ramo quite a few years ago. I finally fired up my dinosaur of a laptop so that I could look at images of my specimen, and you are right, It does look different.  

[Brett Breakin' Rocks]

5 minutes ago, GeschWhat said:

I finally fired up my dinosaur of a laptop so that I could look at images of my specimen, and you are right, It does look different.  

Wow, that's a really great example!  

 

If you feel like you need some more fish coprolites in-situ let me know and I'll send along a hunk of this stuff to you. Thanks again for your feedback. 

 

B

[Brett Breakin' Rocks]

A few of the new finds. Lots of shark and fish teeth in these samples. 

 

There was a partial crown I ran into that I thought was initially a shark tooth partial. The teeth from these vinegar treated stones are very re-worked and worn. I'm not as familiar with denticle shapes from Cretaceous sharks. @Troodon This doesn't look like a reptile tooth or something other than a shark tooth does it ? This specimen is about 3mm long, and split in half. Thanks !

 

[Troodon]

Cool tooth and weird but nothing I'm familiar with. 

[Yoda]

@Brett Breakin' Rocks

Nice micro finds 

[Brett Breakin' Rocks]

My process as it has evolved to smaller and smaller micros. No amount of sifting will capture and keep what I need (apart from sorting out the fine silt in solution) 

 

So after my soak.

I pour what the Vinegar (Acetic Acid) has not dissolved into a glass dish. And rinse carefully with a fresh water flush. I pour that onto a good paper-towel. 

And dry slowly using the radiant heat from my toaster oven. (I'm too lazy to let it air dry) I understand there is a possibility this will cause cracking or damage to fragile fossils, but did I mention I'm impatient as well ?

 

Dryed stock goes onto a slightly opaque (milky) surface, perfact for scattering and diffusing the light beneath and around the fossils. 

And my budget setup for picture and video, has been working great so far. Maybe a true scope/binocular scope in the future, but for now the budget setup is working well. The images are saved on a MiniSD card and can be transferred directly via cable to the computer, or uploaded with a card reader. 

Paintbrush for picking things up and moving them to their collection points. 

 

Cheers,
Brett

Edited May 12, 2023 by Brett Breakin' Rocks

[Yoda]

@Brett Breakin' Rocks

Thanks for showing your process 

[Brett Breakin' Rocks]

These micros are pretty beat up, but occasionally there are a few shark teeth that are robust enough to survive. (mostly intact)
 

 

Haven't run ID's on these yet, but here are a few more teeth to survive the churn. Maybe this is from a Palaeobalistem sp. ? (Pycnodont fish)

 

Edited May 17, 2023 by Brett Breakin' Rocks

[Notidanodon]

great finds! preservation reminds me of mesaverde fm?

[Brett Breakin' Rocks]

14 minutes ago, Notidanodon said:

mesaverde fm

Oh wow, my best lead so far. That is the right time period (late Cretaceous) and location for the Western Interior seaway. Thank you, I'll do some digging in that direction. I appreciate it ...

Cheers,
Brett

[Brett Breakin' Rocks]

Process photos .. (not the best) acid prep in progress. 

 

[Brett Breakin' Rocks]

A few new interesting finds.
Cantioscyllium sp. (?) - Extinct Nurse Shark 

 

Shark/Ray Denticle (approx 1mm)

 

Unknown Tooth (?) - approx 1mm

 

Fish Tooth Plate Partial 

 

Isolated pycnodont teeth are not uncommon

Edited May 20, 2023 by Brett Breakin' Rocks

[Brett Breakin' Rocks]

A few updates on the finds. Lots of fish parts, with most being broken up and unrecognizable. Occasionally though, a few of the more robust bones make it through the wash and repeat .... Here is an Opercular from a bony fish's face. 

Chiloscyllium greeni - Bamboo shark teeth

Osteichthyes - My first bony fish scale

Pycnodont fish teeth

Unidentified shark teeth with Ray Dermal Denticle (a first intact)

Ptychotrygon sp. - Sawfish tooth

Ptychodus shark teeth are fairly common but usually broken into tiny pieces. Here are two examples. 

This one has a (fish ?) tooth with it. 

 

Not 100% but probably another very small sawfish oral tooth. 

 

Cheers,
Brett

 

 

Edited May 25, 2023 by Brett Breakin' Rocks

[Bobby Rico]

On 5/11/2023 at 5:48 PM, Brett Breakin' Rocks said:

And dry slowly using the radiant heat from my toaster oven. (I'm too lazy to let it air dry) I understand there is a possibility this will cause cracking or damage to fragile fossils, but did I mention I'm impatient as well ?

Hi Brett micro matrix is great fun and you got some lovely shark teeth their. 
 

haha you’re post reminds me of a resent topic about the obsession of been a collector. It goes like this  “ you know you’re a fossil collector when” you’re other half does not question why,  you are marinading your fossils in vintager and then grilling them on a low heat until nicely done.  
 

all the best my friend. Bobby 

Edited May 25, 2023 by Bobby Rico

[old bones]

These are beautiful finds, Brett. The Ptychodus are especially nice.

[rocket]

we sometimes have this in sandy sediments, we think this are coprolites

 

[Brett Breakin' Rocks]

1 hour ago, rocket said:

we sometimes have this in sandy sediments, we think this are coprolites

Thanks for the insights ... these are fairly common in this size (approx 1mm). I have many examples in the 1cm+ range that are not "polished" that I think are coprolites as well. They survived the acid bath.

Cheers,
Brett

 

10 hours ago, Bobby Rico said:

 you are marinading your fossils in vintager and then grilling them on a low heat until nicely done.  

 

haha ... Yeah, "As long as I don't burn down the house !" is my wife's refrain. It is always a delicate operation, I have to use odd available spaces. She inadvertently opened a cabinet to return some books, and tossed about 2 months worth of work all over the shelf. She could not understand why I was acting like she stepped on my cat .... 

Edited May 25, 2023 by Brett Breakin' Rocks

[deltav2]

this one looks similar to an eotrigonodon tooth i have in my collection

Edited May 26, 2023 by deltav2

[Brett Breakin' Rocks]

3 hours ago, deltav2 said:

this one looks similar to an eotrigonodon tooth i have in my collection

Cool.
Indeed, this form for bony fish tooth has not changed much in the geologic eras. These pharyngeal teeth in the images are most likely from the Upper/Late Cretaceous.  Maybe something similar like Hadrodus sp. as described from the Blue Hill Shale (Nebraska)

 

and Juana Lopez Member of the Carlile Shale in SE Colorodo. 

 

Cheers,
Brett

[Brett Breakin' Rocks]

The sorting continues ...... 

B

[Brett Breakin' Rocks]

The first Ceratodus sp. Lungfish tooth. (3mm)