Strange Finds from the Austin Ozan. A Test for the Ozan Experts.

[Mikrogeophagus]

I decided to take a trip to an Ozan spot after some rain a couple weeks ago. The gravel finds were sparse, but I fortunately remembered to bring some of my trusty excavating tools with me from Dallas to Austin. After the trek to the main exposure at this site, I got to scouring the shaly creek bed. In previous trips, I usually didn't spend much time doing this as I had limited tools for digging. With some newly acquired technology by my side, I encountered a facet of this location I hadn't experienced before. A lot of the fossils that preserve in this formation are too fragile to survive once exposed to the elements. I was surprised to see the wide array of species I had been missing out on in the past. Some things were easy to recognize. I came across a chunk of matrix filled with fragments of heart urchins. Not much of it was worth keeping even after I poked and pried my way through it. In the end, I only decided to keep what I think is a long urchin spine (B) with some echinoid bits on the underside. I also found some crustacean parts for the first time in the Ozan (C). I believe I managed to find the scattered remains of what once was a decently sized crab. It's extremely fragile and there appear to be limbs scattered every which way. I got to this ID by spotting a couple of spiny shelled projections poking out at various points. Later cleaning revealed some more. The thing is so destroyed, however, I might give up on it. I also came across what looks like a piece of a crab claw.

 

My most enigmatic find was something I almost overlooked completely. Here and there throughout the exposure were these broad, dark patches of shale (A). I assumed they were flat, but when I accidentally kicked one, a section popped right out of the matrix and revealed its 3D nature. After working out the others parts by it, I noticed that these things had some regularity to them and perhaps were the remnants of an animal or plant or whatever. On both sides of the specimens, there appears to be a darkened indention running down the midline. I also noticed curved lines running across the pieces in a pattern reminding me of the banding found on the shells of baculites. The cross section of these finds appear to just be shale and do not present much information. The pieces start off wide and gradually thin themselves towards one side before ending in a point. I wish I took pictures of them in situ, but I unfortunately only have pics from my room. One specimen had pyritic inclusions which are typical for fossils from this exposure (I've seen pyrite in bones, crustaceans, urchins, oysters, etc.). When I look at them, I start thinking of cephalopods, but that's a big jump. They could be some sort of trace fossil, but that doesn't quite feel right. I don't know if any Ozan experts on here will recognize these, but I am really curious to try and pin down some ID if there is one to be found.

 

To round off the trip, I also came across a horn-shaped coral (D) that I suppose washed down from the Austin Chalk up stream. Some more typical finds (E) were also to be had. It was nice to get back out and enjoy the cool waters of an Austin creek. I won't be sticking around long, however, as I am about to make a couple of trips across Texas for school interview stuff in the near future, so look forward to future posts outside of my usual grounds.  

 

Picture:

 

A). Main Enigmatic Finds. This is the bigger piece. It continued under the shale below the unstable wall of the creek. Decided it was dangerous to dig to the end of it.

 

Second piece I brought back. Much smaller, has pyrite, and still partially in the matrix

 

 

B). Urchin Spine?

 

C). Crustaceans. The top shows the pyritic scattered one. The bottom shows the claw.

 

 

D). Coral I think washed from the Austin Chalk.

 

E). Typical finds (Goblin Shark teeth on the left and enchodus tooth on the right. Small mosasaur vert on the bottom I think from the Austin Chalk)

 

Thanks for reading!

[Thomas.Dodson]

Your first 2 finds are compressed Baculites. We could use more in-focus, better lit images of the crustacean pieces.

[Mikrogeophagus]

@Thomas.Dodson Thanks for the exciting ID. Next time I will be on the look out for a better baculites specimen. Have you seen compressed ones like these before or did you reach that conclusion just from the info I provided? I will try to get some better photos of the crustacean as well when I am able to!

[BobWill]

No need to look in the Austin Chalk for those little button corals, we find them in the Ozan north of Dallas. Trochocyathus sp. I believe.

 

I agree with flattened Baculites sp.  Most things can get compressed in preservation.

[Thomas.Dodson]

3 hours ago, EPIKLULSXDDDDD said:

@Thomas.Dodson Thanks for the exciting ID. Next time I will be on the look out for a better baculites specimen. Have you seen compressed ones like these before or did you reach that conclusion just from the info I provided? I will try to get some better photos of the crustacean as well when I am able to!

I have collected compressed ones from the Ozan before.

 

It's always interesting how things in the Ozan (and other formations) can compress in such interesting ways. Last time I was up that way I collected a big Anchura on the North Sulphur that was flattened like a pancake. It's one of my favorite inverts from the area.

[JohnJ]

Echinoid spines are typically preserved as calcite in the Texas Cretaceous.  This doesn't look like that at first glance.  Is there a base or acetabulum visible beneath that bit of matrix?

[DPS Ammonite]

Here is the most interesting one: bone, feather? I agree with John, not an urchin spine: too smooth and too dark.

 

 

Edited September 5, 2022 by DPS Ammonite

[Mikrogeophagus]

@JohnJ@DPS Ammonite On the leftmost portion of the "spine" there seems to be a lip that I often see on the bases of urchin spines online. It's difficult to make out because that section of the "spine" is the same color as the matrix. Another interesting thing to note is that, travelling to the right, the "spine" steadily widens. The rightmost point was not preserved with the specimen, unfortunately, as there appears to be a break. This could just be due to preservation and a bivalve being underneath it, but towards the right end, the "spine" suddenly bends upwards. I believe there are no urchin parts immediately underneath it.

 

As for an acetabulum, could you tell me what that is? I tried looking it up, but I couldn't find much in the way of a definition.

 

As a disclaimer I would also like to emphasize that the imprints and markings made around the "spine" are due to my "prep work" if you can even call it that  . They are by no means natural! This was originally not exposed at all so there are scrapes everywhere from my digging.

 

I will take more pictures tomorrow when I get the chance.

[DPS Ammonite]

2 minutes ago, EPIKLULSXDDDDD said:

As a disclaimer I would also like to emphasize that the imprints and markings made around the "spine" are due to my "prep work" if you can even call it that  . They are by no means natural! This was originally not exposed at all so there are scrapes everywhere from my digging.

 

Thanks for explaining; your marks sort of looked like part of a feather.
 

Does the either small end of the spine have the perfect cleavage of calcite? Urchin spines are single calcite crystals.

[Mikrogeophagus]

@DPS Ammonite I think both ends do, but it is difficult to tell. The light brown end is also semi-translucent. I would have cleaned more on the left end, but I was worried of breaking it so it's just encased in paraloid. Despite this, you can still make out the undertones of black and brown from the spine beneath the thin layer of light grey shale.

[Coco]

Hi,

 

19 minutes ago, EPIKLULSXDDDDD said:

@JohnJ@DPS Ammonite On the leftmost portion of the "spine" there seems to be a lip that I often see on the bases of urchin spines online.

 

I think I understood you to mean the area of the thorn that attaches to the sea urchin. This part of a sea urchin spine is located on the "biggest" or thickest tip of the spine most of the time, and there it would be on the thinnest part. An observation that goes against the sea urchin spine in my opinion.

[DPS Ammonite]

25 minutes ago, EPIKLULSXDDDDD said:

@DPS Ammonite I think both ends do, but it is difficult to tell. The light brown end is also semi-translucent. I would have cleaned more on the left end, but I was worried of breaking it so it's just encased in paraloid. Despite this, you can still make out the undertones of black and brown from the spine beneath the thin layer of light grey shale.

If the spine is calcite is should fizz in acid; try it.

[JohnJ]

7 hours ago, DPS Ammonite said:

If the spine is calcite is should fizz in acid; try it.

 

Might not be a good idea even if it wasn't coated in paraloid. Controlling a pinpoint of acid without weeping onto the surrounding matrix would be a challenge.

 

 

8 hours ago, EPIKLULSXDDDDD said:

As for an acetabulum, could you tell me what that is? I tried looking it up, but I couldn't find much in the way of a definition.

Echinoid spine morphology.

[DPS Ammonite]

1 hour ago, JohnJ said:

Might not be a good idea even if it wasn't coated in paraloid. Controlling a pinpoint of acid without weeping onto the surrounding matrix would be a challenge.

 

Be careful; caution is needed. Put 1 drop of acid on far right where the spine is already broken. Observe if it fizzes. Immediately pour lots of fresh water on the fossil to stop reaction. Soak fossil in fresh water.
 

Looking at the right end of the spine with a hand lens should allow you to see perfect cleavage of calcite, if it exists. An irregular or conchoidal break means that it is not calcite.

[JohnJ]

2 hours ago, DPS Ammonite said:

 

Be careful; caution is needed. Put 1 drop of acid on far right where the spine is already broken.

 

Again, he said it is coated in paraloid. 

 

Rather than risk any acid on something so fragile, it might be easier to just try cleaning it up a bit more to reveal any identifying characteristics 

[DPS Ammonite]

4 minutes ago, JohnJ said:

 

Again, he said it is coated in paraloid. 

 

Rather than risk any acid on something so fragile, it might be easier to just try cleaning it up a bit more to reveal any identifying characteristics 

Thanks. I missed the part about being coated in paraloid; acid test would be useless. 

[Mikrogeophagus]

Additional Pics of "Spine"

 

@Coco You are correct in that the thinner part of the "spine" is the side I have referred to as the base.

 

@DPS Ammonite @JohnJ I tried the acid test, but nothing fizzed probably due to the paraloid. I then tried cleaning a bit more around the base, but I guess I got overambitious and the thing ended up snapping in two places. I believe the fracture qualifies as "perfect cleavage" as would be expected for calcite. One thing I forgot to mention before is that the object flattens gradually as your eyes travel to the right as if it were smushed. With the broken base I was able to look at the underside that had been previously covered with matrix. The lip that I noted before is present all around the "spine".

 

 

Thankfully paraloid was able to save the day.

[Mikrogeophagus]

@Thomas.Dodson Apologies for the not-so-great quality images. Photography is definitely something I could invest more time and money in improving.

 

I took some extra pictures of the crustacean. This thing is so fragile and fragmented I am probably going to give up on it. Too much hassle to be worthwhile. I'm not sure if Ptychodus sharks drank crab smoothies, but my running theory is that this guy was dropped in a blender before he got preserved.

 

The bottom portion is what I think is left of a claw. You can see a couple of spines towards the bottom sandwiching a ball of pyrite. I think the part above is mayyybe the carapace.

A spine that I photographed in the OG post. After some cleaning there is some shell to be seen underneath it.

A couple more spines are seen here. One is in the center while the other is poking out of the edge on the bottom.

What I believe are a mishmash of legs.

 

Again, I am not super enthused by this guy, but at least this gives me hope that a better preserved crab might be waiting out there for a future trip.

[DPS Ammonite]

Here is what I find the most odd about the spine: most urchin spines taper toward the end away from the attachment point. This one keeps getting bigger. Given the brown to black color, could this be a bone or part of a crustacean?
 

Can anyone find a similar urchin spine from the Cretaceous?

 

@Uncle Siphuncle

Edited September 6, 2022 by DPS Ammonite

[JohnJ]

2 hours ago, EPIKLULSXDDDDD said:

One thing I forgot to mention before is that the object flattens gradually as your eyes travel to the right as if it were smushed. With the broken base I was able to look at the underside that had been previously covered with matrix. The lip that I noted before is present all around the "spine".

 

Good work on the cleaning and repair.  The paraloid, camouflaging matrix, and rare shape had me wondering if there was a base hiding in there.  It is an echinoid spine.  The form is rare.  I only know of one group of echinoids with this spine morphology - Echinothuriidae.  I have encountered this type spine associated with an undescribed echinoid @erose and I are working on from the Glen Rose formation.  Your spine discovery hints at the potential for a new rare echinoid from the Texas Late Cretaceous!  Congratulations on such a rare discovery.  Look for the plates of its owner.  Unlike most echinoids, these typically came apart soon after death.

[JohnJ]

2 hours ago, EPIKLULSXDDDDD said:

I took some extra pictures of the crustacean. This thing is so fragile and fragmented I am probably going to give up on it. Too much hassle to be worthwhile. 

 

This is also an uncommon find!  Track the layer it came from and find a better preserved one.  

 

@MB

@caterpillar

[Mikrogeophagus]

That's great to hear! I will definitely be on the lookout. Amazing detective work on your part and others. I'd say this test was passed with flying colors.

Edited September 6, 2022 by EPIKLULSXDDDDD
Grammar

[Coco]

Hi,

 

With the new photos, I agree that it can be a sea urchin spine. I didn’t really see the end of the spine, which reminds me of something I saw, but I don’t know what genus.

 

Great find !

 

Coco, can't wait to know more.

 

Coco

[caterpillar]

Some Phymosomatidae have radioles with a flattened end, such as Phymosoma savini from the Upper Cretaceous.

[Thomas.Dodson]

I agree with JohnJ, even fragmentary crustacean finds are good finds. Not all crustaceans can be crab concretion level of preservation.

 

I suspect you are correct in your assumption of the first pic being a partial carapace and the latter being a claw. I can look at what species have been reported in the Ozan later in some books I have but it is a good chance it will go unidentified. Nevertheless, a nice specimen.