This first pic (if you click on it) is an EXTREMELY hi-res shot, over 2k pixels wide. This one is a real oddball:

It looks almost like gypsum, but found in the Boone Limestone formation, must be ... a fossil? You tell me!

What do you think?

I found some sedimentary rocks with fossils in the vicinity of Devil's Den State Park near Winslow, Arkansas yesterday. The rock is more like sandstone than limestone, and it is often sandwiched between thin layers of shale. Perhaps my geologist friends can help me out here? Ed. note: this appears to be in the vicinity of the Bloyd shale formation. The Bloyd shale is primarily sandstone, secondarily shale. Its time period is middle Pennsylvanian.

The rock is quite soft and porous. It also made of rather coarse particles, and the fossils are very thin and delicate. The actual fossils of what I believe are brachiopod shells often show little detail, with the cast being much better preserved.

Here's a particularly well-preserved example of one of the small coiled shells, 1/4" in size. It appears to be the same species as the larger example appearing in the previous entry. They make up 80% of the fossils found in the rock.

Note the toothlike structures on this bivalve, each about 1/3 mm.

This crumbling crinoid stem fragment is typical of the extremely delicate fossils found in this particular rock.

I'm particularly interested in getting an identification of the coiled shells. Anyone have any ideas?

Cracking one open, I found fossils. This was excitation for me, because there is almost 700 feet in elevation difference from Benton county. I'm talking different geological era! Big stuff, friends. Different species of fauna, etc. For a landlocked fossil enthusiast, that much of a change in elevation means traveling to a foreign country, so to speak. Ed. note: this appears to be in the vicinity of the Bloyd shale formation. The Bloyd shale is primarily sandstone, secondarily shale. Its time period is middle Pennsylvanian

Here's the shell, still in its matrix.

Here's the top view of the shell.

So, is this a nautiloid? Inquiring minds want to know!

Again, the soft, porous limestone that is generally colored the same as red clay. Only this find was made in a lighter colored section of the rock that had hardened.

Trilobites are about as common in Benton county, Arkansas as speeding Buicks in Bella Vista. When you see one, you sit up and take notice.

I've been fossil hunting pretty hard for the last couple of months, and I've found one weathered cast on the exterior of a rock, and two posterior halves inside rocks I had cleaved open.

I found this specimen about two hours ago. It was an exciting moment, like having a Buick with a handicapped license plate blast around you doing 75! More pics in the article.

Here's the trilly with the matrix cleared away. There was a fragile razor-thin edge on the shell which unfortunately broke free during the clearing process. I cemented it back in place.

Nice trilly tail, a thrill to find!

Grey fragments of mollusk shells can often be found in the crinoid-rich limestone of Benton county, Arkansas. This is a nicely intact specimen dug from the matrix. Note the parasitic borings on the enlarged version of the picture.

This elf's cap-shaped critter has a tail that reminds me of a brachiopod, but it is elongated too much to be one, IMOH. Any ideas? More pics in this article. Update: Thanks to visitor Barry for identifying both of these specimens as Platyceras species!

Front view of the cap-shaped mollusk (Platyceras sp.).

Rear view, note the elongated shell on the right side. Looks to long to be a brach, at least to me! (Actually a Platyceras species)

This branching crinoid stalk in matrix looks to be the same species as by bodacious huge stalk pictured elsewhere on this site.

This tube-shaped fossil has turned up from time to time in soft, porous limestone. I have found some twice this one's diameter. Any ideas? Update: This fossil has been identified by visitor Angela as a rugose coral. Thanks!

Another view of the same creature.

Imagine my shock at finding a dinosaur tooth in the Mississippian period! Just kidding. Some sort of conical, flat mollusk. Anyone know what it is?

This appears to be a cast of the same conical creature, this one in the blastoid-laden lightweight chert you can find in a certain Benton county creekbed.

Closeup of the fine detail preserved in the soft red limestone that can be found in Benton county. Each of those little appendages is about 1/5mm wide.

Again from the very soft red rock that I've referenced elsewhere, almost more like dirt clod than solid rock, here are some strange looking fossils which I presume are bryozoan in nature. This is a shot of a cast.

This is a second cast, you can see that the rock is so fragile that it's splitting. That fragile rock preserves some amazing detail, though.

Here's the actual fossil that was in the previous cast. When i first saw it, I thought I had stumbled onto a starfish arm! I know, wrong period.

Please identify this species for me if you know.

My friends over at http://www.lakeneosho.org/ have already done most of the work for me here. This is clearly an evactinopera species. Thanks, Barry, for correcting my identification of this species to, and I quote: plates from a crinoid ... often the crinoid head falls apart before fossilization and the different plates are fossilizes separately.I have never before found one, then again they are easy to lose in the melange of small fossils that populate the limestone in which I spotted this one. I'll be keeping my eyes peeled for more, that's for sure.

Anyhow, an exact species identification would be great, if anyone knows!

This one is a total mystery. It was found in some hard limestone that was mostly layer upon layer of three of four species of brachiopods. There was also a lovely trilobite in the cube-shaped rock that was about ten inches square. I was able to repeatedly cleave it with the grain so that I kept uncovering layer after layer of goodies.

Any ideas?

I found this specimen inside some soft limestone that is almost like sandstone in its consistency. The rock is quite porous and soaks up a lot of water.

The specimen is about 1/4" in size. It has a maze of tiny structures resembling arms. My microscope cam magnified them nicely.

Here's a shot from straight overhead.

Closeup of the holdfast.

Any ideas, anyone?

There it sat, so huge that I didn't think it was a fossil.

I found some very nice limestone in a ditch just north of Bentonville. It was in many layers, a bunch of individually formed rocks ranging from palm-sized to perhaps three feet around, all an inch or three thick. I found a bunch of nice crinoid stems and a piece of a calyx. However, everything was typically crinoid-sized.

There were a few thick slabs that lined the bottom of the wash, and this puppy was sticking out like a sore thumb. However, I had looked at it two or three times without recognizing it as a crinoid stalk.

However, I finally looked closer and about jumped out of my skin when I recognized the five-sided interior as a crinoid fossil. I had to return the next day with a sledge hammer in order to liberate it from the 7" thick slab. It was sticking out of the end, having sat there for eons, waiting for me to liberate it.

It broke loose cleanly, and went home with me. Later, I began freeing it from its matrix. This flavor of limestone is crystallized inside, so it wasn't completely clean in its escape from the rock. But the body held up very nicely, and many of the little stalks that were attached to it glued back almost perfectly.

For someone who is used to finding crinoid stalks the size of pencils, this massive critter caused a real rush!

Anybody out there able to identify this monster for me?