UPDATE! Thanks to cyberpal Angela for identifying this specimen as a styolite, i.e. a mineral!
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!
Click on photos to enlarge.
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.
I found this shell today, making a trip to southern Washington County, Arkansas. Near the community of Winslow, and Devil's Den St. Park, I followed a dirt road and found some exposed rock in a ditch.
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.
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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.
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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!
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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!
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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.
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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!
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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.
Click on images to enlarge, found in Benton county, Arkansas, Boone limestone formation
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.
