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Showing results for tags 'decorah formation'.
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Spring is finally coming around. Here in Missouri, we are getting a mix of nice weather, lots of rain, and even still some colder frosty days. I was off work yesterday, and the great weather had inspired me to go check out an Ordovician road cut I did some recon on last month. The roadcut isnt very large, but with the hard rain we had received this past week I figured it would be a good chance to rummage through the bedrock and scree pile. Within 5 minutes, I found my first find. It is likley an enrolled Eomonorachus intermedius trilobite. Unfortunately there was a crack running right through it. The trilobite was very small, measuring in at .25 inches. This is were things went wrong. I didn't bring any glue with me, and figured I would chance trying to extract it as-is, even with the crack running through it. Big mistake, as it can out in two pieces. This specimen was missing it's eyes and some shell, so I wasn't too distraught. About 10 minutes later, I found another enrolled specimen, this time with the tail exposed upright. It also measured in a .25 inches in length. It is likley also an Eomonorachus intermedius, but will need cleaned for a confident ID. After extraction, I walked to my car to put up my grinder and I couldn't believe what I saw just laying on the ground. Another trilobite! It is a miracle this bug was intact. I was amazed to turn the trilobite around and see some of its eye lenses looking back at me. It is a great day when you find a trilobite in Missouri with how rare they are, but to find three in one day is downright spectacular. This specimen isn't perfect either. It's compressed, missing it's genal spines, and also has it's tail tucked under the cephalon likley due to compression. Regardless, I am very happy with it. It should clean up well! I also snagged a nice little Isotelus hypostome. After that, I packed up and headed for home. I had a great time out, and will definitely have to check out this location again after time has passed, and some more weathering takes place. Thanks for reading!
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A nice Dictyonema flabelliforme dendroid graptolite from Oslo Fields in Norway. It's Tremadoc, Lower Ordovician in age and is thus maybe around 480 mya. Another angle :
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I found some interesting specimens today I would like a second opinion on. Thinking both of these essentially complete bugs are Eomonorachus intermedius, but I'm not certain as they are both exposed ventrally. #1 After some cleaning #2- the second ventral specimen here is preserved hiding underneath an Isotelus pygidium and is very tiny! After some cleaning I think both of these partials are Eomonorachus as well. Almost exposed pygidium Half exposed cephalon showing good eye facet detail. Thanks for any feedback. -Jay
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From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Flatter than A. recurvirostis and a bit bigger. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Very recently in 2023 paper came out that basically places all Zygospira earlier than Mayville/Richmondian in genus Anazyga. Cinnicinntea website also had name change for Anazyga recurvirostis since it also extends into maysville formation. The Decorah Formation Twin Cities can have a lot of those but oddly enough to me they are very specific to muddy limestone as I never find them in the weaker shales for unknown reasons. One of the tiniest Decorah Formation Brachiopod species I have ever found, tiny enough to balance on eraser end of pencil. Compare to the other Anazyga species it is much smaller and more inflated in shape. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Those are the closest specimen I could find that I think is Anazyga lebanonensis. Described as longer in length than the other two Anazyga species from Decorah Formation. -
From the album: Minnesota Ordovician Decorah Cephalopods
Above view of fragile specimen of Triptoceras lambi -
From the album: Minnesota Ordovician Decorah Cephalopods
different specimen, very fragile. Side view showing the siphuncle. Uncommon in Decorah Formation Twin Cities Minnesota. -
From the album: Minnesota Ordovician Decorah Cephalopods
One of the largest Triptoceras species I have found in Decorah Formation Twin Cities Minnesota. This is a very worn specimen with septae lines barely visible. -
From the album: Minnesota Ordovician Decorah Cephalopods
Side view of the largest Triptoceras species in Decorah Formation Twin Cities Minnesota showing the trademark shape of genus Triptoceras. -
From the album: Minnesota Ordovician Decorah Cephalopods
Triptoceras oweni - heavily bryozoan encrusted specimen. Medium sized for a Decorah Formation Cephalopod. Twin Cities Minnesota Ordovician. -
From the album: Minnesota Ordovician Decorah Cephalopods
Triptoceras planodorsatum Decorah Formation, Twin Cities, Minnesota. Very small, this is a side view showing the bend. -
From the album: Minnesota Ordovician Decorah Cephalopods
Triptoceras planoconvexum appear to be medium sized compared to the other Triptoceras species from Decorah Formation in Twin Cities. Rare. -
From the album: Minnesota Ordovician Decorah Cephalopods
Apparently Whitfieldoceras mumiaforme lasts into Decorah Formation from Platteville formation. This specimen has barely visible septae and is very thin. Seem to have enlargement on the left side which is constant with Whitfieldoceras and a bend along a certain portion of the shell. Ordovician, Decorah Formation, Twin Cities Minnesota. Rare. -
From the album: Minnesota Ordovician Decorah Cephalopods
Top view - Rare in Decorah Formation Twin Cities. Small size, the muddy limestone made it hard to tell what species it is. -
From the album: Minnesota Ordovician Decorah Cephalopods
Poterioceras apertum found in St. Paul Decorah Shale Spring 2023. Rare from the looks of it. -
From the album: Bryozoan of Minnesota Ordovician
One of the longest rugosa bryozoan that i have found so far in Decorah Shale Formation. Branches subcylindrical, branching of equal thickness. Long intervals between branches. Clusters of large cells are conspicuous, The one in the northern most part of this picture might have a crinoid holdfast. -
Ordovician, Decorah Formation Minnesota Just want your opinions on it before I post it to my image gallery. I'm not a crinoid expert and this is rare - only my second crinoid from the Decorah Formation with more than 60% completeness. The first is a tiny one not even 2 inches from crown to base. This is more of a medium size with 110 mm from head to base. Using paint I pinpointed different areas for helpful info. #1 Is the arms - can't really see in picture but very clear to me some scavenger buried the arms - I could see a few faint tunnels a short distance away. #2 is most of the main stem - partial exposed. #3 is scattered stem pieces, a couple belong to a different genus which I had not identify yet. #4 is a fragment of arm? #5 is the base.
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From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Largest of the two Vinlandostrophia species in Minnesota Decorah formation. Resembles Dinorthis pectinella strongly. Seem to be fragile as I couldn't find any whole specimens of this uncommon brachiopod. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Rare Inarticulated brachiopod. Author claimed to only found one. Decorah Formation. Rounded with slightly raised edges. Unidentified bryozoan sp. can be seen on a single film covering part of the shell. Have parallel lines going from one end to another. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Highly variable brachiopod species which had two invalid species merged into a third species. O. inquassa is the largest of the two Oepikina species. Mainly Decorah Formation but maybe in Platteville Formation but I hadn't found hard evidences yet. #1 shows (its harder to photograph) distinct septae that is pronounced in some individuals and absent in others. It always start with a curved septae and one central septae that goes out a bit of distance. Then in some individuals there are clearly short septae random radiates outward from the center. #2 shows the clear distant growth lines that Oepikina only have. #3 shows the hinge teethes which is the largest and most noticeable among the Strophomenid brachiopods of Decorah Formation. Even O. minnesotensis have much smaller teeth by compare -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
The major difference between S. billingsi and S. filitexta is the lack of enclosed muscle scars and S. billingsi tend to be smaller. #2 shows the difficulty for me - it shows a muscle scar - is it a broken enclosed one or is this normal for S. billingi? I don't know for sure. #3 S. billingi wasn't reported by authors as occurring into Platteville formation but I found shell hashes full of it into Mifflin Formation. I still have to look through a lot of individual platteville fossils in the future to see if other Strophomena species are represented - I have seen hints of possible S. septae. S. billingsi occurs in both Platteville and Decorah formation. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Most abundant of the three Strophomena species in Decorah Formation and the largest. #1 shows the most significant feature that differs S. filitexta from S. billingi - the complete enclosed muscle ridges. #2 shows the significant different (at least in individuals that have both halves of shells) between Strophomena from Oepikina/Rafinesquina. Only Strophomena have the triangular structure enclosing where its weak hinge teeth are. #3 Shows the diversity into shapes - this is one of the few highly inflated forms I have found of S. filitexta. I have a lot of difficulty telling the smaller individuals apart between S. filitexta and S. billingi at present if muscle scars is not shown. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Locally common? Most of those individuals were found in one layer this year. One of three official species of Strophomena from Decorah/Platteville Formation at least in Minnesota. #1 It resembles Strophomena filitexta into having an enclosed muscle scar. But it differs greatly from Strophomena filitexta into several ways - one of the most noticeable ways is into having a prominent central septae that run down the center. The other two Strophomena species lacks that prominent central septae that runs all the way down the shell. #2 is a false sulcus that runs down the outside of the shell. In vast majority of individuals that I have looked at, only one half have the false sulcus on the outside and often it is not that easy to find, being a subtle depression that runs down the middle of the shell on the outside. #3 On the outside of the shell the costae is more uniform compare to the other two Strophomena species. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Oepikina inquassa - While sorting through this spring collection of brachiopods this one stood out. It came from the soft shale so was mostly intact instead of embedded into limestone which makes seeing underside difficult if not impossible. From the documentary: Oepikina inquassa is larger than Oepikina minnesotensis and is less convex. No muscle scar ridges check. Strong medium septum omits S. billingi check. Fine ridges you can see by all that iron particles/clay sticking to it check. Is more delicate than I thought plus this one have a weird quirk - two strong ridges can be seen running down it and connected to the septum. The documentaries didn't mention this, interesting. You can see hinge teeth is prominent but much smaller compare to Rafinesquina interesting.
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