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Showing results for tags 'brachiopod'.
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Hi, just wanted to show you prep of a quite nice preserved Lacunosella cracoviensis - endemic specie of my Jurassic area prepped with a Engraver and a little bit of vinegar for surface cleaning. Started as a 20 pounds chunk
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Chonetes bastini was first described from the Leighton Fm, also called the Pembroke Fm. It is differentiated from other species by the number of spines and its finer more numerous striae. Most specimens are missing the hinge spines. The above pictures show the pedicle valve. A poorly preserved original or cast of the shell exterior is in the left side photo. Some of the exterior of the shell may be missing since there is a horizontal groove above the shell where shell may have once filled it. The right photo shows an exterior impression or mold. Williams, Henry Shaler (1985). "New species of Silurian fossils from the Edmunds and Pembroke Formations of Washington County, Maine." Proceedings U.S. National Museum, 45, 319-358. https://repository.si.edu/bitstream/handle/10088/14399/1/USNMP-45_1985_1913.pdf
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From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Pionodema conradi. I knew I had some tiny orthid brachiopod from Middle Platteville Formation but after checking book and this website: https://2dgf.dk/xpdf/bull26-01-02-115-132.pdf Kind of weird. I think Hesperorthis concava was invalid - too similar and two very close look alike can't compete with each other. One other brachiopod mention on the list Campylorthis deflecta look too much like Strophomena species despite a website saying genus name is valid. -
With the nicer weather last week, I was able to make two brief trips to kick of the year. There still ended up being a lot of snow on the ground, but it was manageable. My first trip was to one of my favorite sites, a roadcut in the Pennsylvanian LaSalle Limestone in Illinois. Lots of the usual stuff was found, but the two trip makers were a small Peripristis shark tooth and a Linoproductus mass mortality plate. Here's the tooth. I think it will clean up nicely. And here are the Linoproductus. There's around 50 individuals present, and they are all quite small compared to most Linoproductus specimens I find at this site. This is probably the best brach plate I've found here. Here's a random shot I took of the headwall. Most of the common brachiopod species at this site are visible. A few days later I had a couple hours free in the morning and checked out some new Ordovician spots in southern Wisconsin. Here's a neat roadcut I drove past, showing the contact between the Ancell and Sinnipee Groups. The lower unit is the St. Peter Sandstone and the upper unit is the Pecatonica Member of the Platteville Formation. The Glenwood Shale is the narrow shale unit between the two. The site I ended up hunting was in the Grand Detour Member of the Platteville. In this area it's mostly dolomite, and most fossils are internal molds. The preservation is thus not great, but splitting rock can yield nice mollusks on occasion. Here's a typical example of the molluscan hash. This large Ctenodonta was a nice treat. It's about 6cm at the widest dimension. The trip maker was a coiled nautiloid, the first I've found. I am not sure on the ID. It measures about 2cm in diameter.
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From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Zygospira sp. Apparently there are a mystery with this genus when it comes to Twin Cities. I first noticed it only from Middle Platteville Formation - 100% nonexistent from upper Platteville Formation. Much more finer costae compare to Rostricellula minnesotensis and generally smaller. Belongs in Spiriferid family despite it strong resemble to Rhyconellid family. Then after a very long absent either the same species or a very similar species popped up again in upper Decorah formation and became very abundant. I suspects the reason for this seemly weird pattern is they may be much more specialized into the type of sediments that laid on the ocean floor. The middle platteville had layers of high carbonate shale mixed in, which does not exists in upper and lower Platteville formation. Then upper Decorah formation had a harder type of shale - middle and lower Decorah formation have shale that breaks into pieces very easily. Plus from my experiences with modern Florida gastropods there are two endemic species of gastropods that had very narrow ranges. One I don't have specimens of is Sanbriel Island turret snail which is endemic to southwest mainland Florida. Not found anywhere else. The other snail species, Shiny Atlantic auger, Hastula hastata is only found generally around Jupiter Island on Atlantic side. At first it may seem like the two snail species have nothing in common but I find it interesting that they occurs in a small zone in between the carbonate sediments of far southern Florida to the keys and the sandy rubble to the north. -
From the album: Platteville to Decorah formation Ordovician Twin Cities
I think the two large brachiopod, one in NW corner and one SE corner is maybe new to me. The muscle ridges are very different with two parallel to each other extending from hinge line. Also seem like Upper Decorah Formation tend to have more varieties of Strophomenid brachiopods that is rarer in Middle and Lower Decorah Formation. One new thing I just learned today is Sowerbyella minnesotensis tend to be very variable in # from site to site. It is very characterized of Upper Decorah Formation as well too, being entirely absent from Middle and Lower Decorah Formation. One site had Sowerbyella minnesotensis making up vast majority of shell hash while yesterday site where I collected most of the fossils have Sowerbyella minnesotensis in low densities. -
From the album: Platteville to Decorah formation Ordovician Twin Cities
Some orthid brachiopods, mainly Cincinnetina and Dinorthis along with several lookalikes tend to be found only in Upper Decorah Formation. Upper Decorah tend to overlaps with Galena Formation and Richmondian formation. That's why you can find some of the same orthid brachiopod species from Minnesota to Ohio to Kentucky. -
From the album: Platteville to Decorah formation Ordovician Twin Cities
Another interesting thing about Upper Decorah Formation is numerous of unidentified Zygospira species along with orthids of different sizes. For some unknown reasons Zygospira species are largely missing from lower to middle Decorah Formation even though they're abundant in Middle Platteville as well too in Twin Cities. -
From the album: Platteville to Decorah formation Ordovician Twin Cities
First Vinlandostrophia brachiopod find of the year! I will have to compare it to the other two species later. Hash is much more fragmentary - I call it bryozoan hash. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
?Oepikina minnesotensis. I'm not 100% sure yet. Oepikina tend to have very fine costae and those specimens are literally loaded with costae making them darker. There's two in the leftmost rock specimens along with a Strophomena. The annoying thing is its hard to see hinge line for a positive id. Among the most inflated brachiopod I have seen from Decorah formation, only inarticulate brachiopods are this inflated. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Sowerbyella minnesotensis. Upper Decorah formation, all of Galena Formation. Tend to be characterizing into identification of Upper Decorah formation (only exposed in Lilydale Regional Park and southern Minnesota). Other locations in Twin Cities tend to be lower (maybe middle) Decorah formation. Very abundant, can make up a big section of some shell hash. The one specimen in the middle is the largest and complete that I had found so far. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
?Cincinnetina minnesotensis. Middle Platteville Formation, rare. I hadn't found any Hesperorthis in middle Platteville yet and there's lack of information on Platteville orthid brachiopods as I have one to two other species from middle platteville but they're tiny and difficult for me to photograph at current. The big brachiopod in NE rock is Oepikina inquassa - they have very fine costae and may appear to be darker because of it. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Unlabeled inarticulate brachiopods. Common in Decorah formation and middle Platteville Formation. I had an interesting discussion with another person recently - turn out only inarticulate brachiopods tend to keep their shells - the other extreme lookalike which is non coiled limpet like Monoplacophora tend to be preserved as molds like true gastropods. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Unidentified orthid for now. Strongly resembles Dalmanella sculpta but have sharp edges. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
not identified yet. Two very similar genus. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Vinlandostrophia (formerly Platystrophia) trentonensis. Practically the only Minnesota Decorah formation orthid that I know of that have wings (Strophomena filitexta from a different family have wings but not as pronounced). Rare - hadn't found any 100% intact adult specimen yet as one wing always seem to be broken off. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Hesperorthis tricenaria - from Decorah formation. Seem like it have more diversity of shapes in Decorah than platteville, mostly in height. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Hesperorthis tricenaria. This is upper Platteville formation which is very abundant and the most easily identified brachiopod from that layer - diversity of fossils in upper platteville while abundant, tend to be very low in diversity. Among brachiopods of upper platteville, mainly Strophomena filitexta, Hesperorthis tricenaria, Oepikina minnesotensis, Rafinesquina sp, and maybe Oepikina inquassa is practically the only brachiopod species found in upper Platteville. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Oepikina minnesotensis. Occurs mainly in upper Platteville formation. I'm not 100% sure if they occurs in decorah formation as I had found unusual circular inflated shells but its much harder to see their hinge line or muscle scars at present. Either the decorah version is a extreme version of Doleriodes pervetus or Oepikina minnesotensis. They usually differs from Strophomena filitexta into being more compact and rounder, also more inflated. They're much smaller compare to Oepikina inquassa and less variable in shapes. You can see the fossil in the farthest left of the picture have unusual well preserved muscle scar. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Strophomena filitexta - very abundant in both decorah formation and platteville formation. Usually more variable in shape and get bigger in decorah formation. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Strophomena septata. Much rarer than Strophomena filitexta. Tend to be uniform in costae and more finer than Strophomena filitexta. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Dinorthis pectinella Tend to occurs in the same layers as Cincinnetina meedsi. Strongly costae, no inferior costae compare to Cincinnetina meedsi. Also tend to separate in halves when the brachiopod dies. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Pionodema subaequata Rectangular shaped compare to Doleriodes pervetus and tend to have more of broader posterior. Seem to be fragile and loves to flakes off into thin layers. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Doleriodes pervetus. Tend to be found more commonly along Pionodema subaequata in scattered layers of decorah formation. Often strongly resembles Athyra species from Devonian. Tend to be very deeply cupped, only inarticulate brachiopods are just as deeply cupped. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Rostricellula minnesotensis. Seem to be Platteville formation only for me. Easily mistaken for Rhynchotrema wisconsinense until I noticed something odd with my specimens. The sulcus barely exists and sources usually says Rostricellula generally are smaller than Rhynchotrema. Plus the picture I had seen of Zygospira recurvirostris look significant different.
