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Showing results for tags 'crinoid holdfast'.
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A while back I made a quick stop at a small exposure of the Waldron Shale (Silurian) in southern Indiana. I only picked up a couple of items but since I have not previously collected the Waldron, I wanted to confirm (or get the correct ID) on two small items. I'm hoping one of our Waldron experts such as @Herb, @Ken K, @crinus or @squalicorax or anyone else that has some Waldron knowledge can help me out. The first item is a small, nicely preserved brachiopod. Based on what I could find, I suspect it might be a Stegorhynchus but I wanted to confirm this and if anyone can add a species, that would be awesome. Alternately, if you have a good suggestion for reference material for Waldron brachiopods, I'd love to know it and would be happy to read up some more. The black bar in each picture is 1 cm. This little guy is 1.2cm wide, 1.1 cm long and 0.75 cm high. The second item is a crinoid holdfast with a very obvious pentastellate lumen. Its also hard to see in the picture (due to some matrix and some pyrite growth) but under the microscope, you can see that the articular surface has crenulae that extend from the outer edge all the way to the lumen. I can also see in edge view that the individual columnals are very thin. Again, the scale bar divisions are 1 cm. I know that Eucalyptocrinus is a common genus in the Waldron, but from what I can find, it does not have a pentastellate lumen, but admittedly most of the pictures I see of it do not show the columnal cross sections. I'm hoping one of our members is more familiar with this genus that I am (not too hard to do) and can confirm that for me. In looking through Moore and Jeffords (1968) CLASSIFICATION AND NOMENCLATURE OF FOSSIL CRINOIDS BASED ON STUDIES OF DISSOCIATED PARTS OF THEIR COLUMNS, I see they have a species identified as Cyclochorax fasciatus that fits the description (and age and formation) of my specimen (see #7 and 8 in the snippet below from their Plate 23) but after a quick search, the only reference I see for this genus is Moore and Jeffords. I'm wondering if anyone is familiar with what a calyx of this genus looks like or if anyone has knowledge of some other existing Waldron crinoid that has this columnal pattern. Look forward to any and all responses and any help that can be offered. Thanks Mike
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