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Showing results for tags 'rhynchotrema'.
Found 5 results
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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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- amplexopora
- amplexopora septosa
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From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Lepidocyclus - Decorah Formation only? For me I hadn't found it in Platteville formation for unknown reason - could be locations. Very abundant and highly variable in forms - I suspects quite a few genus and species can be easily mistaken for this one. Part of it is I only find the smallest ones as strongly triangular and more flat with sulcus not as prominent. But all the bigger one are much more inflated. Plus costae is pretty uniform over all species. Transverse growths are sometimes prominent on anterior portion of the shell, usually on adult specimens. -
From the album: Brachiopods of Platteville/Decorah Twin Cities Minnesota
Rhynchotrema ainslei Decorah shale, Twin Cities Minnesota. This species appear to be much less common than Rhynchotrema wisconsinense. How to tell the two species apart? Rhynchotrema have much more costae than R. wisconsinense. Size and shape are variable, but compare to R. wisconsinense R. ainslei is more fragile and more easily deformed by the fossilization procession. -
As with the adult this has more costae than any other brachiopod found in this formation. In this case 32. and 5 of them on the fold. The fold and sulcus are not yet very noticeable, as this species only develops a noticeable fold as it matures.
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- brachiopod
- cummingsville member
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Brachiopods, perhaps rhynchonellids most of all, are notoriously hard to identify without their internal features exposed. However, if you know the formation and rough location and have faunal lists it can be possible. Rhynchonella ainsliei, for example, has 26-34 costae with 5-7 of these appearing on the fold. This specimen has 30 and 5 respectively and is the only species that has so many found in this formation. It also has the correct shape and size to support the match.
