Search the Community
Showing results for tags 'caradoc'.
Found 3 results
Rhynchonellids are hard to identify by exterior morphology as they often need to have their internal structures visible to be sure of an id. However if you know the faunal lists from a specific area, you can reduce the candidates considerably. The specimen here has 22 costae with 4 on the fold and thus, at this size must be one of two species, Rostricellula minnesotensis or Rhynchotrema wisconsinensis. The only completely safe way to differentiate between the two is the presence or absence of a cardinal process in the brachial valve but this is not possible here. However, Rostricellula usually, though not always, devoid of shell ornamentation, such as ridges or the presence of growth lines, and Rhynchotrema wisconsinensis usually, though not always, shows these, though they can also be seemingly absent through wear. But, R. wisconsinensis never shows a length to width ratio of 1.00, only from 0.80 to 0.95 and this specimen has a ratio of 1.00 which does occur in Rostricellula. Furthermore, the fold of Rostricellula is wider and less sharply developed Finally, good specimens of Rostricellula are far more common than R wisconsinense at the locality as the species most commonly found here is Rhynchotrema ainsiei which is describe elsewhere and not to be confused with the other two due to it's larger number of costae Thus, I am fairly confident with my id
Hello everyone, these fossils are quite common in at least one Czech locality of Bohdalec formation (upper Caradoc/Beroun) and I wondered if anyone has seen anything similar somewhere. The fossils are lentil shaped, with a thin egg-like shell that could be cracked and removed to expose inner layer of different color and structure. The size is 1 to 4 mm in diameter. I've consulted some experts and although they've all encountered similar fossil, they have no idea what it is. One of the opinions was that it could be a juvenile cystoid of some sort, for example Echinosphaerites seems to be common in this formation, although never found on this locality. However no one seems to have done any research into this yet. Associated fauna are small cyclopygid and illaenid trilobites, small brachiopods, graptolites, bivalves and ostracods. Thanks in advance for your thoughts Ondrej