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Trilobite Id Please


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Hello, found this trilobite pygidium in Wales, near Builth Wells (?Llanvirn). It has a bizarre feature I've never seen before - round the margin there is a band of parallel lines curving round with the margin (best seen in the oblique photo). Hopefully this will help someone identify it. All id suggestions welcome please. Many thanks!




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On 4/7/2014 at 6:12 AM, squalicorax said:

Looks like Ogygiocarella



Agreed emo71.gif


If the pygidium is essentially complete then Ogygiocarella debuchii is correct with 11 pairs of pygidial ribs. Ogygiocarella angustissima typically have 13. The lines around the margin are called terrace lines, a functional feature of asaphid trilobites. Terrace lines assisted with frictional resistance for trilobites interacting with sediments.


Part VII of this excellent 9 part monograph series has a thorough description of Ogygiocarella:


Whittard, W.F. (1964)

The Ordovician Trilobites of the Shelve Inlier, West Shropshire. (Part VII)

Palaeontographical Society, London, 501:229-264




  • I found this Informative 1


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