Here is a beautiful and inflated preserved Agnostus of the rare species Pentagnostus (Meragostus) segmenta. The species was revised in 2012, previously this species was known as Peronopsis segmenta. In the same publication, for example, Peronopsis interstricta (White, 1874) was placed in the genus Itagnostus. Pentagnostus (Meragostus) segmenta is one of the more seldom trilobites from the Marjum Formation of Utah.

Naimark, E.B. (2012). "Hundred species of the Genus Peronopsis Hawle et Corda, 1847". Paleontological Journal. 46 (9): 945–1057. Bibcode:2012PalJ...46..945N. doi:10.1134/S0031030112090018

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