| Ptyocephalus 
        yersiniTrilobites 
        Order Asaphida, Family Asaphidae, Subfamily Ptyocepalinae Geological 
        Time: Ordovician Size: Trilobite
        15 mm long by 8 mm wide on a 35 mm by 20 mm matrix Fossil Site: 
        Fillmore Formation, Millard County, Utah 
 
         
          |  Description: 
              Utah (as well as other Western States) is well known for its Cambrian 
              fauna and trilobites in particular. Trilobites from the Ordovician 
              also occur but in far fewer exposures. In Utah, the Fillmore, Garden 
              City, Pogonip, Swan Peak, and Wah Wah Formations yield Ordovician 
              trilobites. No trilobites from Utah are known that are younger than 
              the middle Ordovician. This trilobites comes from my own lease in 
              the lower, middle Ordovician Fillmore formation. These trilobites 
              are not commonly offered. Ptyocephalus yersini is normally found 
              enrolled, making this a most unusual and thus highly desirable specimen.
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