Pseudogygites Trilobites from Canada

Pseudogygites latimarginatus is an Asaphid trilobite (Order: Asaphida; Family: Asaphidae Subfamily Isotelinae) coming from the Ordovician Whity Formation strata of Ontario, Canada. This trilobite was first known as Pseudogygites canadensis until it was found that the name Asaphus latimarginata had precedence over Asaphus canadensis. Once the trilobite was placed in the current species, the generic name became latimarginatus. They are similar in morphology to the genus Ogyginus of the United Kingdom, differing in the hypostome and facial suturing. This is a good pair of counterpart examples. Like Isotelus, the genal spines became smaller as the trilobites got older, with full-grown examples having none detectable. Note the strange-looking item near the Pseudogygites to the lower left in the first photo. It looks very much like the vertebral column of a fish! There are several partial cephalons to be seen on the reverse, making this a nice death assemblage plaque.