Exceptionally Isotelus Maximus With Hypostome

This fine specimen, Isotelus maximus, is a small representative of another asaphid trilobite that is found in the Ordovician Arnheim formation in Ohio. These trilobites have been named the official "state fossil" of Ohio.

This particular specimen came from a private lease near Mt. Orab, Ohio. A few adult (holaspid) trilobites of this species have been found that exceed 13" in length. Although this specimen is only 2" - because it has genal spines that are longer than the entire thorax and full number (8) of thoracic segments - it is classified as an adult. Another interesting feature on this plate is the complete, forked hypostome (hard trilobite mouth plate) of a somewhat larger Isotelus located alongside the specimen. This feature is completely natural (not composited) and a rare occurrence.

The vast majority of Isotelus trilobites collected are found enrolled and missing a great deal of shell material. Many fossils found on these damp shales are damaged by improper care or preservation and need substantial restoration. This specimen is prone, centered on the matrix and nearly perfect. Unlike many trilobites extracted from this area, this superb, complete trilobite was properly stabilized from the cracking which occurs during the "drying out" of specimens and required minimal repair. This gorgeous fossil would enhance any serious trilobite collection.

Isotelus is a genus of asaphid trilobites from the middle and upper Ordovician period. Various species are fairly common throughout northeastern United States, northwest Manitoba, southwestern Quebec and southeastern Ontario. During the Ordovician, the paleo-continent of Laurentia (present-day North America) was home to Asaphids that evolved into relative giants. One species, Isotelus rex, is currently the world's largest trilobite ever found at nearly three quarters of a meter in length (720 mm)
Isotelus maximus
Mt. Orab, Ohio
Arnheim Formation
2" long
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