Mazarn Shale

The Mazarn Shale is an Early Ordovician geologic formation in the Ouachita Mountains of Arkansas and Oklahoma. This interval was first described in 1892, but remained unnamed until 1918 as part of a study by U.S. Geological Survey geologist Hugh Dinsmore Miser.

Graptolites

 * Caryocaris
 * C. wrighti


 * Cryptograptus
 * C. antennarius


 * Didymograptus
 * D. caduceus
 * D. caduceus nana
 * D. extensus
 * D. filiformis
 * D. nitidus
 * D. similis


 * Diplograptus
 * Glossograptus
 * G. hystrix


 * Mesograptus
 * Phyllograptus
 * P. typus


 * Retiograptus
 * Tetragraptus
 * T. clarkei
 * T. fruticosus
 * T. quadribrachiatus
 * T. pendens
 * T. serra
 * T. similis