Introduction to a New Series of Studies of Ordovician Echinoderms

A massive collection of Ordovician echinoderms has been accumulated primarily from northeastern Iowa and southeastern Minnesota but including material from other states; it is in process of being studied. A brief history of the inception of the study and the process of bringing the material together is presented. Individuals are named but only brief details are given. Primarily this is a report of a concentrated effort to produce a significant study of echinoderms from Middle and Upper Ordovician strata, the people involved and the methods of obtaining material

A Preliminary Study of Echinoderms with the Aid of a Scanning Electron Microscope

A microcrinoid (Passalocrinus), camerate crinoid (Dichocrinus) and small blastoid (Diploblastus) are examined at high magnification and reveal latticework endoskeletal plates with slightly varied patterns of voids and interlocking rods. Cirrals from the base of a modern comatulid are illustrated for comparison

Erisocrinids (Crinoidea-Inadunata) from Middle Pennsylvanian Rocks of Iowa and Colorado

Erisocrinus knoxvillensis n. sp. is described from rocks of the Desmoinesian Stage exposed near Knoxville, Marion County, Iowa. Two specimens from the Madera Formation, Desmoinesian Stage, Heurfano Park, Colorado, reported by Tischler, 1963, as belonging to the genus Erisocrinus are described as Exaetocrinus maderaensis n. sp. and Pontotocrinus coloradoensis n. sp. The lectoholotype of Erisocrinus typus Meek & Worthen, type species of the genus, is illustrated

Occurrence of Cranocrinus Wanner in North America

The cladid inadunate genus Cranocrinus Wanner is typically from Upper Permian rocks of the Island of Timor, Indonesia, and has been reported from Lower Permian rocks of the Ural Mountains of Russia. Arendt (1970) has demonstrated that juvenile C. praestans lacks radials (is pseudomonocyclic) while adult specimens have radials (are dicyclic). Both conditions are noted for C. eximius n. sp. from Morrowan (Lower Pennsylvanian) rocks of Oklahoma and are described herein. Possible methods of feeding and respiration are considered in the discussion of Cranocrinus

A New Edrioasteroid

Two specimens of an edrioasteroid in excellent preservation have been found in the Pella beds, Upper Mississippian, by Amel Priest of Peru, Iowa at an abandoned quarry northeast of Knoxville, Marion County, Iowa. The interior of the theca is exposed in the smaller specimen and the existence of a stone canal is disclosed. The species is described as Discocystis priesti, new species

Praepholidocidaris, a New Echinoid from the Pella Formation (Mississippian) of Iowa

Praepholidocidaris pellaensis, n. gen., n. sp., is described from basal Chesterian rocks in the vicinity of Oskaloosa and Givin, Mahaska County, Iowa. The new genus is characterized by its small number of ambulacral and interambulacral plate columns, adorally expanded ambulacra, unequal ambulacrals with perforate primary spines, and interambulacrals with primary spines only on adradial plate columns. Age relationships of the Pella Formation and the paleoecology of its echinoderm fauna are reviewed. It is concluded that the echinoderms represent an opportunistic assemblage and the bulk of the echinoderm fauna supports assignment of unit C of the formation to the Talarocrinus Zone (of Horowitz and Strimple, 1974), basal Chesterian

Megaliocrinus johnsoni, a New Camerate Crinoid Species from Middle Pennsylvanian Rocks of Illinois

The steinkern of a camerate crinoid found in rocks of Middle Pennsylvanian age is of considerable interest in that very few genera or species have been reported. Megaliocrinus johnsoni, new species, is from the Cherokee Group, exposed in the Collinson quarry near Milan, Rock Island County, Illinois. Internal nerve canals radiating from the chambered organ are preserved as ridges

Notes Concerning Delocrinus and Graffhamicrinus (Crinoidea: Inadunata)

The purpose of the present study is to describe an historically important crown (cup with arms attached) of Delocrinus hemisphericus from Virgilian strata in Taylor County, Iowa, collected by C. A. White sometime during his tenure as State Geologist of Iowa (1866-1869) , and to clarify the present status of the genus Delocrinus. Several crowns of D. hemisphericus, one crown of Graffhamicrinus nodosarius (Strimple), and a divergent form described as Delocrinus elongatus n. sp. from the Virgilian of Oklahoma are illustrated. Possible phylogenies are discussed with emphasis on the genera Delocrinus. Graffhamicrinus. and Diphuicrinus

Suggested Growth Pattern in the Mississippian (Chester) Echinoid Lepidesthes formosa Miller

1167-1177http://deepblue.lib.umich.edu/bitstream/2027.42/48590/2/ID452.pd

Edrioasteroids (Echinodermata) of the Maquoketa Formation of Iowa

Two specimens of edrioasteroids have been found in the Maquoketa Formation, Richmond Group, Upper Ordovician of Iowa. This occurrence extends the geographic range of both genera, lsorophus Foerste (1917) and Edriophus Bell (1975) into Iowa which is the westernmost occurrence of these genera formerly recorded only east of Illinois. Isorophus was found in a horizon essentially barren of fossils but Edriophus is coexistent with more common echinoderms of the Maquoketa, including the crinoid genera Carabocrinus and Porocrinus