Cole et al.—Camerates from an Upper Ordovician Lagerstätte, Ontario


491


Figure 2. Phylogenetic placement of Priscillacrinus n. gen. (indicated by star) relative to other Ordovician camerate genera.


within this clade suggests it belongs within the Anthracocrini- dae. Further support for this conclusion on the basis of skeletal morphology is given below following the systematic description of Priscillacrinus n. gen.


Repositories and institutional abbreviations.—New material described here is reposited in the University of Michigan Museum of Paleontology (UMMP). Additional material exam- ined is from the Cincinnati Museum Center Invertebrate Paleontology Collection (CMCIP) and the Smithsonian National Museum of Natural History (NMNH). Type material not examined is from the Geological Survey of Canada (GSC) and the Field Museum of Natural History (FMNH).


Systematic paleontology


Classification and terminology.—The classification of crinoid higher taxa used here follows Ausich et al. (2015), Cole (2017),


and Wright et al. (2017). Other aspects of suprageneric classi- fication used herein follow Moore and Teichert (1978) and Brower and Veinus (1974). Morphologic terminology follows Ubaghs (1978a). The


plating of interrays is given in the standard abbreviated form as the number of plates in each range from the proximal-most plate to the last range before the tegmen. In the posterior interray, the primanal is indicated by “P” and the first interradial in regular interrays is indicated by “1.” The shorthand notation used to describe the nodal-internodal structure of heteromorphic columns is fromWebster (1974).


Remarks.—In addition to Reteocrinus, the genera Gaurocrinus, Cnemecrinus, and Quechuacrinus were previously assigned to family Reteocrinidae (Guensburg and Waisfeld, 2015). Phylogenetic evaluation of all Ordovician camerate crinoids by Cole (2017) did not recover Gaurocrinus or Cnemecrinus as members of Reteocrinidae, although Cnemecrinus is closely related to the family. The diagnosis for Reteocrinidae given above is emended from recent diagnoses (Guensburg, 1984; Guensburg and Waisfeld, 2015) to reflect exclusion of Gaurocrinus and Cnemecrinus from the family (Cole, 2017).


Genus Reteocrinus Billings, 1859 Type species.—Reteocrinus stellaris Billings, 1859. Class Crinoidea Miller, 1821


Subclass Camerata Wachsmuth and Springer, 1885 Family Reteocrinidae Wachsmuth and Springer, 1885


Included genera.—Reteocrinus Billings, 1859 and Quechua- crinus Guensburg and Waisfeld, 2015.


Diagnosis.—Dicyclic camerates with prominent ray ridges; depressions or gaps between basal and infrabasal plates; radial circlet interrupted in all rays; posterior with ray-like anitaxial series; interrays depressed, presumably not ankylosed or only weakly cemented, comprised of small and irregularly arranged plates; position of primaxil highly variable; arms uni- serial, apinnulate; stem pentameric in at least distal portion.


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