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  • Pleurocystites squamosus Billings, 1874





    Kingdom: Animalia
    Phylum: Echinodermata Klein 1754
    Class: Rhombifera Zittel 1879
    Order: incertae sedis
    Family: Pleurocystitidae Neumayr 1889
    Genus: Pleurocystites
    Species: Pleurocystites squamosus
    Author Citation Billings, 1874

    Geological Time Scale

    Eon: Phanerozoic
    Era: Paleozoic
    Period: Ordovician
    Sub Period: None
    Epoch: Late
    International Age: Sandbian - Katian


    Simcoe Group
    Kirkfield Formation


    Acquired by: Purchase/Trade


    Length: 5 cm
    Width: 1.6 cm


    Brechin, Carden Quarry
    Simcoe County


    Synonym: Pleurocystites robustus Billings, 1854.

    Alternative spelling: Pleurocystis.

    Taxonomy from fossilworks.org.

    Diagnosis (Sprinkle et al., 1985): “Theca rounded-triangular, nearly symmetrical; 3 rhombs elliptical, dichopores occupying less than 40% of sutures; periproct occupying 70% of lower side, about 680-700 periproctals, no rectal lobe, anal pyramid away from margin; ornament composed of medium growth lines and few ridges radiating to the plate sides and corners; brachioles having large groove extending up aboral side, cover plates fairly large; proximal stem slowly tapering and moderately ridged.”

    ID determined by oilshale.


    Billings, E. (1874). Paleozoic Fossils, v. II, pt. I. Canada Geological Survey 1-144

    Parsley, R. L. (1970). Revision of the North American Pleurocystitidae (Rhombifera-Cystoidea). Bulletins of American Paleontology 58:135-213.

    Sprinkle, J., Henry, L., Zimmer, F., Kelley, L., & Whiteley, J. (1985). New Pleurocystites from the Bromide Formation of Oklahoma. Journal of Paleontology, 59(6), 1476-1480.

    Brower, J. (1996). Growth and Functional Morphology of Pleurocystites Squamosus Billings, An Ordovician Rhombiferan Echinoderm. The Paleontological Society Special Publications, 8, 48-48. doi:10.1017/S2475262200000502

    Paton, T. (2017). Paleo Pompeii; Genesis and Preservation of an Upper Ordovician Mounded Hardground with a Diverse Encrusting Community. Master-thesis, University of Cincinnaty. 

    Paton, T. and  Brett, C. E. (2019). Revised stratigraphy of the middle Simcoe Group (Ordovician, upper Sandbian-Katian) in its type area: An integrated approach. Canadian Journal of Earth Sciences 57(1).

    User Feedback



    Amazing! Look at the detail, its so well preserved!

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    Very nice little bugger! 



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