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  • Ostrea alifera var. pediformis Craigin


    DPS Ammonite



    Kingdom: Animalia
    Phylum: Mollusca
    Class: Bivalvia
    Order: Ostreoida
    Family: Ostridae
    Genus: Ostrea
    Species: O. alifera var. pediformis
    Author Citation Craigin 1893

    Geological Time Scale

    Eon: Phanerozoic
    Era: Mesozoic
    Period: Cretaceous
    Sub Period: None
    Epoch: Late
    International Age: Turonian


    Eagle Ford Group
    Arcadia Park Formation


    Collector: Me
    Acquired by: Field Collection


    Length: 44 mm
    Width: 22 mm
    Thickness: 9 mm


    Post Oak Creek south side of Sherman, Texas
    Grayson County
    United States


    This is a Cretaceous oyster that I found in Post Oak Creek in Sherman, Texas. The oyster has traces of a yellowish calcite-cemented sandstone found in the upper part of the Arcadia Park Formation of the Eagle Ford Group.


    "Pediformis" in the name, Ostrea alifera var. pediformis, means foot-shaped or pediform because the oyster looks like a foot or boot.


    In Hill 1898, the author

    eliminated the Ostrea alifera Cragin, and Ostrea alifera var. pediformis Cragin names because he considered them to be Ostrea lugubris Conrad. I disagree with Hill's decision because my oyster is larger than most O. lugubris (now Cameleolopha lugubris) and lacks an attachment scar characteristic of O. lugubris. My oyster may be a genus Cameleolopha since both Cameleolopha bellaplicata and Cameleolopha lugubris occur nearby. Unless new information can be found, my oyster should be called: Ostrea alifera variety pediformis Craigin.


    For more information and drawings of Ostrea alifera and Ostrea alifera variety pediformis Craigin see:


    Cragin,  F. W. 1893. "A Contribution to the Invertebrate Paleontology of the Texas Cretaceous", Austin, Texas, B.C. Jones & Co., State printers.


    Hill, Robert T. & T. W. Vaughan. 1898. The Lower Cretaceous *Grypheas* of the Texas region. U. S. Geological Survey, Bulletin 151: 139 pp.



    User Feedback

    Has anyone found similar oysters in Post Oak Creek or from the Arcadia Park Formation?

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    Beachdog rockhound


    This is completely amazing. The molluscs I find are no where near this detailed. Thanks for telling pics

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