NMITA:Neogene Marine Biota of Tropical America

Opisthonema aff. oglinum (LeSeur, 1818)

Specimen details:
Sample Number: PPP2541
Type Status: nontype
Scale Bar is 0 mm
Type: SEM
Orientation: mesial
Locality: Paraguana, Paraguana, Venezuela

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Morphologic Description:

    Otolith shape: oblong to fusiform;
    Thickness: moderately thin;
    Form: -Mesial slightly convex;
    Form: -Lateral slightly convex;
    Dorsal margin: approximately straight, angled to rostrum;
    Dorsal margin sculpture: irregular in middle;
    Ventral margin: gently rounded and dentate;
    Posterior margin: rounded and irregular;
    Sulcus acusticus: ostial, heterosulcoid;
    Colliculum: homomorph;
    Pseudocolliculum: absent;
    Ostium: narrow and very large;
    Cauda: short, oval, poorly defined posteriorly;
    Ostio-caudal differentiation: dorso-ventrally constricted;
    Collum: absent;
    Crista superior: ridge-like and curved over the cauda, poor over ostium, absent at tip;
    Crista inferior: ridge-like and curved under the cauda, well developed under ostium;
    Dorsal depression: oblong;
    Ventral depression: small and shallow below ridge;
    Rostrum: very large and pointed;
    Antirostrum: short and pointed;
    Excisura: moderately wide, notch depth, angle acute;
    Early Miocene: Cantaure Fm., Paraguana, Venezuela;

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