A sample of the Gatuncillo Formation in Quebrancha syncline, Panama, has been examined to determine its exact age in terms of ranges of planktonic Foraminifera. The well-preserved foraminiferal fauna indicates the age to be lower Oligocene, Globigerina sellii zone (equals G. oligocaenica zone). A portion of the type sample of the Globorotalia cerroazulensis zone (equals G. cocoensis zone) of the San Fernando Formation of Trinidad has been examined; finding of Cassigerinella chipolensis indicates post-Eocene, possibly Oligocene, age. Further work on separating the reworked Eocene Foraminifera from the autocthonous may yield more evidence of Oligocene age for the San Fernando.

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