Abstract
AbstractThis paper reports the successive occurrence ofPtychagnostus sinicusLu, 1957 andPtychagnostus atavus(Tullberg, 1880) from the lower part of the Machari Formation, Yeongwol Group, Korea. Morphometric approaches of using the landmark and principal component analyses make it possible to differentiateP.sinicusfromP.atavuswith clarity: pygidia ofP.sinicushave a relatively narrow M1, a transverse F2, and a weakly developed M2 tubercle, whereas those ofP.atavusare characterized by a broadly arching M1, a chevron-shaped F2, and a prominent M2 tubercle. Recognition ofP.atavus, for the first time in Korea, allows the determination of the base of the Drumian Stage in Korea and aids correlation with other parts of the world.
Published Version
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