Stromboidea
Original diagnosis:
- "Medium size Onustus with undulated upper surface and double spiral cord along the suture. "
Original Description of Onustus undosus by Raven, 2021
- "Medium size for the genus (h ~15 mm, w 50.5 mm), very low spire (apical angle 130o) with concave outline, ~7 flat whorls, with a narrow and thin peripheral flange. The outline is weakly scalloped, the suture partially marked by a thick, variably shaped spiral chord. Fine objects are present at varied positions on the early whorls, but as these are worn only part of them are preserved. The upper surface has irregular, broad undulations aligned with the growth lines (23 on the last whorl), on the last whorl orthogonally crossed by faint riblets. Outer edge not preserved. Lower surface not visible. "
Stratum typicum: Seria Formation, late Miocene
Locus typicus: Tutong 13 outcrop, Tutong, Brunei
Onustus undosus Raven, 2021; Holotype; Tutong 13 outcrop, Tutong, Brunei; Seria Formation, Late Miocene; RGM 783532
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