Gryponautilus is a genus of Upper Triassic nautilids (generally coiled nautiloid cephalopods) belonging to the trigonoceratacean family Grypoceratidae, characterized by involute, inflated shells, which at maturity develop narrowly rounded keel-like venters.

Venters on inner whorls are truncated and broadly convex to concave.

Immature forms bear a resemblance to Grypoceras.

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