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Species / Anchura Gibbera


Original Description of Anchura gibbera by Webster, 1983, p. 1095:

  • "Shell large for genus, turriculate, with about 12 convex whorls; apical angle about 21; whorls ornamented by slightly oblique, smoothly curved, sigmoidal axial ribs, crossed by 4 evenly spaced revolving cords that produce a cancellate pattern; lowermost cord become progressively more prominent as whorls enlarge, and have 6 to 8 extremely fine striae in the interspaces; sutural ramp flat, sloping at about 45 to a pronounced carina formed by the most adapical cord on body whorl; abapical 2 cords on body whorl widely spaced, much enlarged, but not forming angulations. Outer lip expanded, with a thickened margin, constricted at the carina then widening into a flattened wing; a long smoothly-tapered spine projects adapically beyond the spire and is deflected outward from it at an angle of about 40; in apertural view, spine also deflected away from observer at about 25 angle, with deflection increasing toward distal end of spine; anteriorly, wing produced into a short, broad, abapically directed spur, abruptly tapered to a sharp point and carinate on outer surface; both anterior spur and posterior spine bear a shallow, medial channel on inner surface; Shoulder of body whorl continued onto wing as a sharp carina, disappearing at base of posterior spine; lower cords of body whorl absent on wing. Aperture ovate, narrowed slightly posteriorly but with no canal, constricted anteriorly into a long, narrow canal, deflected slightly away from the observer in apertural view; exact length of rostrum unknown, but at least longer than aperture. Posterior margin of labrum bordered by athick callus deposit that spreads into anterior half of penultimate whorl and down onto inner lip. A large, drooping, tubercular process, convex above, concave below, and rounded at the distal end, projects outward from parietal wall in front of aperture; columellar wall smooth, callused."

Locus typicus: Coll. LACMIP no. 2858; Arroyo Santa Catarina, Baja California State, Baja California Peninsula, Mexico

Stratum typicum: Rosario Formation, late Campanian to early Maastrichtian, upper Cretaceous

Types: holotype LACMIP 6465, paratypes LACMIP 6466 - 6471, IG-UNAM IGM 3284

Etymology: gibbera (Latin) = "humped"


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