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Species / Anchura Turricula

Anchura Turricula


Original description of Anchura turricula by Stephenson, 1952:

  • "Shell of medium size, turreted, with spiral angle ranging from 27 to 32 on different individuals. Protoconch not preserved. Suture closely appressed, slightly impressed. Whorls about 8, broadly convex in lateral profile, ornamented with both spiral and axial ridges, the latter dominant except on the body whorl. Axials on penultimate whorl numerous, irregular, closely crowded, crossing the side in a strong curve concave toward the front, numbering about 23 on the holotype; the axials number 21 on the antepenultimate whorl and become weak and fade out on the next earlier whorl; 3 or 4 of the early apical whorls are smooth, probably owing to mechanical wear. Most of the available shells show considerable wear, probably due in part to the movements of the animal during life and in part to mechanical wear on or near a beach prior to fossilization. The holotype is less worn than most specimens, but many of the finer details have been destroyed. On this type the upper part of the penultimate whorl bears 3 or 4 rather weak, irregularly noded primary spiral ribs, with more or less obscure secondaries and tertiaries in the interspaces; additional still finer lining may be seen in places. On the lower part of this whorl the spiral lining is very obscure. The spiral ornamentation continues rearward onto the antepenultimate whorl, where it becomes progressively weaker and more obscure. On the body whorl the axial ribs are small, weak, and closely spaced. On the upper part of this whorl the spiral sculpture is about the same as on the penultimate. At about the beginning of the last half of the body whorl a prominent, round-crested ridge abruptly appears on the line of greatest inflation and continues forward on the expanded outer lip, where it bends upward and continues to the tip of the upturned spurlike extension of the lip. The broadly rounded base bears 7 or 8 weak to obscure spirals, the upper 3 or 4 of which are coarser than the ones below. Growth lines sinuous in trend, with a strong convexity forward on the base and an opposite broad concavity in the same direction on the upper part of the whorl. The axial ribs follow the trend of the growth lines. Aperture long-lanceolate, with a wide anal angle at the rear, and projected forward at the front into a narrow, twisted siphonal canal; in the holotype an undetermined portion at the distal end of the canal is broken away, but it is probably short. On all other available specimens the canal is still less completely preserved. The outer lip is thick and is expanded into a long, moderately broad, thick wing that curves strongly upward spurlike to a point at the distal end. The ridge, which traverses the outer surface of this wing to its tip, is reflected on the inner surface by a narrow canal that also extends to the tip. The lower, outer part of the wing expands somewhat, producing a broadly convex margin; this appears to correspond to the short spurlike projection forming the lower part of the wing of the typical Anchura abrupta Conrad. Intermediate between this outer expansion and the columella is a lesser but fairly conspicuous marginal expansion, which is slightly warped. This corresponds to a similar expansion on A. abrupta. The inner lip is broadly excavated above and forms a thick callus that spreads forward on the parietal wall to a maximum of 11 or 12 mm and extends from above the anal angle downward to and out onto the siphonal canal."

Locus typicus: Slate Shoals, Red River, 8 miles east of Arthur City, Lamar County, Texas, USA

Stratum typicum: Templeton Member, Woodbine Formation, Cenomanian, upper Cretaceous

Dimensions Holotype: height 59+ mm; diameter exclusive of expanded lip, about 22 mm; diameter including lip, 45 mm

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