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Orthonema cortum
Taxonomy
Orthonema cortum was named by Kues (2004) [“Orthonema” cortum]. Its type specimen is UNM 13,342, a shell, and it is a 3D body fossil. Its type locality is Carrizo Arroyo Unit 52, which is in a Virgilian marine limestone/shale in the Red Tanks Formation of New Mexico.
Synonymy list
| Year | Name and author |
|---|---|
| 2004 | Orthonema cortum Kues pp. 174 - 175 figs. 10.7-10.10 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
†Orthonema cortum Kues 2004
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| B. S. Kues 2004 | Shell small, slightly cyrtoconoid, narrowly conical in shape but broader than is typical of Orthonema, with convex whorl profile and flattened upper whorl surface throughout growth; ornamentation of two main spiral lirae at midheight, at or just above periphery, two or three smaller lirae below them, and one lira at upper suture.
Shell small (to about 4 mm in height), anomphalous, consisting of up to nine whorls, broadly conical in juveniles to moderately high spired at maturity; whorl expansion rate decreasing somewhat with growth; spiral angle of small specimens about 50 degrees, but decreasing to about 32 degrees on larger specimens; protoconch slightly heliciform, consisting of two smooth, inflated whorls; shell height of mature specimens a little more than twice maximum width; whorl height less than one half width; whorl profile moderately convex, slightly pendant; later whorls with slightly flattened upper surface and moderately convex across middle and lower surface; sutures moderately impressed; aperture not well preserved on available specimens but apparently suboval; columellar lip straight proximally, thickened; inductura very thin, barely extending from aperture; base of body whorl flatly rounded, curving evenly into lateral whorl surface, unornamented or with hint of one or two spiral lirae; ornamentation of early teleoconch whorls (whorls 3, 4) consisting of two spiral lirae located about at midheight; with growth (whorl 6) a subsutural lira is added on upper whorl surface and a fourth lira is added just above lower suture; later whorls include a subsutural lira, an incipient lira below it, the original two strong primary lira, and two or three additional spiral lirae below, continuing on to base of body whorl; growth lines faint, apparently broadly opisthocyrt. |
Measurements
No measurements are available
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| Source: c = class | |||||
| Reference: Kiessling 2004 | |||||