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Streptochetus californiana
Taxonomy
Streptochetus californiana was named by Squires (1987). Its type specimen is LACMIP 7480 and is a 3D body fossil.
Sister species lacking formal opinion data
Synonymy list
| Year | Name and author |
|---|---|
| 1987 | Streptochetus californiana Squires p. 41 figs. 56, 57 |
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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.
†Streptochetus californiana Squires 1987
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| R. L. Squires 1987 | Generic assignmen t based on the small, fusi- form shell, mode rately long anterior canal with siphonal fasciole showing an umbilical slit, and ornament ofnoded col- labral costae crossed by spira l ribs. Specific assignment based on the 12 to 13 collabral costae and numerous primary spiral ribs alterna ting with secondary ribs.
Streptochetus californiana new species is very similar to Streptochetus obliquatus (Deshayes , 1824:542, pl. 74, figs. 13, 14; Cossmann and Pissarro , 1910-1913:pl. 40, fig. 197- 7) from lower Eocene strata (Cuisian Substage) of the Paris Basin , Fran ce. Streptochetus californiana differs from S. ob- liquatus in the following features : 12 to 13 collabral costae rather than seven or eight, primary spiral ribs not as strongly developed on the upper spire , and collabra l costae more strongly developed on the spire. Description. Shell small , elongate-fusiform , with five and one-half whorls. Suture area coincident with one to two prominent spiral ribs that form a band. Protoconch missing. Teleoconch whorls angulate anterior to this sutural band and with 12 to 13 collabral costae that are as strongly developed in this sutural band region as elsewhere . Th e collabra l costae also tend to become obsolete on the body whorl. Costae are noded where crossed by finer primary spira l ribs that number about six on the spire whorls and about ten on the body whorl. The posteriormost two primary spi ral ribs on the body whorl occupy the sutural area and form a distinct area in which the collab ral costae are no t strongly developed. On the anterior portion of the penultimate whorl there can be a secondary spiral rib between the primaries tha t approaches the primaries in strength. On the posterior of the body whorl , there can be one to three secondary spiral ribs or three tertiary spiral riblets between the primaries. Teleoconch covere d by very fine growth lines. Oblique neck area moderately long with about eight primary spira l ribs that can have a secondary rib in the interspaces. Aperture oval. Outer lip missing. Siphonal fasciole well developed and showing an umbilical slit. Holotype height (nearly complete) 19 mm , width (complete) 8 mm. |
Measurements
No measurements are available
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| Source: f = family, c = class | |||||
| References: Hendy et al. 2009, Kiessling 2004 | |||||