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Cyrtoceras minneapolis
Taxonomy
Cyrtoceras minneapolis was named by Clarke (1897). It is the type species of Cyrtorizoceras.
It was recombined as Cyrtorizoceras minneapolis by Hyatt (1900) and Teichert (1930).
It was recombined as Cyrtorizoceras minneapolis by Hyatt (1900) and Teichert (1930).
Sister species lacking formal opinion data
Synonymy list
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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.
†Cyrtoceras minneapolis Clarke 1897
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J.M. Clarke 1897 | Shell arcuate, rapidly expanding to the aperture. Body-chamber without constriction; apical curvature not known. Surface laterally compressed; sides broad; dorsum narrow, venter still narrower and more arcuate. Transverse section subelliptical, the major and minor diameters being as 11 to 9 at the next to the last septum, and as 16 to 11 at the aperture. The lateral margins of the aperture are convex, the dorsal and ventral margins broadly and narrowly concave or re-entrant, respectively. The septa are regularly and evenly, though not deeply concave, the deepest concavity being at about the center. The sutures are transver::;e and simple, without lobes or saddles save for a slight upward inclination on the venter, which gives to the air-chambers a greater depth on the ventral than on the dorsal side. Sipho ventral, submarginal, expanded in each air-chamber. Surface covered with closely crowded concentric lines, conforming in curvature to the aperture. On the internal cast are traces of longitudinal ridges over the body-chamber. A small and typical example has the aperture 16 mm. in major, and 11 mm. in minor diameter. At the next septum to the last these dimensions are 11 and 9 mm. In a large specimen the aperture is 21.5x15 mm. and at the third septum from the aperture 15x12 mm. This species has some similarity to Cyrtoceras camurum | |
| A. Hyatt 1900 | Sections more compressed than in Rizoceras, living chamber shorter and apt to be more or less laterally compressed in gerontic stage, but the dorso-ventral diameters only very slightly so or not at all. Sutures more sinuous, and with decided ventral and dorsal saddles. | |
| C. Teichert 1930 | "Querschnitt mehr seitlich zusammengedriickt als bei Rizoceras, Wobnkammer kiirzer uud neigt dazu, im Altersstadiummehr odeI' weniger seitlich zusammengedriicktder dorsoventrale Durchmesser nur sehr gering oder iiberhaupt Suturen mehr gebogen und mit betonten Dorsal-und Ventral zu werden, wahrend nicht verengert wird satteln, |