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Protocycloceras debilis
Taxonomy
Protocycloceras debilis was named by Clark (1935). It is not extant. Its type locality is H. Slopes of hillock, Hill near Mount Pisgah, which is in a Whiterockian marine shale in the Swan Peak Formation of Utah.
Synonymy list
| Year | Name and author |
|---|---|
| 1935 | Protocycloceras debilis Clark p. 242 figs. Pl. 24, Fig. 7 |
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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.
†Protocycloceras debilis Clark 1935
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| T. H. Clark 1935 | Several specimens of an annulated cone are all crushed flat, the state of preservation leaving much in doubt. Shell thin tapering, with strong annulations; in
holotype annulations 2.5 mm. apart where shell is 16 mm. wide, 2 mm. apart where shell is 10 mm. wide; largest specimen 16 mm. wide, the annulations 3.3 mm. apart. Both inner and outer surfaces of the shell ornamented with fine annular striae, ridges on the exterior, furrows on the interior; striae sub-parallel, never touching each other. Index of tapering about 1 in 6 or 1 in 6 1/2, as also in the original conical shell. No internal structures can be determined. In the holotype the interior of the shell is well shown, and the absence of septal structures indicates that the larger end of this specimen is the living chamber. However, septa would probably have been as thin and incompetent as the shell itself, and might not be observable in the specimens in their present crushed condition. No trace of the siphuncle can be seen. Fairly common at loc. H (holotype), rare at G, both in the Swan Peak formation south of Mount Pisgah, Utah. It is difficult to contrast these specimens with others. White described a species of annulated "Orthoceras" (O. colon, Lower Ordovician Utah),5 but his species possess a strong shell, with a peripheral siphuncle, and lacks surface markings. Of the species of Protocycloceras known in eastern North America only P. whitfieldi Ruedemann (Beekmantown, Fort Cassin, Vermont) is described as possessing "fine encircling lines."6 Orthoceras priamzis Billings (Beekmantown?, New Brunswick, and Chazy, Newfoundland)7 resembles this species in surface ornamentation |