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Orthonychia variablis
Taxonomy
Platyceras (Orthonychia) variablis was named by Tyler (1965). Its type specimen is YPM 16487, a shell, and it is a 3D body fossil. Its type locality is river bed immediately downstream from the Four Mile Dam on Thunder Bay River, which is in a Givetian carbonate limestone in the Four Mile Dam Formation of Michigan.
It was recombined as Orthonychia variablis by Wagner (2023).
It was recombined as Orthonychia variablis by Wagner (2023).
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.
†Orthonychia variablis Tyler 1965
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Diagnosis
| Reference | Diagnosis | |
|---|---|---|
| J. H. Tyler 1965 | Shell erect, curved-conical to elongate, slightly flattened unguiform; general form of shell extremely variable from very stout, rapidly expanding to elongate; apical part typically downcurved beak which may curve very slightly sinistrally downward when viewed in apical aspect; downcurved beak commonly uncurved to side, producing bilaterally symmetrical, steeply patelliform profile in stouter individuals; apical part of more slender and elongate individuals tending to have small whorl of one-half to three-fourths of volution, thence rapidly flaring out, becoming elongate; whorl profile varying from gently rounded in stouter individuals to sharply carinate in more elongate individuals; shell surface typically showing more or less regularly spaced, sinuous, collabral growth lines; strongly defined apertural sinuses lying on sides of shell; smaller sinuses perhaps present along other parts of aperture; elongate shell structures may be present, consisting of crudely defined plications lying mostly in mature half of shell; individual variation reflected in crudely bundled distortion of shell, producing strongly fluted structures extending lengthwise on shell. |
Measurements
No measurements are available
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| Source: g = genus, c = class | |||||
| References: Kiessling 2004, Ohern and Maynard 1913 | |||||