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Protoceratoikiscum clarksoni
Taxonomy
Protoceratoikiscum clarksoni was named by Danelian and Floyd (2001). It is a 3D body fossil.
Synonymy list
Year | Name and author |
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2001 | Protoceratoikiscum clarksoni Buckman and Aitchison p. 363 |
2001 | Protoceratoikiscum clarksoni Danelian and Floyd figs. figs. 5a-c |
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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.
†Protoceratoikiscum clarksoni Danelian and Floyd 2001
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Diagnosis
Reference | Diagnosis | |
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S. Buckman and J. C. Aitchison 2001 | Skeleton made up of seven (7) straight rod-like primary spines situated hori- zontally and distributed radially along a circle formed by three rows of arches (or straight by-spines) joining the primary spines. The latter taper gently distally, but also rapidly proxi- mally towards the center, inwards of the innermost circle. The median row is in general circular-oval and follows closely the shape of the innermost row, although parts of it are slightly off- set in some specimens. First and fourth primary spines posi- tioned on opposite sides of a practically straight line, while the angle formed between the first and seventh primary spines is smaller (20?-33?) than the angles formed between other spines. A characteristic triangular structure is thus formed on most specimens, made of the two primary spines (first and seventh) and straight by-spines, which are often offset with respect to the adjacent arches/by-spines. Secondary spines may be present and positioned radially on the median row, but do not extend in- wards to the center of the skeleton |