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Perissopyge triangulata
Taxonomy
Perissopyge triangulata was named by Blaker et al. (1996). Its type specimen is LACMIP 7716 and is not a trace fossil.
Synonymy list
Year | Name and author |
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1996 | Perissopyge triangulata Blaker et al. |
2008 | Perissopyge triangulata Stein and Peel |
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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.
†Perissopyge triangulata Blaker et al. 1996
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Diagnosis
Reference | Diagnosis | |
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M. Stein and J. S. Peel 2008 | Examination of the type suite illustrated by Blaker et al. (1997, fig. 7) indicates shortening, stretching and oblique
distortion of individual specimens, presumably as a result of tectonic deformation. Thus, the holotype is antero-posteriorly shortened relative to the paratype illustrated here (Fig. 2A). The presence of pleural spines on the lateral border of the pygidium (Fig. 2A) sheds doubt on the reported presence of seven thoracic segments in the holotype (LACMIP 7716) of P. triangulata. The tagma boundary between thorax and pygidium is not readily identified in that specimen (Fig. 2B). At least one of the supposed thoracic segments may belong to the pygidium. For other specimens (e.g. LACMIP 7417, 7418), seven thoracic segments can be confirmed. As the holotype specimen is larger than the remainder, it seems unlikely that it represents a late meraspis. It should be noted that the cephalothoracic boundary is poorly preserved, the posterior cephalic border being somewhat deformed. It is possible that the anteriormost thoracic tergite partly underlies the posterior margin of the cephalon and hence is not recognized. |