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Pygidium (i.e. 'tail' segment)
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Wenndorfia expansa
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The trilobite Wenndorfia expansa is amongst several species previously reported from the Reefton and Baton formations. In the past it has gone under several names, including Homalonotus expansus, Burmeisteria expansus, B. huttoni and Digonus margaritifer. Its identification has most recently been determined by Sanford (2005), who provides a detailed description and photographs. Key features relevant to this specimen are summarised to the lower right and indicated on the diagram below.
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Description, based on Sanford (2005): Pygidium short with a length only ca. 0.7 times its width and weakly concave sides; axial furrows poorly defined, indicated by flexure of pleurae, almost indistinct anteriorly (i.e. towards the front); 9 pleural ribs. Pygidial axis wide, about 0.4 times pygidial width and very poorly defined anteriorly. Further Reading: Sanford, A.C. 2005 Homalonotid trilobites from the Silurian and Lower Devonian of south-eastern Australia and New Zealand (Arthropoda: Trilobita: Homalonotidae). Memoirs of Museum Victoria 62(1), 1–66. |