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Agnostotes orientalis
''Agnostotes orientalis'' is a species of agnostid trilobite belonging to the genus ''Agnostotes''. It existed during the Jiangshanian Age ( million years ago) of the Cambrian. It is an important index fossil in biostratigraphy.
==Description==
''Agnostotes orientalis'', like all members of the suborder Agnostina, possesses two thoracic segments, has a cephalon and pygidium that are more or less the same size and shape (isopygous), and is completely blind.
The axial lobe of the cephalon is narrow. At the front of the glabella is a notch (frontal sulcus), a characteristic unique to the species, making it easy to distinguish from other members of the genus. The posterior end of the axial lobe of the pygidium also widens significantly, another distinct characteristic of the species. Along the margins of the pygidium are a pair of very small backward-pointing spines. Both the pygidium and the cephalon are ornamented with small pits (scrobicules) and wrinkles, extending mostly inwards from the margins. These ornamentation are less numerous and distinct in younger specimens, increasing in number and depth as they grow. Older individuals also tend to have proportionally wider anterior ends of the pygidial axial lobe.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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