Peronopsis Agnostid Trilobite from Kaili Formation

Peronopsis sp.

Class Trilobita (Trilobites); Trilobite Order Agnostida; Family Peronopsidae

Geological Time: Early Middle Cambrian Peronopsidae

Size: 2 mm across by 4 mm long

Fossil Site: Kaili Formation, Maiobanpo Section, Taijiang County, Kaili, Guizhou Province, China

PeronopsisThe Kaili Biota of Guiznou Province China, like the fantastic Chengjiang and Burgess Shale Fauna, preserve some of the earliest radiations of complex life known on the planet. The formation is some 220 m in thickness and spans the Late Early to Early Middle Cambrian. As such it is intermediate in age between the Changjiang and Burgess Shale Faunas. Representatives of some 110 genera are known, representing 11 phyla. The Kaili Biota includes both soft-bodied and skeletonized animals, and is dominated by trilobites, with eocinoids as the second most common fossil. It shares roughly 30 genera in common with Chengjiang and nearly 40 with the Burgess Shale. The presence of Burgess Shale–like fauna over a large part of southwestern China shows that the faunal community was quite cosmopolitan in nature, indicating that preservation was more of a factor in finding these concentrations of animals than was the existence of isolated communities suitable for harboring these myriad life forms.

This trilobite is a species of Peronopsis, a member of the Order Agnosida. Trilobites from this timeframe were members of the Redlichiida, Ptychopariida, Corynexochida, and the Agnostida, with the balance of the orders appearing later in time. The agnostids are well known for the reduced number of thoracic segments, as well as their “pushme-pullyou” appearance; it is hard to decide which was the cephalon and which the pygidium.

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