Order Ptychopariida, Family Ptychopariidae
Time: Early Middle Cambrian
Site: Kaili Formation, Maiobanpo Section, Taijiang County, Kaili,
Guizhou Province, China
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 eocrinoids 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
trilobite is Xingrenaspis xingrensis, a member of the Order Ptychopariida.
Trilobites from this timeframe were members of the Redlichiida,
Ptychopariida, Corynexochida, and the Agnostida, with the balance
of the orders appearing later in time.