Redlichiodea; Yunannocephalidae: Yunnanocephalus yunnanensis
Time: Early Cambrian, (~525 million years ago)
inch): 11 mm long on a 40 mm by 30 mm matrix
Chengjiang Biota, Quiongzhusi Section, Yu’anshan Member, Heilinpu
Formation Mafang, Anning, Yunnan Province, China
This trilobite is a member of the Order Redlichiida (some researchers
place it in the Ptychopariida), Family Yunannocephalidae from the
Early Cambrian Heilinpu Formation deposits near Yuxi, in Chengjiang
Couty, Yunnan Province, China, known as Yunnanocephalus yunnanensis.
The species is one found in several locations within Yunnan Province,
the souce of the name of the genus and species. The diversity of
soft-tissue fossils from the Cjengjiang Biota is astonishing: algae,
medusiforms, sponges, priapulids, annelid-like worms, echinoderms,
arthropods (including trilobites), hemichordates, chordates, and
the first agnathan fish make up just a small fraction of the total.
Numerous problematic forms are known as well, some of which may
have represented failed attempts at diversity that did not persist
to the present day.
Redlichioids of this type are considered to be the sister-group
comprising all of the “higher” (non-Olenelloid) trilobites
by Richard Fortey. Yunnanocephalus is thought to have lived on or
close to the seafloor. This is a well-preserved 3-D member of the
Chengjiang Biota that made up a glimpse of the Cambrian Explosion
some 5-10 million years before the Burgess Shale fauna came into