Arthropoda, Class Dinocaridida, Order Radiodonta, Family Opabiniidae
Time: Early Cambrian (~525 million years ago)
is 26 mm long
Site: Chengjiang Biota, Qiongzhusi Section, Yu'anshan Member, Heilinpu
Formation, Maotianshan Hill, Yuxi, Chengjiang County, Yunnan Province,
thought by some scientists to be one of the great appendage arthropods
known as the opabinids, named after Opabinia from the Burgess Shale Fauna.
Other opabinids from Chengjiang are Jianfengia and Leanchoilia.
long antenna and exceptional detail of the appendages are readily
apparent in this fine specimen. The taxon is unknown outside
Chengjiang Biota. This is a truly exceptional specimen and representative
of the Cambrian explosion.
Discovered in 1984, the Chengjiang Biota now ranks as the most diverse
faunal fossil assemblage of all the Burgess Shale like deposits. It is
also some 10 million years older than the Burgess Shale. Like the Burgess
Shale, non-mineralized soft tissue parts are often extraordinarily well
preserved with high resolution as aluminosilicate films, sometimes with
oxidized iron content. Various taphonomic processes leading extensive preservation
of soft tissue have been proposed, including rapid death by asphyxia followed
by rapid burial in anoxic sediment undisturbed by turbidity. The Chengjiang
biota is dominated by phyla Arthropoda and Porifera. There are seven lobopodians,
more than any other Lagerstätte that some scientists elevate to phylum
rank, and seven members of the extinct phylum Vetulicolia. Members or potential
members of phyla Priapulida, Nematomorpha, Hyolitha, Hemichordata, Echinodermata,
Ctenophora, Chordata, Cnidaria, Chaetognatha, and Brachiopoda are found.
A large number of enigmatic animals of uncertain affinity are found as
well, some of which may represent failed evolutionary experiments, or even
new phyla that did not persist for long in the early Cambrian, or were
rapidly replaced by more derived forms. Among the diverse Maotianshan Shales
fauna, of utmost important are the putative early chordates, particularly
Haikouella, potentially an ancestor to or the earliest craniate chordate.
Myllokunmingia and Haikouichthys are interpreted as early Craniata, and
possibly very primitive agnathids, the progenitor of the fishes and all
Also see: Chengjiang