This unusual arthropod is known as Waptia ovata. The species
known mostly from the distinctive wrinkled carapace, but this one
has much soft tissue preserved. The discovery of the Chengjiang
Biota by Hou Xian-guang in 1984 opened a window onto a remarkable
array of life forms from what is termed the Cambrian
The diversity of soft-tissue fossils is astonishing: algae, medusiforms,
sponges, priapulids, annelid-like worms, echinoderms, arthropods
(including trilobites), hemichordates, chordates, and the first
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.
systematic position of this taxon has undergone several revisions.
It was originally placed within the Ostracodiform genus Mononotella,
then later referred to a new genus Chaundianella. More recent
of remains other than the carapace have shown it to be similar
to the Burgess Shale arthropod
Waptia fieldensis. However, Chuandianella has notably different
features, including classic arthropod biramous limbs. While
the species is known from other Lower Cambrian locations in Yunnan,
Shaanxi Provinces, only those from the Chengjiang Biota are known
to show soft part preservation. This one shows the antennae preserved
as well. The negative image makes the antennae
more apparent. Note as well the threedimensional nature of the
shells, a most unusual preservation
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, and 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 the 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
to middle 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 vertebrates.
X. G.; Bergstrom J, (1991) The arthropods of the Lower
Cambrian Chengjiang fauna, with relationship and evolutionary
p. 179-187. In A. M. Simonetta and S. Conway Morris (eds.),
The Early Evolution of Metazoa and the Significance of Problematic
Taxa. Cambridge University Press, Cambridge.
Liu & De-Gan Shu (2004). "New
information on Chuandianella from the Lower Cambrian Chengjiang
Fauna, Yunnan, China". Journal of
Northwest University (Natural Science Edition) (in Chinese) 34
see: Chengjiang Maotianshan Shales, Chengjiang