|  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 vertebrates.
This
unusual specimen is Chengjiangocaris, a taxon known from only
a
handful of specimens. It is the only genus and species within the
Family Chegjiangocaridae, and is also only known from the Chengjiang
Biota.
Also
see: Chengjiang
Biota, Chengjiang
Fossils, Cambrian
Explosion |
