This unusual arthropod is known as Candaspis
lavigata, an animal whose systematic position
has undergone several
revisions. It has affinities with the younger Canadaspis perfecta,
the type species. While it has been thought by some to be a
most think that is not the case, and that its primitive level of
organization places it close to Fuxianhuia
and its kin.
genus Canadaspis is additionally found in the House
Range formations in Utah, alnong with other Burgess
Shale type fauna, and in the Lower Cambrian Pioche
Shale of Nevada (see .
Of these, Canadaspis laevigata from from
the Chengjiang Maotianshan Shales is about 10 million years
older than Canadapsis
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 other vertebrates.
Phyllocarid Fossil from Utah Pioche