This Phyllocarid arthropod is known as Branchiocaris
The affinity of Branchiocaris is disputed. Some rank it as being
within a stem group of euarthropods, and others as a primitive
branchiopod crustacean within the arthropod crown
latter being the most accepted classification.
have a large carapace that protects the anterior part
of the body.
This carapace structure hinged along the dorsal
edge in the same manner as a bivalve. Usually only the carapace
is fossilized, and only very rarely are the soft parts preserved
in as in this case in lagerstatte fossil sites.
taxon is also known from the Burgess Shale of British Columbia,
where it is rare, while another member of the genus (Branchiocaris
yunnanensishas) is described from the Chengjiang
(1929) named the genus Protocaris and classified it as a phyllocarid
crustacean, but other workers later considered
more closely related to trilobites. Four decades later Briggs (1976)
erected the new genus Branchiocaris, prefering a stem arthropod
(1997) later placed Branchiocaris was a calmanostracan branchiopod,
while other's phylogenetic analyses placed it close to Marrella
(Briggs, Fortey and Wills, 1992). Budd (2008) argued Branchiocaris
a stem euarthropod, belonging to a clade also containing
Perspicaris and Canadaspis.
Thus, Brachiocaris continues its enigmatic legacy.
subclass Phyllocarida contains three orders, one extant (Leptostraca,
classified as a Malacostracan), and two extinct
(Hymenostraca and Archaeostraca).
See: Utah Cambrian
Explosion Fossils Pseudoarctolepis Phyllocarid Fossil from
DE. 1976. The arthropod Branchiocaris n. gen. Middle Cambrian,
Burgess Shale, British Columbia. Geological Survey of Canada
Bulletin, 264: 1-29.
DE. FORTEY, MA., and WILLS, MA. 1992.
Morphological disparity in the Cambrian. Science, 256: 1670-3.
Budd, GE. 2008. Head structures in upper stem-group euarthropods.
Palaeontology, 51: 561-573.