''Parapeytoia'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of Cambrian

arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

. The type and only described

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

is ''Parapeytoia yunnanensis'', which lived over 518 million years ago (

Cambrian Stage 3 Cambrian Stage 3 is the still unnamed third stage of the Cambrian. It succeeds Cambrian Stage 2 and precedes Cambrian Stage 4, although neither its base nor top have been formally defined. The plan is for its lower boundary to correspond approxima ...

) in the

Maotianshan shales The Maotianshan Shales () are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation or Heilinpu Formation, famous for their '' Konservat Lagerstätten'', deposits known for the exceptional preservation of fossilized orga ...

Yunnan Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. Unidentified

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

s from the same genus have also been discovered from the nearby Wulongqing Formation ( Cambrian Stage 4).

Classification

Initially, ''Parapeytoia'' was interpreted as a radiodont ("anomalocaridid" at that time) dinocaridid with legs alongside '' Cucumericrus'', purported to be an indicator that radiodonts might have legs underneath their body flaps in general, comparable to '' Pambdelurion''. With the combination of megacheiran and presumably radiodont features (see text), it was also suggested to be an intermediate form between the two taxa. However, later studies revealed it was most likely nested within megacheira, and the group as a whole was no longer thought to have originated from radiodonts. Within megacheira, ''Parapeytoia'' was possibly closest to the multisegmented (with over 20 trunk segments) taxa like '' Fortiforceps'' and '' Jianfengia'', united under the family Jianfengiidae.

Description

20191021 Parapeytoia yunnanensis interpretation

''Parapeytoia'' is known from a few incomplete

materials with part of its ventral structures preserved. The frontmost

appendage An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...

s were a pair of great appendages consisting of a robust peduncle and 4 distal segments with a serrated spine on each of them, a feature shared by some other megacheirans such as '' Yohoia'' and '' Fortiforceps''. Behind the great appendages were 2 or 3 pairs of short appendages, and numerous pairs of well-developed biramous appendages, each formed by a basipod with a spiny gnathobase, lobe-like exopod and leg-like endopod with 8 segments. A narrow, hourglass-like sternite was associated between each of those appendages. Some features originally interpreted as radiodont-like are now considered questionable. Radial sclerites interpreted as Parapeytoia mouthparts (oral cone) have since been assigned to another genus of animal, '' Omnidens''. While some subsequent studies suggest those features are genuine, they most likely represent ancestral traits originating from more basal arthropods instead of any indicators of radiodont affinities. This is the case for the gnathobases, and the presence of arthropodized endopods underneath the purported body flaps (exopods), which conflict with the radiodont trunk appendages as well (the radiodont ventral body flaps are most likely homologous to euarthropod endopods). ''Parapeytoia'' was probably a

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

feeder, spending most of its time on the ocean floor hunting (or possibly scavenging) for prey.

References

Dinocaridids: anomalous arthropods or arthropod-like worms? by Hou Xianguang & Jan Bergström 2006
arguing that this genus is a dinocaridid

External links

{{Taxonbar, from=Q2732162 Megacheira Cambrian arthropods Maotianshan shales fossils Prehistoric arthropod genera Cambrian genus extinctions