''Misszhouia'' 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 small to average sized (up to long) marine

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

-like

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 ...

s within the

Naraoiidae Naraoiidae is a family, of extinct, soft-shelled trilobite-like arthropods, that belongs to the order Nektaspida. Species included in the Naraoiidae are known from the second half of the Lower Cambrian to the end of the Upper Silurian. The total ...

family, that lived during the early

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

period. The species are ''M. longicaudata'', from 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 ...

, described in 1985, and ''M. canadensis'', from the

Burgess Shale The Burgess Shale is a fossil-bearing deposit exposed in the Canadian Rockies of British Columbia, Canada. It is famous for the exceptional preservation of the soft parts of its fossils. At old (middle Cambrian), it is one of the earliest fos ...

and described in 2018, although later species may belongs to genus ''

Naraoia ''Naraoia'' is a genus of small-to-average-size (about long) marine arthropods within the family Naraoiidae, that lived from the early Cambrian to the late Silurian period. The species are characterized by a large alimentary system and sideways ...

'' instead.

Etymology

''Misszhouia'' was named after "Miss Zhou" (Zhou Guiqin), to honour her for her skilled preparation of Chengjiang fossils.

Description

''Misszhouia longicaudata'' is almost flat (dorso-ventrally). The upper (or dorsal) side of the body consists of a non-calcified headshield (

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino Jr., Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont ...

) and tailshield (

pygidium The pygidium (: pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compos ...

) without body segments between. The body is narrowed at the articulation between cephalon and pygidium. The long many-segmented antennae are directed forward. There are no eyes. The gut has a relatively small diameter, and there are four pairs of relatively small digestive sacs (or caeca) in the cephalon only, and no branches towards the edge of the cephalon (unlike ''

''). There are 25 limb pairs with two branches on a common base, like ''Naraoia'' and

s. The outer branch (or

exopod The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip (a ...

) has many parallel long fine flattened side branches (setae) that probably functioned as gills with a large surface area. This exopod is attached along the whole length of the base segment ( coxa) and at least the proximal part of the first segment of the inner branch (

endopod The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, : ...

). The shaft of the exopod tapers gently towards its tip. The endopod is composed of seven

podomere The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, : ...

s including a terminal claw.

Differences from ''Naraoia''

The sister genus ''Naraoia'' differ from ''Misszhouia longicaudata'' in having the following characteristics: *A large, ramifying anterior pair of digestive branches (or diverticula) almost reaching the cephalon edges. *A bloated, mud-filled gut. *Laterally deflected antennae.

Distribution

''Misszhouia longicaudata'' has been collected from the Lower Cambrian (late

Atdabanian 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 approxi ...

) of China (Yu'anshan Member of the Heilinpu Formation at Maotia’shan, the classic

Chengjiang Chengjiang (; earlier Tchinkiang) is a city located in Yuxi, Yunnan Province, China, just north of Fuxian Lake. Administrative divisions Chengjiang City has 2 subdistricts and 4 townships. ;2 subdistricts * Fenglu () * Longjie () ;4 towns C ...

locality) and also been found in the Niutitang Formation. ''Misszhouia canadensis'' is known from the Middle Cambrian Burgess Shale in the

Marble Canyon Marble Canyon is the section of the Colorado River canyon in northern Arizona from Lee's Ferry to the confluence with the Little Colorado River, which marks the beginning of the Grand Canyon. Lee's Ferry is a common launching point for riv ...

(Kootenay National Park).

Ecology

All Naraoids were probably marine bottom dwellers. ''Misszhouia'' probably lived as a

predator Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...

scavenger Scavengers are animals that consume Corpse decomposition, dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a he ...

. This can be deduced from the robust and spiny basal segments of the legs, which resemble the gnathobases of trilobites. These were likely used for chewing. Such

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

behaviour is confirmed by the relatively small digestive system, that indicates high nutrition value food.

Taxonomy

''Misszhouia longicaudata'' was formerly considered a member of the genus ''Naraoia'', originally known as "''Naraoia longicaudata''", until separated in 1997. A cladistic analysis conducted in 2021 suggested that ''Misszhouia'' represented a monophyletic subgroup within ''Naraoia'' as traditionally broadly defined.

References

External links

''Misszhouia longicaudata''
The Virtual Fossil Museum {{Taxonbar, from=Q1939241 Nektaspida Maotianshan shales fossils Cambrian arthropods Paleozoic life of British Columbia Cambrian genus extinctions