The

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Pygocephalomorpha is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

group of

peracarid The superorder Peracarida is a large group of malacostracan crustaceans, having members in marine, freshwater, and terrestrial habitats. They are chiefly defined by the presence of a brood pouch, or ''marsupium'', formed from thin flattened pla ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s. Pygocephalomorpha appeared in the Late

Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...

, were abundant from the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

era until their

extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

in the Early

Permian The Permian ( ) is a geologic period and System (stratigraphy), stratigraphic system which spans 47 million years, from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.902 Mya. It is the s ...

era. This group constituted part of the freshwater and aquatic crustacean assemblages. The carapace is relatively axially shortened, with a prominent gastric region. Laterally, a cervical groove is visible, with carapace margins which is defined by an acute spine or process, including a somewhat well developed branchiostegites"

Families

The order contains extinct five families, and seven genera ''

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'': * Jerometichenoriidae **'' Jerometichenoria'' * Notocarididae **'' Notocaris'' **'' Paulocaris'' * Pygocephalidae **'' Anthracaris'' **'' Mamayocaris'' **'' Pygocephalus'' *? Tealliocarididae (Affinity as pygocephalomorph is uncertain) **'' Tealliocaris'' **'' Laevitealliocaris'' * Tylocarididae **'' Chaocaris'' **'' Fujianocaris'' **'' Liocaris'' **'' Pseudogalathea'' **'' Tylocaris'' *Pygocephalomorpha **'' Bellocaris'' **'' Hoplita'' **'' Iraticaris'' **'' Permocaris'' **'' Pittinucaris'' **'' Pygaspis'' **'' Sosiocaris''

References

Prehistoric Malacostraca Carboniferous crustaceans Permian animals Carboniferous first appearances Permian extinctions Crustacean orders {{paleo-crustacean-stub

Families

See also

References