Redlichiina is a suborder of the order

Redlichiida Redlichiida is an order of trilobites, a group of extinct marine arthropods. Species assigned to the order Redlichiida are among the first trilobites to appear in the fossil record, about halfway during the Lower Cambrian. Due to the difficult ...

Trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

s. The suborder contains three superfamilies:

Emuelloidea Emuelloidae are a small superfamily of trilobites, a group of extinct marine arthropods, that lived during the late Lower Cambrian (late Botomian) of the East Gondwana Gondwana () was a large landmass, often referred to as a supercontine ...

, Redlichioidea and

Paradoxidoidea The Paradoxidoidea Hawle & Corda 1847,HAWLE, J. & CORDA, A. J. C. 1847. ''Prodrom einer Monographieder bohmischen Trilobiten''. 176 pp. J. G. Calve, Prague are a superfamily of trilobites, a group of extinct marine arthropods. They occurred durin ...

. These trilobites are some of the oldest trilobites known. They originated at the beginning of the

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

Period and disappeared (possibly by evolving into members of the

Ptychopariida Ptychopariida is a large, heterogeneous order of trilobite containing some of the most primitive species known. The earliest species occurred in the second half of the Lower Cambrian, and the last species did not survive the Ordovician–Silurian ...

order) at the end of the middle Cambrian.

Physiology

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

: Opisthoparian facial sutures. Early forms tend to have tapering, conical glabella with furrows extending far backwards while later forms with glabella expanding forwards to inflated frontal lobe. The

hypostome In zoology, the hypostome can refer to structures in distinct animal groups: *Hypostome (trilobite), the ventral mouthpart plate in trilobites *Hypostome (tick) The hypostome (also called the maxilla, radula, or labium) is a calcified harpoo ...

is conterminant (e.g.,

Redlichia ''Redlichia'' is a genus of redlichiida, redlichiid trilobite in the family Redlichiidae, with large to very large species (up to long). Fossils of various species are found in Lower Cambrian (Toyonian)-aged marine strata from China, Korea, Paki ...

) or natant (e.g., Dolerolenus). The rostral plate is narrower than in suborder

Olenellina Olenellina is a suborder of the order Redlichiida of trilobites that occurs about halfway during the Lower Cambrian, at the start of the stage called the Atdabanian. The earliest trilobites in the fossil record are arguably Olenellina, although ...

, bound by rostral and connective sutures.

Thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

: Fulcrate or non-fulcrate, typically with many segments (60+ in an Emmuelid). The axis is infrequently spine-bearing.

Pygidium The pygidium (plural 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 compo ...

: Typically small, but can be larger and with many segments.

References

* * * * * Redlichiida Cambrian trilobites Cambrian first appearances Cambrian extinctions Arthropod suborders {{Redlichiidae-stub