Olenellina
Encyclopedia
Olenellina is a suborder of the order Redlichiida
of Trilobite
s. The suborder contains two superfamilies: Olenelloidea (with 2 families), and Fallotaspidoidea (with 5 families). The Olenillina are some of the most primitive trilobites. They originated at the beginning of the Cambrian
era and became extinct at the end of the lower Cambrian.
Cephalon: Lacking facial sutures and the glabella
typically has rather deep lateral furrows. In some species the front glabellar lobe is an almost circular boss. There is a conterminant hypostome with a very wide rostral plate extending between genal angles, with a perrostral suture (no connective sutures).
Thorax: Numerous segments, is non-fulcrate with the axis often spine-bearing.
Pygidium: Narrow, with few segments.
Olenellina are the earliest trilobites in Cambrian stratigraphy. No calcified protaspis is known, the body is flattened and the cuticle is thin.
Redlichiida
Redlichiida is an order within the major extinct arthropod class Trilobita. The Redlichids are one of the four older classes of trilobites that originated in the Lower Cambrian....
of Trilobite
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
s. The suborder contains two superfamilies: Olenelloidea (with 2 families), and Fallotaspidoidea (with 5 families). The Olenillina are some of the most primitive trilobites. They originated at the beginning of the Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
era and became extinct at the end of the lower Cambrian.
Physiology
(See Trilobite: Terminology for definitions of morphological terms)Cephalon: Lacking facial sutures and the glabella
Cephalon (arthropod head)
The cephalon is the head section of an arthropod. It is a tagma, i.e., a specialized grouping of arthropod segmentsThe word cephalon derives from the Greek κεφαλή , meaning "head". It is rather used in Trilobite terminology. In insects, head is a preferred term...
typically has rather deep lateral furrows. In some species the front glabellar lobe is an almost circular boss. There is a conterminant hypostome with a very wide rostral plate extending between genal angles, with a perrostral suture (no connective sutures).
Thorax: Numerous segments, is non-fulcrate with the axis often spine-bearing.
Pygidium: Narrow, with few segments.
Olenellina are the earliest trilobites in Cambrian stratigraphy. No calcified protaspis is known, the body is flattened and the cuticle is thin.