''Fremontella'' 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 ...

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 ...

from a well-known class of

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 ...

marine

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, the

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 ...

s. It lived during the part of the Toyonian stage. This faunal stage was part of the

Cambrian Period 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 Ordovici ...

. ''Fremontella'' shares with the other genera of the

Bristoliinae The Bristoliinae is an extinct subfamily of trilobites, fossil marine arthropods, with species of small to average size. Species belonging to this subfamily lived during the Botomian and Toyonian stage (''Olenellus''-zone), 522-513 million years ...

subfamily, Lochmanolenellus and Bristolia conspicuous and long curved spines (called genal spines) on the headshield (or cephalon). These reach back equal to 4–5 thorax segments (measured parallel to the midline). The furrows that separate border, eye ridges, glabella and its lobes are distinct (unlike in the

Biceratopsinae The Biceratopsinae is an extinct subfamily of redlichiid trilobites within the family Biceratopsidae, with species of small to average size. Species belonging to this subfamily lived during the Toyonian stage (Upper ''Olenellus''-zone), 516-51 ...

). The area outside of the axis (or pleural lobes) of the third segment of the thorax is enlarged, and carries large trailing spine on each side.

Distribution

''Fremontella halli'' has been collected in the Upper ''Olenellus''-zone of Alabama, USA (

Rome Formation The Rome Formation is a geologic formation in Alabama, Georgia, and Tennessee. It preserves fossils dating back to the Cambrian period. See also * List of fossiliferous stratigraphic units in Tennessee * Paleontology in Tennessee Paleontolog ...

, North-East of Helena).

References

Cambrian trilobites Fossils of the United States Redlichiida genera Biceratopsidae {{Redlichiida-stub