The Mesonacinae comprise an extinct

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

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 that lived during the

Botomian Cambrian Stage 4 is the still unnamed fourth stage of the Cambrian and the upper stage of Cambrian Series 2. It follows Cambrian Stage 3 and lies below the Wuliuan. The lower boundary has not been formally defined by the International Commission on ...

, found in North-America, Greenland and North-Western Scotland. The two genera in this subfamily are ''

Mesonacis ''Mesonacis'' is an extinct genus of trilobite that lived during the Botomian, found in North-America (excluding Greenland), and the United Kingdom (North-Western Scotland). Some of the species now regarded part of ''Mesonacis'', have previously ...

'' and ''

Mesolenellus ''Mesolenellus'' is an extinct genus of trilobites that lived during the lower Cambrian (Botomian), found in Greenland and Spitsbergen. Etymology ''Mesolenellus'' is a contraction of meso - middle - and ''Olenellus'', the genus from which it w ...

''.

References

External links

''Photo of M. vermontanus''''Trilobite info''
Olenellidae Cambrian trilobites Cambrian Series 2 first appearances Cambrian Series 2 extinctions Arthropod subfamilies {{Redlichiida-stub