Anomalocarididae (occasionally mis-spelt Anomalocaridae) is an extinct family of

Cambrian The Cambrian Period ( ; sometimes symbolized 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 years ago ( ...

radiodont Radiodonta is an extinct order of stem-group arthropods that was successful worldwide during the Cambrian period. They may be referred to as radiodonts, radiodontans, radiodontids, anomalocarids, or anomalocaridids, although the last two origi ...

s, a group of

stem-group In phylogenetics, the crown group or crown assemblage is a collection of species composed of the living representatives of the collection, the most recent common ancestor of the collection, and all descendants of the most recent common ancestor. ...

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chitin, o ...

s. Around 1990s and early 2010s, Anomalocarididae included all radiodont species, hence the previous equivalent of the common name "anomalocaridid" to the whole Radiodonta. This is no longer the case after the revision done by Vinther et al. 2014, as Anomalocarididae restricted to only '' Anomalocaris'' and, if any, a few of closely-related genera since then. Wu et al. 2021 accepted only ''Anomalocaris'' (excluding ''"A." saron'', ''"A." kunmingensis'' and ''"A." briggsi'') and '' Lenisicaris'' as the member of Anomalocarididae, while ''

Paranomalocaris ''Paranomalocaris'' is a genus of primitive radiodont recovered from Wulongqing Formation, eastern Yunnan. It contains two species, ''Paranomalocaris multisegmentalis'' and ''P. simplex''. It is only known from its frontal appendage (now known t ...

'' is questionably included by some studies as well. Anomalocarididae distinguished from the similar family

Amplectobeluidae ''Amplectobeluidae'' is a clade of Cambrian radiodonts. Definition In 2014, ''Amplectobeluidae'' was defined as the most inclusive clade including '' Amplectobelua symbrachiata'' but not '' Anomalocaris canadensis'', '' Tamisiocaris borealis' ...

(e.g. '' Amplectobelua'', ''

Lyrarapax '' Lyrarapax'' is a radiodont genus of the family Amplectobeluidae that lived in the early Cambrian period 520 million years ago. Its neural tissue indicates that the radiodont frontal appendage is protocerebral, resolving parts of the arthropod h ...

'') by the presence of triradial oral cone and non-hypertrophied first distal endite. Compared to

Hurdiidae Hurdiidae is an extinct cosmopolitan family of radiodonts, a group of stem-group arthropods, which lived during the Paleozoic Era. It is the most long-lived radiodont clade, lasting from the Cambrian period to the Devonian period. Description ...

and

Tamisiocarididae Tamisiocarididae is a family of radiodonts, extinct marine animals related to arthropods, that bore finely-spined appendages that were presumably used in filter-feeding. When first discovered, the clade was named Cetiocaridae after a speculativ ...

, this two radiodont families shared a lot of characters (i.e. alternated endite length; streamlined body; small head with ovoid sclerites; well-developed swimming flaps; caudal furcae; raptorial predatory lifestyle) and forming a clade in multiple phylogenetic analysis.

References

{{Taxonbar, from=Q134939 Anomalocaridids Cambrian Series 2 first appearances Guzhangian extinctions Prehistoric arthropod families