Amplectobeluidae

In 2014, Amplectobeluidae was defined as the most inclusive clade including Amplectobelua symbrachiata but not Anomalocaris canadensis, Tamisiocaris borealis, or Hurdia victoria.[1]

Amplectobeluids could be recognized by frontal appendages with well-developed first distal endite, which forming a pincer-like structure that presumably better suited for a grasping function.[1][2] Complete body fossils of amplectobeluids are only known by Amplectobelua and Lyrarapax, both showing combination of characters resembling Anomalocaris (i.e. streamlined body; small head with ovoid sclerites; well-developed swimming flaps; a pair of caudal furcae).[3][4][5][6][7] Another distinctive features only known in amplectobeluid genera were pairs of gnathobase-like structures (known by Amplectobelua and Ramskoeldia),[6][8] or an oral cone with combination of tetraradial arrangement and scale-like nodes (known by Lyrarapax and "Anomalocaris" kunmingensis).[5][9][10]

Early in 2014, "Anomalocaris" kunmingensis was tentatively assigned to Amplectobelua by Vinther et al.[1] Later that year, however, the discoverers of Lyrarapax unguispinus ignored that assessment and created a genus within Amplectobelua sensu Vinther et al.[4] Indeterminate frontal appendages assignable to this group are known from the Parker Formation of Vermont.[11]

An a posteriori-weighted phylogenetic analysis in 2014 found the following relationships within the Amplectobeluidae:[4]