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Temporal range: ChengjiangMiddle Cambrian
Underside of Amplectobelua symbrachiata
Scientific classification e
Kingdom: Animalia
Phylum: Arthropoda
Class: Dinocaridida
Order: Radiodonta
Family: Anomalocarididae
Genus: Amplectobelua
Hou, Bergström & Ahlberg, 1995
  • A. symbrachiata Hou, Bergström & Ahlberg, 1995
  • A. stephenensis Daley & Budd, 2010

Amplectobelua is an extinct genus of late Early Cambrian anomalocaridid, a group of stem arthropods that lived as free-swimming predators during the first half of the Paleozoic Era. Like other anomalocaridids, Amplectobelua had a pair of jointed grasping appendages, large eyes, a limbless body, and a series of fins or swimming lobes on both sides that extended along the length of its body. It was smaller than the related Anomalocaris, however, and had a specialized grasping appendage, in which the spine on the fourth segment hooked forward to oppose the tip of the appendage, allowing it to grasp prey like the pincer of a crab. The fins differ as well; the front fins are very long and slender, while the middle pair of tail fins are specialized into a pair of long streamers, or furci.

Two species are known, A. symbrachiata from the Chengjiang biota and A. stephenensis from the later Burgess Shale.[1] A. symbrachiata is known from complete specimens, while A. stephenensis is known only from isolated claws. A. stephenensis is more advanced, with the pincer being more specialized for grasping: the fourth spine is larger and the spines on outer segments are reduced.


Amplectobelua shares a unique feature among Anomalocarids with Ramskoeldia, in having gnathobase-like structures behind its mouth, at least 6, up to eight. They functioned like the gnathobases of arthropods, being able to rotate and move to shred prey. They were connected to reduced anterior lateral flaps. Additionally, the mouth of Amplectobelua was different from typical Anomalocarids, lacking the typical Peytoia-style mouth and possessing numerous flat tooth-plates arranged tetraradially. [2]


  1. ^ Daley, A. C.; Budd, G. E. (2010). "New anomalocaridid appendages from the Burgess Shale, Canada". Palaeontology. 53 (4): 721. doi:10.1111/j.1475-4983.2010.00955.x.
  2. ^ Cong, Peiyun; Daley, A. C.; Edgecombe, Gregory D.; Hou, Xianguang (2017). "The functional head of the Cambrian radiodontan (stem-group Euarthropoda) Amplectobelua symbrachiata". BMC Evolutionary Biology. 17 (208). doi:10.1186/s12862-017-1049-1. PMC 5577670.

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