Megacheira

Megacheira ("great hands") is an extinct class of predatory arthropods. They had a pair of short enlarged appendages at the front.Stein, Martin 2010. A new arthropod from the early Cambrian of North Greenland, with a 'great appendage'-like antennula. Zoological Journal of the Linnean Society 158 (3): 477–500.   They look like early chelicerates. Tanaka, Gengo et al 2013. Chelicerate neural ground pattern in a Cambrian great appendage arthropod. Nature 502 (7471): 364–367.  

Most of them lived in marine environments round the world from the lower to middle Cambrian. It looks like they were quite common then. However, one perfectly preserved specimen of Enalikter was found in the Silurian of Herefordshire (England).Dayantis, Harry 2014. The 425-million-year-old 'bottle brush' beastie. Oxford University Science blog.   Another species (Bundenbachiellus) was found in the early Devonian of Germany.

 References 

Category:Arthropods
Category:Cambrian