Thoracotremata (Brachyura, Decapoda) is the most derived crab group, encompassing 1,248 extant species. It currently comprises four superfamilies: Grapsoidea MacLeay, Ocypodoidea Rafinesque, Cryptochiroidea Paulson and Pinnotheroidea De Haan.
Click here for original story, Study reveals evolution of crab group Thoracotremata
Source: Phys.org