After Hou & Bergström, 1997
<==o †Proschizoramia sensu stricto? |--o †Paracrustacea Hou & Bergström, 1997 | `--o †Canadaspidida Novozhilov in Orlov, 1960 [incl. Hymenostraca Rolfe, 1969; Prophyllocarida Simonetta & Delle Cave, 1975] | |--o †Canadasipididae Novozhilov in Orlov, 1960 | | `--o †Canadaspis Novozhilov in Orlov, 1960 [Hymenocaris Salter, 1853] | | |-- †C. perfecta (Walcott, 1912) [Hymenocaris perfecta Walcott, 1912] | | `-- †C. laevigata (Hou & Bergström, 1991) [Perspicaris? laevigata Hou & Bergström, 1991] | |--o †Hymenocarididae Haeckel, 1896 [=? Canadaspididae] | | `--o †Hymenocaris Salter, 1853 | | `-- †H. vermicauda Salter, 1853 | `--o †Perspicarididae Briggs, 1978 | `--o †Perspicaris Briggs, 1977 | |-- †P. recondita Briggs, 1977 | |?- †P.? dilatus Robison & Richards, 1981 | |?- †P.? ellipsopelta Robison & Richards, 1981 | `?- †P.? laevigata Hou & Bergstrom, 1991 `--o †Megacheira Hou & Bergström, 1997 |--o †Fortiforcipida Hou & Bergström, 1997 | `--o †Fortiforcipidae Hou & Bergström, 1997 | `-- †Fortiforceps foliosa Hou & Bergström, 1997 `--+--o †Yohoniida Simonetta & Delle Cave, 1975 | `--o †Yohoiidae Henriksen, 1928 | |-- †Jianfengia multisegmentalis Hou, 1987 | `-- †Yohoia tenuis Walcott, 1912 `--+-- †Haikoucaris ercaiensis Chen, Waloszek & Maas, 2004 `--o †Leanchoiliida Størmer, 1944 `--o †Leanchoiliidae Raymond, 1935 [incl. Alalcomenaeidae Simonetta & Delle Cave, 1975; Actaeidae Simonetta & Delle Cave, 1975] |--o †Alalcomeneus Simonetta, 1970 [Alalcomenaeidae Simonetta & Delle Cave, 1975] | |-- †A. cambricus Simonetta, 1970 | `-- †A. elegans (Luo & Hu in Luo et al., 1999) `--+-- †Oestokerkus megacholix Edgecombe, García-Bellido & Paterson, 2011 `--o †Leanchoilia Walcott, 1912 |-- †L.? hanceyi Briggs & Robison, 1984 |-- †L. persephone Simonetta, 1970 |?- †L. protogonia Simonetta, 1970 `--+-- †L. superlata Walcott, 1912 `-- †L. illecebrosa (Hou, 1987) [Alalcomeneus? illecebrosus Hou, 1987; Alalcomeneus illecebrosus Hou; Chen et al., 2004]
Note:
Phylogenetic treatment of Chen et al. (2004) differs greatly from that of Hou & Bergström (1997). In last revision of this page I decided to include †Haikoucaris Chen et al., 2004 to the Megacheira Hou & Bergström, 1997, because they are the only taxa treated by Chen et al. when discussing the relationships of †Haikoucaris. The phylogeny of Chen et al. differs in placing †Haikoucaris closer to Chelicerata sensu stricto. Chen et al. also place megacheirans as paraphyletic basal polytomy of their Chelicerata sensu lato.
While describing a new Leanchoiliid species, Oestokerkus megacholix, Edgecombe et al. (2011) reanalysed relationhips of Megacheira. In their analysis Haikoucaris is indeed a Megacheiran. They also reinstated megacheirans as a potential sistergroup of Chelicerata.
Reference(s):
- Chen, J.-Y., Waloszek, D. & Maas, A., 2004: a new ‘great-appendage’ arthropod from the Lower Cambrian of China and homology of chelicerate chelicera and raptorial antero-ventral appendages.
–Lethaia: Vol. 37, #1, pp. 3-20 - Conway Morris, S., 1993: The fossil record and early evolution of the Metazoa.
–Nature, vol. 361, 21 January, pp. 219-225 - Edgecombe, G. D., García-Bellido, D. C. & Paterson, J. R., 2011: A new leanchoiliid megacheiran arthropod from the lower Cambrian Emu Bay Shale, South Australia.
–Acta Palaeontologica Polonica: Vol. 56, #2, pp. 385-400 [doi: 10.4202/app.2010.0080] - Hou X. & Bergström, J., 1997: Arthropods of the Lower Cambrian Chengjiang fauna, southwest China.
–Fossils & Strata, Number 45, 22nd December 1997, pp. 1-116