| Palæos: |  |
Arthropoda |
| INVERTEBRATES | Atelocerata |
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| Palæos: | |
Arthropoda |
| INVERTEBRATES | Atelocerata |
| Page Back | Unit Home | Animal Kingdom | Metazoa | Mikko's Phylogeny Home |
| Page Next | Page Up | Invertebrates | Kingdoms Index | Vertebrates Index |
Atelocerata is as a daughter clade of the Mandibulata (see rival phylogenies) (Snodgrass 1938 and others) that unites hexapods (insects and their kin) and myriapods. The taxon went out of favour when S. M. Manton erected the Uniramia, but with the more recent rejection of Arthropod polyphyly it has become more popular again.
However, a rival theory - the Pancrustacea hypothesis - suggests that the Crustacea are the stock from which the Hexapoda arose (i.e. Hexapods and Crustacea form a monophyletic group apart from the Myriapoda). The characteristics uniting Myriapoda with Hexapoda might have evolved independently as adaptations to terrestrialism (1, 2). see also note
<==o ARTHROPODA
|-- CHELICERATA
`--o MANDIBULATA
|-- CRUSTACEA
`--o ATELOCERATA
|-- MYRIAPODA
`-- HEXAPODA
<==o ATELOCERATA
|--o †EUTHYCARCINOIDEA
| `--†Euthycarcinida
|--o MYRIAPODA
| |-- CHILOPODA
| `--o PROGONEATA
| |-SYMPHYLA
| `--+- PAUROPODA
| | ?- †ARTHROPLEURIDA
| | ?- †ARCHIPOLYPODA
| `-- DIPLOPODA
`--o HEXAPODA
|--o DIPLURA
|--+--o PROTURA
| `-- COLLEMBOLA ( springtails)
`--INSECTA (insects)
The Atelocerata family tree. The exact relationship of the euthycarcinoids is not clear, but they appear to be basal atelocertans.
"Myriapod-insect relationships as opposed to an insect-crustacean sister group relationship" - Wolfgang Dohle, Berlin (from abstract of paper)
"The homology of characters brought forward in favour of a close relationship between myriapods and insects (absence of second antennae, formation of Malpighian tubules, postantennal organs and tracheae) cannot well be established. These characters may be due to convergence. This is especially true for the tracheae.
In contrast, the homology and synapomorphy of characters combining insects and crustaceans, malacostracans in particular, ( axonogensis in early differentiating neurons, formation of neuroblasts, fine structure of ommatidia, expression patterns of the engrailed gene) seem to be much better substantiated. "
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