Palæos:		Arthropoda
INVERTEBRATES		Hexapoda

Parent Unit: Pancrustacea	Sister Unit: Crustaceamorpha	Child Unit: Diplura	Home
Child Unit: Protura	Child Unit: Columbella	Child Unit: Insecta	Parent Cladogram

Hexapoda

 

Arthropoda Home Introduction Evolution and Fossil Record Phylogeny links References

Arthropoda Arthropod Phylogeny Panarthropoda Lobopoda Anomalocarida basal Arthropods Arachnomorpha Trilobita Chelicerata Crustacea Myriapoda Hexapoda

As the name indicates the Hexapoda have six legs, one pair per thoracic segment.  The body segments are fused into three body regions: a head, thorax, and abdomen..  A single pair of preoral antennae are present.  The waxy epicuticle protects against desiccation.  The superclass Hexapoda includes so-called true insects and several classes of primitive wingless proto-insects.  Of the four or so hexapod classes, only the Class Insecta possess wings.

Evolution and Fossil Record

The oldest well-known fossil hexapod is called Rhyniella praecursor, a collembolan from the Early Devonian-age Rhynie Chert. This and other small, wingless forms may have been an important part of the early terrestrial ecosystem, mainly detritivores foraging in soil and plant litter (the most primitive of the true insects, the Thysanura or silverfish, have a similar lifestyle, and have adapted well to human habitats). By the middle Carboniferous, a number of insect lineages appeared, and insects have dominated the terrestrial microfauna ever since.

Hexapod Phylogeny

The Hexapods are related most closely either to the Myriapods or the Crustacea

<==o HEXAPODA  
      |--o DIPLURA
      |--+--o PROTURA  
      |  `-- COLLEMBOLA ( springtails)  
      `--INSECTA (insects)

Links

Links

Hexapoda

Carpenter, F.M. 1992. Treatise on Invertebrate Paleontology. Part R: Arthropoda 4; Volume 3: Superclass Hexapoda. Geological Society of America and University of Kansas Press, Boulder and Lawrence.

S. M. Manton, Functional Morphology and the Evolution of Hexapod Classes, pp.387-465, in Arthropod Phylogeny, ed. A. P. Gupta, Van Nostrand Reinhold Company, 1979