Myriapods
Fossils of a group of arthropods called the Myriapoda have also been discovered in the Rhynie chert. Myriapods lack external gills, instead they possess an internal tube-like respiratory system called the tracheae, a feature that has enabled the group to pervade the terrestrial environment. The myriapods are distinguished from other mandibulate ('jawed') arthropods by their large number of legs and also the fact that these animals are divided into two parts, a distinct body and head. Myriapods include the extant centipedes, millipedes and the tiny litter-dwelling symphylans and pauropods (see inset below), and also some enigmatic extinct forms such as the arthropleurids.
