Structure and development of onychophoran eyes: What is the ancestral visual organ in arthropods?
The complete mitochondrial genome of the onychophoran Epiperipatus biolleyi reveals a unique transfer RNA set and provides further support for the Ecdysozoa hypothesis.
Reproductive biology of the onychophoran Euperipatoides rowelli.
Consequently reports on hitherto unknown aspects of the biology and life history of onychophorans are urgently needed.
solorzanoi, is even longer with 22cm and its size can be only compared with extinct taxa, namely as the fossil Xenusion Pompeckj, 1927 from the Baltic, with 20cm (Dzik & Krumbiegel 1989) and the not fully identified fossil Jianshanopodia decora that may reach an equal size if confirmed as being an onychophoran (Liu et al.
solorzanoi is close to the practical limit for a functional onychophoran because they lack a hard skeleton and cannot excavate their own burrows (Monge-Najera et al.
A note on the structure of synapses in the ventral nerve cord of the onychophoran Peripatoides leukarti.
Onychophorans have a cylindrical and unsegmented body, with a pair of antennae on its anterior end, one eye at the base of each antenna, and a ventraly located mouth with a well-developed jaw, which represents a modification of the anterior region of the body.
In a more extensive comparison of complete sequences of crustacean phenoloxidases with other members of the arthropod hemocyanin superfamily, the four major clades plus an onychophoran
protein all branch from a common ancestor, and all show high bootstrap values.
Except for mandibles, onychophoran
bodies are soft and unlikely to fossilize, but special conditions led to the fossilitation of several specimens (Monge-Najera and Hou 2000), mainly in Chengjiang (China) and Burgess Shale (Canada), where they were marine during the Cambrian (all known living species are terrestrial and their continental distribution has been studied paleobiogeographically, MongeNajera 1996).
Comparison of Cambrian onychophoran
marine communities with a similar modern marine community
This paper revisits the controversy (with emphasis in onychophorans
, which include emblematic organisms such as Hallucigenia), presents new data about the Chengjiang (Cambrian of China) faunal community and compares it and the Burgess Shale (Cambrian of Canada) with on ecologically similar but modern tropical marine site where onychophorans
are absent, and with a modern neotropical terrestrial onychophoran
In contrast to arthropods, onychophorans
do not have segmented limbs, as is also the case with their presumed common fossil ancestors, says Georg Mayer.
Terrestrial mollusks, arthropods, and vertebrates are tolerant of desiccation and therefore are more fully terrestrial than are cryptozoic taxa such as platyhelminths, nemerteans, annelids, and onychophorans
Based on the view that the onychophorans
predate the crustaceans, the lack of myofibrils may be construed as a primitive feature.