REVIEW Evolution and systematics of the Chelicerata

  title={REVIEW Evolution and systematics of the Chelicerata},
  author={Peter Weygoldt},
  journal={Experimental \& Applied Acarology},
  • P. Weygoldt
  • Published 1 February 1998
  • Biology
  • Experimental & Applied Acarology
After approximately 40 years of discussion about the question of whether the Arthropoda are a monophyletic or a paraphyletic group or even a polyphyletic assemblage of unrelated taxa, most morphologists, palaeontologists and molecular taxonomists agree that the Arthropoda are a monophylum. The Euarthropoda are composed of the Arachnomorpha and Mandibulata. Myriapods are usually considered to be mandibulates; however, new molecular data as well as some morphological characters show similarities… 
Geological history and phylogeny of Chelicerata.
  • J. Dunlop
  • Geology, Biology
    Arthropod structure & development
  • 2010
Phylogenetic relationships of basal hexapods among the mandibulate arthropods: a cladistic analysis based on comparative morphological characters
The results support the monophyly of the Mandibulata, Crustacea, Atelocerata (Tracheata) and Hexapoda, but the assemblage of Myriapoda appears poorly supported.
The affinities of mites and ticks: a review
Previous hypotheses of mite affinities are reviewed to highlight important character sets which should be included in subsequent phylogenetic analyses, as well as useful areas for future investigations: particularly tagmosis and the nature of the gnathosoma.
A phylogenetic analysis of the arachnid orders based on morphological characters
Results suggest that attempts to resolve specific nodes based on individual characters, lists of similarities, evolutionary scenarios, etc., are problematic, as they ignore broader impacts on homoplasy and analytical effects on non-target nodes.
The Origin of Mites: Fossil History and Relationships
Mites are members of the arthropod subphylum Chelicerata, a group with a long fossil history of about 500 million years (Dunlop 2010) (Fig. 2.1). The earliest chelicerate fossils are known from the
Modern Analogs for the Study of Eurypterid Paleobiology
The lack of a single, clear eurypterid analog from among extant chelicerates may reflect that euryopterids occupied an ecological niche intermediate between xiphosurans and arachnids, and is not likely to yield a single model organism.
The arthropod Offacolus kingi (Chelicerata) from the Silurian of Herefordshire, England: computer based morphological reconstructions and phylogenetic affinities
The small, non–biomineralized, three–dimensionally preserved arthropod Offacolus kingi Orr et al. is re–evaluated, and the new family Offacolidae erected, placing it basally within the Chelicerata, but more derived than the Devonian Weinbergina.


Morphology and Systematics of ear ly Arthropods
  • Geography
  • 2018
cularly on the basis of the morphology of various Palaeozoic groups. Uniramians are considered as a distinct phylum. Fragmentary Gambrian arthropods may repre­ sent marine, well sclerotized
The Early Radiation and Relationships of the Major Arthropod Groups
Cladistic analysis of characters of Cambrian and living representatives (excluding Uniramia) shows that trilobites and chelicerates are relatively advanced compared with "crustaceans," and there are doubts whether the latter constitute a national group.
Phylogenetic Hypotheses of the Relationships of Arthropods to Precambrian and Cambrian Problematic Fossil Taxa
A morphological cladistic analysis of seven Vendian "arthropodlike" taxa compared with 21 representative Cambrian arthropods, lobopods, and weird wonders finds no compelling reason to accept the hypothesis that the Vendian organisms included here are not metazoans.
A cladistic analysis of the 11 Recent arachnid orders suggests that Arachnida is monophyletic and composed of two principal lineages, Micrura and Dromopoda.
Arthropod Phylogeny: A Modern Synthesis
Factual evidence provided by the fields of functional morphology and of the newer functional studies of embryology using the concept of fate maps indicates that the Arthropoda are probably
The trilobita as a natural group
It is shown that there are more synapomorphies uniting accepted trilobites with the olenellids, than there are uniting olenelids with chelicerates.
Morphology of locomotor appendages in Arachnida: evolutionary trends and phylogenetic implications
Cladistic analysis suggests that Arachnida is monophyletic and that absence of extensor muscles is a primitive condition, and phylogenetic relationships among ‘extensorless’ groups cannot be resolved solely on the basis of appendicular characters.
The phylogenetic status of arthropods, as inferred from 18S rRNA sequences.
It is suggested that a previous study's inference of the Arthropoda as paraphyletic may be the result of having two few arthropod taxa available for analysis and including long-branched taxa, and that the evolutionary-parsimony method, like distance and parsimony, may be biased by taxa with long branches.
Reflections on arthropod evolution
A polyphyletic concept of arthropod evolution from soft-bodied, segmented, haemocoele-possessing, non-annelid worms is elaborated and the degree of convergence demanded is amply matched by proven examples of the phenomenon.
Olenelloid Trilobites: Type Species, Functional Morphology and Higher Classification
Type or topotype specimens of the type species of the genera Olenellus , Nevadia , Wanneria and Elliptocephala are redescribed, together with similar specimens of 0. vermontanus and 0 . robsonensis .