A palaeontological solution to the arthropod head problem

  title={A palaeontological solution to the arthropod head problem},
  author={Graham E. Budd},
  • G. Budd
  • Published 16 May 2002
  • Environmental Science
  • Nature
The composition of the arthropod head has been one of the most controversial topics in zoology, with a large number of theories being proposed to account for it over the last century. Although fossils have been recognized as being of potential importance in resolving the issue, a lack of consensus over their systematics has obscured their contribution. Here, I show that a group of previously problematic Cambrian arthropods from the Burgess Shale and Chengjiang faunas form a clade close to crown… 

The origin and evolution of the euarthropod labrum.

  • G. Budd
  • Biology, Environmental Science
    Arthropod structure & development
  • 2021

Burgess Shale fossils illustrate the origin of the mandibulate body plan

The presence of crustaceomorph traits in the Cambrian larvae of various clades basal to Mandibulata is reinterpreted as evidence for the existence of distinct ontogenetic niches among stem arthropods and Hymenocarines now illustrate that the subdivision of the basipod and the presence of proximal endites are likely to have been ancestral conditions critical for the evolution of coxal and pre-coxal features in mandibulates.


The headures of several important taxa, Fuxianhuia, Canadaspis, Odaraia, Chengjiangocaris and Branchiocaris are redescribed, revealing the essential similarity between them, including an anterior sclerite that appears to be a widespread feature of basal arthropods.

Neuroanatomy of sea spiders implies an appendicular origin of the protocerebral segment

The developmental neuroanatomy of a putative basal arthropod, the pycnogonid sea spider, is investigated with immunohistochemical techniques and it is shown that the first pair of appendages, the chelifores, are innervated at an anterior position on the protocerebrum.

New ideas about the euchelicerate stem-lineage

In the scenario presented here euchelicerates did not lose (and indeed never had) long, sensory antennae, but probably evolved their chelicerae from a leg-like pair of uniramous appendages.

Pycnogonid affinities : a review

Morphologically some characters – the presence of gonopores on the trunk and absence of a labrum, nephridia and intersegmental tendons – support Cormogonida (Euarthropoda excluding pycnogonids), yet even the putative autapomorphy of chelicerae needs to be treated with caution.



The Evolution of the Insect Head: the Endless Dispute

The proposal is made that the ancestor of the insect was annelid-like, that the prostomium became the acron and that the six originally postoral segments joined the acron to form the head tagma.

Stem group arthropods from the Lower Cambrian Sirius Passet fauna of North Greenland

  • G. Budd
  • Geography, Environmental Science
  • 1998
Discussion of fossil evidence for the origin and early evolution of the arthropods has been dominated for many years by the evidence from the Middle Cambrian Burgess Shale from British Columbia

The morphology and phylogenetic significance of Kerygmachela kierkegaardi Budd (Buen Formation, Lower Cambrian, N Greenland)

  • G. Budd
  • Biology, Geography
    Transactions of the Royal Society of Edinburgh: Earth Sciences
  • 1998
The combination of characters found in Kerygmachela allows it to be allied with the lobopods, represented in the extant fauna by the onychophorans, tardigrades, and possibly the pentastomids, and in the Cambrian fossil record by a morphologically diverse set of taxa, some of which are not assignable to the extant groupings.

Phylogenetic analysis of the Malacostraca (Crustacea)

  • Scholtz
  • Biology, Environmental Science
  • 2001
The present analysis supports the basal position of the Stomatopoda, and suggests a sister-group relationship is suggested between Euphausiacea and Peracarida (including Thermosbaenacea), with the Syncarida as the sister group to both taxa.

Evidence for a clade of nematodes, arthropods and other moulting animals

The results suggest that ecdysis (moulting) arose once and support the idea of a new clade, Ecdysozoa, containing moulting animals: arthropods, tardigrades, onychophorans, nematodes, Nematomorphs, kinor-hynchs and priapulids.

The place of tardigrades in arthropod evolution

The phylum Tardigrada is an engaging but enigmatic group composed of minute metazoans with four pairs of stubby lobopodous appendages that share important derived characters with arthropods but, as a consequence, the phylogenetic position of the taxon remains uncertain.

Upper Cambrian stem-lineage crustaceans and their bearing upon the monophyletic origin of Crustacea and the position of Agnostus

Three new arthropods in uncompressed condition have been discovered in Upper Cambrian limestone nodules of Vastergotland, Sweden and their morphology provides new insights into the evolutionary path and progressive development of ground plan characteristics along the stem-lineage and gives further support for the monophyletic origin of Crustacea.

The Upper Cambrian Rehbachiella and the phylogeny of Branchiopoda and Crustacea

This study on Rehbachiella supports the monophyly of the crown-group Crustacea and reveals that only the first maxilla was morphologically and functionally included into the crustacean head, while subsequent limbs were addted to the head in a stepwise manner and became modified separately within the different crustacea lineages, which is of great relevance when evaluating the relationships between these.

Relationships of Cambrian Arachnata and the systematic position of Trilobita

Reweighted characters favor Trilobita and Helmetiida as closest relatives, with Petalopleura and then Naraoiidae as sister groups.