A new view of insect–crustacean relationships I. Inferences from neural cladistics and comparative neuroanatomy

Strausfeld, Nicholas J.; Andrew, David R.

doi:10.1016/j.asd.2011.02.002

Cited by 82 publications

(63 citation statements)

References 71 publications

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“…The latter is supported by a number of independent lines of evidence, including nuclear ribosomal genes 8,15 , mitochondrial genomes and gene order, nuclear protein-coding genes 1 and transcriptomics [2][3][4] , but has so far remained elusive in morphological phylogenies, apart from those based solely on neural characters 16 , which resolve malacostracan crustaceans closer to hexapods than to branchiopods. The position of the pycnogonids is equally controversial, being variously resolved as the closest relatives of euchelicerates 1,3,15 (Fig.…”

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confidence: 74%

Arthropod fossil data increase congruence of morphological and molecular phylogenies

2013

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The relationships of major arthropod clades have long been contentious, but refinements in molecular phylogenetics underpin an emerging consensus. Nevertheless, molecular phylogenies have recovered topologies that morphological phylogenies have not, including the placement of hexapods within a paraphyletic Crustacea, and an alliance between myriapods and chelicerates. Here we show enhanced congruence between molecular and morphological phylogenies based on 753 morphological characters for 309 fossil and Recent panarthropods. We resolve hexapods within Crustacea, with remipedes as their closest extant relatives, and show that the traditionally close relationship between myriapods and hexapods is an artefact of convergent character acquisition during terrestrialisation. The inclusion of fossil morphology mitigates long-branch artefacts as exemplified by pycnogonids: when fossils are included, they resolve with euchelicerates rather than as a sister taxon to all other euarthropods.

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confidence: 74%

Arthropod fossil data increase congruence of morphological and molecular phylogenies

2013

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“…13. optic lobes) and unspecialized VNC of remipedes (5, 7). If the neurological organization of fuxianhuiids reflects an ancestral condition as suggested by their phylogenetic position, it would support the symplesiomorphic nature of a malacostracan-like brain for Pancrustacea/Tetraconata (6,8) and also imply an independent increase in VNC complexity among extant crustacean lineages. However, the lack of consensus pertaining to the phylogenetic placement of Branchiopoda, Remipedia, and Malacostraca relative to Hexapoda based on molecular and neuromophological data (5)(6)(7)27) complicates deciding between these hypotheses based on the available paleoneurological information.…”

Section: Discussionmentioning

confidence: 99%

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda

Yang

Ortega‐Hernández

Butterfield

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

142

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Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda.stem-group Euarthropoda | Onychophora | phylogeny | Cambrian Explosion | Xiaoshiba Lagerstätte T he nervous system represents a critical source of phylogenetic information and has been used extensively for exploring the evolutionary relationships of extant Panarthropoda (i.e., Onychophora, Tardigrada, Euarthropoda) (1-7). Identification of fossilized nervous tissues has provided a unique perspective on early euarthropod brain neuroanatomy and suggests that broad patterns of extant neurological diversity were already in place by the Cambrian (8-11). The ventral nerve cord (VNC) reflects fundamental aspects of panarthropod body organization that complement the organization of the brain and together illuminate the evolution of the CNS (1-3, 5, 7, 12-16). The early evolutionary history of the panarthropod postcephalic CNS, however, remains obscure due to the exclusive preservation of brains in most available fossils (8,10,11). Moreover, the unresolved phylogenetic relationships within Panarthropoda complicate accurate reconstruction of the CNS ground pattern (16)(17)(18)(19)(20)(21)(22). In this study, we demonstrate the exceptional preservation of postcephalic neurological features in the early Cambrian fuxianhuiid Chengjiangocaris kunmingensis, an upper stem-group euarthropod (17) from the Xiaoshiba Lagerstätte, South China (23). These fossils clarify the neurological organization of the VNC in early euarthropod ancestors, thereby polarizing the evolution of the panarthropod CNS.

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“…Modern phylogenies of Arthropoda based on large molecular datasets [119 -121] or using anatomical data [122] reject the traditional view that myriapods and hexapods share a unique common ancestor. Many of the locomotory and respiratory characters that were classically used to unite myriapods with hexapods are now viewed as convergences related to terrestrial life habits, and hexapods are recognized as a clade of terrestrial crustaceans.…”

Section: Land Colonization: Timetrees (A) Approaches To Tree Calibrationmentioning

confidence: 99%

A timeline for terrestrialization: consequences for the carbon cycle in the Palaeozoic

Kenrick

Wellman

Schneider

et al. 2012

Phil. Trans. R. Soc. B

243

196

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The geochemical carbon cycle is strongly influenced by life on land, principally through the effects of carbon sequestration and the weathering of calcium and magnesium silicates in surface rocks and soils. Knowing the time of origin of land plants and animals and also of key organ systems (e.g. plant vasculature, roots, wood) is crucial to understand the development of the carbon cycle and its effects on other Earth systems. Here, we compare evidence from fossils with calibrated molecular phylogenetic trees (timetrees) of living plants and arthropods. We show that different perspectives conflict in terms of the relative timing of events, the organisms involved and the pattern of diversification of various groups. Focusing on the fossil record, we highlight a number of key biases that underpin some of these conflicts, the most pervasive and far-reaching being the extent and nature of major facies changes in the rock record. These effects probably mask an earlier origin of life on land than is evident from certain classes of fossil data. If correct, this would have major implications in understanding the carbon cycle during the Early Palaeozoic.

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A new view of insect–crustacean relationships I. Inferences from neural cladistics and comparative neuroanatomy

Cited by 82 publications

References 71 publications

Arthropod fossil data increase congruence of morphological and molecular phylogenies

Arthropod fossil data increase congruence of morphological and molecular phylogenies

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda

A timeline for terrestrialization: consequences for the carbon cycle in the Palaeozoic

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