The position of the Arthropoda in the phylogenetic system

Schmidt‐Rhaesa, Andreas; Bartolomaeus, Thomas; Lemburg, Christian; Ehlers, Ulrich; Garey, James R.

doi:10.1002/(sici)1097-4687(199812)238:3<263::aid-jmor1>3.0.co;2-l

Cited by 182 publications

(93 citation statements)

References 121 publications

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“…S1). We regard this bulbous structure as a suctorial pharynx on account of its resemblance in position and shape to the pharynx of extant tardigrades and onychophorans1920 (Supplementary Fig. S7).…”

Section: Resultsmentioning

confidence: 99%

Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda

Shu

Mayer

2012

Nat Commun

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Cambrian lobopodians are important for understanding the evolution of arthropods, but despite their soft-bodied preservation, the organization of the cephalic region remains obscure. Here we describe new material of the early Cambrian lobopodian Onychodictyon ferox from southern China, which reveals hitherto unknown head structures. These include a proboscis with a terminal mouth, an anterior arcuate sclerite, a pair of ocellus-like eyes and branched, antenniform appendages associated with this ocular segment. These findings, combined with a comparison with other lobopodians, suggest that the head of the last common ancestor of fossil lobopodians and extant panarthropods comprized a single ocular segment with a proboscis and terminal mouth. The lack of specialized mouthparts in O. ferox and the involvement of non-homologous mouthparts in onychophorans, tardigrades and arthropods argue against a common origin of definitive mouth openings among panarthropods, whereas the embryonic stomodaeum might well be homologous at least in Onychophora and Arthropoda.

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Section: Resultsmentioning

confidence: 99%

Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda

Shu

Mayer

2012

Nat Commun

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“…Although 1904 EST sequences from onychophorans are available on PubMed (Roeding et al, 2007; Roeding et al, 2009) they came from adults so the absence of any recognizable CP sequences is not significant. Furthermore, given the similar cuticle construction throughout the Ecdysozoa (Schmidt-Rhaesa et al, 1998), it is intriguing that the arthropods seem to have adopted so many unique configurations for their CPs.…”

Section: Cuticular Protein Familiesmentioning

confidence: 99%

Structural cuticular proteins from arthropods: Annotation, nomenclature, and sequence characteristics in the genomics era

Willis

2010

Insect Biochemistry and Molecular Biology

267

312

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The availability of whole genome sequences of several arthropods has provided new insights into structural cuticular proteins (CPs), in particular the distribution of different families, the recognition that these proteins may comprise almost 2% of the protein coding genes of some species, and the identification of features that should aid in the annotation of new genomes and EST libraries as they become available. Twelve CP families are described: CPR (named after the Rebers and Riddiford Consensus); CPF (named because it has a highly conserved region consisting of about forty-four amino acids); CPFL (like the CPFs in a conserved C-terminal region); the TWDL family, named after a picturesque phenotype of one mutant member; four families in addition to TWDL with a preponderance of low complexity sequence that are not member of the families listed above. These were named after particular diagnostic features as CPLCA, CPLCG, CPLCW, CPLCP. There are also CPG, a lepidopteran family with an abundance of glycines, the apidermin family, named after three proteins in Apis mellifera, and CPAP1 and CPAP3, named because they have features analogous to peritrophins, namely one or three chitin-binding domains.Also described are common motifs and features. Four unusual CPs are discussed in detail. Data that facilitated the analysis of sequence variation of single CP genes in natural populations are analyzed.

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“…Priapulids are known from 7 modern genera, and a diverse Cambrian fauna456. Priapulids possess a tri-layered moulting cuticle diagnosing them as ecdysozoans, and a scalid lined introvert which they share with other scalidophorans (kinorhynchs and loriciferans)7. There is some ambiguity as to whether the Scalidophora are sister taxa to all other Ecdysozoa or are united with nematoids in the Cycloneuralia (Fig.…”

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confidence: 99%

Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus

Sansom

2016

Sci Rep

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The exceptionally preserved Cambrian fossil record provides unique insight into the early evolutionary history of animals. Understanding of the mechanisms of exceptional soft tissue preservation frames all interpretations of the fauna and its evolutionary significance. This is especially true for recent interpretations of preserved nervous tissues in fossil ecdysozoans. However, models of soft tissue preservation lack empirical support from actualistic studies. Here experimental decay of the priapulid Priapulus reveal consistent bias towards rapid loss of internal non-cuticular anatomy compared with recalcitrant cuticular anatomy. This is consistent with models of Burgess Shale-type preservation and indicates that internal tissues are unlikely to be preserved with fidelity if organically preserved. This pattern, along with extreme body margin distortion, is consistent with onychophoran decay, and is therefore resolved as general for early ecdysozoans. Application of these patterns to phylogenetic data finds scalidophoran taxa to be very sensitive to taphonomically informed character coding, but not panarthropodan taxa. Priapulid decay also have unexpected relevance for interpretation of myomeres in fossil chordates. The decay data presented serve not only as a test of models of preservation but also a framework with which to interpret ecdysozoan fossil anatomies, and the subsequent evolutionary inferences drawn from them.

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The position of the Arthropoda in the phylogenetic system

Cited by 182 publications

References 121 publications

Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda

Cambrian lobopodians and extant onychophorans provide new insights into early cephalization in Panarthropoda

Structural cuticular proteins from arthropods: Annotation, nomenclature, and sequence characteristics in the genomics era

Preservation and phylogeny of Cambrian ecdysozoans tested by experimental decay of Priapulus

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