Molting polychaete jaws—ecdysozoans are not the only molting animals

  title={Molting polychaete jaws—ecdysozoans are not the only molting animals},
  author={Hannelore Paxton},
  journal={Evolution \& Development},
  • H. Paxton
  • Published 1 July 2005
  • Biology
  • Evolution & Development
Summary Jaw shedding and replacement of Diopatra aciculata (Onuphidae, Eunicida), by the same process as arthropod molting, involving apolysis and ecdysis, is described here. These observations suggest that molting has either evolved convergently in eunicidan polychaetes and ecdysozoans or it was present in the last ecdysozoan/lophotrochozoan common ancestor and thus may not represent a synapomorphy of the ecdysozoans. 

Polychaete jaw apparatuses and scolecodonts from the Silurian Ireviken Event interval of Gotland, Sweden

Abstract Articulated polychaete jaw apparatuses and scolecodonts from the uppermost Llandovery—lower Wenlock Ireviken Event strata of Gotland, Sweden, are illustrated and discussed and one new

The phylogeny of the annelid genus Ophryotrocha (Dorvilleidae)

This work attempts to shed light on the phylogeny of the Ophryotrocha group by adding an additional gene (cytochrome c oxidase subunit I) to the previous analyses of the group, but the results are still incongruent with the results from the morphological data.

Replacement of adult maxillary jaws in Eunicida (Polychaeta)

Jaw replacement in Ctenognatha, where the new elements form in sac-like epithelial structures ventrolateral to the existing maxillae, is probably limited to this group.

Functional Morphology of Eunicidan (Polychaeta) Jaws

Comparison of jaw kinematics and morphology of two distantly related eunicidan taxa with superficially similar jaw structures compared to improve understanding of early annelid communities by linking fossil teeth to the ecological roles of extant species with similar morphologies.

Earth’s oldest ‘Bobbit worm’ – gigantism in a Devonian eunicidan polychaete

Whilst the fossil record of polychaete worms extends to the early Cambrian, much data on this group derive from microfossils known as scolecodonts. These are sclerotized jaw elements, which generally

Hooking some stem‐group “worms”: fossil lophotrochozoans in the Burgess Shale

  • N. Butterfield
  • Biology, Environmental Science
    BioEssays : news and reviews in molecular, cellular and developmental biology
  • 2006
Analysis of the fossil record of two famously problematic worms, Odontogriphus and Wiwaxia, reveals pronounced anatomical and histological discrepancies with molluscan analogues, such that they are more reliably interpreted as primitive features of the superphylum Lophotrochozoa.

Origin of ecdysis: fossil evidence from 535-million-year-old scalidophoran worms

These basal scalidophorans moulted in a manner similar to that of extant priapulid worms, extricating themselves smoothly from their old tubular cuticle or turning their exuviae inside out like the finger of a glove, the oldest record of moulting in ecdysozoans.

Jaw-bearing polychaetes of the Silurian Eramosa Lagerstätte, Ontario, Canada

Abstract. The Wenlock (middle Silurian) Eramosa Lagerstätte of the Bruce Peninsula, Ontario, Canada, is becoming known for its rich and diverse faunas, different preservational styles, and a

Ghosts from the past – ancestral features reflected in the jaw ontogeny of the polychaetous annelids Marphysa fauchaldi (Eunicidae) and Diopatra aciculata (Onuphidae)

This study opens a new perspective on evolutionary patterns, discusses asymmetry in jaw apparatuses relating to the basal plate concept, the apparent absence of early ontogenetic stages from the fossil record and cautions the use of architectural types in the interpretation of fossil maxillary appar atuses.

Annelids in evolutionary developmental biology and comparative genomics.

A hitherto unsuspected level of complexity in these ancestors is revealed, revealing the ancestral conditions at various levels of the animal phylogeny, including the bilaterian ancestor and the nature of the annelid ancestor.



Diopatra Audouin and Milne Edwards (Polychaeta: Onuphidae) from Australia, with a discussion of developmental patterns in the genus

  • H. Paxton
  • Biology
    The Beagle : Records of the Museums and Art Galleries of the Northern Territory
  • 1993
Analysis of all available information for the Diopatra Audouin and Milne Edwards genus allows the identification of four developmental patterns ranging from brooding in the parental tube to presumed broadcast spawning.

Evidence for shedding of maxillary jaws in eunicoid polychaetes

Circumstantial evidence is summarized which suggests that periodic replacement of maxillae is typical of eunicoid polychaetes.

The significance of moulting in Ecdysozoan evolution

The evolution of planktotrophic larvae may have been independently achieved at least three times within Bilateria, and the nonmoulting clades evolved larvae that swim and feed via ciliated tufts and bands, presumably intercalating these forms within their early developmental systems.

Small Bilaterian Fossils from 40 to 55 Million Years Before the Cambrian

Ten phosphatized specimens of a small animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, and provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.

The position of the Arthropoda in the phylogenetic system

There are morphological characters that support Articulata, but molecular as well as morphological data advocate Ecdysozoa, and comparative morphology suggests Gastrotricha as the sister group of Ecdy sozoa with the synapomorphies.

Modern mucociliary creeping trails and the bodyplans of Neoproterozoic trace-makers

Abstract The bulk of Neoproterozoic trace fossils can be interpreted as horizontal creeping trails produced by minute vermiform organisms moving on or just beneath the seafloor or under algal mats.

Animal phylogeny and the ancestry of bilaterians: inferences from morphology and 18S rDNA gene sequences

Because chaetognaths and lophophorates, taxa traditionally allied with deuterostomes, occupy basal positions within their respective protostomian clades, deuterstomy most likely represents a suite of characters plesiomorphic for bilaterians.


Many questions persist concerning relationships within Ecdysozoa and Lophotrochozoa, poriferan monophyly, and the placement of many less-studied taxa (e.g., kinorhynchs, gastrotrichs, gnathostomulids, and entoprocts).

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.

Jaw growth and replacement in Ophryotrocha labronica (Polychaeta, Dorvilleidae)

The internal structure of the Ophryotrocha forceps demonstrates that they are not homologous to the labidognath maxilla I as has been suggested.