Javascript är avstängt eller blockerat i din webbläsare. Detta kan leda till att vissa delar av vår webbplats inte fungerar som de ska. Sätt på javascript för optimal funktionalitet och utseende.

Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Mats Eriksson

Mats Eriksson

Professor

Mats Eriksson

Early Middle Ordovician scolecodonts from north-western Argentina and the emergence of labidognath polychaete jaw apparatuses

Författare

  • Olle Hints
  • Petra Tonarová
  • Mats E. Eriksson
  • Claudia V. Rubinstein
  • G. Susana de la Puente

Summary, in English

Scolecodonts provide fossil evidence of the evolution and diversification of jaw-bearing polychaetes from the latest Cambrian onwards. However, their record before the Darriwilian (Middle Ordovician) is scarce worldwide, which limits our understanding of key evolutionary events. One such event is the emergence of taxa possessing the asymmetrical labidognath-type jaw apparatus architecture, which became common in the Middle Ordovician and is often dominant throughout the Palaeozoic. Here, we document a small collection of Dapingian scolecodonts from the Capillas section, Sierras Subandinas, north-western Argentina. The isolated elements recovered allowed us to reconstruct the distinctive jaw apparatus, and to introduce a new taxon, Andiprion paxtonae gen. et sp. nov. The maxillary apparatus of Andiprion is intermediate between the symmetrognath type of the Early Ordovician Kadriorgaspis and the labidognath type that is present in polychaetaspids and related taxa. The apparatus architecture of Andiprion corresponds best to the labidognath type, but the morphology of the individual jaws suggests that it may be the most primitive representative of this lineage currently known. We propose that Andiprion-like forms were ancestral to polychaetaspids, polychaeturids and ramphoprionids. The Capillas collection provides supporting evidence for the evolutionary homology of the 'basal plate' and the left first maxilla. Thus the labidognath-type asymmetry, with an unpaired left maxilla III, developed as a result of gradual reduction in size of the first right jaw ('basal plate') in front of the carriers, instead of loss or fusion of anterior maxillae.

Avdelning/ar

  • Geologiska institutionen

Publiceringsår

2017-07

Språk

Engelska

Sidor

583-593

Publikation/Tidskrift/Serie

Palaeontology

Volym

60

Issue

4

Dokumenttyp

Artikel i tidskrift

Förlag

Wiley-Blackwell

Ämne

  • Zoology
  • Other Earth and Related Environmental Sciences

Nyckelord

  • Argentina
  • Eunicida
  • Evolution
  • Ordovician
  • Polychaete jaw apparatus
  • Scolecodonts

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0031-0239