Life cycle and morphology of a cambrian stem-lineage loriciferan

PLoS One. 2013 Aug 9;8(8):e73583. doi: 10.1371/journal.pone.0073583. eCollection 2013.

Abstract

Cycloneuralians form a rich and diverse element within Cambrian assemblages of exceptionally preserved fossils. Most resemble priapulid worms whereas other Cycloneuralia (Nematoda, Nematomorpha, Kinorhyncha, Loricifera), well known at the present day, have little or no fossil record. First reports of Sirilorica Peel, 2010 from the lower Cambrian Sirius Passet fauna of North Greenland described a tubular lorica covering the abdomen and part of a well developed introvert with a circlet of 6 grasping denticles near the lorica. The introvert is now known to terminate in a narrow mouth tube, while a conical anal field is also developed. Broad muscular bands between the plates in the lorica indicate that it was capable of movement by rhythmic expansion and contraction of the lorica. Sirilorica is regarded as a macrobenthic member of the stem-lineage of the miniaturised, interstitial, present day Loricifera. Like loriciferans, Sirilorica is now known to have grown by moulting. Evidence of the life cycle of Sirilorica is described, including a large post-larval stage and probably an initial larva similar to that of the middle Cambrian fossil Orstenoloricusshergoldii.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Invertebrates / anatomy & histology
  • Invertebrates / physiology*

Grants and funding

The work was funded by Swedish Research Council, www.vr.se, grant no. 621 2008-3446 (80344601). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.