Phenetic phylogenetics of tentaculitoids – extinct, problematic calcareous tube-forming organisms

Abstract

Tentaculitoids have traditionally been assigned to either Mollusca or Annelida. In addition, cnidarian, brachiopod, bryozoan, phoronid and sponge affinities have been proposed. Similarity analyses carried out with tentaculitoid characters place them in a cluster together with Brachiozoa (Brachiopoda+Phoronida). Tentaculitoids are less similar to Mollusca and Bryozoa. No support was found for the annelid, cnidarian and sponge affinities. Thus, tentaculitoids belong to Lophotrochozoa with a high degree of certainty. They are best classified as “lophophorates”, most likely Brachiozoa.

Keywords:

• biological affinities
• Tentaculita
• Brachiopoda
• Phoronida
• tubeworms
• Palaeozoic

Acknowledgements

We are grateful to J.-P. Cuif and J. Stolarski for comments on coral skeletal structures, to P.D. Taylor for comments on the morphology of Bryozoa and to J. Dzik for comments on the earlier version of the manuscript. O.V. is grateful to The Paleontological Society for receipt of a J.J. Sepkoski Grant, to the Estonian Science Foundation for grant ETF9064 and to a target-financed project (from the Estonian Ministry of Education and Science), number SF0180051s08 (Ordovician and Silurian climate changes, as documented from the biotic changes and depositional environments in the Baltoscandian Palaeobasin) for financial support. M.A. Wilson, The College of Wooster, read earlier versions of the manuscript. We are grateful to Loren E. Babcock (Columbus, Ohio) for constructive review. This research is a contribution to three International Geoscience Programme projects: IGCP 591, IGCP 596 and IGCP 572.