Critical appraisal of tubular putative eumetazoans from the Ediacaran Weng’an Doushantuo biota

John A Cunningham*, Kelly M Vargas, Liu Pengju, Veneta Belivanova, Federica Marone, Carlos Martínez-Pérez, Manuel Guizar-Sicairos, Mirko Holler, Stefan Bengtson, Philip C J Donoghue

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

19 Citations (Scopus)
325 Downloads (Pure)

Abstract

Molecular clock analyses estimate that crown-group animals began diversifying hundreds of millions of years before the start of the Cambrian period. However, the fossil record has not yielded unequivocal evidence for animals during this interval. Some of the most promising candidates for Precambrian animals occur in the Weng'an biota of South China, including a suite of tubular fossils assigned to Sinocyclocyclicus, Ramitubus, Crassitubus and Quadratitubus, that have been interpreted as soft-bodied eumetazoans comparable to tabulate corals. Here, we present new insights into the anatomy, original composition and phylogenetic affinities of these taxa based on data from synchrotron radiation X-ray tomographic microscopy, ptychographic nanotomography, scanning electron microscopy and electron probe microanalysis. The patterns of deformation observed suggest that the cross walls of Sinocyclocyclicus and Quadratitubus were more rigid than those of Ramitubus and Crassitubus. Ramitubus and Crassitubus specimens preserve enigmatic cellular clusters at terminal positions in the tubes. Specimens of Sinocyclocyclicus and Ramitubus have biological features that might be cellular tissue or subcellular structures filling the spaces between the cross walls. These observations are incompatible with a cnidarian interpretation, in which the spaces between cross walls are abandoned parts of the former living positions of the polyp. The affinity of the Weng'an tubular fossils may lie within the algae.
Original languageEnglish
Article number20151169
Number of pages9
JournalProceedings of the Royal Society B: Biological Sciences
Volume282
Issue number1812
Early online date15 Jul 2015
DOIs
Publication statusPublished - 7 Aug 2015

Keywords

  • Doushantuo
  • Ediacaran
  • Exceptional fossilization
  • Tubular fossils

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