Hyoliths are Palaeozoic lophophorates

Moysiuk, J.; Smith, M.R.; Caron, J.-B.

doi:10.1038/nature20804

Hyoliths are Palaeozoic lophophorates

Moysiuk, J.; Smith, M.R.; Caron, J.-B.

Authors

J. Moysiuk

Dr Martin Smith martin.smith@durham.ac.uk
Associate Professor

J.-B. Caron

Abstract

Hyoliths are abundant and globally distributed ‘shelly’ fossils that appear early in the Cambrian period and can be found throughout the 280 million year span of Palaeozoic strata1, 2. The ecological and evolutionary importance of this group has remained unresolved, largely because of their poorly constrained soft anatomy and idiosyncratic scleritome, which comprises an operculum, a conical shell and, in some taxa, a pair of lateral spines (helens)3, 4, 5. Since their first description over 175 years ago, hyoliths have most often been regarded as incertae sedis4, 6, related to molluscs7, 8 or assigned to their own phylum1, 2. Here we examine over 1,500 specimens of the mid-Cambrian hyolith Haplophrentis from the Burgess Shale and Spence Shale Lagerstätten. We reconstruct Haplophrentis as a semi-sessile, epibenthic suspension feeder that could use its helens to elevate its tubular body above the sea floor3, 9, 10, 11, 12. Exceptionally preserved soft tissues include an extendable, gullwing-shaped, tentacle-bearing organ surrounding a central mouth, which we interpret as a lophophore, and a U-shaped digestive tract ending in a dorsolateral anus. Together with opposing bilateral sclerites and a deep ventral visceral cavity, these features indicate an affinity with the lophophorates (brachiopods, phoronids and tommotiids), substantially increasing the morphological disparity of this prominent group.

Citation

Moysiuk, J., Smith, M., & Caron, J. (2017). Hyoliths are Palaeozoic lophophorates. Nature, 541, 394-397. https://doi.org/10.1038/nature20804

Journal Article Type	Article
Acceptance Date	Oct 25, 2016
Online Publication Date	Jan 11, 2017
Publication Date	Jan 11, 2017
Deposit Date	Nov 4, 2016
Publicly Available Date	Jul 11, 2017
Journal	Nature
Print ISSN	0028-0836
Electronic ISSN	1476-4687
Publisher	Nature Research
Peer Reviewed	Peer Reviewed
Volume	541
Pages	394-397
DOI	https://doi.org/10.1038/nature20804