The evolutionary origins of the Hemichordata (Enteropneusta & Pterobranchia) - A review based on fossil evidence and interpretations.

 

Authors: Maletz J

Published in: Bulletin of Geosciences, volume 99, issue 2; pages: 127 - 147; Received 5 December 2023; Accepted in revised form 11 March 2024; Online 26 April 2024

Keywords: Hemichordata, Enteropneusta, Pterobranchia, fossil record, evolution,

full text (PDF, 6.62 MB)

Export to RIS

 

Abstract

Few fossils demonstrate the presence of the Hemichordata (Enteropneusta, Pterobranchia - excluding benthic and planktic Graptolithina) in the early Palaeozoic. Many of these early records are questionable and are not supported by a reliable fossil record. First definitive fossils are found in the Fortunian (early Cambrian) with the record of Sokoloviina representing fragments of the tubarium of the Pterobranchia. Possible Enteropneusta have been described from the Miaolingian (Wuliuan) and the slightly older Cambrian Series 2, Stage 3, but the record is largely based on poor inconclusive material. However, the Fortunian pterobranchs clearly indicate that a differentiation of the Enteropneusta and Pterobranchia must have happened earlier, even though a definitive fossil record is not available. The evolutionary origin of the Hemichordata (Enteropneusta & Pterobranchia), thus is likely to be found in the latest Ediacaran. Fossil burrows of Gyrolithes spp. at the Ediacaran-Cambrian GSSP may represent the activity of Enteropneusta, but cannot demonstrate without doubt their presence. Difficult is also the interpretation of meandering deep-water feeding traces or faecal traces in the Cambrian (cf. Nereites ichnofacies) that are similar to those produced by extant Enteropneusta (Torquaratoridae). The possible erect housing construction identified as Margaretia is unlikely to be built by an enteropneust and is not comparable in any way with the organic-walled tubarium constructions of the Pterobranchia.

References

Bardack, D. 1997. Wormlike animals: Enteropeusta (Acorn worms), 89-92. In Shabica, C.W. & Hay, A.A. (eds) Richardson’s Guide to the fossil fauna of Mazon Creek. Northeastern Illinois University, Chicago.

Bateson, W. 1885. The later stages in the development of Balanoglossus kowalevskii, with a suggestion as to the affinities of the Enteropneusta. Quarterly Journal of Microscopical Science 25, 81-122.View article

Bertling, M., Braddy, S.J., Bromley, R.G., Demathieu, G.R., Genise, J., Mikulas, R., Nielsen, J.K., Rindsberg, A.K., Schlirf, M. & Uchman, A. 2006. Names for trace fossils: a uniform approach. Lethaia 39, 265-286.View article

Botting, J.P., Muir, L.A., Pates, S., McCobb, L.M.E., Wallet, E., Willman, S., Zhang, Y. & Ma, J. 2023. A Middle Ordovician Burgess Shale-type fauna from Castle Bank, Wales, UK. Nature Ecology & Evolution 7, 666-674.View article

Boulter, E. 2003. A new enteropneust-like hemichordate from the Middle Cambrian Burgess Shale. Palaeontological Association Newsletter 54, 120.

Bourne, D.W. & Heezen, B.C. 1965. A wandering enteropneust from the abyssal Pacific, and the distribution of ’spiral’ tracks on the sea floor. Science, New Series 150, 60-63.View article

Briggs, D.E.G. & Mongiardino Koch, N. 2023. A Silurian pseudocolonial pterobranch. Current Biology 33, 1-8.View article

Bromley, R.G. 1996. Trace Fossils: Biology, Taphonomy and Applications, 2nd Edition. 361 pp. Chapman & Hall, London.

Budd, G.E. & Jensen, S. 2000. A critical reappraisal of the fossil record of the bilaterian phyla. Biological Review 75, 253-295.View article

Bulman, O.M.B. 1970. Graptolithina, 1-163. In Teichert, C. (ed.) Treatise on Invertebrate Paleontology, Part V, second edition. Geological Society of America and University of Kansas Press, Lawrence.

Cai, Y., Hua, H., Schiffbauer, J.D., Sun, B. & Yuan, X. 2014. Tube growth patterns and microbial mat-related lifestyles in the Ediacaran fossil Cloudina, Gaojiashan Lagerstätte, South China. Gondwana Research 25, 1008-1018.View article

Cai, Y., Cortijo, I., Schiffbauer, J.D. & Hua, H. 2017. Taxonomy of the late Ediacaran index fossil Cloudina and a new similar taxon from South China. Precambrian Research 298, 146-156.View article

Cameron, C.B. 2002. The anatomy, life habits, and later development of a new species of enteropneust, Harrimania planktophilus (Hemichordata: Harrimaniidae) from Barkley Sound. Biological Bulletin 202, 182-191.View article

Cameron, C.B. 2005. A phylogeny of the hemichordates based on morphological characters. Canadian Journal of Zoology 83, 196-215.View article

Cameron, C.B. 2018. Part V, second revision, Chapter 2: Class Enteropneusta: Introduction, morphology, life habits, systematic descriptions, and future research. Treatise Online 109, 1-22.View article

Cameron, C.B. 2023. Introduction to the Enteropneusta. 5-16. In Maletz, J. (coor.) Treatise on invertebrate paleontology, Part V, Hemichordata, Second Revision, including Enteropneusta, Pterobranchia (Graptolithina). Lawrence, Kansas: The University of Kansas, Paleontological Institute.

Cameron, C.B. & Ostiguy, A. 2013. Three new species of Glossobalanus (Hemichordata: Enteropneusta: Ptychoderidae) from western North America. Zootaxa 3630(1), 43-154.View article

Cameron, C.B., Swalla, B.J. & Garey, J.R. 2000. Evolution of the chordate body plan: new insights from phylogenetic analysis of deuterostome phyla. Proceedings of the National Academy of Sciences of the United States of America 97(9), 4469-4474.View article

Cannon, J.T., Rychel, A.L., Eccleston, H., Halanych, K.M. & Swalla, B.J. 2009. Molecular phylogeny of Hemichordata, with updated status of deep-sea enteropneusts. Molecular Phylogenetics and Evolution 52, 17-24.View article

Cannon, J.T., Swalla, B.J. & Halanych, K.M. 2013. Hemichordate molecular phylogeny reveals a novel cold-water clade of Harrimaniid acorn worms. The Biological Bulletin 225(3), 194-204.View article

Cannon, J.T., Kocot, K.M., Waits, D.S., Weese, D.A., Swalla, B.J., Santos, S.R. & Halanych, K.M. 2014. Phylogenomic resolution of the Hemichordate and echinoderm clade. Current Biology 24, 2827-2832.View article

Caron, J.-B., Conway Morris, S. & Shu, D. 2010. Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes. PLOS ONE 5(3), 1-13.View article

Caron, J.-B., Conway Morris, S. & Cameron, C.B. 2013. Tubicolous enteropneusts from the Cambrian period. Nature 495, 503-506.View article

Cedhagen, T. & Hansson, H.G. 2013. Biology and distribution of hemichordates (Enteropneusta) with emphasis on Harrimaniidae and description of Protoglossus bocki sp. nov. from Scandinavia. Helgoländer Marine Research 67, 251-265.View article

Chen, J.Y. & Erdtmann, B.-D. 1991. Lower Cambrian fossil lagerstätte from Chengjiang, Yunnan, China: Insights for reconstructing early metazoan life, 57-76. In Simonetta, A. M. & Conway Morris, S. (eds) The early evolution of metazoan and the significance of problematic taxa. Cambridge University Press.

Chen, J.Y. & Zhou, G. 1997. Biology of the Chengjiang fauna. Bulletin of the National Museum of Natural Science 10, 11-105.

Chen, J.Y., Dzik, J., Edgecombe, G.D., Ramskjöld, L. & Zhou, G.Q. 1995. A possible early Cambrian chordate. Nature 377, 720-722.View article

Conway Morris, S. 1977. A new entoproct-like organism from the Burgess Shale of British Columbia. Palaeontology 20(4), 833-845.

Conway Morris, S. 1986. The community structure of the Middle Cambrian phyllopod bed (Burgess Shale). Palaeontology 29(3), 423-467.

Conway Morris, S. 2009. The Burgess Shale animal Oesia is not a chaetognath: A reply to Szaniawskki (2005). Acta Palaeontologica Polonica 54(1), 175-179.View article

Conway Morris, S. & Robison, R.A. 1988. More soft-bodied animals and algae from the Middle Cambrian of Utah and British Columbia. The University of Kansas Paleontological Contributions 122, 1-48.

Damas, D. & Stiasny, O. 1961. Les larves planctoniques d’entéropneustes. Mémoires. Académie Royale de Belgique, Classe des Sciences 15(2), 1-68.

Eiserhardt, K.-H., Koch, L. & Eiserhardt, W.L. 2001. Revision des ichnotaxon Tomaculum Groom, 1902. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 221(3), 325-358.View article

Evans, S.D., Hughes, I.V., Gehling, J.G. & Droser, M.L. 2020. Discovery of the oldest bilaterian from the Ediacaran of South Australia. PNAS 117(14), 7845-7850.View article

Ezhova, O.V., Lukinykh, A.I., Galkin, S.V., Krylova, E.M. & Gebruk, A.V. 2021. Deep-sea acorn worms (Enteropneusta) from the Bering Sea with the description of a new genus and a new species of Torquaratoridae dominating soft-bottom communities. Deep-Sea Research II 195, 105014.View article

Ezhova, O.V., Trukhan, M.A., Lukinykh, A.I., Galkin, S.V., Gebruk, A.V., Schepetov, D.M., Tiunov, A.V., Rozanova, O.L., Georgiev, A.A. & Malakov, V.V. 2023. Digestive system and feeding of deep-sea acron worm Quatuoralisa malakovi (Enteropneusta: Torquaratoridae) from the Bering Sea. Deep-Sea Research I 203, 104196.View article

Fatka, O. & Vodička, J. 2022. Putative Ordovician green alga Krejciella reinterpreted as enteropneust hemichordate tube (Czech Republic). Palaeontologia Electronica 25(2), a25.View article

Foster, J.R., Sroka, S.D., Howells, T.F., Cothren, H.R., Dehler, C.M. & Hagadorn, J.W. 2022. New Cambrian vermiform organisms from Burgess Shale-type deposits of the western United States. Bulletin of Geosciences 97(3), 269-288.View article

Gegenbaur, C. 1870. Grundzu¨ge der vergleichenden Anatomie. Zweite, umgearbeitete Auflage. 892 pp. Wilhelm Engelmann, Leipzig.

Gingras, M.K., Dashtgard, S.E., MacEachern, J.A. & Pemberton, S.G. 2008. Biology of shallow marine ichnology: a modern perspective. Aquatic Biology 2, 255-268.View article

Groom, T. 1902. The sequence of the Cambrian and associated beds of the Malvern Hills. Quarterly Journal of the Geological Society London 58, 89-149.View article

Hadfield, M.G. & Young, R.E. 1983. Planctosphaera (Hemichordata: Enteropneusta) in the Pacific Ocean. Marine Biology 73, 151-153.View article

Hagadorn, J.W. & Allmon, W.D. 2019. Paleobiology of a three-dimensionally preserved paropsonemid from the Devonian of New York. Palaeogeography, Palaeoclimatology, Palaeoecology 513, 208-214.View article

Halanych, K.M. 1995. The phylogenetic position of the pterobranch hemichordates based on 18S rDNA sequence data. Molecular Phylogenetics and Evolution 4, 72-76.View article

Halanych, K.M., Cannon, J.T., Mahon, A.R., Swalla, B.J. & Smith, C.R. 2013. Modern Antarctic acorn worms form tubes. Nature Communications 4, 2738.View article

Hall, J. 1865. Figures and descriptions of Canadian organic remains. Decade II, Graptolites of the Quebec Group. 154 pp. Geological Survey of Canada, A.B. Dawson Brothers, Montreal.View article

Havlíček, V., Vaněk, J. & Fatka, O. 1993. Floating algae of the genus Krejciella as probable hosts of epiplanktic organisms (Dobrotiva Series, Ordovician; Prague Basin). Journal of the Czech Geological Society 38, 79-88.

Holland, N.D., Clague, D.A., Gordon, D.P., Gebruk, A., Pawson, D.L. & Vecchione, M. 2005. ’Lophenteropneust’ hypothesis refuted by collection and photos of new deep-sea hemichordates. Nature 434, 374-376.View article

Holland, N.D., Jones,W.J., Ellena,J., Ruhl,H.A. & Smith, K.L. 2009. A new deep-sea species of epibenthic acorn worm (Hemichordata, Enteropneusta). Zoosystema 31(2), 333-346.View article

Holland, N.D., Osborn, K.J. & Kuhnz, L.A. 2012. A new deep-sea species of harrimaniid enteropneust (Hemichordata). Proceedings of the Biological Society of Washington, 125(3), 228-240.View article

Holland, N.D., Osborn, K.J., Gebruk, A.V. & Rogacheva, A. 2013. Rediscovery and augmented description of the HMS ’Challenger’ acorn worm (Hemichordata, Enteropneusta), Glandiceps abyssicola, in the equatorial Atlantic abyss. Journal of the Marine Biological Association of the United Kingdom 93(8), 2197-2205.View article

Hou, X. & Bergström, J. 2003. The Chengjiang fauna - the oldest preserved animal community. Palaeontological Research 7(1), 55-70.View article

Hou, X., Ramskjöld, L. & Bergström, J. 1991. Composition and preservation of the Chengjiang fauna - a Lower Cambrian soft-bodied biota. Zoologica Scripta 20, 395-411.View article

Hou, X.-G., Aldridge, R.J., Siveter, D.J., Siveter, D.J., Williams, M., Zalasiewicz, J. & Ma, X.-Y. 2011. An Early Cambrian Hemichordate Zooid, Current Biology 21, 1-5.View article

Hou, X., Siveter, D.J., Siveter, D.J., Aldridge, R.J., Con, P., Gabbott, S.E., Ma, X., Purnell, M.A. & Williams, M. 2017. The Cambrian Fossils of Chengjiang, China: The Flowering of Early Animal Life, Second Edition. John Wiley & Sons Ltd.View article

Hu, S., Erdtmann, B.-D., Steiner, M., Zhang, Y., Zhao, F., Zhang, Z. & Han, J. 2018. Malongitubus, a possible pterobranch hemichordate from the early Cambrian of South China. Journal of Paleontology 92(1), 26-32.View article

Hua, H., Chen, Z., Yuan, X., Zhang, L. & Xiao, S. 2005. Skeletogenesis and asexual reproduction in the earliest biomineralizing animal Cloudina. Geology 33(4), 277-280.View article

Jabr, N., Archambault, P. & Cameron, C.B. 2018. Biogeography and adaptations of torquaratorid acorn worms (Hemichordata: Enteropneusta) including two new species from the Canadian Arctic. Canadian Journal of Zoology 96, 1221-1229.View article

Johnston, K.J., Johnston, P.A. & Powell, W.G. 2009. A new, Middle Cambrian, Burgess Shale-type biota, Bolaspidella Zone, Chancellor Basin, southeastern British Columbia. Palaeogeography, Palaeoclimatology, Palaeoecology 277, 106-126.View article

Jones, D.O.B., Alt, C.H.S., Priede, I.G., Reid, W.D.K., Wigham, B.D., Billett, D.S.M., Gebruk, A.V., Rogacheva, A. & Gooday, A.J. 2013. Deep-sea surface-dwelling enteropneusts from the mid-Atlantic Ridge: their ecology, distribution and mode of life. Deep-Sea Research II 98, 374-387.View article

Kaźmierczak, J. & Pszczółkowski, A. 1969. Burrows of Enteropneusta in Muschelkalk (Middle Triassic) of the Holy Cross Mountains, Poland. Acta Palaeontologica Polonica 14(2), 299-318.

Kirjanov, V.V. 1968. Paleontology and stratigraphy of the Baltic deposits in the Volhyn-Podolia, 5-27. In Karandievskiy, V.S. & Kirjanov, V.V. (eds) Paleontology and Stratigraphy of the Lower Paleozoic of Volhyn-Podolia. Naukova Dumka, Kiev. [in Russian]

Knaust, D. 2021. Balanoglossites-burrowed firmground - the most common ichnofabric on Earth? Earth-Science Reviews 220, 103747.View article

Kosevich, I.A. 2006. Changes in the patterning of a hydroid colony. Zoology 109, 244-259.View article

Kozłowski, R. 1938. Informations préliminaires sur les Graptolithes du Tremadoc du Pologne et sur leur portée théoretique. Annales Musei Zoologici Polonici 13(16), 183-196.

Kozłowski, R. 1949. Les graptolithes et quelques nouveaux groupes d’animaux du Tremadoc de la Pologne. Palaeontologia Polonica 3, 1-330.

Krishtofovich, A.N. 1953. Discovery of Lycopodiaceae in the Cambrian deposits of eastern Siberia. Doklady Akademii Nauk SSSR, 91, 1377-1379.

Kwafo, S., Singha, A., Pandit, M. & Meert, J. 2023. Reply to the comment by Retallack et al. (2023) on ’Stinging News: ’Dickinsonia’ discovered in the Upper Vindhyan of India not worth the buzz’. Gondwana Research 118, 160-162.View article

Laing, B.A., Buatois, L.A., Mángano, M.G., Narbonne, G.M. & Gougeon, R.C. 2018. Gyrolithes from the Ediacaran-Cambrian boundary section in Fortune Head, Newfoundland, Canada: Exploring the onset of complex burrowing. Palaeogeography, Palaeoclimatology, Palaeoecology 495, 171-185.View article

Lankester, E.R. 1877. Notes on the embryology and classification of the animal kingdom; comprising a revision of speculations relative to the origin and significance of the germlayers. Quarterly Journal of Microscopical Science, N.S. 17, 339-454.View article

Lemche, H., Hansen, B., Madsen, F.J., Tendal, O.S. & Wolff, T. 1976. Hadal life as analyzed from photographs. Videnskabelige Medddelelser fra Dansk Naturhistorisk Forenening 139, 262-336.

Lester, S.M. 1985. Cephalodiscus sp. (Hemichordata: Pterobranchia): observations of functional morphology, behavior and occurrence in shallow water around Bermuda. Marine Biology 85, 263-268.View article

Lin, Y. 1985. On the discovery of Siberiograptus from Upper Cambrian in North China. Acta Palaeontologica Sinica 24, 237-242.

Linnaus, C. 1758. Systema natura per regna tria natura, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. 824 pp. Salvius, Holmia.View article

Liu, J., Steiner, M., Dunlop, J.A. & Shu, D. 2018. Microbial decay analysis challenges interpretation of putative organ systems in Cambrian fuxianhuiids. Proceedings of the Royal Society B285, 20180051.View article

LoDuca, S.T. & Kramer, A. 2014. Graptolites from the Wheeler and Marjum Formations (Cambrian, Series 3) of Utah. Journal of Paleontology 88(2), 403-410.View article

LoDuca, S.T., Caron, J.-B., Schiffbauer, J.D., Xiao, S. & Kramer, A. 2015a. A reexamination of Yuknessia from the Cambrian of British Columbia. Journal of Paleontology 89(1), 82-95.View article

LoDuca, S.T., Wu, M., Zhao, Y., Xiao, S., Schiffbauer, J.D., Caron, J.-B. & Babcock, L.E. 2015b. Reexamination of Yuknessia from the Cambrian of China and first report of Fuxianospira from North America. Journal of Paleontology 89(6), 899-911.View article

MacGabhann, B.A. & Murray, J. 2010. Non-mineralised discoidal fossils from the Ordovician Bardahessiagh Formation, Co. Tyrone, Ireland. Irish Journal of Earth Sciences 28, 1-12.View article

Mägdefrau, K. 1932. Über einige Bohrgänge aus dem Unteren Muschelkalk von Jena. Paläontologische Zeitschrift 14, 150-159.View article

Maletz, J. 2014. Hemichordata (Pterobranchia, Enteropneusta) and the fossil record. Palaeogeography, Palaeoclimatology, Palaeoecology 398, 16-27.View article

Maletz, J. 2017a. Graptolite Paleobiology. 323 pp. John Wiley & Sons Ltd.View article

Maletz, J. 2017b. Graptolites: fossil and living. Geology Today 33(6), 233-240.View article

Maletz, J. 2018. Part V, Second revision, Chapter 5: Hemichordate taphonomy. Treatise Online 110, 1-15.View article

Maletz, J. 2019. Tracing the evolutionary origins of the Hemichordata (Enteropneusta and Pterobranchia). Palaeoworld 28, 58-72.View article

Maletz, J. 2020. Hemichordata (Enteropneusta & Pterobranchia, incl. Graptolithina): A review of their fossil preservation as organic material. Bulletin of Geosciences 95(1), 41-80.View article

Maletz, J. 2023a. Graptolites - survival in the Palaeozoic seas. Historical Biology, 1-11.View article

Maletz, J. 2023b. Benthic graptolites (Graptolithina, Pterobranchia) in the Miaolingian (Cambrian Series 3). Palaeobiodiversity and Palaeoenvironments.View article

Maletz, J. & Beli, E. 2018. Part V, Second revision, Chapter 15: Subclass Graptolithina and incertae sedis family Rhabdopleuridae: Introduction and systematic descriptions. Treatise Online 101, 1-14.View article

Maletz, J. & Cameron, C.B. 2016. Part V, Second revision, Chapter 3: Introduction to class Pterobranchia Lankester, 1877. Treatise Online 82, 1-15.View article

Maletz, J. & Cameron, C.B. 2021. Part V, second revision, Chapter 1: Introduction to the Hemichordata. Treatise Online 157, 1-9.View article

Maletz, J. & Gonzalez, P. 2017. Part V, Second Revision, Chapter 14: Order Cephalodiscida: Introduction and systematic descriptions. Treatise Online 100, 1-8.View article

Maletz, J. & Steiner, M. 2021. Part V, Second revision, Chapter 29: uncertain genera. Treatise Online 152, 1-17.View article

Maletz, J., Steiner, M. & Fatka, O. 2005. Middle Cambrian pterobranchs and the Question: What is a graptolite? Lethaia 38, 73-85.View article

Maletz, J., Lenz, A.C. & Bates, D.E.B. 2016. Part V, Second revision, Chapter 4: Morphology of the Pterobranch tubarium. Treatise Online 76, 1-63.View article

Maletz, J., Melchin, M.J., Bullock, P. & Russel-Houston, J. 2019. Paramonoclimacis sidjachenkoi (Obut & Sobolevskaya) and the evolution of the streptograptid thecal aperture in the Silurian (Graptolithina, Monograptidae). Papers in Palaeontology 5(3), 499-520.View article

Maletz, J. et al. 2023. Treatise on invertebrate paleontology, Part V, Hemichordata, Second Revision, including Enteropneusta, Pterobranchia (Graptolithina). 538 pp. The University of Kansas, Paleontological Institute, Lawrence, Kansas.

Martynov, A.V. & Korshunova, T.A. 2022. Renewed perspectives on the sedentary-pelagic last common bilaterian ancestor. Contributions to Zoology 91, 285-352.View article

McIlroy, D. 2022. Were the first trace fossils really burrows or could they have been made by sediment-displacive chemosymbiotic organisms? Life 2022 12, 136.View article

Meert, J.G., Pandit, M.K., Kwafo, S. & Singha, A. 2023. Stinging News: ’Dickinsonia’ discovered in the Upper Vindhyan of India not worth the buzz. Gondwana Research 117, 1-7.View article

Mitchell, C.E., Melchin, M.J., Cameron, C.B. & Maletz, J. 2013. Phylogenetic analysis reveals that Rhabdopleura is an extant graptolite. Lethaia 46, 34-56.View article

Moosavizadeh, S.M.A. & Knaust, D. 2022. The trace fossil Gyrolithes lorcaensis from the Lower Cretaceous of the Kopet-Dagh Basin, NE Iran. Ichnos 29(1), 11-26.View article

Muscente, A.D., Allmon, W.D. & Xiao, S.H. 2016. The hydroid fossil record and analytical techniques for assessing the affinities of putative hydrozoans and possible hemichordates. Palaeontology 59(1), 71-87.View article

Naimark, E., Kirpotin, D., Boeva, N., Gmoshinskiy, V., Kalinina, M., Lyupina, Y., Markov, A., Nikitin, M., Shokurov, A. & Volkov, D. 2021. Taphonomic experiments imply a possible link between the evolution of multicellularity and the fossilization potential of soft-bodied organisms. Ecology and Evolution 11, 1037-1056.View article

Nanglu, K. & Caron, J.-B. 2021. Symbiosis in the Cambrian: enteropneust tubes from the Burgess Shale co-inhabited by commensal polychaetes. Proceedings of the Royal Society B 288, 20210061.View article

Nanglu, K., Caron, J.-B., Conway Morris, S. & Cameron, C.B. 2016. Cambrian suspension-feeding tubicolous enteropneusts. BMC Biology 14, 56.View article

Nanglu, K., Caron, J.-B. & Cameron, C.B. 2020. Cambrian tentaculate worms and the origin of the hemichordate body plan. Current Biology 30, 4238-4244.View article

Nanglu, K., Cole, S.R., Wright, D.F. & Souto, C. 2022. Worms and gills, plates and spines: the evolutionary origins and incredible disparity of deuterostomes revealed by fossils, genes, and development. Biological Reviews 98, 316-351.View article

Nanglu, K., Waskom, M.E., Richards, J.C., Ortega-Hernández, J. 2023. Rhabdopleurid epibionts from the Ordovician Fezouata Shale biota and the longevity of cross-phylum interactions. Communications Biology 6, 1002.View article

O’Brian, L.J. & Caron, J.-B. 2012. A new stalked filter-feeder from the Middle Cambrian Burgess Shale, British Columbia, Canada. PLos One 7(1), e29233.View article

Obrhel, J. 1968. Neue Pflanzenfunde im mittelböhmischen Ordovizium. Věstník Ústředního ústavu geologického 43, 463-464.

Osawa, H., Caron, J.-B. & Gaines, R.R. 2023. First record of growth patterns in a Cambrian annelid. Royal Society Open Science 10, 221400.View article

Osborn, K.J., Kuhnz, L.A., Priede, I.G., Urata, M., Gebruk, A.V. & Holland, N.D. 2012. Diversification of acorn worms (Hemichordata, Enteropneusta) revealed in the deep sea. Proceedings of the Royal Society B279, 1646-1654.View article

Osborn, K.J., Gebruk, A.V., Rogacheva, A. & Holland, N.D. 2013. An externally brooding acorn worm (Hemichordata, Enteropneusta, Torquaratoridae) from the Russian Arctic. Biological Bulletin 225, 113-123.View article

Ou, Q., Han, J., Zhang, Z., Shu, D., Sun, G. & Mayer, G. 2017. Three Cambrian fossils assembled into an extinct body plan of cnidarian affinity. PNAS 114(33), 8835-8840.View article

Pandey, S.K., Ahmad, S. & Sharma, M. 2023. Dickinsonia tenuis reported by Retallack et al. 2021 is not a fossil, instead an impression of an extant ’fallen beehive’. Journal of the Geological Society of India 99, 311-316.View article

Pawson, D.L. 2003. Deep-sea dreams: diary of a mad lophenteropneust watcher. Deep-Sea Newsletter 32, 6.

Philippe, H., Brinkmann, H., Copley, R.R., Moroz, L.L., Nakano, H., Poustka, A.J., Wallberg, A., Peterson, K.J. & Telford, M.J. 2011. Acoelomorph flatworms are deuterostomes related to Xenoturbella. Nature 470, 255-260.View article

Qiao, Y., Cui, L., Xing, G., Fu, D., Chang, C., Gaines, R. & Zhang, X. 2023. Thermal history of Cambrian Burgess Shale-type deposits: new insights from the early Cambrian Chengjiang and Qingjiang fossils of South China. Journal of Earth Science, 1-48.View article

Ramírez-Guerrero, G.M. & Cameron, C.B. 2021. Systematics of pterobranchs from the Cambrian Period Burgess Shales of Canada and the early evolution of graptolites. Bulletin of Geosciences 96(1), 1-18.View article

Ramskjöld, L. & Hou, X. 1991. New early Cambrian animal and onychophoran affinities of enigmatic metazoans. Nature 351, 225-228.View article

Retallack, G.J., Matthews, N.A., Master, S., Khangar, R.G. & Khan, M. 2021. Dickinsonia discovered in India and late Ediacaran biogeography. Gondwana Research 90, 165-170.View article

Retallack, G.J., Master, S., Khangar, R.G. & Khan, M. 2023. Discussion on ’Stinging News: ’Dickinsonia’ discovered in the Upper Vindhyan of India not worth the buzz’ by Meert, et al. (2023). Gondwana Research 118, 163-164.View article

Ritter, W.E. 1902. The movements of the Enteropneusta and the mechanism by which they are accomplished. Biological Bulletin 3(6), 255-261.View article

Röttinger, E. & Lowe, C.J. 2012. Evolutionary crossroads in developmental biology: hemichordates. Development 139, 2463-2475.View article

Röttinger, E. & Martindale, M.Q. 2006. Ventralization of an indirect developing hemichordate by NiCl2 suggests a conserved mechanism of dorso-ventral (D/V) patterning in Ambulacraria (hemichordates and echinoderms). Developmental Biology 354, 173-190.View article

Saleh, F., Lustri, L., Gueriau, P., Potin, G.J.-M., Pérez-Peris, F., Laibl, L., Jamart, V., Antoine Vite, A., Antcliffe, J. B., Daley, A.C., Nohejlová, M., Dupichaud, C., Schöder, S., Bérard, E., Lynch, S., Drage, H.B., Vaucher, R., Vidal, M., Monceret, E., Monceret, S. & Lefebvre. B. 2024. The Cabrieres Biota (France) provides insights into Ordovician polar ecosystems. Nature Ecology & Evolution.View article

Sars, G.O. 1874. On Rhabdopleura mirabilis (M. Sars). Journal of Microscopical Science 14, 23-44.View article

Scheltema, R.S. 1970. Two new records of Planctosphaera larvae (Hemichordata: Planctosphaeroidea). Marine Biology 7, 47-48.View article

Seilacher, A. 2007. Trace Fossil Analysis. 226 pp. Springer, Berlin, Heidelberg & New York.

Selly, T., Schiffbauer, J.D., Jacquet, S.M., Smith, E.F., Nelson, L.L., Andreasen, B.D., Huntley, J.W., Strange, M.A., O’Neil, G.R., Thater, C.A., Bykova, N., Steiner, M. Yang, B. & Cai, Y. 2020. A new cloudinid fossil assemblage from the terminal Ediacaran of Nevada, USA. Journal of Systematic Palaeontology 18(4), 357-379.View article

Shu, D. & Conway Morris, S. 2006. New diploblasts from Chengjiang lagerstätte. Earth Science Frontiers 13(6), 227-233.

Shu, D., Zhang, X. & Chen, L. 1996. Reinterpretation of Yunnanozoon as the earliest known hemichordate. Nature 380, 428-430.View article

Simakov, O. et al. 2015. Hemichordate genomes and deuterostome origins. Nature 527, 459-465.

Slater, B.J. & Bohlin, M.S. 2022. Animals origins: The record from organic microfossils. Earth-Science Reviews 232, 104107.View article

Slater, B.J., Willman, S., Budd, G.E. & Peel, J.S. 2017. Widespread preservation of small carbonaceous fossils (SCFs) in the early Cambrian of North Greenland. Geology 46(2), 107-110.View article

Slater, B.J., Harvey, T.H.P. & Butterfield, N.J. 2018. Small carbonaceous fossils (SCFs) from the Terreneuvian (Lower Cambrian) of Baltica. Palaeontology 61(3), 417-439.View article

Sokolov, B.S. 1997. Essayes on the Advent of the Vendian System. 156 pp. KMK Scientific Press Ltd., Moscow.

Song, X., Ruthensteiner, B., Lyu, M., Liu, X., Wang, J. & Han, J. 2021. Advanced Cambrian hydroid fossils (Cnidaria: Hydrozoa) extend the medusozoan evolutionary history. Proceedings of the Royal Society B 288, 20202939.View article

Spengel, J. 1932. Planktosphaera pelagica. Report on the Scientific Results of the ’Michael Sars’ North Atlantic Deep Sea Expedition 5, 1-28.

Steiner, M. 2018. How soft-tissued are Cambrian soft-bodied fossil lagerstätten? 95-96. Programme & Abstracts. International Conference on Ediacaran and Cambrian Sciences, 12th to 16th August, 2018, Xi’an, China.

Steiner, M., Zhu, M., Zhao, Y. & Erdtmann, B.-D. 2005. Lower Cambrian Burgess Shale-type fossil associations of South China. Palaeogeography, Palaeoclimatology, Palaeoecology 220, 129- 152.View article

Stiasny, G. 1910. Zur Kenntnis der Lebensweise von Balanoglossus clavigerus Delle Chiaje. Zoologischer Anzeiger 35, 561-565, 633.

Swalla, B.J. 2006. Building divergent body plans with similar genetic pathways. Herredity 97, 235-43.View article

Swalla, B.J. & Smith, A.B. 2008. Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives. Philosophical Transactions of the Royal Society B 363, 1557-1568.View article

Tagawa, K. 2019. Evo-Devo lessons learned from Hemichordates, 1-25. In Nuno de la Rosa, L. & Müller, G. (eds) Evolutionary Developmental Biology - A Reference Guide. Springer.View article

Tassia, M.G., Cannon, J.T., Konikoff, C.E., Shenkar, N., Halanych, K.M. & Swalla, B.J. 2016. The global diversity of Hemichordata. PLoS ONE 11(10), e0162564.View article

Tassia, M.G., Cannon, J.T. & Halanych, K.M. 2018. Chapter 9 Enteropneusta, 299-325. In Schmidt-Rhaesa, A. (ed.) Handbook of Zoology - Miscellaneous Invertebrates. De Gruyter, Berlin & Boston.View article

Törnquist, S.L. 1881. Om nagra graptolitarter fran Dalarne. Geologiska Föreningens i Stockholm Förhandlingar 5(10), 434-445.View article

Twitchett, R.J. 1996. The resting trace of an acorn-worm (Class: Enteropneusta) from the Lower Triassic. Journal of Paleontology 70, 128-131.View article

Van der Horst, C.J. 1934. The burrow of an enteropneust. Nature 134, 852.View article

Van der Horst, C.J. 1940. The Enteropneusta from Inyack Island, Delagoa Bay. Annals of the South African Museum 32(5), 293-380.

Walcott, C.D. 1911. Cambrian geology and paleontology. Middle Cambrian annelids. Smithsonian Miscellaneous Collections 57(5), 107-144.

Walcott, C.D. 1931. Addenda to descriptions of Burgess Shale fossils. Smithsonian Miscellaneous Collections 85(3), 1-46.

Winchell, C.J., Sullivan, J., Cameron, C.B., Swalla, B.J. & Mallatt, J. 2002. Evaluating hypotheses of deuterostome phylogeny and chordate evolution with new LSU and SSU ribosomal DNA data. Molecular and Biological Evolution 19(5), 762-776.View article

Worsaae, K., Sterrer, W., Kaul-Strehlow, S., Hay-Schmidt, A. & Giribet, G. 2012. An anatomical description of a miniaturized acron worm (Hemichordata, Enteropneusta) with asexual reproduction through paratomy. Plos One 7(11), e48529.View article

Yang, B., Steiner, M., Schiffbauer, J. D., Selly, T., Wu, X., Zhang, C. & Liu, P. 2020. Ultrastructure of Ediacaran cloudinids suggests diverse taphonomic histories and affinities with non-biomineralized annelids. Scientific Reports 10, 535.View article

Yang, X., Kimmig, J., Lieberman, B.S. & Peng, S. 2020. A new species of the deuterostome Herpetogaster from the early Cambrian Chengjiang biota of South China. The Science of Nature 107(37), 1-8.View article

Yang, X., Kimmig, J., Schiffbauer, J.D. & Peng, S. 2023. Herpetogaster collinsi from the Cambrian of China elucidates the dispersal and palaeogeographic distribution of early deuterostomes and the origin of the ambulacrarian larva. PeerJ 11, e16385.View article

Yang, X., Kimmig, J., Cameron, C.B., Nanglu, K., Kimmig, S.R., Zhang, C., Yu, M. & Peng, S. 2024. An early Cambrian pelago-benthic acorn worm and the origin of the hemichordate larva. Palaeontologia Electronica, 27.1.a17.View article

Zeng, L. & Swalla, B.J. 2005. Molecular phylogeny of the protochordates: chordate evolution. Canadian Journal of Zoology 83, 24-33.View article

Zhao, Y., Hou, X.-G. & Cong, P.-Y. 2023. Tentacular nature of the ’column’ of the Cambrian diploblastic Xianguangia sinica, Journal of Systematic Palaeontology 21(1), 2215787.View article