Early Cambrian Pentamerous Cubozoan Embryos from South China

Han, Jian; Kubota, Shin; Li, Guoxiang; Yao, Xingyu; Yang, Xiaoguang; Shu, Degan; Li, Yong; Kinoshita, Shunichi; Sasaki, Osamu; Komiya, Tsuyoshi; Yan, Gang

doi:10.1371/journal.pone.0070741

Cited by 44 publications

(110 citation statements)

References 37 publications

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“…Han et al . () did not share the concerns of Steiner et al . () in fitting a cnidarian bodyplan to the internal structures described by Dong et al .…”

Section: History Of Research Into Olivooidesmentioning

confidence: 71%

Developmental biology of the early Cambrian cnidarian Olivooides

Vargas

Cunningham

et al. 2016

Palaeontology

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Fossilized embryos afford direct insight into the pattern of development in extinct organisms, providing unique tests of hypotheses of developmental evolution based in comparative embryology. However, these fossils can only be effective in this role if their embryology and phylogenetic affinities are well constrained. We elucidate and interpret the development of Olivooides from embryonic and adult stages and use these data to discriminate among competing interpretations of their anatomy and affinity. The embryology of Olivooides is principally characterized by the development of an ornamented periderm that initially forms externally and is subsequently formed internally, released at the aperture, facilitating the direct development of the embryo into an adult theca. Internal anatomy is known only from embryonic stages, revealing two internal tissue layers, the innermost of which is developed into three transversally arranged walls that partly divide the lumen into an abapertural region, interpreted as the gut of a polyp, and an adapertural region that includes structures that resemble the peridermal teeth of coronate scyphozoans. The anatomy and pattern of development exhibited by Olivooides appears common to the other known genus of olivooid, Quadrapyrgites, which differs in its tetraradial, as opposed to pentaradial symmetry. We reject previous interpretations of the olivooids as cycloneuralians, principally on the grounds that they lack a through gut and introvert, in embryo and adult. Instead we consider the affinities of the olivooids among medusozoan cnidarians; our phylogenetic analysis supports their classification as totalgroup Coronata, within crown-Scyphozoa. Olivooides and Quadrapyrgites evidence a broader range of life history strategies and bodyplan symmetry than is otherwise commonly represented in extant Scyphozoa specifically, and Cnidaria more generally.Key words: development, embryo, Cnidaria, Scyphozoa, Kuanchuanpu, Cambrian. et al. 2015), the tempo of early animal evolution is astonishing given the scale of innovation achieved (Erwin et al. 2011): the establishment of all phylum-level body plans that are sufficiently distinct that they are effectively defined by the limits of comparative anatomy (Bengtson 1986). Insights into the processes that brought about this remarkable episode in evolutionary history are afforded through comparative embryology of living animals, facilitating inference of the embryology of ancient ancestors and, indeed, into the evolution of development that brought about the origin of animal bodyplans. Inevitably, this approach is confused by the subsequent developmental evolution that serves to conflate homologies and convergences. Hence, the discovery of a fossil record of embryology from early in animal evolutionary history affords a more direct insight into the embryology of ancient ancestors, free from the confounding effects of half a billion years of subsequent evolutionary history. T H O U G H there remains considerable debate over the timing of ori...

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“…Han et al . () did not share the concerns of Steiner et al . () in fitting a cnidarian bodyplan to the internal structures described by Dong et al .…”

Section: History Of Research Into Olivooidesmentioning

confidence: 71%

Developmental biology of the early Cambrian cnidarian Olivooides

Vargas

Cunningham

et al. 2016

Palaeontology

View full text Add to dashboard Cite

show abstract

“…A small number of specimens have shown that the external pentaradial symmetry is imposed more fundamentally upon the internal anatomy which has been preserved in only the most exceptional of circumstances, revealing a series of circumference parallel walls with pentaradial divisions and diverticulations, leading to an open adapertural space otherwise occupied by an axial pentaradial process (Dong et al 2013 ;Han et al 2013 ). Additionally, a set of two juxtaposed pentaradial objects has been described in association with Olivooides and interpreted as ephyrae (juvenile medusae) in the process of strobilation (budding in scyphozoan cnidarians; see Chapter 6 ) (Dong et al 2013 ).…”

Section: Olivooides and Quadrapyrgitesmentioning

confidence: 99%

“…Debate over the affi nity of the olivooids has been wide-ranging, including echinoderms , scalidophorans (Steiner et al 2014 ), cnidarians (Bengtson and Yue 1997 ;Yue and Bengtson 1999 ;Han et al 2013 ), and diploblastic stem-eumetazoans (Yasui et al 2013 ). The hypothesis of echinoderm affi nity is based on little more than pentaradial symmetry and can be rejected since the olivooids lack key echinoderm apomorphies, not least a mineralised skeleton comprised of calcite stereom (Dong et al 2013 ;Han et al 2013 ;Steiner et al 2014 ).…”

Section: Olivooides and Quadrapyrgitesmentioning

confidence: 99%

“…The hypothesis of echinoderm affi nity is based on little more than pentaradial symmetry and can be rejected since the olivooids lack key echinoderm apomorphies, not least a mineralised skeleton comprised of calcite stereom (Dong et al 2013 ;Han et al 2013 ;Steiner et al 2014 ). The scalidophoran interpretation is based principally on the general similarity between the theca of olivooids and the lorica of loriciferans and larval priapulids, together with similarities in general symmetry and the requirement of the aperture to open and close akin to a scalidophoran introvert (Steiner et al 2014 ).…”

Section: Olivooides and Quadrapyrgitesmentioning

confidence: 99%

“…The pattern of pentaradial symmetry seen in Olivooides is also unusual for cnidarians, as is the aperture which is diffi cult to rationalise with the presence of a polyp. Many of these concerns are diminished if not dismissed based on recent description of internal anatomy, which Han et al ( 2013 ) interpret (and likely grossly over-interpret) in the image of a cubozoan polyp. Details of this comparison are problematic, not least the evident fact that the embryo of Olivooides develops into a sessile polyp (if it is indeed a cnidarian), not a medusa, and what is more, the polyp stage of living cubozoans is grossly reduced.…”

Section: Olivooides and Quadrapyrgitesmentioning

confidence: 99%

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