Embryology in Deep Time

Donoghue, Philip C. J.; Cunningham, John A.; Xi, Dong; Bengtson, Stefan

doi:10.1007/978-3-7091-1862-7_3

Cited by 11 publications

(18 citation statements)

References 65 publications

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“…Unfortunately, the evolutionary significance of the majority of fossilized embryos has yet to be realized because only disparate stages of embryology are preserved, providing insufficient evidence to constrain their phylogenetic affinity, or else insufficient evidence in order to make material comparisons to the embryology of living relatives (Donoghue et al . ). The olivooids, known from the early Cambrian Kuanchuanpu Fauna of South China, are a remarkable exception in that they are represented by a broad range of embryonic and post‐embryonic stages of development preserved with great fidelity (Bengtson & Yue ; Yue & Bengtson ).…”

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confidence: 97%

Developmental biology of the early Cambrian cnidarian Olivooides

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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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confidence: 97%

Developmental biology of the early Cambrian cnidarian Olivooides

Vargas

Cunningham

et al. 2016

Palaeontology

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“…prima comes exclusively from the outer surface because no internal structures have been discovered yet. The affinity of Pseudooides has been debated for a long time (Donoghue et al, 2015). Steiner et al (2004b) interpreted the paired compartments as a possible “germ band”, and compared them with the “germ band” of modern arthropod embryos.…”

Section: Phylogenetic Perspectivesmentioning

confidence: 99%

“…However, an arthropod affinity of P . prima is unlikely and was challenged by Donoghue et al (2006b, 2015) because the anatomy of P . prima is unusual for any modern arthropods.…”

Section: Phylogenetic Perspectivesmentioning

confidence: 99%

“…Olivooides and Quadrapyrgites have exclusively been reported from the Cambrian Fortunian Stage of South China (Donoghue et al, 2015). Due to comparable morphology and ontogenetic sequence, Steiner et al (2014) proposed that Olivooides and Quadrapyrgites should be sister groups, constituting the taxon Olivooidae Steiner et al, 2014, and might be early cycloneuralians.…”

Section: Phylogenetic Perspectivesmentioning

confidence: 99%

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Diversity of cnidarians and cycloneuralians in the Fortunian (early Cambrian) Kuanchuanpu Formation at Zhangjiagou, South China

et al. 2018

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The latest discovery of microfossils from the lower Cambrian (Fortunian Stage) Zhangjiagou Lagerstätte in South China are presented. This lagerstätte is rich in exceptionally preserved microfossils, including embryos of Olivooides multisulcatus, Olivooides mirabilis, and Pseudooides prima; hatched stages of O. multisulcatus, O. mirabilis, Hexaconularia sichuanensis, and Quadrapyrgites quadratacris; and cycloneuralians represented by Eopriapulites sphinx. The largest known fragment of O. mirabilis implies that its adult length can be more than 9.0 mm with at least 50 annuli, and the longest known specimen of Q. quadratacris has at least 18 annuli. These unusually large specimens refute the non-feeding larvae hypothesis for Olivooides and Quadrapyrgites.Based on the current material, it is inferred that (1) early cnidarians have a high diversity in the Fortunian Stage; (2) P. prima might represent the embryonic stages of H. sichuanensis; (3) adults of Olivooides and Quadrapyrgites may have reached centimeter-scale dimensions with more than 50 annuli; (4) Olivooides and Quadrapyrgites may be better interpreted as coronate scyphozoans; (5) cycloneuralians also had a high diversity in the Zhangjiagou Lagerstätte; and (6) cycloneuralians might have originally been part of the early Cambrian meiofauna rather than belonging to the macrobenthos. Such ancestral cycloneuralians might have been Eopriapulites-like, possessing pentaradially symmetric, backward pointing, and internally hollow introvert scalids used as locomotory devices.

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“…With the exception of Pseudooides , the affinities of which are unclear (Donoghue et al . ), most radial animals are generally accepted as cnidarians (Conway Morris & Chen ; Dong et al . ), whereas Eolympia pediculata is probably a scalidophoran (Liu et al .…”

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A new scyphozoan from the Cambrian Fortunian Stage of South China

et al. 2017

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Animals with radial symmetry are abundant in the Cambrian Fortunian Stage of South China, but with relatively low diversity: representatives include Olivooides, Quadrapyrgites, carinachitiids, hexangulaconulariids and Pseudooides. Here, we report a new radial animal, Qinscyphus necopinus gen. et sp. nov., from the Fortunian small shelly fauna of southern Shaanxi Province, South China. Qinscyphus necopinus has a cup-shaped profile, with slightly raised annuli and five groups of triangular thickenings in pentaradial symmetry. This organism has a comparable morphology to, and thus a close affinity with, Olivooides and Quadrapyrgites, and is interpreted as a coronate scyphozoan. This discovery adds a new crown-group cnidarian to the Cambrian Explosion.

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Embryology in Deep Time

Cited by 11 publications

References 65 publications

Developmental biology of the early Cambrian cnidarian Olivooides

Developmental biology of the early Cambrian cnidarian Olivooides

Diversity of cnidarians and cycloneuralians in the Fortunian (early Cambrian) Kuanchuanpu Formation at Zhangjiagou, South China

A new scyphozoan from the Cambrian Fortunian Stage of South China

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