The early Cambrian fossil embryo Pseudooides is a direct developing cnidarian, not an early ecdysozoan
| Autor: | John A. Cunningham, Luis Porras, Philip C. J. Donoghue, Kelly Vargas, Xi-Ping Dong, Baichuan Duan |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
0106 biological sciences
010506 paleontology General Immunology and Microbiology biology embryo Embryo General Medicine Biological evolution Pseudooides biology.organism_classification 010603 evolutionary biology 01 natural sciences General Biochemistry Genetics and Molecular Biology Cnidaria Evolutionary biology MSc Palaeobiology Cambrian Ecdysozoa General Agricultural and Biological Sciences development 0105 earth and related environmental sciences General Environmental Science |
| Zdroj: | Baichuan, D, Dong, X-P, Porras, L, Vargas, K, Cunningham, J & Donoghue, P 2017, ' The early Cambrian fossil embryo Pseudooides is a direct developing cnidarian, not an early ecdysozoan ', Proceedings of the Royal Society B: Biological Sciences, vol. 284, no. 1869, 20172188 . https://doi.org/10.1098/rspb.2017.2188 |
| DOI: | 10.1098/rspb.2017.2188 |
| Popis: | Early Cambrian Pseudooides prima has been described from embryonic and post-embryonic stages of development, exhibiting long germ-band development. There has been some debate about the pattern of segmentation, but this interpretation, as among the earliest records of ecdysozoans, has been generally accepted. Here, we show that the ‘germ band’ of P. prima embryos separates along its mid axis during development, with the transverse furrows between the ‘somites’ unfolding into the polar aperture of the ten-sided theca of Hexaconularia sichuanensis , conventionally interpreted as a scyphozoan cnidarian; co-occurring post-embryonic remains of ecdysozoans are unrelated. We recognize H. sichuanensis as a junior synonym of P. prima as a consequence of identifying these two form-taxa as distinct developmental stages of the same organism. Direct development in P. prima parallels the co-occuring olivooids Olivooides, and Quadrapyrgites and Bayesian phylogenetic analysis of a novel phenotype dataset indicates that, despite differences in their tetra-, penta- and pseudo-hexa-radial symmetry, these hexangulaconulariids comprise a clade of scyphozoan medusozoans, with Arthrochites and conulariids, that all exhibit direct development from embryo to thecate polyp. The affinity of hexangulaconulariids and olivooids to extant scyphozoan medusozoans indicates that the prevalence of tetraradial symmetry and indirect development are a vestige of a broader spectrum of body-plan symmetries and developmental modes that was manifest in their early Phanerozoic counterparts. |
| Databáze: | OpenAIRE |
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