Re-evaluating the phylogenetic position of the enigmatic early Cambrian deuterostome Yanjiahella

Zamora, Samuel; Wright, David F.; Mooi, Rich; Lefèbvre, Bertrand; Guensburg, Thomas E.; Gorzelak, Przemysław; David, Bruno; Sumrall, Colin D.; Cole, Selina R.; Hunter, Aaron W.; Sprinkle, James; Thompson, Jeffrey R.; Ewin, Timothy A.M.; Fatka, Oldřich; Nardin, Élise; Reich, Mike; Nohejlová, Martina; Rahman, Imran A.

doi:10.1038/s41467-020-14920-x

Cited by 11 publications

(31 citation statements)

References 13 publications

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“…Echinoderms possess a calcitic skeleton with a distinctive three-dimensional mesh-like microstructure called stereom, that is considered a major synapomorphy of the Echinodermata 3 . Zamora et al 2 highlighted the absence of stereom in Y. biscarpa, additionally stating that we had omitted appropriate methods, specifically latex casting, that may confirm the presence of stereom in our specimens. We concede that initially we did not latex cast any specimens of Y. biscarpa, predominantly due to the fragile nature and the associated risk of damaging the specimens in question.…”

mentioning

confidence: 77%

“…Our interpretation and our phylogenetic analysis suggest that Y. biscarpa is a stem-echinoderm, which would confirm that echinoderms acquired plates before pentaradial symmetry and that their history is firmly rooted in bilateral forms. Zamora et al 2 however, have criticized our interpretation, arguing against an echinoderm affinity, instead suggesting that the phylogenetic placement of Y. biscarpa is dubious and its significance for understanding deuterostome evolution is uncertain.…”

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confidence: 82%

“…In response to Zamora et al 2 we have cast a specimen in latex to investigate whether stereom can be detected in Y. biscarpa. No pitting, resembling stereom is evident on the plates ( Fig.…”

mentioning

confidence: 99%

“…1) and the latex casts do not appear to offer any further information that was not detectable using light photography and SEM, as predicted. The statement from Zamora et al 2 that latex casting could have resolved many of the uncertainties surrounding the composition, shape and arrangement of the plates and the morphology of the stalk is an overstatement and ambitiously delivered without direct examination of the fossil specimens.…”

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confidence: 99%

“…We openly state that we cannot observe stereom in the original manuscript and we maintain our stance that this likely is due to taphonomic factors. Zamora et al 2 raise additional questions over the interpretation of particular morphological features of Y. biscarpa. Zamora et al 2 highlight that the configuration of the two feeding appendages in Y. biscarpa differ from previously reported echinoderms, in particular Ubaghsicystis, Dibrachicystis and Pleurocystites.…”

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confidence: 99%

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confidence: 77%

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confidence: 82%

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confidence: 99%

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confidence: 99%

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Current understanding on the Cambrian Explosion: questions and answers

Zhang

Shu

2021

PalZ

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The Cambrian Explosion by nature is a three-phased explosion of animal body plans alongside episodic biomineralization, pulsed change of generic diversity, body size variation, and progressive increase of ecosystem complexity. The Cambrian was a time of crown groups nested by numbers of stem groups with a high-rank taxonomy of Linnaean system (classes and above). Some stem groups temporarily succeeded while others were ephemeral and underrepresented by few taxa. The high number of stem groups in the early history of animals is a major reason for morphological gaps across phyla that we see today. Most phylum-level clades achieved their maximal disparity (or morphological breadth) during the time interval close to their first appearance in the fossil record during the early Cambrian, whereas others, principally arthropods and chordates, exhibit a progressive exploration of morphospace in subsequent Phanerozoic. The overall envelope of metazoan morphospace occupation was already broad in the early Cambrian though it did not reach maximal disparity nor has diminished significantly as a consequence of extinction since the Cambrian. Intrinsic and extrinsic causes were extensively discussed but they are merely prerequisites for the Cambrian Explosion. Without the molecular evolution, there could be no Cambrian Explosion. However, the developmental system is alone insufficient to explain Cambrian Explosion. Time-equivalent environmental changes were often considered as extrinsic causes, but the time coincidence is also insufficient to establish causality. Like any other evolutionary event, it is the ecology that make the Cambrian Explosion possible though ecological processes failed to cause a burst of new body plans in the subsequent evolutionary radiations. The Cambrian Explosion is a polythetic event in natural history and manifested in many aspects. No simple, single cause can explain the entire phenomenon.

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First report of lepidocystid echinoderm in the Cambrian of North China: Evolutionary and Palaeobiogeographic implications

Wang,

Nohejlová,

Sun

et al. 2024

Palaeogeography, Palaeoclimatology, Palaeoecology

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Re-evaluating the phylogenetic position of the enigmatic early Cambrian deuterostome Yanjiahella

Cited by 11 publications

References 13 publications

Reply to ‘Re-evaluating the phylogenetic position of the enigmatic early Cambrian deuterostome Yanjiahella’

Reply to ‘Re-evaluating the phylogenetic position of the enigmatic early Cambrian deuterostome Yanjiahella’

Current understanding on the Cambrian Explosion: questions and answers

First report of lepidocystid echinoderm in the Cambrian of North China: Evolutionary and Palaeobiogeographic implications

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