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Viewing the Ediacaran biota as a failed experiment is unhelpful
In Pubblicazioni e ricerche
Stefano Mazza
Apr 27, 2019
Grande Enrico. In effetti, questa tesi era stata in parte anticipata nel 2018 in un lavoro di Dunn, Liu e Donoghue, che abbiamo già citato in questo forum: Dunn, F. S., Liu, A. G. and Donoghue, P. C. (2018), Ediacaran developmental biology. Biol Rev, 93: 914-932. doi:10.1111/brv.12379 https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12379 La cui conclusione era che il percorso evolutivo dei primi metazoi, fra cui si annoverano rangeomorfi e dickinsoniomorfi, fosse caratterizzato già in origine da una notevole complessità e che si sia svolto mediante uno sviluppo molto contorto e tuttora poco compreso: "The recognition of some the most enigmatic members of Ediacaran fossil assemblages as probable metazoans offers support to recent suggestions of considerable developmental complexity in early‐branching metazoans (e.g. Ferrier, 2015), and lends credence to the idea that the early metazoan tree cannot be rationalised in terms of gradually increasing complexity, but may have followed a much more cryptic path." Ma qui ci si fermava alla collocazione di alcuni Ediacarans nel regno Animalia, mentre in quest'ultimo articolo la prospettiva si estende ancora oltre, fino a proporre un importante cambio di prospettiva sullo sviluppo della vita. Facendo una cronistoria molto rapida, al limite del demenziale: - 2011: i principali cladi del regno animale possono aver avuto origine nel criogeniano (da 850 a 635 milioni di anni fa) ed aver ottenuto un successo ecologico-evolutivo durante l'Ediacarano (635-541 Ma) e il Cambriano (541-488 Ma) [The Cambrian Conundrum: Early Divergence and Later Ecological Success in the Early History of Animals. Douglas H. Erwin, Marc Laflamme, Sarah M. Tweedt, Erik A. Sperling, Davide Pisani, Kevin J. Peterson. Science 25 Nov 2011. https://science.sciencemag.org/content/334/6059/1091.full] - 2017: - La Dickinsonia è un metazoo [Hoekzema RS, Brasier MD, Dunn FS, Liu AG. 2017. Quantitative study of developmental biology confirms Dickinsonia as a metazoan. Proc. R. Soc. B 284: 20171348. http://dx.doi.org/10.1098/rspb.2017.1348] - Vengono ritrovate antichissime evidenze di movimenti da parte di bilateria: icnofossili di gallerie scavate risalenti all'Ediacarano [Luke A. Parry, Paulo C. Boggiani, Daniel J. Condon, Russell J. Garwood, Juliana de M. Leme, Duncan McIlroy, Martin D. Brasier, Ricardo Trindade, Ginaldo A. C. Campanha, Mírian L. A. F. Pacheco, Cleber Q. C. Diniz & Alexander G. Liu. Ichnological evidence for meiofaunal bilaterians from the terminal Ediacaran and earliest Cambrian of Brazil. Nature Ecology & Evolution 2017] - 2018: Rangeomorfi e Dickinsoniomorfi sono metazoi primordiali [Dunn, F. S., Liu, A. G. and Donoghue, P. C. (2018), Ediacaran developmental biology. Biol Rev, 93: 914-932. doi:10.1111/brv.12379 https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12379] - 2019: la fauna dell'Ediacarano non è una semplice curiosità da paleontologi con scarse prospettive di carriera: ci si possono intravedere i primi meccanismi evolutivi che avrebbero poi portato ai successivi sviluppi del regno animale. [Viewing the Ediacaran biota as a failed experiment is unhelpful. Dunn, Liu. NATURE ECOLOGY & EVOLUTION | VOL 3 | APRIL 2019. https://www.nature.com/articles/s41559-019-0815-4] Molto interessante come sempre, grazie.
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TRILOBITI, IL libro del Museo (seconda edizione)
In Pubblicazioni e ricerche
La fauna di Ediacara spiegata da S.J. Gould
In Precambrian Area
Stefano Mazza
Feb 06, 2019
Grazie Enrico. Di Retallak si trova questo del 1994: Were the Ediacaran Fossils Lichens? Paleobiology Vol. 20, No. 4 (Autumn, 1994), pp. 523-544 Abstract Ediacaran fossils are taphonomically similar to impressions of fossil plants common in quartz sandstones, and the relief of the fossils suggests that they were as resistant to compaction during burial as some kinds of Pennsylvanian tree trunks. Fossils of jellyfish are known from siderite nodules and fine-grained limestone, and even in these compaction-resistant media were more compressed during burial than were the Vendobionta. Vendobionta were constructed of materials that responded to burial compaction in a way intermediate between conifer and lycopsid logs. This comparative taphonomic study thus falsifies the concept of Vendobionta as thin softbodied creatures such as worms and jellyfish. Lichens, with their structural chitin, present a viable model for the observed preservational style of Vendobionta, as well as for a variety of other features that now can be reassessed from this new perspective. The diversity of Ediacaran body plans can be compared with the variety of form in fungi, algae, and lichens. The large size (ca. 1 m) of some Ediacaran fossils is reasonable for sessile photosynthetic symbioses, and much bigger than associated burrows of metazoans not preserved. Microscopic tubular structures and darkly pigmented cells in permineralized late Precambrian fossils from Namibia and China are also compatible with interpretation as lichens. The presumed marine habitat of Ediacaran fossils is not crucial to interpretation as lichens, because fungi and lichens live in the sea as well as on land. https://www.researchgate.net/publication/254199337_Were_the_Ediacaran_Fossils_Lichens
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