Journal ArticleDOI
Possible ctenophoran affinities of the Precambrian "sea-pen" Rangea.
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The Namibian Kuibis Quartzite fossils of Rangea are preserved three‐dimensionally owing to incomplete collapse of the soft tissues under the load of instantaneously deposited sand, and it is proposed that the irregularly distributed dark spots on the fusiform units of the petaloid of Thaumaptilon represent a kind of macrocilia and that the units are homologous with the ctenophoran comb organs.Abstract:
The Namibian Kuibis Quartzite fossils of Rangea are preserved three-dimensionally owing to incomplete collapse of the soft tissues under the load of instantaneously deposited sand. The process of fossilization did not reproduce the original external morphology of the organism but rather the inner surface of collapsed organs, presumably a system of sacs connected by a medial canal. The body of Rangea had tetraradial symmetry, a body plan shared also by the White Sea Russian fossil Bomakellia and possibly some other Precambrian frond-like fossils. They all had a complex internal anatomy, smooth surface of the body, and radial membranes, making their alleged colonial nature unlikely. Despite a different style of preservation, the Middle Cambrian Burgess Shale frond-like Thaumaptilon shows several anatomical similarities to Rangea. The body plan of the Burgess Shale ctenophore Fasciculus, with its numerous, pinnately arranged comb organs, is in many respects transitional between Thaumaptilon and the Early Cambrian ctenophore Maotianoascus from the Chengjiang fauna of South China. It is proposed that the irregularly distributed dark spots on the fusiform units of the petaloid of Thaumaptilon represent a kind of macrocilia and that the units are homologous with the ctenophoran comb organs. These superficial structures were underlain by the complex serial organs, well represented in the fossils of Rangea. The Precambrian "sea-pens" were thus probably sedentary ancestors of the ctenophores.read more
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The ctenophore genome and the evolutionary origins of neural systems
Leonid L. Moroz,Kevin M. Kocot,Mathew R. Citarella,Sohn Dosung,Tigran P. Norekian,Inna S. Povolotskaya,Anastasia P. Grigorenko,Christopher A. Dailey,Eugene Berezikov,Katherine M. Buckley,Andrey A. Ptitsyn,Denis A. Reshetov,Krishanu Mukherjee,Tatiana P. Moroz,Yelena Bobkova,Fahong Yu,Vladimir V. Kapitonov,Jerzy Jurka,Yuri V. Bobkov,Joshua J. Swore,Joshua J. Swore,David Orion Girardo,David Orion Girardo,Alexander Fodor,Fedor Gusev,Fedor Gusev,Rachel Sanford,Rebecca Bruders,Rebecca Bruders,Ellen L. W. Kittler,Claudia E. Mills,Jonathan P. Rast,Romain Derelle,Victor V. Solovyev,Fyodor A. Kondrashov,Billie J. Swalla,Jonathan V. Sweedler,Evgeny I. Rogaev,Kenneth M. Halanych,Andrea B. Kohn +39 more
TL;DR: The draft genome of Pleurobrachia bachei, Pacific sea gooseberry, together with ten other ctenophore transcriptomes, are presented, and show that they are remarkably distinct from other animal genomes in their content of neurogenic, immune and developmental genes.
Journal ArticleDOI
On the eve of animal radiation: phylogeny, ecology and evolution of the Ediacara biota.
TL;DR: Ediacara fossils document an important evolutionary episode just before the Cambrian explosion and hold critical information about the early evolution of macroscopic and complex multicellular life.
Journal ArticleDOI
Modular Construction of Early Ediacaran Complex Life Forms
TL;DR: Newly discovered, exceptionally preserved, soft-bodied fossils near Spaniard's Bay in eastern Newfoundland exhibit features not previously described from Ediacaran (terminal Neoproterozoic) fossils.
Journal ArticleDOI
The Ediacaran Biotas in Space and Time
TL;DR: Parsimony analysis of endemism (PAEEE) has been used to classify Ediacaran organisms into three major groups: the Avalon, White Sea and Nama Assemblages as mentioned in this paper.
Journal ArticleDOI
The hidden biology of sponges and ctenophores
TL;DR: Key details of this new model hinge on a better understanding of the Porifera and Ctenophora, which have each been hypothesized to be sister to all other animals, but are poorly studied and often misrepresented.
References
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Journal ArticleDOI
Biostratigraphic and Geochronologic Constraints on Early Animal Evolution
TL;DR: For example, the authors showed that the most diverse assemblages of Ediacaran animals existed within 6 million years of the Precambrian-Cambrian boundary and that simple discoid animals may have appeared at least 50 million years earlier.
Journal ArticleDOI
Monophyletic origins of the metazoa: an evolutionary link with fungi
TL;DR: A phylogenetic framework inferred from comparisons of small subunit ribosomal RNA sequences describes the evolutionary origin and early branching patterns of the kingdom Animalia and shows the animal lineage is monophyletic and includes choanoflagellates.
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Microbial mats in terminal Proterozoic siliciclastics; Ediacaran death masks
TL;DR: A variety of sedimentary structures and patterns in Proterozoic siliciclastic sedimentary rocks cannot be explained by known inorganic processes as discussed by the authors, and they are demonstrably the mechanical products of microbially bound sediment and microbial mats.
Journal ArticleDOI
Calibrating rates of early Cambrian evolution.
Samuel A. Bowring,John P. Grotzinger,Clark E. Isachsen,Andrew H. Knoll,Shane M. Pelechaty,Peter Kolosov +5 more
TL;DR: Uranium-lead zircon data from lower Cambrian rocks located in northeast Siberia indicate that the Cambrian period began at approximately 544 million years ago and that its oldest (Manykaian) stage lasted no less than 10 million years.