Journal ArticleDOI
Small Bilaterian Fossils from 40 to 55 Million Years Before the Cambrian
Jun-Yuan Chen,David J. Bottjer,Paola Oliveri,Stephen Q. Dornbos,Feng Gao,Seth Ruffins,Huimei Chi,Chia-Wei Li,Eric H. Davidson +8 more
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TLDR
Ten phosphatized specimens of a small animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, and provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.Abstract:
Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.read more
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U-Pb ages from the neoproterozoic Doushantuo Formation, China
TL;DR: U-Pb zircon dates from volcanic ash beds within the Doushantuo Formation (China) indicate that its deposition occurred between 635 and 551 million years ago, indicating synchronous deglaciation.
Journal ArticleDOI
The Cambrian conundrum: Early divergence and later ecological success in the early history of animals
Douglas H. Erwin,Douglas H. Erwin,Marc Laflamme,Sarah M. Tweedt,Sarah M. Tweedt,Erik A. Sperling,Davide Pisani,Kevin J. Peterson +7 more
TL;DR: A compilation of the patterns of fossil and molecular diversification, comparative developmental data, and information on ecological feeding strategies indicate that the major animal clades diverged many tens of millions of years before their first appearance in the fossil record.
Journal ArticleDOI
Paleontological Evidence to Date the Tree of Life
TL;DR: This work provides "hard" minimum and "soft" maximum age constraints for 30 divergences among key genome model organisms; these should contribute to better understanding of the dating of the animal tree of life.
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Bioturbation: a fresh look at Darwin's last idea
TL;DR: From an evolutionary perspective, recent investigations provide evidence that bioturbation had a key role in the evolution of metazoan life at the end of the Precambrian Era.
Journal ArticleDOI
The timing of eukaryotic evolution: Does a relaxed molecular clock reconcile proteins and fossils?
TL;DR: It is shown that, according to 95% credibility intervals, the eukaryotic kingdoms diversified 950-1,259 million years ago (Mya), animals diverged from choanoflagellates 761-957 Mya, and the debated age of the split between protostomes and deuterostomes occurred 642-761 Mya.
References
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Journal ArticleDOI
A Neoproterozoic Snowball Earth
TL;DR: Negative carbon isotope anomalies in carbonate rocks bracketing Neoproterozoic glacial deposits in Namibia, combined with estimates of thermal subsidence history, suggest that biological productivity in the surface ocean collapsed for millions of years.
Journal ArticleDOI
Evidence for a clade of nematodes, arthropods and other moulting animals.
Anna Marie A. Aguinaldo,James M. Turbeville,Lawrence S. Linford,Maria C. Rivera,James R. Garey,James R. Garey,Rudolf A. Raff,James A. Lake +7 more
TL;DR: The results suggest that ecdysis (moulting) arose once and support the idea of a new clade, Ecdysozoa, containing moulting animals: arthropods, tardigrades, onychophorans, nematodes, Nematomorphs, kinor-hynchs and priapulids.
Book
Genomic Regulatory Systems: Development and Evolution
TL;DR: Genomic Regulatory Systems: Development and Evolution hierarchisch: generelle Dinge wie anterior/posterior Ausrichtung zuerst, dann mehr und mehr Details "heart of pattern formation: regional specification".
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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.
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Neoproterozoic ‘snowball Earth’ simulations with a coupled climate/ice-sheet model
TL;DR: Computer simulations of this unusual climate stage with a coupled climate/ice-sheet model and a general circulation model result in an equatorial belt of open water that may have provided a refugium for multicellular animals.