rośliny-i-grzyby: Ediacaran biota

Evidence: 45 • authority: 72

The Ediacaran biota ( EE-dee-ACK-ər-ən; formerly Vendian) is a group of large, biologically complex, mostly soft-bodied organisms, which lived during the Ediacaran Period (c. 635–538.8 Mya). These were unusual tube and frond-shaped, mostly sessile, organisms. Three distinct assemblages of these organisms have been discovered, preserved as trace fossils in Ediacaran sandstone. They represent the earliest known complex multicellular organisms. The Ediacaran biota may have undergone evolutionary radiation in a proposed event called the Avalon explosion, 575 million years ago. This was after the Earth had thawed from the Cryogenian period's extensive glaciation. This biota largely disappeared w…

Evidence: 37 • authority: 92

Re-evaluating molecular clock maximum age calibrations revives pre-Ediacaran divergence estimates for animals.. Divergent models persist for the emergence of animals. Lipid biomarkers suggest animals originated before 635 million years ago (Ma), but their body fossil record extends to only 574 Ma. Molecular clocks might differentiate between these records, but we demonstrate how their accuracy and precision hinge on maximum age calibrations. We evaluate the Ediacaran Weng'an Biota (China) as a maximum calibration utilizing microfossils from the Kheseen Biota (Mongolia). These two biotas have similar preservation and microfossil assemblages, containing no definitive animals. The Kheseen Biot…

Evidence: 32 • authority: 72

The Maotianshan Shales (simplified Chinese: 帽天山页岩; traditional Chinese: 帽天山頁岩; pinyin: Màotiānshān yèyán) are a series of Early Cambrian sedimentary deposits in the Chiungchussu Formation or Heilinpu Formation, famous for their Konservat Lagerstätten, deposits known for the exceptional preservation of fossilized organisms or traces. The Maotianshan Shales form one of some 40 Cambrian fossil locations worldwide, exhibiting exquisite preservation of rarely preserved, non-mineralized soft tissue, comparable to the fossils of the Burgess Shale of British Columbia, Canada. They take their name from Maotianshan Hill (Chinese: 帽天山; pinyin: Màotiānshān; lit. 'Hat Sky Mountain') in Chengjiang County…

Evidence: 32 • authority: 92

Earliest evidence of behavioural handedness in the Ediacaran motile bilaterian Spriggina floundersi.. Fossils of the Ediacara Biota preserve the oldest macroscopic communities that include animals. Classification of many of these taxa has proved contentious. Instead, studies of ecological characters reveal key insights. Here we examine the Ediacaran fossil Spriggina floundersi from the Ediacara Member, Flinders Ranges and surrounding region. Specimens from Nilpena Ediacara National Park (NENP) and the South Australia Museum (SAM) present significant morphological variation. Fossils found in situ on discrete bedding planes at NENP reveal no systematic orientation of features, suggesting vari…

Evidence: 32 • authority: 72

The Ediacaran ( EE-dee-AK-ər-ən, ED-ee-) is a geological period of the Neoproterozoic Era that spans 96 million years from the end of the Cryogenian Period 635 million years ago to the beginning of the Cambrian Period 538.8 million years ago. It is the last period of the Proterozoic Eon as well as the last of the so-called "Precambrian supereon", before the beginning of the subsequent Cambrian Period marks the start of the Phanerozoic Eon, where recognizable fossil evidence of life becomes common. The Ediacaran Period is named after the Ediacara Hills of South Australia, where trace fossils of a diverse community of previously unrecognized lifeforms (later named the Ediacaran biota) were fi…

Evidence: 27 • authority: 72

The End-Ediacaran extinction, also called the Kotlin Crisis, is a mass extinction believed to have occurred near the end of the Ediacaran period, the final period of the Proterozoic eon. Evidence suggesting that such a mass extinction occurred includes a massive reduction in diversity of acritarchs, the sudden disappearance of the Ediacara biota and calcifying organisms, and the time gap before Cambrian organisms "replaced" them. Some lines of evidence suggests that there may have been two distinct pulses of the extinction event, one occurring 550 million years ago and the other 539 million years ago.

Evidence: 27 • authority: 92

Discovery of White Sea assemblage fossils from Laurentia.. The dawn of animal life is preserved by fossils of the Ediacara Biota, which have been separated into three biotic assemblages: the Avalon, White Sea, and Nama. Geographic and temporal isolation of these faunas leads to uncertainties regarding patterns of change. We report the discovery of unambiguous fossil communities belonging to the White Sea assemblage from the paleocontinent of Laurentia in the Blueflower Formation, Mackenzie Mountains, Canada. Unlike previous localities, sedimentological and geochronological evidence supports an older origin and deeper-water setting for this assemblage, including the oldest motile bilaterians…

Evidence: 25 • authority: 92

Polychaete annelids from the earliest Cambrian Period.. Unambiguous body fossils of annelids (ringed worms) first appear in the Cambrian Period but are so far known exclusively as flattened specimens preserved in Burgess Shale-type Lagerstätten. Here, we report phosphatized microfossils, interpreted as polychaete annelids, from a distinct taphonomic window (i.e., three-dimensional Orsten-type preservation) in the earliest Cambrian (early Fortunian Age, ca. 535 Ma) Zhangjiagou Lagerstätte of South China. The fossils are millimetric in length and preserved as three-dimensional endocasts of the body. They exhibit clear trunk segmentation, with each segment bearing a pair of lateral or ventrola…

Evidence: 21 • authority: 80

Newly-discovered Middle and Late Cambrian fossils from the Wagonga Beds of New South Wales, Australia

Evidence: 21 • authority: 88

Fossils of the Middle Cambrian Burgess Shale, British Columbia, Canada: distribution and biostratinomic change through time. Over 30 years of commercial hydrocarbon drilling exploration on the Canadian Atlantic Margin has provided the Geological Survey of Canada (GSC) with a priceless collection of micropaleontological samples and data from the thick Jurassic-Quaternary sedimentary wedge underlying our continental margin. This material has allowed a small cadre of GSC scientists and technicians to document and correlate, using standardized methods of preparation and study, the micropaleontological assemblages found in the offshore wells. There has also developed a better understanding of th…

Evidence: 21 • authority: 72

The Francevillian biota (Also referred to as Gabon macrofossils, Gabonionta or Francevillian group fossils) are a collection of 2.1-billion-year-old Palaeoproterozoic macroscopic structures, controversially suggested to be fossils, known from the Francevillian B Formation in Gabon, a black shale province notable for its lack of any noticeable metamorphism. The structures have been postulated by some authors to be evidence of the earliest form of multicellular life, and of eukaryotes. They were discovered by an international team led by Moroccan geologist Abderrazak El Albani, of the University of Poitiers, France. While they have yet to be assigned to a formal taxonomic position, they have…

Evidence: 21 • authority: 92

Uranium Isotope Evidence for Persistent Global Ocean Anoxia Across the Ediacaran-Cambrian Transition in Siberia.. The enigmatic Ediacara biota represents Earth's earliest example of macroscopic, complex life, yet the driving forces promoting their mid-Ediacaran evolution and subsequent extinction across the Ediacaran-Cambrian boundary remain speculative. If these were true animals requiring oxygen for aerobic respiration, their rise has often been linked to dramatic changes in the redox state of seawater. Their disappearance from the fossil record-whether gradual or abrupt-and replacement with Cambrian animals has similarly been linked to redox fluctuations, suggesting an environmental driv…