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Parvancorina
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Life in the Precambrian may have been much livelier than previously thought

The Garden of the Ediacaran was a period in the ancient past when Earth's shallow seas were populated with a bewildering variety of enigmatic, soft-bodied creatures. Scientists have pictured it as a tranquil, almost idyllic interlude that lasted from 635 to 540 million years ago. But a new interdisciplinary study suggests that the organisms living at the time may have been much more dynamic than experts have thought.
The new findings concern one of the most enigmatic of the Ediacaran genera, a penny-sized organism called Parvancorina, which is characterised by a series of ridges on its back that form the shape of a tiny anchor. By analysing the way in which water flows around Parvancorina's body, an international team of researchers has concluded that these ancient creatures must have been mobile: specifically, they must have had the ability to orient themselves to face into the current flowing around them. That would make them the oldest species known to possess this capability, which scientists call rheotaxis.

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Earth's first ecosystems were more complex than previously thought, study finds

The international team of researchers from Canada, the UK and the USA, including Dr Imran Rahman from the University of Bristol, studied fossils of an extinct organism called Tribrachidium, which lived in the oceans some 555 million years ago. Using a computer modelling approach called computational fluid dynamics, they were able to show that Tribrachidium fed by collecting particles suspended in water. This is called suspension feeding and it had not previously been documented in organisms from this period of time.
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A Lost Way of Making Bodies Before Skeletons and Shells

The rangeomorphs were part of the so-called Ediacaran biota that lived between 540 and 575 million years ago. There's nothing like them now. They died off completely during the Cambrian Explosion - the event when most of the major living animal groups seemingly exploded into existence. If you condense Earth's history into a single calendar year, the rangeomorphs would appear on the 15th of November before disappearing on the 18th, during the Cambrian Explosion.
There's a lot of disagreement about what they were. Most scientists would agree that they were composed of many cells. Some have described them as algae, fungi, lichens, or an entirely different kingdom of life. The most popular guess is that they were early animals, or closely related to us. Whatever the case, they had a very basic body plan with no obvious no traces of organs or internal structures.

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Were Weirdo Ediacarans Really Lichens, Fungi, and Slime Molds?

Yesterday, Nature published an article by Retallack that makes a radical claim: the Ediacaran Biota (635-542 mya) of bizarre creatures that preceded the Cambrian Explosion were not pneumatic semi-mobile marine animals, but instead sessile land-dwelling lichens and protists living high and very much dry on land.
For those of us raised on pictures and dioramas of puffy Ediacaran animals ensconced happily on the seafloor, this is a bit of a shocker.

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Flinders Ranges fossils
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NASA taps fossils for ET clues

Australia's ancient fossil sites revealing the dawn of life are helping NASA scientists in their quest to find extraterrestrial life on Mars.
The US space agency is funding work at an Ediacaran fossil site in South Australia's Flinders Ranges to help it identify what the earliest signs of life look like.

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Ash fall preserved 'nursery' of earliest animals

A volcanic eruption around 579 million years ago buried a 'nursery' of the earliest-known animals under a Pompeii-like deluge of ash, preserving them as fossils in rocks in Newfoundland, new research suggests.
A team from the Universities of Oxford and Cambridge, in collaboration with the Memorial University of Newfoundland, looked for evidence of life from the mysterious Ediacaran period (635-542 million years ago) in which the first 'animals' - complex multicellular organisms - appeared.
The team discovered over 100 fossils of what are believed to be 'baby' rangeomorphs; bizarre frond-shaped organisms which lived 580-550 million years ago and superficially resemble sea-pen corals but, on closer inspection, are unlike any creature alive today. This 'nursery' of baby rangeomorphs was found in rocks at the Mistaken Point Ecological Reserve in Newfoundland, Canada.

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Coronacollina acula
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Oldest Organism With Skeleton Discovered in Australia

A team of paleontologists has discovered the oldest animal with a skeleton. Called Coronacollina acula, the organism is between 560 million and 550 million years old, which places it in the Ediacaran period, before the explosion of life and diversification of organisms took place on Earth in the Cambrian.
The finding provides insight into the evolution of life - particularly, early life - on the planet, why animals go extinct, and how organisms respond to environmental changes. The discovery also can help scientists recognize life elsewhere in the universe.
The Ediacaran Period, named after the Ediacara Hills of South Australia, ranges 630-542 million years ago. The Cambrian Period, marked by a rapid diversification of life-forms on Earth as well as the rise of mineralised organisms, ranges 542-488 million years ago.

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550 million years ago rise in Oxygen drove evolution of animal life

Researchers funded by the Biotechnology and Biological Sciences Research Council (BBSRC) at the University of Oxford have uncovered a clue that may help to explain why the earliest evidence of complex multicellular animal life appears around 550 million years ago, when atmospheric oxygen levels on the planet rose sharply from 3% to their modern day level of 21%.
The team, led by Professor Chris Schofield, has found that humans share a method of sensing oxygen with the world's simplest known living animal - Trichoplax adhaerens - suggesting the method has been around since the first animals emerged around 550 million years ago.
This discovery, published today (17 December) in the January 2011 edition of EMBO Reports, throws light on how humans sense oxygen and how oxygen levels drove the very earliest stages of animal evolution.

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Title: The hypoxia-inducible transcription factor pathway regulates oxygen sensing in the simplest animal, Trichoplax adhaerens
Authors: Christoph Loenarz, Mathew L Coleman, Anna Boleininger, Bernd Schierwater, Peter W H Holland, Peter J Ratcliffe and Christopher J Schofield

The hypoxic response in humans is mediated by the hypoxia-inducible transcription factor (HIF), for which prolyl hydroxylases (PHDs) act as oxygen-sensing components. The evolutionary origins of the HIF system have been previously unclear. We demonstrate a functional HIF system in the simplest animal, Trichoplax adhaerens: HIF targets in T. adhaerens include glycolytic and metabolic enzymes, suggesting a role for HIF in the adaptation of basal multicellular animals to fluctuating oxygen levels. Characterization of the T. adhaerens PHDs and cross-species complementation assays reveal a conserved oxygen-sensing mechanism. Cross-genomic analyses rationalize the relative importance of HIF system components, and imply that the HIF system is likely to be present in all animals, but is unique to this kingdom.

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Iceblocks Hold Traces of Early Life

The discovery of blocks of gravel which sank to the bottom of the sea trapped in ancient icebergs has sparked a new understanding of a bizarre group of creatures.
The research, published in the Australian Journal of Earth Sciences, has also forced a rethink of the conditions that existed more than 500 million years ago.
Associate Professor Victor Gostin and colleagues at the University of Adelaide found evidence of ancient icebergs mixed in with volcanic rocks which were spewed out when an asteroid hit the earth between 635-542 million years ago.
The 4.7-kilometer asteroid left a 90-kilometer crater in what is now Lake Acraman in the Gawler Ranges of South Australia.

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Title: Ediacaran ice-rafting and coeval asteroid impact, South Australia: insights into the terminal Proterozoic environment
Authors: V. A. Gostina; D. M. McKirdya; L. J. Webstera; G. E. Williamsa

Isolated quartzose pebbles, clusters of quartz granules, orthogonal aggregates of poorly sorted quartzose coarse sand, and ovoid pellets (<2 mm long) of quartz silt occur in hemipelagic marine mudstone of the mid-Ediacaran Bunyeroo Formation exposed in the Adelaide Geosyncline (Adelaide Rift Complex), and ovoid pellets of quartz silt in cores of the correlative marine Dey Dey Mudstone from deep drillholes in the Officer Basin, South Australia. This detritus is interpreted respectively as dropstones, dumps, and frozen aggregates dispersed by sea ice possibly of seasonal origin, and till pellets transported by glacial ice. The ice-rafted material in the Bunyeroo Formation only has been found <10 m stratigraphically below and above a horizon of dacitic ejecta related to the 90 km diameter Acraman impact structure in the Mesoproterozoic Gawler Range Volcanics 300 km to the west. Furthermore, till pellets have been identified 4.4 to 68 m below distal Acraman ejecta in the Dey Dey Mudstone >500 km northwest of the impact site. The Acraman impact took place at a low paleolatitude (~12.5) and would have adversely affected the global environment. The stratigraphic observations imply, however, that the impact occurred during, but did not trigger, a cold interval marked by sea ice and glacial ice, although the temporal relationship with Ediacaran glaciations elsewhere in Australia and on other continents is unclear. Release from the combined environmental stresses of a frigid, glacial climate near sea-level and a major impact in low latitudes may have been a factor influencing subsequent Ediacaran biotic evolution.

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