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@ediacarans-blog
Australia needs more state fossil emblems, but let the public decide
New South Wales has joined Western Australia to become the second state or territory in Australia to have formally adopted a fossil emblem.
The 365-million-year-old Devonian fish Mandageria fairfaxi was last month announced as the state fossil emblem of NSW.
Read more...
Slippery customers
An excerpt from the article:
The Ediacarans are a mystery, not least because none of those known from fossils has any sign of a gut, or any other obvious way of feeding itself. But a study of Trichoplax, just published in PLOS One, by Carolyn Smith of the National Institute of Neurological Diseases and Stroke, in Bethesda, Maryland, and her colleagues, may explain how they did it.
Read more.
The article referenced: Coordinated Feeding Behavior in Trichoplax, an Animal without Synapses
See also: Dickinsonia from Ediacara: A new look at morphology and body construction
Palaeocast Episode 50: Rangeomorph Reproduction
On today’s episode we’re revisiting Mistaken Point, Newfoundland, Canada. At this lagerstätte it is possible to find large bedding planes full of Precambrian organisms called rangeomorphs. These are an enigmatic group, which still can’t be placed on the ‘tree of life’.
We are joined by Dr Emily Mitchell of the University of Cambridge, who’s recent paper in Nature was able to show that you don’t need to be able to fully understand the anatomy of an organism to discern some of its most intricate details.
Link to podcast.
Fractofusus: How Undersea Enigmas Reproduced Before the Dawn of Sex
by Brian Switek
Birds do it. Bees do it. And over 541 million years ago, weird organisms that looked like armored carpets did it. Exactly how they did so, though, was a bit different from the ways we’re familiar with.
University of Cambridge paleontologist Emily Mitchell and colleagues were the ones to reconstruct how these puzzling species reproduced. They focused on a species from the Ediacaran period called Fractofusus.
The fossil is a strange, branching frond preserved as flat impressions in the ancient sediment, but it’s so unlike anything alive today that scientists are still unsure whether it was an animal, a plant, or what. Nevertheless, by studying the geographic pattern of how these fossils are preserved across the rocks of Newfoundland, Canada, Mitchell and coauthors have been able to reconstruct how Fractofusus made more Fractofusus.
It wasn’t as simple as catching Fractofusus in The Act. This was still tens of millions before the earliest days of internal fertilization, after all. Rather, Mitchell and colleagues write, the clusters of Fractofusus are patterned in such a way that suggests they’re organized by reproductive factors rather than by currents or other environmental details…
(read more: National Geographic)
Art by C. G. Kenchington
Evidence that Earth's first mass extinction was caused by critters not catastrophe
The Earth's first mass extinction event 540 million years ago was caused not by a meteorite impact or volcanic super-eruption but by the rise of early animals that dramatically changed the prehistoric environment.
Read more of the press release.
Biotic replacement and mass extinction of the Ediacara biota
Abstract
The latest Neoproterozoic extinction of the Ediacara biota has been variously attributed to catastrophic removal by perturbations to global geochemical cycles, ‘biotic replacement’ by Cambrian-type ecosystem engineers, and a taphonomic artefact. We perform the first critical test of the ‘biotic replacement’ hypothesis using combined palaeoecological and geochemical data collected from the youngest Ediacaran strata in southern Namibia. We find that, even after accounting for a variety of potential sampling and taphonomic biases, the Ediacaran assemblage preserved at Farm Swartpunt has significantly lower genus richness than older assemblages. Geochemical and sedimentological analyses confirm an oxygenated and non-restricted palaeoenvironment for fossil-bearing sediments, thus suggesting that oxygen stress and/or hypersalinity are unlikely to be responsible for the low diversity of communities preserved at Swartpunt. These combined analyses suggest depauperate communities characterized the latest Ediacaran and provide the first quantitative support for the biotic replacement model for the end of the Ediacara biota. Although more sites (especially those recording different palaeoenvironments) are undoubtedly needed, this study provides the first quantitative palaeoecological evidence to suggest that evolutionary innovation, ecosystem engineering and biological interactions may have ultimately caused the first mass extinction of complex life.
The paper.
Tribrachidium are one of the very amazing representatives of ediacaran fauna, they had lived approximately 560-550 million years ago. They had triradial symmetry as convex structures that radially diverge from the center to the edges under equal angle. It is believed that tribrachidium had bottom and passive lifestyles; also they might been fixed animals. Presumably they belonged to either cnidaria or echinodermata.
Keep reading
“Ediacarans #1” (2014) - 16"x20" For sale - $400 (s/h included) An homage to the Ediacaran fauna of prehistoric Australia, fossils so bizarre they appear to have no relationship to any living creatures and may have emerged as a completely independent attempt at multicellular life possibly unrelated to animals or plants. One of ancient life’s great mysteries…
The Eoandromeda octobrachiata (2008)
Kingdom : incertae sedis Genus : Enandromeda Species : E. octobrachiata
Ediacaran (580 - 550 Ma)
4 cm wide (size)
Doushantuo formation, China (map)
A few dozen fossil specimens are known, ranging from about 1 to 4 cm in diameter; they are circular in outline and their eight arms, with closed ends, spiral either clockwise or counterclockwise. Ridges cut across both the inside and outside of the spiral arms. The arms of the Australian individuals are longer and more tightly coiled than those of the Chinese, despite the Australian individuals not attaining as large a diameter; they are more often kinked.
The organism was first interpreted as a trace fossil, and has also been considered to represent an agglutinating foraminiferan. However, the discovery of the Chinese fossils, which have preserved organic matter, ruled out these interpretations, because the Burgess shale type preservation displayed required relatively robust organic material to start with. Its spiral form has also led to comparison with the fossil embryos also preserved in the Doushantuo formation; the jury will remain out on this verdict until intermediate forms are found.
The organism bears a very superficial resemblance to echinoderms, ctenophores and to some of the other Ediacara biota, but it lacks sufficient physical characteristics to ascertain with any degree of certainty whether it is indeed an animal or not. If it is, it would be the earliest known fossil of an adult animal; and its anatomy is consistent with that expected from the earliest animals. However, it is not perfectly clear that it is an animal; algae, the dominant constituent of the Doushantuo biota, cannot be ruled out, except that Eoandromeda seems a little too complex.
Millions of Years Ago the Earth Was Covered in Ice
Welcome to “Snowball Earth”
700 million years ago, the earth was encased in a sheet of ice up to 3 kilometres thick. Good job there was only plankton around to endure it
These days, if you want to see a glacier near the equator, you must scale the rarefied heights of Mount Kenya or the Ecuadorian Andes. Around 700 million years ago it was a bit less of an effort. In fact, you’d struggle to find somewhere that wasn’t frozen over.
You’ve arrived in the middle of the Cryogenian period, so called because the planet was repeatedly sheathed in ice in a series of “snowball Earth” episodes. The greatest of these Cryogenian snowballs, the Sturtian glaciation, began 716.5 million years ago. In the space of a few years, land and sea across the globe were swallowed up by sheets of ice that eventually became kilometres thick.
Find out more here: BBC - Snowball Earth
(via: New Scientist)
Image: John Eastcott and Yva Momatiuk/National Geographic Creative
Folded and warped
These sedimentary rocks in the southern Australian outback date from the latest Precambrian, and were deposited some 540 million years ago in a basin, before being uplifted into a mountain range and eroded into soft hills. The region is known as the Adelaide Rift Complex (or to use an older, now mostly abandoned, vocabulary geosyncline) and flows from the flinders ranges, through the Fleurieu Peninsula (of wine growing terroir fame) southwards to Kangaroo Island.
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Amelia Penny is a second-year PhD student at the University of Edinburgh’s School of GeoSciences. She is working on the palaeoecology of early calcified animals in the Nama Group, and redox conditions across the Precambrian-Cambrian boundary. She occasionally blogs at Life in Deep Time about geology, deep time and science in general.
This illustration shows, on the left, the Ediacaran fauna, mostly sessile and filter feeding, contrasting with the explosion of Mid Cambrian Burgess Shale life forms on the right, like Anomalocaris, Hallucigenia, and Pikaia, with their novel body plans, armor and anatomical inventions enabling predation.
‘Aliens of sea’ provide new insight into evolution
Exotic sea creatures called comb jellies may reshape how scientists view early evolution—as their genes suggest nature created more than one way to make a nervous system. Read more at: http://phys.org/news/2014-05-aliens-sea-insight-evolution.html#jCp
Have to make a presentation tomorrow about these guys wish me luck bye
Good luck!
Ediacaran Fossils
When the cod fishery collapsed in Newfoundland in the early 1990s, the hopes of the local fish harvesters collapsed with it. Hundreds of Newfoundlanders moved away and businesses that depended on the cod fishery closed. But retired schoolteacher Kit Ward of Portugal Cove South wasn’t content to watch her community vanish with the cod. She and some friends teamed up to find a solution that was right under their feet, in the reddish rocks of Mistaken Point: http://theterramarproject.org/thedailycatch/ediacaran-fossils/
Earth at 550 million years ago
This was just before the onset of the so-called Cambrian Explosion (figure is depicting breakup of conjectured super-continent Pannotia), THE first major radiation of macroscopic metazoans (animals).
Perhaps an even more effective way of grasping our extreme recentness as a part of this 4.5-billion-year-old picture is to stretch your arms to their fullest extent and imagine that width as the entire history of the Earth. On this scale, according to John McPhee in Basin and Range, the distance from the fingertips of one hand to the wrist of the other is Precambrian. All of complex life is in one hand, ‘and in a single stroke with a medium-grained nail file you could eradicate human history
Bill Bryson (via solid-gold-satellites)
Mechanics drove selection of similar fins in early evolution of marine vertebrates
Similar traits not present in a last common ancestor are often the basis for constructing phylogenetic trees like the one seen above, but convergent evolution can foil the effort. Just published research in PLOS Biology on a group of like-finned, swimming vertebrates concludes that their refined propulsion mechanics likely evolved independently eight different times (convergent evolution). What a nice example how evolution by means of natural selection of favorable traits can be so powerful, and how new millennia scientists still learn by observed evidence the way Charles Darwin did. Note the time scale on the y-axis of the phylogentic tree that begins with the emergence of bilaterans during the Ediacaran more than 550 million years ago; Kimberella (shown in the lower image above) is the earliest undisputed bilateran fossil from this time.
But Kimberella is disputed.
