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Topic: Dickinsonia

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	Dickinsonia
		Dickinsonia is an ancient ovoid fossil with somewhat radial tubes from a (sometimes missing) central ridge.
		Dickinsonia is known from neoproterozoic beds in both the Alice Springs and Ediacara regions of Australia, as well as Rajastan, Podolia, and the White Sea region of Russia.
		Dickinsonia is generally regarded as a member of the Vendazoa -- a group of somewhat obscure animals that thrived just before most of the modern multicellular animal phyla appeared.
	www.sciencedaily.com /encyclopedia/dickinsonia (264 words)

	DEATH, DECAY AND DESTRUCTION OF DICKINSONIA (Site not responding. Last check: 2007-10-05)
		Dickinsonia is the iconic Ediacaran fossil, a characteristic late Precambrian megafossil of South Australia and the Russian White Sea.
		Dickinsonia has been compared with annelid worms, jellyfish, scleractinian corals, or extinct Vendobionta, and the unusual preservation of such a soft-bodied creature in quartz sandstones attributed to a late Precambrian regime of decay different from that of today.
		Dickinsonia was thin and ground hugging, as it did not disrupt overlying cross-bedding.
	gsa.confex.com /gsa/2004AM/finalprogram/abstract_73713.htm (454 words)

	Name: Ediacara Assemblage
		However superficially similar, close study revealed that Dickinsonia is bilaterally symmetrical across the body and asymmetrical down the middle, while Phyllozoon is asymmetrical in both directions.
		Dickinsonia grew continuously by the addition of tiny new segments to what was believed to be its posterior, as the whole organism grew, the new segments similarly increased in size.
		Furthermore a rare specimen of Dickinsonia appears not to have Seilacher's diagnostic mattress design (although as a rare occurrence the alternative morphology could be a relict of diagenesis).
	palaeo.gly.bris.ac.uk /Palaeofiles/Lagerstatten/Ediacara/flora%20and%20fauna.htm (971 words)

	Precambrian perambulations (Site not responding. Last check: 2007-10-05)
		The youngest Precambrian beds are exposed in a rugged part of the Heysen Range, and the steep walls are due to outcrops of a shallow-water white quartzite known as the Rawnsley Quartzite.
		The Dickinsonia (left) were found in near-shore, shallow water sequences, and a time-frame very close to the recognised boundary of the Cambrian.
		In this way the mats protected them from outright destruction in times of storm surge, and, although they were soft-bodied, they were frequently buried beneath sand horizons ultimately to be preserved on the underside of beds, such as those in the Brachina Gorge.
	www.heysentrail.asn.au /precamperam.html (1643 words)

	Dictionary of Meaning www.mauspfeil.net
		Dickinsonia is generally regarded as a member of the Vendazoa -- a group of somewhat obscure animals that thrived just before most of the modern multicellular animal phylum phyla appeared.
		Another Vendazoa vendazoan known as Marywadea somewhat resembles Dickinsonia and may be related.
		There you find a list of all editors and the possibility to edit the original text of the article Dickinsonia.
	www.mauspfeil.net /Dickinsonia.html (264 words)

	Scientists have long puzzled over how to classify Ediacarans (Site not responding. Last check: 2007-10-05)
		Scientists have long puzzled over how to classify Ediacarans, little floppy sea creatures that lived about 600 million years ago, because the only evidence they left are impressions in sandstone.
		Now two paleontologists, Kenneth Schopf of Harvard and Tomasz Baumiller of the University of Michigan, Ann Arbor, have done a novel modeling experiment that they believe will help with Ediacaran taxonomy by showing that at least one type, the flat, oval-shaped Dickinsonia, may not have lived on the seabed surface, as is generally supposed.
		Soren Jensen of Cambridge University says modeling Ediacarans in gel has "great potential"--but he still favors a scenario that places Dickinsonia in quiet locales where sticky microbial mats helped them adhere to the seabed.
	cas.bellarmine.edu /tietjen/images/scientists_have_long_puzzled_ove.htm (216 words)

	Brainstorms: Rabbits in the Precambrian -- Is Darwinism Criticizable?
		For example, why can't one argue that Dickinsonia being at least potentially a bilaterally symmetric, segmented "critter", but basically the most primitive one in the fossil record, is a point for evolutionary biology, in that it indicates that (very primitive) bilaterans existed before the Cambrian explosion?
		I have to leave this thread momentarily because of needing to prepare for an upcoming lecture at Andrews University.
		Furthermore, the issue isn't where Dickinsonia lands on the metric (relative to Bugs), but whether we have a natural pathway to the one critter, where we would lack it for the other (i.e., if Bugs were actually to turn up in the Precambrian).
	www.iscid.org /boards/ubb-get_topic-f-6-t-000012.html (3339 words)

	Northern Calcareous Alps (Site not responding. Last check: 2007-10-05)
		On one hand computer science may provide a reliable tool to investigate aspects of morphology and ecology of a fossil organism, which cannot be gained by the fossil record.
		To keep the artificial model simple Dickinsonia costata, a member of the Precambrian Ediacaran biota, was chosen as template for the evolution of parts of the external morphology of a fossil species.
		In the field of paleontology and computer science further applications of the herein proposed artificial evolutionary system are conceivable like investigations on phenotypic plasticity, simulating locomo-tion of extinct organisms (and therefore a possible linking of fossil traces and its originator), new ap-proaches in development and control of modular robots.
	www.palinst.unizh.ch /schatz/research/Dickinsonia.html (619 words)

	Mawsonites Dickensonia Charniodiscus Kimberella Vendian Ediacara (Site not responding. Last check: 2007-10-05)
		Dickensonia fossils are found around the world, and it surely was a major player in the early history of multicellular life.
		Dickinsonia is known from Vendian rocks of south Australia and north Russia.
		It is often considered to be a segmented worm.
	www.dinosaurcollector.150m.com /edicara.htm (513 words)

	sgoldberg2
		This is Dickinsonia, the fossil that lead Sprig to believe he was dealing with something more than plants and gas bubbles.
		Frond shaped fossils such as this Pteridinium were thought to be ancestors of the sea pens, a relative of sea anemones (image thanks to www.shef.ac.uk).
		Dickinsonia (which we saw above) was thought to be an annelid, a segmented worm because of its resemblance to Spinther (image thanks to njussien.e-constraints.net/ familles-dessins.html).
	www.earth.rochester.edu /ees207/Goldberg/sgoldberg2.html (668 words)

	VOYAGE TO THE BOTTOM OF THE EDIACARAN SEA: WHAT’S MISSING FROM THE PICTURE? (Site not responding. Last check: 2007-10-05)
		The size-frequency plot for Aspidella is consistent with a single population.
		Bed 3 is dominated by Dickinsonia but includes other taxa such as Spriggina, Parvancorina, Tribrachidium and Rugoconites.
		Bed 4 has abundant distinctive problematic “mop-like” structures (possibly a form of actinian) that are commonly associated with disks, referred to as Aspidella and Eoporpita, as well as a very large frond attached to a holdfast.
	gsa.confex.com /gsa/2003AM/finalprogram/abstract_67566.htm (453 words)

	Dzik publications
		The rhynchocoel of the nemerteans and (at least) the most anterior dorsal chamber of Dickinsonia may appear thus homologous, which is consistent with the idea of its homology with the notochord and myocoel of the chordates.
		The phosphatic elements of the westergaardodinid ‘paraconodont’ apparatuses seem to represent a stage in the development of mineral skeleton transitional between nemertean stylets and conodont elements.
		Dickinsonia, Odontogriphus, Yunnanozoon, and Pikaia may thus represent a developmental series, from muscular dorsal chambers to the organization of myomeres typical for all later chordates (Fig.
	www.paleo.pan.pl /people/Dzik/Dzik2000a.htm (658 words)

	Dickinsonia
		It is often considered to be an annelid worm because of its apparent similarity to one genus of extant polychaete, Spinther.
		The specimen pictured above is an adult one from the Ediacara Hills of southern Australia.
		We also have a picture of a young Dickinsonia costata from the Winter Coast of the White Sea, in the collections of the Paleontological Institute of the Russian Academy of Sciences in Moscow.
	www.ucmp.berkeley.edu /vendian/dickinsonia.html (112 words)

	Dzik publications (Site not responding. Last check: 2007-10-05)
		Dickinsonia tenuis group from a recently discovered fossiliferous horizon at the White Sea shore, Russia, exquisitely preserved in fine sediment, offers the needed anatomical evidence.
		In several specimens which show the originally high convexity of the body, the dorsal segmented unit (normally being the only preserved structure in the dickinsoniids) was specifically deformed under the sudden sediment load.
		A pharyngeal structure is represented by a circular imprint and the intestine by a wide axial furrow.
	www.paleo.pan.pl /people/Dzik/Dzik2002b.htm (182 words)

	Vendian World (Site not responding. Last check: 2007-10-05)
		Dickinsonia is one of these deceptively simple creatures.
		Some scientists have even suggested Dickinsonia was some sort of lichen, but no definitive answer has emerged.
		Another creature, called Spriggina, may be the oldest ancestor of the arthropods and thus may be the greatest grandmother of all insects, crabs, trilobites and other related beasts.
	members.aol.com /ncanvas2/NCWeb/Articles/Venworld.html (600 words)

	Windermeria aitkeni, Northwest Territories, Canada (Site not responding. Last check: 2007-10-05)
		Windermeria is a segmented fossil similar to the famous fossil Dickinsonia from Australia.
		Dickinsonia reaches sizes up to a metre in length, but Windermeria is much smaller (only about 2cm long).
		Some scientists think these are fossil worms,but others view them as a failed experiment unrelated to any modern animal.
	geol.queensu.ca /museum/exhibits/ediac/winder.html (62 words)

	Vendian biota - Wikipedia, the free encyclopedia
		Several supposed Vendian-like forms have been identified from the Cambrian, however many of these have since been redescribed as trace fossils or pseudofossils.
		Well known Vendian forms include Arkarua, Charnia, Dickinsonia, Ediacaria, Marywadea, Onegia, Yorgia and Pteridinium.
		The full list runs to 100 or more taxa.
	en.wikipedia.org /wiki/Vendian_Biota (421 words)

	Pteridinium - Wikipedia, the free encyclopedia
		Its relation to other known Vendazoa is no clearer.
		There are no identified related forms, although there is some vague resemblance to other Vendian forms such as Dickinsonia that share some of its enigmatic characteristics.
		Pternidium has no known descedants other than possibly an enigmatic Cambrian form known as Emmonaspis.
	en.wikipedia.org /wiki/Pteridinium (306 words)

	The Ediacaran Assemblage
		In some specimens of Dickinsonia, the segments do not appear to correspond across the mid-line on the dorsal surface.
		However, as noted in Gehling 1991 (though the original observation is attributed to Bruce Runnegar), in all specimens where the ventral side is preferentially preserved, segments clearly continue across the mid-line, so offset on the dorsal side must be a product of flattening.
		It is only in rare specimens of Dickinsonia elongata that the alternate insertion and overlap of segments along the mid line is difficult to explain.
	www.peripatus.gen.nz /paleontology/Ediacara.html (7477 words)

	Precambrian HSU NHM
		Among the best known and common impressions of animals thought to represent bilateria are the fossils of Dickinsonia.
		The Dickinsonia varied greatly in size, from small coin-sized to doormat sized.
		The original ink drawing by Rachel Rogge at the left is an artists representation of a living Dickinsonia commissioned by the museum (©2002 HSU NHM).
	www.humboldt.edu /~natmus/lifeThroughTime/PreCam.web/index.htm (3087 words)

	k14 Ediacaran fossils (Site not responding. Last check: 2007-10-05)
		To gain an insight into how current may have affected Dickinsonia if, in life, it lay bathmat-like on a seafloor of fine sand, Kenneth M. Schopf and Tomasz K. Baumiller have, in 1998, fashioned two Dickinsonia models, one using latex molds and the other employing plastic bags filled with solutions of Karo syrup.
		They observed how at densities from a value equal to that of water to a much meatier substance these fared in a tank with a moving current of water.
		Not to be, Dickinsonia, as modeled, was either denser than paleontologists previously suspected, or the organism was held down by the mats of microbes that covered the ocean bottom at the time.
	www.geowords.com /histbooknetscape/k14.htm (1246 words)

	DAAC Study: Breakup of the Ward Hunt Ice Shelf
		Among the changes in the Northern Hemisphere that Serreze has recently reported are earlier spring breakups of river ice, increased freshwater runoff, shrinking glaciers, and trees and shrubs invading Arctic tundra.
		One of the oldest fossils of multicelluar oganisms is Dickinsonia.
		Estimated at 560 million years old, Dickinsonia may have evolved after the end of the last Neoproterozoic global glaciation.
	earthobservatory.nasa.gov /Study/wardhunt (2183 words)

	Pharyngula: Precambrian chordate (Site not responding. Last check: 2007-10-05)
		The cool thing about it is that it was found in the Flinders Range of Australia, a place with very old rocks, about 560 million years old; that makes it Vendian, or pre-Cambrian.
		I'd heard of Flinders Range fossils before, as they contain some of the classic pre-Cambrian fauna, like Dickinsonia.
		This is good to see, but it's actually not unexpected that chordates or some closely related pre-chordate animals would have existed before the Cambrian explosion.
	www.pharyngula.org /comments/A105_0_1_0_C (306 words)

	[No title]
		Rare and unique fossils from the Flinders Ranges area are showcased in this new and evolving gallery.
		the Ripples of Time, a fossil seafloor displayed as a wall preserving hundreds of tiny specimens of Dickinsonia.
		the largest known fossil animal of its time, a doormat-sized specimen of Dickinsonia rex - truly the king of early marine animals, 550 million years old.
	www.samuseum.sa.gov.au /page/default.asp?site=1&page=529&id=529 (273 words)

	My Favorite Fossls (Site not responding. Last check: 2007-10-05)
		All photos can be seen in greater detail when you click on the image.
		Large vendobiont, Dickinsonia costata, from Late Precambrian Ediacara Member of the Rawnsley Quartzite in Brachina Gorge, Flinders Ranges, South Australia.
		Many of these enigmatic fossils make too good an impression in deeply buried quartzites to have been soft bodied animals.
	darkwing.uoregon.edu /~dogsci/retall/fossils.html (623 words)

	Arkarua (Site not responding. Last check: 2007-10-05)
		The name "Arkarua" comes from a mythical giant snake of the Aboriginal peoples who live where the fossil was discovered -- the Flinders Ranges of south Australia, near Adelaide.
		Arkarua occurs alongside Dickinsonia, Tribrachidium, Cyclomedusa, and other familiar Ediacaran animals as well as many new and as yet undescribed species.
		The image of Arkarua shown above was taken from the holotype specimen.
	www.ucmp.berkeley.edu /vendian/arkarua.html (263 words)

	VI The Cambrian explosion
		These structures made it possible at these organisms to absorb oxygen, by epithelial diffusion, with weak concentrations of about 0,07 PO2 P.A.L. (Rudolf, Elizabeth Raff).
		Organisms with flattened forms like the marine worm Dickinsonia (1 m length for a maximum thickness of 6 mm) could have taken enough oxygen at rates between 0,06 and 0,10 PO2 P.A.L. (Bruce Runnegar 1982).
		This rate also allows the collagen production necessary to the conjunctive tissue constitution (Towe 1970).
	www.ifrance.com /dinosaurs/sixthecambrianexplosion.htm (2953 words)

	The Cambrian Explosion Remains an Enigma for Organic Evolution
		These organisms, from the so- called Ediacaran fauna, named after the town of Ediacara in southern Australia where their fossil remains were discovered in 1947, are said to be 600 million years old.
		Figure 1 shows one well-known Ediacaran form, Dickinsonia.
		Now a novel interpretation of these puzzling fossils is generating considerable controversy within the paleontological community.
	www.rae.org /cambrian.html (589 words)

	Ediacaran Animals
		There is a graceless and careless comment in Science from Martin Brasier's group in Oxford.
		They accept Narbonne's analysis without praising it, and say without discussion that it also applies to later Ediacaran animals that look like Dickinsonia.
		Then they go into a riff about the potential value of heterochrony to unravel the real truth about these modular Ediacarans.
	www.geology.ucdavis.edu /~cowen/HistoryofLife/ediacarans.html (679 words)

	research (Site not responding. Last check: 2007-10-05)
		A joint project between the Paleontological Institute and Museum of the University of Zurich (Switzerland), the Geological Institute of the Tadjik Academy of Science (Dushanbe, Tadjikistan), the Geological Faculty of St. Petersburg State University (Russia), and the Department of Earth Sciences of the ETH Zurich
		Combining Genetical, Developmental, and Evolutionary Processes in an Artificial System to Evolve the Morphology of the Precambrian Dickinsonia costata
		A joint project between the Department of Informatics of the University of Zurich (Switzerland) and the Paleontological Institute and Museum of the University of Zurich (Switzerland)
	www.palinst.unizh.ch /schatz/research/index.html (144 words)

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