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Topic: Arkarua

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	Arkarua
		Arkarua is a small precambrian disk like fossil with a raised center, a number of radial ridges on the rim, and a five pointed central depression marked with radial lines of 5 small dots from the middle of the disk center.
		Arkarua is known only from the Ediacaran beds of South Australia.
		McMenamin/Sielacher have proposed 'Arkarua' as a conventional main line member of the Vendazoa with five fold symmetry and non-iterated cell families.
	www.ebroadcast.com.au /lookup/encyclopedia/ar/Arkarua.html (181 words)

	Arkarua - EvoWiki
		Arkarua is known only from the Ediacaran beds of the Flinders Ranges in South Australia.
		McMenamin/Sielacher have proposed Arkarua as a conventional mainline member of the Vendazoa, with five fold symmetry and non-iterated cell families.
		Vendian animals: Arkarua from the Ediacara Hills of Australia, from the University of California Berkeley Museum of Paleontology.
	wiki.cotch.net /index.php/Arkarua (314 words)

	arkarua (Site not responding. Last check: 2007-10-17)
		Arkarua is a small precambrian disk like fossil with a raised center, a number of radial ridges on the rim, and a five pointed central depression marked with radial lines of 5 small dots from the middle of the disk center.
		Arkarua is known only from the Ediacaran beds of South Australia.
		McMenamin/Sielacher have proposed 'Arkarua' as a conventional main line member of the Vendazoa with five fold symmetry and non-iterated cell families.
	www.yourencyclopedia.net /arkarua.html (244 words)

	Palaeos Invertebrates: Deuterostomia: Ambulacraria
		Arkarua adami is a small disc-shaped fossil, about 3 to 10 mm across, known from the Ediacaran of the Flinders Ranges in Australia (UCMP).
		All known examples are external moulds with a five-lobed central region that led to its identification as the earliest echinoderm.
		Arkarua is therefore not here accepted as a deuterostome, and is more likely a cnidarian-grade animal or possibly even an alga.
	www.palaeos.com /Invertebrates/Deuterostomia/Ambulacraria.html (1844 words)

	Arkarua -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-17)
		Because of the five-fold ((mathematics) an attribute of a shape or relation; exact correspondence of form on opposite sides of a dividing line or plane) symmetry, Arkarua has been proposed as a possible precursor to the (Marine invertebrates with tube feet and calcite-covered five-part radially symmetrical bodies) Echinoderms.
		Arkarua is known only from the (Click link for more info and facts about Ediacaran) Ediacaran beds of South (A nation occupying the whole of the Australian continent; aboriginal tribes are thought to have migrated from southeastern Asia 20,000 years ago; first Europeans were British convicts sent there as a penal colony) Australia.
		McMenamin/Sielacher have proposed Arkarua as a conventional mainline member of the (Click link for more info and facts about Vendazoa) Vendazoa, with five fold symmetry and non-iterated cell families.
	www.absoluteastronomy.com /encyclopedia/a/ar/arkarua.htm (236 words)

	Arkarua (Site not responding. Last check: 2007-10-17)
		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 is a small disc-like fossil, and was described as an echinoderm.
		Fossils of Arkarua: Impressions of Arkarua are usually 3 to 10 mm across, so they are not easily seen with the naked eye.
	www.ucmp.berkeley.edu /vendian/arkarua.html (265 words)

	Read about Arkarua at WorldVillage Encyclopedia. Research Arkarua and learn about Arkarua here! (Site not responding. Last check: 2007-10-17)
		Because of the five-fold symmetry, Arkarua has been proposed as a possible precursor to the Echinoderms.
		Arkarua is known only from the Ediacaran beds of South
		Vendian animals: Arkarua from the Ediacara Hills of Australia (http://www.ucmp.berkeley.edu/vendian/arkarua.html), from the University of California Berkeley Museum of Paleontology.
	encyclopedia.worldvillage.com /s/b/Arkarua (205 words)

	Helioplacus
		Other contemporaneous echinoderms are known to have existed from their dissociated plates, but other than a few possible edrioasteroids, helioplacus is the earliest echinoderm that is well enough preserved to analyze its characteristics.
		One much earlier form called Arkarua has been hypothecated as an ancestoral echinoderm because of its five fold symmetry.
		But Arkarua appears to lack both stereoms and a mouth.
	www.ebroadcast.com.au /lookup/encyclopedia/he/Helioplacus.html (273 words)

	Helicoplacus - Wikipedia, the free encyclopedia
		Other contemporaneous echinoderms are known to have existed from their dissociated plates, but other than a few possible edrioasteroids, helicoplacus is the earliest echinoderm that is well enough preserved to analyze its characteristics.
		One much earlier form called Arkarua has been hypothesized to be an ancestoral echinoderm because of its five-fold symmetry.
		But Arkarua appears to lack both stereoms and a mouth.
	en.wikipedia.org /wiki/Helioplacus (278 words)

	Arkarua - Encyclopedia Glossary Meaning Explanation Arkarua (Site not responding. Last check: 2007-10-17)
		There is no sign of the calcium carbonate stereoms (plates) that are diagnostic of echinoderms.
		McMenamin/Sielacher have proposed Arkarua as a conventional mainline member of the Vendazoa, with five fold symmetry and non-iterated cell families.
		* Vendian animals: Arkarua from the Ediacara Hills of Australia, from the University of California Berkeley Museum of Paleontology.
	www.encyclopedia-glossary.com /en/Arkarua.html (243 words)

	[No title]
		Arkarua was a large bowling-ball sized urchin without any spines.
		Although Arkarua went extinct in the Permian period, adaptations from it probably lead to the first true sea urchins and starfish.
		Sea cucumbers, a relative of sea urchins, are common today but have a sparse fossil record indicating that they are a relatively new species.
	wwwutmsi.zo.utexas.edu /people/staff/dunton/GK12/lessons/GeologicTimeline5E.doc (3364 words)

	Fossils
		All species being extinct, they are known only from fossils.
		The species Arkarua adami is 3 to 10mm across.
		Ausia is a curious Precambrian-age fossil that basically consists of a hollow cylinder taping to a cone on one end.
	www.shortopedia.com /F/O/Fossils (1789 words)

	Echinodermata (Site not responding. Last check: 2007-10-17)
		Arkarua, a possible echinoderm, has been described from the Vendian (latest Proterozoic) (Gehling 1987).
		Some early Paleozoic echinoderms are not radially symmetrical (e.g., carpoids and helicoplacoids), while a possible echinoderm from the Vendian (Arkarua) has five-fold radial body organization.
		All extant echinoderms live in the ocean, and there is no fossil evidence of any exception to this.
	tolweb.org /tree?group=Echinodermata&contgroup=Metazoa (2180 words)

	Reference.com/Encyclopedia/Ediacaran biota
		One of the largest and most distinctive Ediacara animals was a flattened, oval-shaped and segmented worm-like form called Dickinsonia that could grow to a metre or more long.
		Arkarua, a tiny circular disc with five, evenly spaced points, suggesting the form of an extinct echinoderm called an edrioaster.
		About 560 million years ago, trace fossils like worm burrows appear in the fossil record together with small body fossils that have bilateral symmetry.
	www.reference.com /browse/wiki/Ediacaran_biota (1191 words)

	Molecular Phylogeny
		If the rate of evolution was approximately constant over long periods of time, the split between Cnidaria and the other Metazoa could have been as early as 800 to 900 Ma before the present" (Runnegar 1992, p.
		In fact there is a probable echinoderm, Arkarua, described from the Vendian.
		Molecular dating, while not always in agreement with fossil evidence, offers an opportunity for timing events that are otherwise unobservable.
	www.peripatus.gen.nz /biology/MolPhy.html (2652 words)

	Arkarua
		Some claim it isn't only an echinoderm, but is specifically an Edrioasteroid.
		It isn't radially symmetric and doesn't possess five fold symmetry.
		Take this note to be able to access this article instantly from any page
	www.fastload.org /ar/Arkarua.html (231 words)

	Palaeos Proterozoic : Ediacaran : Ediacaran Period - 2
		If Kimberella is indeed a mollusc, as suggested by Fedonkin and Waggoner (1997), or the Ediacara/Zimnie Gory traces are correctly interpreted as radula scratches, we have evidence for derived protostomes at 555 Ma.
		Similarly, if Arkarua adami (from the Pound Subgroup, South Australia; Gehling, 1987) is correctly interpreted as an echinoderm, we have evidence for a derived deuterostome of similar age [but see, Mooi (2001) and our discussion of Arkarua at Ambulacraria].
		In either case, it follows that the P-D split must have occurred well before 555 Ma, which is in accordance with most 'molecular clock' studies.
	www.palaeos.com /Proterozoic/Neoproterozoic/Ediacaran/Ediacaran2.htm (1649 words)

	Phylum Echinodermata - Echinoderms
		While echinoderms are known from the Cambrian on, the Vendian period has a few soft-bodied fossils that are putative echinoderms or their ancestors.
		These include Arkarua and Tribrachidium from the Ediacara Hills of Australia.
		Homalozoans, from which echinoderm may have descended, and eocrinoids, that are not directly ancestral to the true crinoids, are abundant in the early Cambrian fossil record.
	www.fossilmuseum.net /Tree_of_Life/Phylum-Echinodermata.htm (783 words)

	[No title]
		GAP=- ; MATRIX [ ] [ ] Arkarua ?
		Note that the phylogenetic position of most fossil echinoderms is still uncertain, and a number of additional extinct taxa will be added to this tree in the future.
		Echinoderms form a well-defined and highly-derived clade of metazoans.
	ag.arizona.edu /ENTO/tree/eukaryotes/animals/echinodermata/Echinodermata.nex (2018 words)

	Science Fair Projects - Vendian biota
		Other than a few dubious fossils from the Upper Cambrian in Ireland, there is no known overlap between the Vendazoa and modern lifeforms.
		Well known Vendian forms include Arkarua, Charnia, Dickinsonia, Ediacaria, Marywadea, Onegia, Yorgia and Pteridinium.
		The full list runs to 50 or more taxa.
	www.all-science-fair-projects.com /science_fair_projects_encyclopedia/Vendian (552 words)

	THE FOSSIL RECORD A NEW LOOK AT THE EVIDENCE (Site not responding. Last check: 2007-10-17)
		There is absolutely no doubt that the quality of the fossil record has dramatically improved since the mid-nineteenth century and continues to improve yearly.
		This fauna includes the first sponges (Dougshantuo China), Cnidarian sea pens Pteridinium, Cnidarian sea anemones Nemiana, Cnidarian jellyfish Mawsonites, molluscs Kimberella, Echinoderms Arkarua, arthropods Spriggina, annelid Dickinsonia and even the first shelled form Cloudina.
		There are many well established intermediate forms that have also been well documented including those of dinosaur-bird transitions, reptile-mammal transition, whale evolution, horse evolution, and elephant evolution to name a few.
	gsa.confex.com /gsa/2006SC/finalprogram/abstract_99968.htm (362 words)

	The Fossil Record
		One of these extinct creatures, the Arkarua, is supposedly related to the Echinodermota, spiny-skinned animals like star fish, sea urchins and others in their phylum.
		Just as higher organisms, such as vertebrates and insects, have bilateral symmetry (a left and a right matching side) Echinodermota have a five-fold symmetry, such as we see with the star fish.
		So as far as the phylogeny (supposed evolutionary "tree") of the Echinodermota, there is no evidence for their evolution, and the evidence that Arkarua is related to the Echinodermota is pure speculation.
	www.thedarwinpapers.com /oldsite/number5/darwin5.htm (13965 words)

	Creation-Evolution Headlines
		The developmental class of explanation, per se, does not address the question of why the origin of such a system should, ipso facto, lead to increased diversity or disparity.
		In fact, if at least one Ediacaran is a bilaterian (Kimberella, Spriggina, Dickinsonia, or Arkarua, for example), then the bilaterian developmental system existed at least a few tens of millions of years prior to the Cambrian “explosion,” suggesting something more than just developmental innovation might be needed to account for the “explosion.”
		Ecological Explanations: Suppose some Precambrian animal develops an eye or a mouth (trilobites, after all, already had complex eyes) Suddenly, the lucky winner is like a burglar with a gun in a supermarket.
	creationsafaris.com /crev200604.htm (14463 words)

	Echinoderm Online Coloring - EnchantedLearning.com
		These slow-moving creatures have a water-vascular system (a rudimentary circulatory system), water-filled channels that go through the body.
		The oldest-known fossil echinoderm is Arkarua, which lived in pre-Cambrian times, during the Vendian period, roughly 560 million years ago, in what is now Australia.
		Some echinoderms include sea stars (also called starfish), brittle stars (which includes basket stars), sea cucumbers, sea urchins, sand dollars, and crinoids (also called feather stars, which have a soft body surrounded by upwards-facing arms).
	www.enchantedlearning.com /painting/echinoderms.shtml (342 words)

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