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Topic: Tommotian

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	Palaeos Paleozoic : Cambrian : Early Cambrian
		The relationships of Tommotian animals to living groups are not understood, but it is likely that mollusks also evolved at this time.
		The Tommotian animals disappeared rather quickly and were followed by the "Cambrian Explosion" of modern groups in the last half of the Early Cambrian (Atdabanian Age).
		During the first 10 million years of the Cambrian Period the Tommotian fauna was replaced by a more diverse biota of larger metazoans participating in more complex communities.
	www.palaeos.com /Paleozoic/Cambrian/EarlyCam.html (1923 words)

	DLESE description of The Tommotian Age: 530 Million Years Ago (Site not responding. Last check: 2007-11-05)
		The Tommotian Age began about 530 million years ago and is a subdivision of the early Cambrian.
		Named for rock exposures in Siberia, the Tommotian saw the first major radiation of the animals, or metazoans, including the first appearance of a great many mineralized taxa such as brachiopods, trilobites, archaeocyathids, molluscs, and echinoderms.
		A few million years before the Tommotian, in the Vendian, the continents had been joined in a single supercontinent called Rodinia.
	www.dlese.org:8080 /dds/catalog_DLESE-000-000-005-226.htm (218 words)

	Palaeos Paleozoic: Cambrian: Early Cambrian: The Tommotian Age
		The Tommotian was an important period which saw the rise of diversified metazoans with skeletons.
		This type of fauna is not restricted to the Tommotian Stage; these fossils are also common in the overlying Atdabanian Stage.
		The term "procoelomate" was coined by the Swedish paleontologist Jan Bergström to slug-like bilaterian animals that evolved from ancestral aschelminthes (priapulid drawn on the left of the diagram) and gave rise to the various coelomate phyla during the Ediacaran-Cambrian transition.
	www.palaeos.com /Paleozoic/Cambrian/Tommotian.htm (1650 words)

	Tommotian Age
		The Tommotian Age, which began about 530 million years ago, is a subdivision of the early Cambrian.
		Named for rock exposures in Siberia, the Tommotian saw the first major radiation of the animals, or metazoans, including the first appearance of a great many mineralized taxa such as brachiopods, trilobites, archaeocyathids, molluscs, echinoderms, and more problematic forms.
		A few million years before the Tommotian, in the Vendian, the continents had been joined in a single supercontinent called Rodinia (from the Russian word for "homeland", rodina.) As the Cambrian began, Rodinia began to fragment into smaller continents which did not always correspond to the ones we see today.
	www.ucmp.berkeley.edu /cambrian/tommotian.html (342 words)

	Tommotian fauna
		The Precambrian-Cambrian transition (just prior to the Cambrian Explosion) is characterized by the appearance of small shelly fossils that are called the Tommotian fauna after the are of Siberia where they were first discovered.
		Prior to the Tommotian fauna, the Ediacaran metazoans were all soft-bodied.
		The Tommotion age is believed by some scientists to be separated from the rest of the early Cambrian by the Botomian extinction event that eliminated many Tommotian forms, which were then followed by more familiar early taxa of the Cambrian Explosion.
	www.fossilmuseum.net /Paleobiology/Tommotian_fauna.htm (239 words)

	WSC: PHYS 0106: Earth History Timeline: The Tommotian Fauna
		The main feature which distinguishes the fauna of the Tommotian is the development of skeletal structures.
		The Tommotian fauna represent an essential part of the fossil record.
		Despite the fact that many of the creatures do not exist today, they represent an important part of earth history, and because of the development of skeletons their fossils will continue to tell the story of the Cambrian and mark its history..
	www.physci.wsc.ma.edu /young/hgeol/geoinfo/timeline/tommotian/tommotian.html (293 words)

	J34 The Cambrian explosion
		Traditionally the "Cambrian explosion" was the sudden appearance in the Lower Cambrian (Atdabanian stage) 520-525 million years ago of a diverse and widely occurring skeletal animals, predominately trilobites and brachiopods, sometimes in association with archaeocyathids that were the first skeletal reef (calcareous bioherm and biostrome) builders.
		The sudden appearance of trilobites as visible (because of their mineralized skeletons) and ubiquitous metazoan fossils inspired the designation "Cambrian explosion" However, Cambrian fauna of tiny shelly forms (and no trilobites) were earlier in existence.
		They were first well described in Russia (their existence had long been known) where they define the Tommotian Stage that spans a duration of about 5 million years.
	geowords.com /histbooknetscape/j34.htm (885 words)

	Cambrian Explosion - Open Encyclopedia (Site not responding. Last check: 2007-11-05)
		These organisms were soft-bodied and are found with various strange body forms.
		The so-called Small shelly fauna of the ensuing Tommotian period included Cloudinia and its kin.
		All phyla in existence today (and all others now extinct) except one were first found in this period.
	open-encyclopedia.com /Cambrian_explosion (314 words)

	WSC: PHYS 0106: Earth History Timeline: The Tommotian Fauna (Site not responding. Last check: 2007-11-05)
		The Tommotian Age, which takes its name from a rock series in Siberia, produced fauna different than any other seen in the early Cambrian.
		The main feature which distinguishes the fauna of the Tommotian is the development of skeletal structures.
		Despite the fact that many of the creatures do not exist today, they represent an important part of earth history, and because of the development of skeletons their fossils will continue to tell the story of the Cambrian and mark its history..
	biology.wsc.ma.edu /physicalscience/young/hgeol/geoinfo/timeline/tommotian/tommotian.html (293 words)

	HALKIERIIDS IN MIDDLE CAMBRIAN PHOSPHATIC LIMESTONES FROM AUSTRALIA Journal of Paleontology - Find Articles
		ABSTRACT-Halkieriids are part of a distinctive Early Cambrian fauna, the "Tommotian fauna" sensu Sepkoski (1992), that is preserved mostly as phosphatic and secondarily phosphatized skeletal elements.
		The distinctiveness of the Tommotian fauna is ascribed, in part, to its preferential elimination during the end-Early Cambrian mass extinction event (the "Botomian extinction").
		Because many elements of the "Tommotian" fauna appear to be both fades restricted and preserved by early diagenetic phosphatization (e.g., Brasier and Hewitt, 1979; Brasier, 1990; Landing, 1992; Mount and Signor, 1992; Dzik, 1994; Khomentovskii and Karlova, 1994), it is useful to compare them with taphonomically and environmentally comparable assemblages of Middle Cambrian age.
	findarticles.com /p/articles/mi_qa3790/is_200405/ai_n9377598 (742 words)

	Cambrian period
		During it, the fossil-producing species of plants and animals first proliferated – a dramatic diversification that has been called the Cambrian Explosion.
		When the fossil record is scrutinized closely, it turns out that the fastest growth in the number of major new animal groups took place during the Tommotian and Atdabanian stages of the Early Cambrian, a period of time which may have been as short as five million years.
		In that time, the first undoubdted fossil annelids, arthropods, brachiopods, echinoderms, molluscs, onychophorans, poriferans, and priapulids show up in rocks all over the world.
	www.daviddarling.info /encyclopedia/C/Cambrian.html (208 words)

	Tommotian Age at AllExperts
		World climate during the Tommotian was mild; there was no glaciation.
		The Tommotian saw the rise of diversified metazoans with skeletons, small shelly fauna, the first archaeocyathids, primitive molluscs - monoplacophorans, Lapworthella, and inarticulate brachiopods.
		The most primitive stage is marked by characteristic elements, such as anabaritids, tommotiids, and hyolithellids, also known as the "Tommotian fauna".
	en.allexperts.com /e/t/to/tommotian_age.htm (394 words)

	ANOXIA BETWEEN EDIACARAN FAUNA AND CAMBRIAN BIORADIATION: CARBON AND SULPHUR ISOTOPE STUDIES
		C of organic carbon is consistently low throughout this period, reflecting organic matter recycling through sulphate reducing bacteria, superimposed on the temporal evolution of the global carbon cycle.
		The apparent isotope fractionation between organic and carbonate carbon is > 32 in the upper Nemakit-Daldynian and lower Tommotian, suggesting an input of chemoautotrophic biomass which is in agreement with the record of previously published organic carbon isotope data (Hayes et al., Chem.
		However chemical proxies measured from the deeper water section suggest that anoxic conditions were still present or re-established in the basinal region and became oxic to dysoxic only in the lower Atdabanian.
	gsa.confex.com /gsa/2005ESP/finalprogram/abstract_88758.htm (468 words)

	Cambrian Explosion
		Then, apparently very suddenly, starting at the beginning of the Tommotian Age (~530 Ma), almost all of the animal phyla known today appear in the fossil reocrd in rapid succession.
		The fossil record is continually yielding more and better evidence of pre-Tommotian life, from the earliest biochemicals extracted from ~3,800 Ma cratonic rocks of southwest Greenland, through the perplexing grotesquery of the Ediacarans.
		The Tommotian and Atdabanian Ages (530 to 519 Ma)
	www.peripatus.gen.nz /paleontology/CamExp.html (3079 words)

	Portable Planetariums Home (Site not responding. Last check: 2007-11-05)
		Many of these organisms were recognized either as of unknown affinity or as representatives or groups that became extinct before the end of the Cambrian.
		The most "primitive" stage is marked by characteristic elements, such as anabaritids, tommotiids, and hyolithellids, known as the "Tommotian fauna." Later SSFs have been identified as sclerites of worm-like animals or as early representatives of the major fossil groups.
		The first macroscopic faunas occur at the end of the Siberian Tommotian Stage, when major reefal complexes were formed by archaeocyaths.
	www.planetarios.com /manualpaleo.htm (3714 words)

	Freeman-Lynde GLY116 Paleozoic Life Questions
		Trilobites and brachiopods are the first abundant shelled organisms preserved in the rock record.
		Trilobites are an important member of the Tommotian Fauna.
		Articulate brachiopods are the dominant bivalve of the ___________ Fauna.
	www.arches.uga.edu /~rfreeman/Paleozoic_life_questions.html (3086 words)

	Chapter Seven - 185
		For a number of years it has been the Tommotian to mark the beginning of the Cambrian, but even this conclusion has turned out to be unsatisfactory.
		The first stage of the Lower Cambrian is known today as Manykaian (trace fossils), after which come the Tommotian (small shelly fossils), the Atdabanian (trilobites), and the Botomian, while the other two stages of the period are still known with the generic names of Middle and Upper Cambrian (Figure 7-1).
		In the last twenty years, in conclusion, paleontology has discovered that in Cambrian times there have been not one but three different “explosions” of animal life: one documented by trace fossils, a second which left behind small shelly fossils, and finally the classical explosion that was dominated by trilobites.
	www.biologiateorica.it /organiccodes/cap7/p185.htm (329 words)

	Chapter 10 Study Guide
		The Tommotian Stage of the Cambrian lasted from 570 to approx.
		Note however, that there is not a correlation between sea level falling and trilobite extinction.
		From the end of the Tommotian Stage of the Early Cambrian to the end of the Cambrian, sea level generally rose, with two short intervals of falling sea level (one in the Middle Cambrian, on in the Late Cambrian).
	www.uvm.edu /~cmehrten/courses/historical/ch13sg.html (1093 words)

	My Collection - Cambrian
		A unique insight into the early cambrian faunas is offered by famous fossil sites like the Burgess Shale in Canada and several sites in China, where completely preserved specimens are abundantly found together with imprints or remains of their soft parts.
		The Lower Cambrian fauna is so characteristic that it's usually referred to as "small shelly fauna" and is used to define the Cambrian's only stage, the Tommotian.
		According to newer research results, the sudden appearance of shelly organisms derives from a critical oxygen level in the earth's atmosphere (approx.
	www.palaeo-online.de /e/sammlung/cambrian.html (380 words)

	Historical Geology (Site not responding. Last check: 2007-11-05)
		The Tommotian fauna includes a host of small skeletal elements that cannot be assigned to any living phylum and that show no relation to any group of fossils found in post-Cambrian rocks.
		The Tommotian also includes a few groups that survive to the present day; sponges, monoplacophorans (Class in Phylum Mollusca – segmented, bilaterally symmetrical crawling animals with cap-shaped shells), and brachiopods.
		After the disappearance of most of the Tommotian fauna, a variety of new skeletonized animals appeared on the scene.
	academic.evergreen.edu /curricular/lifeonearth/lecture6earlypaleoweb.htm (1093 words)

	iqexpand.com (Site not responding. Last check: 2007-11-05)
		The small shelly fauna is the name given to an obscure collection of small hard-shelled fossils found worldwide in beds a bit older than the earliest trilobites and archeocyathids from the Nekamit-Daldynian and Tommotian stages (Lower Cambrian).
		The start of the Cambrian period had classically been set at the first appearance of small shelly fossils.
		Tommotian (small shelly) fauna (earliest Cambrian) Tiny cups, caps, and other hard fossils.
	small_shelly_fauna.iqexpand.com (453 words)

	The Cambrian System in Northwest Argentina
		Paleoichnological studies allowed to recognize different levels with abundant trace fossils, being the only means of dating the earlier mentioned rocks.
		Aceñolaza and Durand (1986) recognized a basin with a SW/NE alignment for the Vendian/ Tommotian.
		This basin was configured by an expansion of the gondwanan margin between the Rio de la Plata Craton (SE) and the Arequipa Massif (NT, both of a Rifean age (aprox 1000 My).
	www.unt.edu.ar /fcsnat/INSUGEO/libro_cambrian/046_The_Cambrian_system.htm (969 words)

	DLESE Find a Resource > Subject: Geologic time + Collections: DCC
		The Tommotian Age began about 530 million years ago and is a subdivision of the early Cambrian.
		Named for rock exposures in Siberia, the Tommotian saw the first major radiation of the animals, or metazoans, including the first appearance of a great many mineralized taxa such as brachiopods, trilobites, archaeocyathids, molluscs, and echinoderms.
		A few million years before the Tommotian, in the Vendian,...
	www.dlese.org /library/browse_su_0d_ky_09-110.htm (716 words)

	VI The Cambrian explosion (Site not responding. Last check: 2007-11-05)
		As basal Cambrian progresses, the organisms with skeletons and distinct members become increasingly abundant.
		One thus often spoke about " tommotian explosion ".
		In Tommotian (0,530/0,527 B.Y.), new phyla are listed: Brachiopods and Porifera (Archaeocyaths reefs), Lapworthella, many phyla with soft body.
	www.freazer.com /perso/extinctions/sixthecambrianexplosion.htm (2953 words)

	Two new pre-trilobite faunas from western North America (Site not responding. Last check: 2007-11-05)
		Perhaps the greatest puzzle in the history of life is the nature and cause of events comprising the Precambrian−Cambrian evolutionary radiation of Metazoa, The major stumbling blocks to resolving this puzzle are a scarcity of late Precambrian and earliest Cambrian faunas in the fossil record and difficulties in correlating the few faunas that are known.
		These new finds may lead to an understanding of the pattern and dynamics of the Precambrian−Cambrian metazoan radiation, and to improved biostratigraphical correlations of the strata recording that event.
		Raaben, M. The Tommotian Stage and the Cambrian Lower Boundary Problem (Amerind, 1981).
	www.nature.com /nature/journal/v303/n5916/abs/303415a0.html (403 words)

	Eonothem Phanerozoic
		This so-called Tomotian fauna, named for the Tommotian Stage of Early Cambrian time, was first discovered in Siberia.
		It includes a host of small skeletal el¬ements that cannot be assigned to any living phylum and that show no relation to any group of fossils found in post-Cambrian rocks.
		The Tommotian fauna also contains the oldest known mem¬bers of a few groups that survive to the present day¬sponges, which are very simple animals monoplacophorans, which were ancestral to all present-day groups of mollusks.
	www.fiu.edu /~longoria/gly1101/LowerPz.html (2664 words)

	Age and biostratigraphy of early Cambrian tuffs from SE Australia and southern China Journal of the Geological Society ...
		Taking account of the Sellick Hill tuff age for the late Atdabanian, the indicated time-duration of the combined Tommotian and Atdabanian is c.
		The Tommotian may be considered to embrace the major diversification of the `Cambrian explosion' and by the early Botomian, the climactic phase of this radiation was in place (Bowring & Erwin 1998; Babcock et al.
		The limits to the measured time span of 11-21 Ma emphasize that an appreciable interval of geological time accommodated this event, and that its apparent rapidity within the fossil record is due substantially to widespread condensation of sedimentation and/or local breaks in deposition.
	www.findarticles.com /p/articles/mi_qa3721/is_200211/ai_n9119454/pg_14 (481 words)

	DLESE description of The Tommotian Age: 530 Million Years Ago
		A few million years before the Tommotian, in the Vendian, the continents had been joined in a single supercontinent called Rodinia.
		As the Cambrian began, Rodinia began to fragment into smaller continents which did not always correspond to the ones we see today.
		No part of the referring document residing on the server may be reproduced or stored in a retrieval system without prior written permission of the publisher, except for educational purposes, and in no case for profit
	www.dlese.org /library/view_resource.do?description=DLESE-000-000-005-226 (218 words)

	MSN Encarta - Search Results - Tommotian fauna
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	encarta.msn.com /encnet/refpages/search.aspx?q=Tommotian+fauna (114 words)

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