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Topic: Trilobite

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	Palaeontology - Research - What are Trilobites?
		Trilobites are an extinct group of arthropods (jointed-legged animals) known from more than 10,000 fossil species.
		The trilobite body is also divided lengthwise into three regions or tagmata: a head or cephalon, a middle region (thorax) composed of several to many articulated segments, and a tail plate called a pygidium, which consists of fused segments.
		Trilobites periodically shed their exoskeleton to accommodate growth; trilobite fossils sometimes preserve so-called moult configurations that show various stages in the release of the old exoskeleton and escape of the then soft-bodied animal.
	www.austmus.gov.au /palaeontology/research/trilobites02.htm (970 words)

	trilobite. The Columbia Encyclopedia, Sixth Edition. 2001-05
		The trilobite body was generally oval and flat and was divided into three roughly equal sections: the head, thorax, and tail.
		Trilobites were abundant inhabitants of the Cambrian and Ordovician geological periods.
		Trilobites are most closely related to the chelicerates, which include the horseshoe crabs and spiders.
	www.bartleby.com /65/tr/trilobit.html (210 words)

	Geobit 6: The Trilobite
		Trilobites are so named because the segments on their upper (dorsal) surface usually possess longitudinal furrows that form a three (tri-) lobed division of the body.
		Trilobites have been found in some post-Silurian Paleozoic rocks in Illinois, but they are much less abundant and diverse than those in the older rocks.
		Trilobites are useful in determining the relative age of some sedimentary rocks.
	www.isgs.uiuc.edu /servs/pubs/geobits-pub/geobit6/geobit6.html (734 words)

	Trilobites - The Eyes Have It! -- The TrueOrigin Archive
		Additionally, trilobites represent some of the most sophisticated arthropods known to man. The trilobite eye, for example has been heralded as a structure far too complex to evolve over time by random variations in the genesof trilobite populations (Armstrong 1973 and 1976; Bergman 1992; DeYoung 2002; Wise 1989).
		This is countered by others, however who maintain that trilobites document the model of punctuated equilibrium, or periods of long stasis with no change followed by rapid bursts of innovation (Eldredge 1985; Eldredge and Gould 1972).
		Clarkson and others have sought the middle ground by their theories that many pulses of trilobite extinctions have occurred (Clarkson 1986; Palmer 1999) thus driving trilobites “back to the drawing board.” Whatever evolutionary mechanisms are proposed for the development of trilobites, however, the field of trilobite classification is in disarray.
	www.trueorigin.org /trilobites_eyes.asp (981 words)

	GeoKansas--Trilobite Fossils
		Ogygopsis was one of the trilobites that abounded in the seas of the Cambrian Period.
		Although trilobite diversity decreased about 440 million years ago, following the major extinction event at the end of the Ordovican Period (see mass extinctions) and again during a series of extinctions in the Middle to Late Devonian Period, trilobites have one of the most extensive fossil records of any group of animals.
		Trilobite fossils are fairly rare in the Pennsylvanian and Permian rocks that crop out in eastern Kansas, a testament to the decline in their diversity during the later Paleozoic.
	www.kgs.ku.edu /Extension/fossils/trilobite.html (1377 words)

	Trilobite - Wikipedia, the free encyclopedia
		Although trilobites were only armored on top, they still had a fairly heavy exoskeleton, composed of calcite and calcium phosphate minerals in a protein lattice of chitin.
		The exact reason for the extinction of the trilobites is not clear, although it would seem to be no coincidence that their numbers began to decrease with the arrival of the first sharks and other early fish in the Silurian and Devonian periods with their strong, hinged jaw.
		Trilobites appear to have been exclusively marine organisms, since the fossilized remains of trilobites are always found in rocks containing fossils of other salt-water animals such as brachiopods, crinoids, and corals.
	en.wikipedia.org /wiki/Trilobite (1750 words)

	Trilobite Page
		Trilobites are extinct, exclusively marine arthropods, known fondly to everybody who has read much about fossils.
		Trilobites are characterised by a generally subelliptical, dorsal, chitinous exoskeleton divided longitudinally into three distinct lobes, a central elevated region and two less elevated lateral regions that run for most of the length of the body, hence their naming.
		1: (A) One of the smallest trilobites, a specimen of Peronopsis montis (Mathew) from the
	www.peripatus.gen.nz /Taxa/Arthropoda/Trilobita/Trilobite.html (3066 words)

	The Trilobite: Enigma of Complexity
		Trilobites are extinct members of the phylum Arthropoda, to which the modern insects belong.
		Trilobites were exquisite forms having elaborate segmented bodies, cephalized nervous systems, with jointed appendages and swimmerets, antennae and compound eyes.
		Because trilobites are extinct forms, we know very little of their life habits except for what we can deduce from association with other forms that do have living representatives, and from careful reconstructions of the depositional environments in which they are found.
	origins.swau.edu /papers/complexity/trilo/default2.html (7833 words)

	Trilobite Fossil Specimens
		The trilobite inhabited the seas over 250 million years ago and was one of the first animals to evolve eyes with some species having no more than a simpl...
		The detail is awesome with a perfect display of the large compound eyes found in some species of trilobites.
		Trilobites inhabited the seas more than 250 million years ago.
	www.bambuddhas.com /thestore/FT.html (165 words)

	Welcome to the Electrolux Trilobite - Electrolux
		The trilobite was a type of arthropod that vacuumed the ocean beds for small animals and particles about 250-560 million years ago.
		Its back was hard, and the trilobite is perhaps the best known of the fossils seen in walls, steps and flooring made of stone.
		The Trilobite now also has improved sonar for navigation (more microphones and enhanced frequency), which improves its "sight", a new fan system and high-performance, environmentally friendly batteries (nickel-metal hydride).
	www.electroluxusa.com /node142.asp (518 words)

	Trilobite - Search Results - MSN Encarta
		Trilobite, common name for a class of extinct marine arthropods.
		Trilobites ranged in length from a few millimetres up to about 65 cm (26 in),...
		Ordovician Period, in geology, second division of the Palaeozoic Era of the geological timescale, spanning a period from 500 million years ago to 448...
	uk.encarta.msn.com /Trilobite.html (117 words)

	The Trilobite (Site not responding. Last check: 2007-10-08)
		Evidence of the complexity of the trilobite reveals the inadequacy of the theory of Darwinian evolution and is interpreted instead by reference to another theory of origins involving an Intelligent Designer.
		Trilobites belong to the same phylum as modern insects, so the corresponding formation of a typical metamorphosing insect, the fruit fly Drosophila, may be considered.
		The regulatory mechanism of the early trilobite eye development must indeed be complex, since an estimated 2,500-5,000 genes appear to be involved in the developmental process of the insect eye.
	www.asa3.org:16080 /ASA/PSCF/2000/PSCF12-00Chadwick.html (5335 words)

	Trilobite Fossil Preparation
		The trilobite fossils found in the devonian formations of Oklahoma, are some of the most beautiful fossils found anywhere in the world.
		Many arduous hours are spent exposing the trilobite containing layers, and then breaking and splitting the tough limestone, to expose faint hints of what may lay within.
		The last layers of matrix covering the trilobite are removed, and the surface of the matrix may be textured to create a museum quality display specimen.
	www.blk-cat-mtn-trilobites.com /trilobite-fossil-preparation.html (553 words)

	Trilobite Classification Chart (via CobWeb/3.1 planetlab1.cs.virginia.edu) (Site not responding. Last check: 2007-10-08)
		Trilobites were for a long time considered the most primitive of Arthropods, since they were among the first Cambrian arthropods discovered, but this turns out to have been mistaken; an artifact of preservation.
		Trilobites are now considered relatively advanced among the Paleozoic arthropods, and the search for the first arthropods and the ancestors of trilobites is pushed back into the Precambrian..
		When Naraoia compacta was described, its similarity to an early meraspid trilobite (with cephalon and pygidium, but no thoracic segments) was noted, and was part of an ontogenetic argument for including Naraoia as a "soft-bodied trilobite." A fuller discussion of the relationship of naraoiids to trilobites is presented on a separate page of this website.
	www.trilobites.info.cob-web.org:8888 /triloclass.htm (3012 words)

	Perfect Trilobite Fossil On Bounce Rock
		This is clearly a fossil of a trilobite, organisms that lived from about half a billion years ago to 210 million years ago on the Earth.
		Mars evolved identical sorts of life forms and this trilobite is proof of that.
		Even imagining what sort of complex movements would be needed to produce a fake trilobite (and the reasons for doing it at all!) given the tools on the arm is difficult.
	www.xenotechresearch.com /marsx.htm (879 words)

	GeoFact No. 06, Isotelus: Ohio's State Fossil
		Not only are specimens of this trilobite, or at least fragments, moderately abundant in the rocks exposed in southwestern Ohio, but they are represented by the Huffman Dam specimen, which is one of the largest complete trilobites ever collected.
		Trilobites are an extinct class of the Phylum Arthropoda, which includes among its living members the horseshoe crab, crabs, lobsters, shrimp, scorpions, spiders, and insects.
		Trilobites lived in marine environments, where they burrowed in sediment, crawled along the sea floor, or were free swimming.
	www.ohiodnr.com /geosurvey/geo_fact/geo_f06.htm (991 words)

	TRILOBITE EXTINCTION
		MADISON, Wis. (May 29, 1997) New research on the molting habits of the trilobite sheds light on the possible causes of the demise of this arthropod that lived on Earth for twice as long as the dinosaurs.
		Trilobites existed during the Paleozoic era, from the Cambrian to the Permian period about 540-245 million years ago.
		Until recently, the demise of the trilobite had been blamed on a sudden increase in the numbers of trilobite predators.
	www.accessexcellence.org /WN/SUA10/trilo597.html (484 words)

	TRILOBITES for SALE
		The Paleozoic is often called the age of the trilobite.Trilobites particularly flourished in the oceans of the Cambrian and Ordovician periods, beginning around 540 million years ago, with a diminishing number of families persisting until the Permian.
		Despite reduced ancestry, with decent with modification ruling, these trilobites filled the same ecological niches such that adaptation led to a repeating of many of the forms of their extinct cousins.
		The age of the trilobite yielded to the age of the insect.
	www.fossilmall.com /Trilobites.htm (417 words)

	Amazon.co.uk: Trilobite: Books: R.A. Fortey (Site not responding. Last check: 2007-10-08)
		This book is over 250 pages long because it covers the personal journey of the author from his first trilobite through the interesting people he met and worked with and whose work he admires (or not) and some interesting snatches of the history of palaeontology and the literature of Thomas Hardy and so on.
		Fortey's enthusiasm for trilobites is utterly infectious as he charts an exploration of their history and the history of those who study them, including himself.
		The book is packed with wonderful details on the structure of trilobite eyes, the protocol for naming fossils, anecdotes from Fortey's own life (being stung by a hornet in China!) and some groan-inducing puns (plans for a movie about rampaging trilobites called 'Thoraic Park'!).
	www.amazon.co.uk /Trilobite-Richard-Fortey/dp/0006551386 (2076 words)

	Trolobites , Kentucky Geological Survey
		Trilobite fossils have been found in Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian rocks in Kentucky, but are perhaps most commonly found in the Ordovician and Silurian rocks.
		Because trilobites are arthropods, they shed their exoskeletons, a process called molting, as they grew.
		Dolomitized cast of calymenid trilobite from the Silurian of Kentucky.
	www.uky.edu /KGS/fossils/trilobites.htm (302 words)

	Trilobite Masks
		Connections can be made between trilobites and living arthropods, for a better understanding of the animal kingdom.
		Also, the examination of fossils of trilobites in order to make the masks, provides a context for discussion of fossils as evidence of past life.
		They are called trilobites because their bodies were divided into three parts.
	www.uky.edu /KGS/education/trilobitemask.html (738 words)

	Trilobite - (Site not responding. Last check: 2007-10-08)
		Long before the fish inhabited the seas and the Dinosaurs roamed the land, Trilobites appeared some 600 million years ago during the Cambrian period.
		Trilobites are the earliest known animal to possess vision.
		The following Trilobites have been prepared by a Master of his Art, Jeffrey Hammer, who spends countless hours under a microscope to open one of these time capsules and to unveil one of Nature's Frozen Masterpieces allowing a view back in time to the Dawn of Life.
	www.trilobite.com (364 words)

	Amazon.com: Electrolux EL520A Trilobite Robotic Vacuum: Kitchen & Housewares (Site not responding. Last check: 2007-10-08)
		Today's Trilobite has been in the works since 1997, when its prototype was introduced on the BBC technology program, Tomorrow's World, and it has been perfected at Electrolux's development facilities in Sweden.
		Once Trilobite knows where the obstacles are, it will speed up in clear areas and slow down until it gets about 1-2 inches away, when it turns and proceeds in another direction.
		When the Trilobite is vacuuming over cords, fringe, or floor transitions, you can audibly hear the as the vacuum automatically cuts suction for a second or two.
	amazon.com /Electrolux-EL520A-Trilobite-Robotic-Vacuum/dp/B0001ZYYYM (2926 words)

	Trilobite- EnchantedLearning.com
		Trilobites are extinct, hard-shelled marine animals that lived in the seas millions of years ago.
		Trilobites were very common and very diverse; over 15,000 species of trilobites are known.
		Anatomy: Trilobites were marine invertebrates that had hard, three-lobed shells (the axial lobe and two pleural lobes), hence the name "trilobite".
	www.enchantedlearning.com /subjects/invertebrates/trilobite (308 words)

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