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Topic: Ammonoid

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	Geology Facts - What is an Ammonoid?
		Ammonoids are frequently found as fossils in marine rock from the Devonian to the Cretaceous periods.
		Relatives to the modern-day pearly nautilus, ammonoids are extinct cephalopods.
		Ammonoid shells are either straight or coiled and serve as protective and supportive structures and also enabling the animal to compensate for varying water depths.
	www.lakegeorgeassociation.org /geology_facts.htm (181 words)

	Ammonoidea
		Formally, ammonoids are distinguished from nautiloids by the construction of their septa, the barriers between different chambers of their shell, which in nautiloids are simple sheets of calcium carbonate, but in ammonoids are intricately wrinkled and folded.
		Ammonoids also distinguish themselves by possessing 12-8 sucker-laden tentacles, a squidlike beak composed of chitin (although in some species, the chitin is replaced by calcite later in life), and a toothed tongue or radula.
		Ammonoids, whose external support at least allows them to survive in a stream without being smashed, are still restricted chemically, and so cannot grow to very large sizes---no species grows larger than the Eurasian ryömäläinen, with a shell diameter of 50 centimeters.
	www.bowdoin.edu /~dbensen/Spec/Ammonoidea.html (1916 words)

	OEDILF - Word Lookup
		An ammonoid is a coiled chambered fossil shell of certain extinct mollusks.
		Ammonoids are (or were) a group of shelled marine creatures related to the modern chambered nautilus.
		Ammonoids are known only from the fossil record because they became extinct, along with the dinosaurs, about 65 million years ago.
	www.oedilf.com /db/Lim.php?Word=ammonoid (196 words)

	Ammonite - Wikipedia, the free encyclopedia
		Originating from within the bactritoid nautiloids, the ammonoid cephalopods first appeared in the Late Silurian to Early Devonian (circa 400 million years ago) and became extinct at the close of the Cretaceous (65 m.y.a.) along with the dinosaurs.
		The classification of ammonoids is based in part on the ornamentation and structure of the septa comprising their shells' gas chambers; by these and other characteristics we can divide subclass Ammonoidea into three orders and eight known suborders.
		The majority of ammonoid specimens, especially those of the Paleozoic era, are preserved only as internal molds; that it to say, the outer shell (composed of aragonite) has been lost through fossilization.
	en.wikipedia.org /wiki/Ammonoid (2369 words)

	Ammonoid showcase
		Unlike the Nautiloids the suture between the chamber wall and the outer shell was folded.
		The ammonoids evolved from the nautiloids during the Devonian.
		Cephalopods are displayed in the ammonoid showcase, in the nautiloid showcase, in the belemnite showcase, and in the
	www.toyen.uio.no /palmus/galleri/montre/english/m_ammon_e.htm (216 words)

	GeoKansas--Ammonoid Fossils
		In fact, ammonoids are relatives of the modern squid, as well as the octopus and chambered Nautilus, all of which belong to the class of animals called cephalopods.
		Because of their rapid evolution and abundance in the fossil record, ammonoids are extremely useful in correlating the ages of sedimentary rocks from different parts of the world.
		Although ammonoids are relatively common fossils in the Cretaceous outcrops of central and western Kansas, they are much less common in eastern Kansas, where smaller fossils occasionally are found in selected Pennsylvanian and Permian outcrops.
	www.kgs.ku.edu /Extension/fossils/ammonoid.html (1022 words)

	Early Triassic Ammonoid Fossils In Nevada
		The entire section lies within what ammonoid enthusiasts call the Meekoceras beds--a unit of cephalopod-bearing rocks in which the ammonoid Meekoceras gracilitatus is the most distinctive and characteristic specimen.
		As a consequence, horizon "a" has suffered a noticeable decline in outstanding ammonoid specimens remaining to be collected; the perfect fossils have become increasingly difficult to find, especially the larger, showy shells, several inches in diameter, for which commercial dealers pay top dollar.
		The ammonoids occur, of course, in the Lower Triassic Thaynes Formation, which is sporadically exposed throughout a specific geographic area of Nevada.
	members.aol.com /Waucoba5/thaynes/nevadaammonoids.html (1134 words)

	Science : Ammonoid and the argonauts - 27 July 1996 - New Scientist (Site not responding. Last check: 2007-11-04)
		Both ammonoids and octopods are cephalopods, a group of mobile molluscs with multiple tentacles and water-jet propulsion.
		Ammonoid shells are common fossils, but few traces remain of the soft-bodied animals that inhabited them.
		Most ammonoid shells consist of a spiral series of ever-larger body chambers, which the animal vacated one after...
	www.newscientist.com /article/mg15120402.900.html (277 words)

	Bibliography
		Evolution of shell morphology and suture complexity in Paleozoic prolecanitids, the rootstock of Mesozoic ammonoids.
		A new prodromitid ammonoid genus from the Hannibal Shale (Lower Mississippian) of Missouri.
		The Upper Devonian (Frasnian) conodont sequence in the Lime Creek Formation of north-central Iowa and comparison with Lime Creek ammonoid, brachiopod, foraminifer, and gastropod sequences.
	www.uiowa.edu /~geology/paleo/Collnrefs.html (3897 words)

	Middle Triassic Ammonoid Fossils From Nevada (Site not responding. Last check: 2007-11-04)
		During the Permian Period both ammonoid and the ammonite varieties became common.
		In the late 1980s, for example, many law-abiding, conscientious amateur collectors, plus swarms of irresponsible, lawbreaking commercial ammonoid hunters (it is illegal to either sell or barter--in other words, trade--fossils collected on Public Lands) "simultaneously rediscovered" the great fossil locality, creating over the past couple of decades an often frenzied frequency of overcollecting.
		The geologic age of the specific, classic ammonoid site is transitional latest Anisian/earliest Ladinian Stage of the Triassic Period, which places the fossils found there directly in the middle of the Mid Triassic, or roughly 235 million years old.
	members.aol.com /Waucoba7/ammonoids/ammonoids.html (712 words)

	Ammonoids at Museum of the Earth
		Before the discovery of the nautilus, ammonoids were thought to be coiled petrified snakes, and during medieval times snakes' heads were often carved into the fossils.
		No one knows exactly why ammonoids died out 65 million years ago, but some scientists believe that their demise may be related to their young, which floated among plankton after hatching.
		Another wall will describe ammonoid biology, including what ammonoids ate, what preyed on them, why their shells were shaped the way they were and how they moved.
	www.news.cornell.edu /stories/July05/Ammonoids.kr.html (754 words)

	g15 Mesozoic Erathem and Era subdivisions
		As a gross generalization, ammonoids typical of the Cretaceous and Jurassic are ammonites (in which the suture line is complexly frilled).
		The radiation of ammonite ammonoids had been mostly accomplished at the beginning of the Jurassic from open-ocean stocks that had survived a profound, worldwide, wave of ammonoid extinctions that marks the end of the Triassic.
		As a gross generalization, ammonoids typical of the Triassic are ceratites (in which only part of the suture line is frilled).
	geowords.com /histbooknetscape/g15.htm (806 words)

	Mid-carboniferous ammonoid biostratigraphy, southern Nye County, Nevada: Implications of the first North American ...
		Four ammonoid assemblages can be recognized at NTS that are homotaxial with the reference successions for the middle and upper Arnsbergian (E,) and Chokierian (H,) Stages, Namurian Series, in western Europe, and their equivalents worldwide.
		The upper Mississippian (Chesterian) portions of the NTS sections yield assemblages referable to a Eumorphoceras girtyi Ammonoid Biozone, representing the middle Arnsbergian Stage (Eb), followed by a Delepinoceras thalassoide Ammonoid Biozone, equivalent to the upper Arnsbergian Stage (Ezc).
		That boundary position is corroborated at Arrow Canyon by foraminifer occurrences, but the globally recognized Eumorphoceras-Homoceras ammonoid zonal transition, proposed initially to approximate the boundary horizon, cannot be pinpointed directly due to a lack of ammonoids in the immediate boundary interval.
	www.findarticles.com /p/articles/mi_qa3790/is_200107/ai_n8971047 (930 words)

	CISURALIAN AMMONOID GENUS URALOCERAS IN NORTH AMERICA Journal of Paleontology - Find Articles
		In North America, the ammonoid Uraloceras Ruzhentsev occurs in Cisuralian (Lower Permian) strata of the northern Yukon Territory, eastern Alaska, Ellesmere Island, southern British Columbia, and Nevada.
		From Sakmarian to Kungurian, species of Uraloceras occupied a narrow belt in the Northern Hemisphere (Boreal paleogeographical realm) that extended from the northern and northwestern margin of the Pangaean supercontinent southward to regions of present-day Siberia, the Ural Mountains, as well as Nei Monggol and Tibet.
		This may represent mixing of cool water ammonoid faunas from the north with warmer water faunas from the south (Spinosa et al., 1991; Schiappa, 1993).
	www.findarticles.com /p/articles/mi_qa3790/is_200503/ai_n11827029 (906 words)

	Palaeos Mesozoic: Triassic: Norian-1
		It was introduced for the Pinacoceras metternichi and Cyrtopleurites bicrenatus ammonoid fauna of the pelagic Hallstatt Limestone facies in the Hallstatt area (Mojsisovics, 1869 cited in Kozur 2003, and Encyclopædia Britannica].
		Ammonoids are important stratigraphic markers, because of their rapid evolutionary change.
		But by the Norian, the Ammonoids were on the wane, following their maximum diversity during the Carnian.
	www.palaeos.com /Mesozoic/Triassic/Norian.htm (2553 words)

	PERMIAN WATER MASSES AND AMMONOID BIOGEOGRAPHY (Site not responding. Last check: 2007-11-04)
		This study tested the utility of the water masses in the fossil record using a spatial database of 923 occurrences of Permian ammonoids compiled from the literature.
		Preliminary analysis of the distributions of the ammonoids indicated that 44 genera were cosmopolitan with respect to water mass types.
		This contrasts strongly with the Earliest Triassic ammonoids, which were highly cosmopolitan in their geographical distribution.
	gsa.confex.com /gsa/2001ESP/finalprogram/abstract_7640.htm (380 words)

	NHM_Exh_AmmonAbund
		As shown in the graph below, ammonoid abundance was influenced by many factors including climatic change, tectonic activity, changes in sea level, competition, predation, and comet-induced destruction.
		As the ammonoids evolved the suture patterns noted on their shells became increasingly complex.
		The ammonoid, for the reasons noted, underwent these trials of change and made remarkable comebacks each time there was near abolishment up until the Cretaceous-Tertiary boundary.
	www.humboldt.edu /~natmus/impFossilTypes/Ammonites/AmmAbund.html (265 words)

	Palaeos Paleozoic: Devonian: The Emsian Age - Birth of the Ammonoids
		Apart from the Bactritids, which are ammonoid - nautiloid transitional forms, all these early ammonoids belong to the suborder Anarcestina of the order Anarcestida.
		These cephalopods were nectonic, ocean-going forms, and even at this very early date had a world-wide distribution, being known not only on the western side of the Armorican micro-continent (Germany and Spain, with a possible Euramerican record from England), but also from Antarctic southeast Gondwana (southeast Australia).
		Despite their early widespread distribution, the ammonoids remained a minor group throughout the Emsian.
	www.palaeos.com /Paleozoic/Devonian/Emsian.htm (595 words)

	Mid-Triassic integrated U-Pb geochronology and ammonoid biochronology from the Balaton Highland (Hungary) Journal of ...
		The sediments are noted for their rich ammonoid faunas, which allow detailed biostratigraphic subdivision and correlation.
		The Balaton Highland is a classical area of Middle Triassic stratigraphy, which contributed to the early development of the ammonoid biostratigraphic scale (Bockh 1873; Mojsisovics 1882) and where continuing work resulted in a modern revision of zonal ammonoid biochronology (Voros 1998).
		The remarkably high resolution of the ammonoid biochronology is underpinned by high evolutionary turnover rate, possibly a feature of the diversity surge following a lengthy interval of suppressed diversity after the latest-Permian mass extinction.
	www.findarticles.com /p/articles/mi_qa3721/is_200303/ai_n9235650/pg_30 (897 words)

	Dr. Neil H. Landman (Site not responding. Last check: 2007-11-04)
		Analysis of a Carboniferous embryonic ammonoid assemblage from Kansas, U.S.A.: implications for ammonoid embryology.
		The importance of a phylogenetically relevant model for the function and behavior of fossil organisms: Ammonoids, coleoids and Nautilus.
		Scaphitid ammonoids from the Upper Cretaceous Pierre Shale.
	research.amnh.org /vertpaleo/landman.html (2174 words)

	alb21-3
		To provide an unbiased evaluation of the boundary proposals, we analysed the ammonoid distribution of 14 key stratigraphic sections from the Southern Alps and the Balaton Highland using quantitative biochronology.
		Priority was given to sections with continuous ammonoid record spanning several zones, preferably with abundant and diverse faunas that are taxonomically well-documented.
		összefoglalása (Triassic ammonoids and biostratigraphy of the Balaton Highland).
	www.biologie.uni-hamburg.de /b-online/kerp/Albart2.htm (2852 words)

	AMMONOID ZONATION OF THE TYPE GUADALUPIAN (MIDDLE PERMIAN SERIES)—ANALYSES OF ZONAL BOUNDARIES VERSUS ... (Site not responding. Last check: 2007-11-04)
		Recent papers have demonstrated confusion on the part of non-ammonoid specialists regarding current ammonoid systematics and ranges in Middle Permian strata.
		Formal ammonoid zonation of the Middle and Upper Permian is based on phylogenesis of the Cyclolobinae.
		Also, the GSSP definitions are based on conodont speciation events, so even though the ammonoid zones characterize their respective stages, their zonal boundaries do not coincide precisely.
	gsa.confex.com /gsa/2002SC/finalprogram/abstract_33134.htm (453 words)

	Tamara Schiappa (Site not responding. Last check: 2007-11-04)
		Invertebrate paleontology, ammonoid and conodont biostratigraphy, stratigraphy, science education and alternative teaching techniques.
		This study examines the ammonoid and conodont biostratigraphy and detailed lithostratigraphy of the Sakmarian boundary and body stratotype section in the southern Ural Mountains, Russia.
		Along with my continued interest in the ammonoid biostratigraphy, I am working on several projects dealing with mixed siliciclastic-carbonate systems of the Pennsylvanian-Permian of Nevada and some beautifully preserved carbonate buildups on the Nevada Test Site.
	pri.boisestate.edu /tamra.htm (344 words)

	Science -- Saunders et al. 286 (5440): 760
		The organic effects of the P/Tr extinction are widely known (16), and ammonoids were
		G. Boyajian and T. Lutz [Geology 20, 983 (1992)] and T. Lutz and G. Boyajian [Paleobiology 21, 329 (1995)] concluded that fractal indices of ammonoid sutures increased in minimum and maximum complexity because of increased variance and passive drift during the Paleozoic, but leveled off or declined during the Mesozoic.
		The ammonoid suture marks the contact between the shell wall and septa, which divide the shell into chambers.
	serendip.brynmawr.edu /bb/brainevolution/Saunders.html (2084 words)

	Amazon.ca: Ammonoid Paleobiology: Books: Landman,Neil H. Landman (Site not responding. Last check: 2007-11-04)
		The book begins with a description of the systematic position of the Ammonoidea within the Cephalopoda, providing the phylogenetic framework for the rest of the book.
		Following discussions include soft- and hard-part morphology of ammonoids, rate of growth and ontogeny, and taphonomy and ecology.
		Closing chapters explore the distribution of ammonoids in time and space as well as their extinction at the end of the Cretaceous.
	www.amazon.ca /Ammonoid-Paleobiology-Landman/dp/0306452227 (240 words)

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