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Topic: Phragmocone

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	Hydrostatics
		Since one main effect of a gas-filled phragmocone consists in a reduction of total weight, in addition to the general protective shell function, any such a weight reduction is advantageous and can facilitate burden and balance of the shell, in particular when moving on a steep slope.
		Since the phragmocone was tenaciously retained during the entire evolutionary history of nautiloids and ammonoids (Engeser 1996), the complete separation of the centres of gravity and buoyancy appears to have been a very important feature.
		The lighter a shell, the greater is the distance between the centres of gravity and buoyancy, corresponding to an increasing length of the phragmocone, respectively a shorter body chamber.
	www.ebel-k.de /Ammoniten/Hydrostatics/hydrostatics.html (4619 words)

	Phragmocone - Wikipedia, the free encyclopedia
		The phragmocone is the chambered portion of the shell of a cephalopod.
		In most nautiloids and ammonoids, the phragmocone is a long, straight, curved, or coiled structure, in which the camarae are linked by a siphuncle which determined buoyancy by means of gas exchange.
		Some nautiloids, such as the Silurian Ascocerida, drop the phragmocone upon maturity, presumably to increase speed and maneuverability.
	en.wikipedia.org /wiki/Phragmocone (161 words)

	NMBGMR Memoir 9 (Site not responding. Last check: 2007-10-16)
		This paper is devoted primarily to the description of some remarkable phragmocones which are plainly to be attributed to the genus Ecdyceras, and which result in a drastic revision of previous concepts of the morphology and taxonomic position of that genus.
		These phragmocones show a structure so completely alien to that of other known orthoconic nautiloids-indeed, to all other nautiloids-that the genus is isolated in evolution, and forms connecting it with simpler nautiloids are as yet unknown.
		The phragmocones show septa which are extremely prolonged forward at their margins, and indeed, there is developed a peripheral zone in which episeptal deposits fill completely the narrow spaces between the steeply inclined septa, except in adoral camerae where the deposits are immature or wanting altogether.
	geoinfo.nmt.edu /publications/memoirs/9/home.html (543 words)

	Freiberger Forschungshefte - Paläontologie, Stratigraphie, Fazies (Site not responding. Last check: 2007-10-16)
		The phragmocone function of ectocochleate cephalopods is discussed from a biomechanical viewpoint using true epibiotism by Placunopsis ostracina BERG on steinkerns of Ceratites DE HAAN and Germanonautilus MOJSISOVICS.
		The phragmocone of the nectonic modern Nautilus is a highly sensitive weight-regulating organ.
		This behaviour is interpreted as an indication that the phragmocone did not necessarily work as a weight-regulating device of swimmers.
	www.geologie.tu-freiberg.de /psf/contents/00071999/00000003.htm (438 words)

	Hydrostatics2
		199), the portion of the phragmocone in relation to the total length is remarkably short although frequently poor preservation, unfortunately, does not allow an exact determination of the ratio of phragmocone to total length.
		For the orientation of the shell it had only to be assured that by a far-reaching evacuation of the phragmocone a more or less upright stable position as in fig.3b or c could be attained, by the separation of the centres of gravity and buoyancy.
		Such comparisons must always critically take into account that there were enormous periods between the first occurrence of nautiloids and ammonoids, their extinction and the presence, during which life has undergone a continuous evolution and has generally increased in complexity due to new and growing require- ments.
	www.ebel-k.de /Ammoniten/Hydrostatics/Hydrostatics2/hydrostatics2.html (4615 words)

	Fossil Coleoidea - Decembrachiata (Site not responding. Last check: 2007-10-16)
		However, it is unknown when the ancestors of the Oegopsida lost their mineralisation and phragmocone.
		Considering the distinctiveness of its long and straight rostrum with a moderately large first chamber and the modified siphuncle classification at suborder level may be warranted.
		The Sepiina, containing the Sepiidae and Belosaepiidae, are characterized by strongly oblique septa, widening of the siphuncle and reduction of the ventral part of the phragmocone.
	userpage.fu-berlin.de /~palaeont/fossilcoleoidea/decembrachiata.html (480 words)

	Cephalopoda (Site not responding. Last check: 2007-10-16)
		It tends to be divided into two main parts: the phragmocone and the chambers.
		The phragmocone is the more developed part of the shell, and is divided internally into chambers by septa.
		There are two chambers: the air chambers, that contain an gaseous mixture similar to atmospheric air but richer in nitrogen, and this supply is controlled by the animal to make the shell lighter or heavier, so that the vertical movements can be carried out.
	hoopermuseum.earthsci.carleton.ca /cephalopoda/morpho2.htm (183 words)

	CARBONATE PARAGENESIS DETERMINED BY CATHODOLUMINESCENCE IN AMMONOID PHRAGMOCONES FROM THE FAYETTEVILLE AND IMO SHALES ... (Site not responding. Last check: 2007-10-16)
		Phragmocones from both horizons were filled initially by ferroan calcite with a variety of later diagenetic carbonate minerals seen as replacements, including ferroan dolomite and nonferroan calcite and dolomite.
		Brightly luminescent nonferroan calcite is seen in the early whorls and as a replacement of the conch and septa in the Imo specimens, but not those of the Fayetteville.
		The bulk of the phragmocone infilling in both horizons appears to be the result of groundwater after formation of the sideritic concretions.
	gsa.confex.com /gsa/2001RM/finalprogram/abstract_6012.htm (357 words)

	Ceph ? Non ceph - the mystery object ! - Page 2 - TONMO.com Forums
		Here's another phragmocone, this one slightly later dated to the Lower Oxfordian Age of the Jurassic (157-159m-ish) and came from somewhere in France.
		The Phragmocone of a shelled cephalopod is made up of air (or gas) chambers separated by the septa.
		Usually when the phragmocone of a belemnite gets fossilized, the chambers are filled with detritus or infilled with calcite.
	www.tonmo.com /forums/showthread.php?p=38338 (843 words)

	BBC - h2g2 - Belemnites
		At one end of the guard, (the blunt end), is the phragmocone.
		The phragmocone is occasionally preserved, but the pro-ostracum is only rarely found.
		Although the internal organs were stored in this arrangement, it was completely hidden from view in the living animal, much in the same way that a cuttlefish body covers its internal support (the white calcareous objects frequently inserted between the bars of a budgie cage).
	www.bbc.co.uk /dna/getwriting/A702596 (1037 words)

	Analysis (Site not responding. Last check: 2007-10-16)
		The centre of buoyancy is the centre of gravity of the displaced fluid in which the body is immersed.
		the water displaced is approximately equal to the volume of the phragmocone and the living chamber, since both are filled (the phragmocone with gas and cameral fluids, the living chamber with the animal).
		The centre of mass is the point at which, from a gravitational point of view, the total mass may be considered to be concentrated.
	www.nhm.ac.uk /hosted_sites/pe/1998_1/monks/analysis.htm (396 words)

	COLEOID CEPHALOPODS FROM THE LOWER CARBONIFEROUS OF NORTH AMERICA (Site not responding. Last check: 2007-10-16)
		Recognition of Paleozoic coleoids rests on the preservation of a mineralized structure called the rostrum that is deposited on the exterior of the outer shell of the phragmocone.
		Three Bear Gulch specimens preserve a clear impression of a narrow, sharply pointed rostrum that covered the apical end of the phragmocone and are therefore these specimens are considered to be coleoid cephalopods.
		Based upon rostrum shape, phragmocone shape, septal spacing, and body chamber length, the Bear Gulch specimens are unlike the coleoid taxa described from Arkansas and Utah.
	gsa.confex.com /gsa/2003AM/finalprogram/abstract_59045.htm (445 words)

	Cephalopoda
		However, belemnoids have not ten tentacles, but eight, and their nether regions, which, in squids, are supported by a flimsy pen, are protected by a complex torpedo-shaped structure similar to the shell of an ammonoid.
		This internal shell, the belemnoid structure, is not coiled, as in most ammonoids, but straight, composed of a bullet-shaped, calcite rostrum, a chambered phragmocone, and a pro-ostracum, which extends to protect the head.
		The phragmocone, which occupies the bulk of the cleaner-squid's hind portion, carries a number of chambers and is used by the animal to regulate buoyancy to sink or float.
	www.bowdoin.edu /~dbensen/Spec/Balaenatheuthia.html (945 words)

	Nautilus - Biocrawler (Site not responding. Last check: 2007-10-16)
		The shell is calcareous and internally divided into chambers; this section of the shell is known as a phragmocone.
		The chambers making up the phragmocone are called camerae (sing.
		The last fully open chamber is the living chamber.
	www.biocrawler.com /encyclopedia/Nautilus (737 words)

	BELEMNITES
		The phragmocone is the open, thin-walled air chamber at the posterior of the shell.
		The gas chamber by which the animal regulated its buoyancy is called the phragmocone.
		In finely preserved specimens, it is a conical, thin-walled opening at the posterior of the shell.
	www.paleodirect.com /be1-001.htm (599 words)

	BHI/Fossils & Minerals/Mollusks/Ammonoids
		An ammonite shell consists of two parts: the Phragmocone, composed of progressively larger chambers that filled with gas to create near neutral buoyancy; and the Body Chamber, the large, terminal section which houses and protects the body.
		The suture pattern is seen beneath the external shell wall of the phragmocone.
		This pattern is formed where the chamber walls (the septa) contact the ammonite's outside shell.
	www.bhigr.com /pages/info/info_ammo.htm (1043 words)

	ooBdoo
		Fossilized ammonoids have been found showing teeth marks from such attacks.
		The chambered part of the ammonite shell is called a phragmocone.
		The phragmocone contains a series of progressively larger chambers, called camerae (sing.
	www.oobdoo.com /wikipedia/?title=Ammonitida (2381 words)

	Introduction (Site not responding. Last check: 2007-10-16)
		Heteromorph ammonite shells are characterized by a departure from the regular planispiral shape of most other ammonites.
		One of the most common themes in heteromorph shell design is that of the planispiral phragmocone and hook-shaped living chamber.
		The simplest form is that of the aspinocone, where the living chamber consists of a shallow U-shaped hook held slightly away from the planispiral phragmocone
	palaeo-electronica.org /1998_1/monks/intro.htm (827 words)

	Ammonite Structure And Classification
		Ammonite shell structure is similar to the chambered nautilus.
		The chambered part of the shell is called the phragmocone, of which each chamber is called a camera.
		The outside of the shell is often ornamented with ridges, spines, or a pattern of lines called lirae.
	www.fossils-facts-and-finds.com /ammonite.html (416 words)

	[No title]
		This specimen measures 18 inches (46 cm) from the tip of the aperture through the umbilicus to the start of the phragmocone, by 13 inches (33 cm) across.
		It measures 4 inches (10 cm) at itís thickest and the phragmocone is uniformly compressed to an average thickness of 1/4 inch (60 mm).
		The compressed phragmocone is multi-hued with rare colors of violet and pink included.
	www.ammonite.com /appraisal2.htm (1850 words)

	Earth Stones Jewelry (Site not responding. Last check: 2007-10-16)
		Like the chambered nautilus, the ammonite's ability to swim was due to the unique construction of its shell.
		The shell contained many air filled chambers, called the phragmocone.
		The "walls" of each chamber, called septa, were penetrated by a tubelike structure called a siphuncle.
	www.estones.com /ammonitelink.html (184 words)

	[No title]
		A spine, the pro-ostracum, attached to the guard extended forward into the body of the animal.
		At the anterior end of the guard was a conical depression, the alveolus, which contained the calcareous chambered phragmocone.
		In most fossils the pro-ostracum is absent and the phragmocone is crushed or also absent.
	www.ammonite.free-online.co.uk /naut.htm (528 words)

	Belemnite showcase (Site not responding. Last check: 2007-10-16)
		Belemnites are members of an extinct group of cephalopods (flfishes).
		Inside their mantle they had a straight, chambered shell, similar to that of the nautiloids, called the phragmocone.
		Outside and behind the phragmocone, they had a strong, massive, projectile-like calcareous shell, called the rostrum.
	www.toyen.uio.no /palmus/galleri/montre/english/m_belemnitt_e.htm (150 words)

	phragmocone - Dictionnaire Français-Anglais WordReference.com
		We found no English translation for 'phragmocone' in our French to English Dictionary.
		Or did you want to translate 'phragmocone' from English to French?
		Forum discussions with the word(s) 'phragmocone' in the title:
	www.wordreference.com /fren/phragmocone (49 words)

	THE FUNCTION OF THE AMMONITE FLUTED SEPTAL MARGINS -- LEWY 76 (1): 63 -- Journal of Paleontology
		The fluted margins of ammonite septa were thought to resist
		the hydrostatic pressure upon the phragmocone while the ammonoid
		However, ammonoids probably did not dive deeper than
	jpaleontol.geoscienceworld.org /cgi/content/abstract/76/1/63 (296 words)

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