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Topic: Acanthodii

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	Primative Fish & the Evolution of Jaws & Lungs (Site not responding. Last check: 2007-10-21)
		Acanthodii were not very large animals, they were maybe a halfa foot or so in length, but they are starting to look more likea real fish.
		It's probablethat there is some common ancestry between the acanthodii andthe Placodermi that is not particularly worked out.
		They were also -- when the acanthodii and the placodermsevolved jaws, then they probably take over as the major predators,and you don't have to worry about it anymore.
	www.csupomona.edu /~dfhoyt/classes/zoo138/PRIM_FISH.HTML (3632 words)

	Acanthodii: early jawed fishes (from fish) -- Encyclopædia Britannica
		Acanthodii: early jawed fishes (from fish) -- Encyclopædia Britannica
		The next class of fishes to appear was the Acanthodii, containing the earliest known jawed vertebrates, which arose in the Upper Silurian, over 400,000,000 years ago.
		More results on "Acanthodii: early jawed fishes (from fish)" when you join.
	www.britannica.com /eb/article-63649?tocId=63649 (778 words)

	Encyclopedia: Acanthodii
		They are distinguished in two respects: they were the first known jawed vertebrates, and they had stout spines supporting their fins, fixed in place and non-movable (like a shark's dorsal fin).
		Raised thorns on the stem of the wait-a-bit climber Thorns on rose stems A spine is a rigid, pointed surface protuberance or needle-like structure on an animal, shell, or plant, presumably serving as a defense against attack by predators.
		In zootomy, several terms are used to describe the location of organs and other structures in the body of bilateral animals.
	www.nationmaster.com /encyclopedia/Acanthodii (892 words)

	National Geoscience Database Of IRAN - Glossary (Site not responding. Last check: 2007-10-21)
		The abyssal plain has a slope of less than 1:1000 and is generally covered in a thick layer of sediment.
		These early fish (Class acanthodii) lived from the Ordovician to the Carboniferous period.
		Although most Acanthodians were small, averaging roughly 5-6 inches (13-15 cm) long, some were much larger (for example, the genus Xylacanthus, known from its huge jaws, is thought to have been perhaps 3 feet (1 m) long).
	www.ngdir.ir /Glossary/Glossary.asp?offset=22 (561 words)

	Acanthodii -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-21)
		Acanthodii (sometimes called spiny sharks) is a class of extinct (Any of various mostly cold-blooded aquatic vertebrates usually having scales and breathing through gills) fishes, having features of both bony fish ((A class of fish having a skeleton composed of bone in addition to cartilage) Osteichthyes) and cartilaginous fish ((Cartilaginous fishes) Chondrichthyes).
		The (An ordered reference standard) scales of Acanthodii are unique and used in determining relative age of (Rock formed from consolidated clay sediments) sedimentary rock.
		Long, J.A. The Rise of Fishes: 500 Million Years of Evolution.
	www.absoluteastronomy.com /encyclopedia/a/ac/acanthodii.htm (228 words)

	Australian Museum - Evolution of Teeth
		The placoderms are the most primitive group of jawed vertebrates, and as such, have much to tell us about the evolution of various features within the group.
		These fossils, remarkable for their 3D preservation and lack of distortion, are held in the Palaeontology collections at the Australian and Western Australian Museums (figure 1).
		For example, these placoderm 'teeth' were added to rows at certain positions along the jaw, at regulated intervals (resulting in evenly spaced teeth) and out of the main biting surface (figure 2), just like the regulated addition of teeth in sharks.
	www.austmus.gov.au /archive.cfm?id=1137 (496 words)

	[No title]
		The Acanthodii are characterized by dermal spines inserted in front of all fins but the caudal one.
		Also, the braincase of placoderms shows a separate ossification containing the nasal capsules, whereas the latter are always included in the braincase in all other gnathostomes.
		The Acanthodii have long been regarded as closely related to either chondrichthyans or placoderms, but they are now almost unanimously regarded as the sister-group of the Osteichthyes.
	ag.arizona.edu /tree/eukaryotes/animals/chordata/!Gnathostomata.nex (1178 words)

	Quiz 5
		Acanthodii have double rows of spines along ventrolateral border
		Antiarchs, another extinct group of primitive gnathostomes, had jointed spony armored pectoral appendages (but no pelvic).
		Acanthodii bear many unique structures that do not suggest they were ancestors of modern fishes
	comenius.susqu.edu /bi/302/Lecture15.htm (928 words)

	[No title] (Site not responding. Last check: 2007-10-21)
		(A) Myxiniformes (B) Petromyzontiformes (C) Ostracoderms (D) Acanthodii (E) Sarcopterygii (s04) Which of the following groups contains organisms that are jawless, have a heterocercal tail, have bony armor near the head and are extinct?
		(A) Petromyzontiformes (B) Ostracoderms (C) Placoderms (D) Holocephali (E) Acanthodii (F) Sarcopterygii (G) Elasmobranchii (s00) The chimaeras are represented in the group ______.
		(A) Osteichthes (B) Placoderms (C) Elasmobranchs (D) Acanthodii (E) none of the above (s99) Which of the following groups contains organisms that have jaws, external armor, a partially ossified internal skeleton, paired fins, a dorsally compressed body, and are extinct?
	www.clemson.edu /biosci/Ichthyologytests/Test1-04.doc (1044 words)

	Acanthodii
		<==o †Acanthodii Owen, 1846 (acanthodians; piikkieväkalat) -- †Lupopsyrus pygmaeus Bernacsek and Dineley, 1977, L. Dev.
		Diplacanthiformes Berg, 1940] `-- †Acanthodiformes [Acanthodidae sensu Carroll, 1988] Acanthodii incertae sedis: †Acanthospina irregulare Valiukevicius, 2003, L. Dev.
		Hanke, G. F., 2001: A revised interpretation of the anatomy and relationships of Lupopsyrus pygmaeus (Acanthodii, Climatiiformes?).
	www.fmnh.helsinki.fi /users/haaramo/Metazoa/Deuterostoma/Chordata/Acanthodii/Acanthodii.htm (241 words)

	OKFishes
		Like many primitive fishes, they had both an anterior and a posterior dorsal fin; in addition to the pectoral and pelvic fins, acanthodians had multiple intermediate fin spines, up to six additional pairs.
		Specimens of Acanthodii have been found in the Early Permian rocks of the Hennessey Formation in Tillman County.
		Other specimens have been found in The Boise 'd Arc Formation of Murray County (Early Devonian).
	www.freewebs.com /oklahomarocks/okfishes.htm (438 words)

	acanthodii - OneLook Dictionary Search (Site not responding. Last check: 2007-10-21)
		We found one dictionary with English definitions that includes the word acanthodii:
		Tip: Click on the first link on a line below to go directly to a page where "acanthodii" is defined.
		Acanthodii : Hutchinson Dictionary of Animals [home, info]
	www.onelook.com /?w=acanthodii (68 words)

	Systematics of major fish groups IV (Site not responding. Last check: 2007-10-21)
		Acanthodii have 3 pair, actinopterygii have 3, sarcopterygii have 2.
		Book lists neural and hemal arches, but these were present in placoderms too
		Radiation in late Paleozoic, as ostracoderms, placoderms, acanthodii diminish
	www.eeb.uconn.edu /Courses/EEB200/eeb200s99/system4.html (228 words)

	Home (Site not responding. Last check: 2007-10-21)
		Intro: Todays notes deal with Osteichthyes - the bony fish, and their close fossil relatives the "Acanthodii".
		Cladists use the name Teleostomi to refer to "All organisms more closely related to Osteichthyes than to Chondrichthyes or Placodermi." This definition points out a basic difference in the ways in which we can define monophyletic groups.
		Really, there are four when we consider Acanthodii or "spiny sharks." The acanthodians lived from the Silurian to the end of the Permian.
	www.geol.umd.edu /~jmerck/honr219d/notes/l12.html (1935 words)

	PhyloCode Discussion - Message 2001-06-0010: Re: Nomina Conversa
		> > > > According to the Dinosauricon :-], it includes Acanthodii and Osteichthyes > > as sister taxa...
		Gnathostomata is an unresolved tetrachotomy [is this correct from Greek?]; Placodermi have been thought to be the sister group of Chondrichthyes or (Acanthodii + Osteichthyes) or Osteichthyes alone or as basalmost gnathostomes, Acanthodii is usually considered the sister group of Osteichthyes...
		Deep gnathostome phylogeny needs to be reviewed in the light of these findings." Fig.
	phylocode.miketaylor.org.uk /archive/messages/2001-06-0010.html (980 words)

	List all Literature
		Keywords: paleontology, fossils, Heterostraci, Thelodonti, Osteostraci, Acanthodii, Teleostei, early vertebrat
		GREEN, T. and G. Late Eocene otolith-based fishes from the Moodys Branch Formation in Louisiana and Mississippi and their paleoecological implications.
		Hanke, G. F., Davis, S. P., and Wilson, M. Description of a new Tetanopsyrus species and phylogenetic analysis of select Early Devonian Acanthodii.
	www.deepfin.org /listLiterature.php (13455 words)

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