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Topic: Nektaspida


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In the News (Tue 17 Nov 09)

  
  Nectaspida - Wikipedia, the free encyclopedia
The Nectaspida (also called Nectaspia and Nektaspida) is an extinct order of soft-bodied arthropods proposed by Raymond in 1920; its taxonomic status is uncertain.
Specimens are known from the early Cambrian to the upper Silurian periods.
Whittington described it in 1985 with the spelling Nektaspida; the revised 1997 Treatise by Raymond and Fortey uses this spelling.
en.wikipedia.org /wiki/Nectaspida   (188 words)

  
 Systematics of the Trilobites and their Allies   (Site not responding. Last check: 2007-09-20)
A third group, the Nektaspida, was not identified until the 1980s; its members include soft-bodied arthropods from the Burgess Shale such as Naraoia.
(1993), the Nektaspida are the sister taxon to the polymerid and agnostid trilobites; whether the Nektaspida should be considered "true" trilobites or not is largely a matter of definition.
Many other Cambrian arthropods, especially those from the world-famous Burgess Shale, were once considered probable trilobite relatives, or "trilobitomorphs." While many of these problematic arthropods are no longer thought to be related to the true trilobites, recent studies have shown that a number of them are closer to the trilobites than to any other arthropods.
www.ucmp.berkeley.edu /arthropoda/trilobita/trilobitasy.html   (357 words)

  
 are Naraoids trilobites?
Based on the similarities to trilobites (particularly limb similarities), Whittington (1985) considered Naraoia and its relatives to be members of an order of trilobites (Nektaspida) that lacks a calcified exoskeleton (he called them "soft-bodied trilobites").
Agnostida arguably represents a secondary loss of eyes, reduction in size and segment number, and specialization of limb form and function within the trilobite clade, while the Naraoiidae never developed dorsal eyes, calcified exoskeletons, or the numerous segments of the typical trilobite, yet share the primitive limb form of most arachnomorphs, including trilobites.
A new late Silurian (Pridolian) naraoiid (Euarthropoda: Nektaspida) from the Bertie Formation of southern Ontario, Canada -- delayed fallout from the Cambrian explosion.
www.trilobites.info /naraoia.htm   (1240 words)

  
 Order Nectaspida
Nektaspids, along with helmetiids and tegopeltids, comprise a small group of early Palaeozoic euarthropods lacking calcified exoskeletons that figure prominently in discussions on the origin and composition of the Class Trilobita.
The extension of the range of the Naraoiidae, and the Nektaspida, from the Late Ordovician to the Late Silurian (some 25 million years) has both ecologic and phylogenetic implications.
(Nektaspida; Early Cambrian, Chengjiang Biota, China) and Limulus (Xiphosurida; Holocene, Atlantic Ocean).
www.peripatus.gen.nz /Taxa/Arthropoda/Trilobita/Nectaspida.html   (1487 words)

  
 Trilobites - EvoWiki   (Site not responding. Last check: 2007-09-20)
Some species, however, were apparently planktonic, with a tendency towards elongate, streamlined bodies with huge, rounded eyes, such as Opipeuterella, Carolinites, and Deiphon.
Trilobita contains ten orders, though two of which, the Agnostida and the Nektaspida, are in dispute.
You can help the EvoWiki by expanding it into a full article.
wiki.cotch.net /index.php/Trilobites   (337 words)

  
 Trilobite Classification Chart
Very recently (2002) split out of the Ptychopariida and elevated from suborder to full order.
NEKTASPIDA - The so called "soft-shelled trilobites" such as Naraoia have been classified as an order of trilobites by some.
Click on the image or link to learn more about them, and to see how they are handled in the 1997 Treatise.
www.trilobites.info /triloclass.htm   (3012 words)

  
 Planar Projection at Systems Resources   (Site not responding. Last check: 2007-09-20)
Your prints have been hung in exhibitions.(Continue Reading)
A NEW LATE SILURIAN (PRIDOLIAN) NARAOIID (EUARTHROPODA: NEKTASPIDA) FROM THE BERTIE FORMATION OF SOUTHERN ONTARIO, CANAD
ABSTRACT- The discovery of a new naraoiid nektaspid in the Upper Silurian (Pridolian) of southeastern Ontario significantly extends the range of this unusual group.
system.theblackrepublican.net /planar-projection.htm   (258 words)

  
 de Trilobiten Trilobites Trilobite fossils Scientific...   (Site not responding. Last check: 2007-09-20)
de:Trilobiten Trilobites Trilobite fossils Scientific classification Kingdom:Animalia Phylum:Arthropoda Class:"Trilobita" Orders Agnostida Redlichiida Corynexochida Lichida Nektaspida?
Phacopida Proetida Asaphida Ptychopariida The class "Trilobita" (commonly called "trilobites") is an extinct group of Arthropods appearing in the Cambrian era and flourishing throughout the lower Palaeozoic before slowly declining to extinction.
A copy of the license is included in the section entitled
www.geodatabase.de /Trilobite   (558 words)

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